TRIUMF: Canada's national laboratory for particle and nuclear physics

Annual report, 1977 TRIUMF Nov 30, 1978

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T R I U M FANNUAL REPORT 1977MESON F A C I L I T Y  OF:U N I V E R S I T Y  OF ALBERTA  SIMON FRASER U N IV ER S I T Y  U N IV ER S I T Y  OF V I C T O R IA  UN I V E R S I T Y  OF B R I T I S H  COLUMBIAA-.- ';TRIUMFANNUAL REPORT 1977TRIUMFUNIVERSITY OF BRITISH COLUMBIA VANCOUVER, B.C.CANADA V6T 1W5BL4A(p) B L 4 A (SERVICEBRIDGECYCLOTRONVAULTPROTONHALLBLAB(p)SERVICE ANNEXBL1(p)MRS SPECTROMETEREXISTINGPROPOSEDLOW ENERGY BEAM4p )SE(BLlb(p) MESON HALLCHEMISTRY ANNEXTHERMALNEUTRONFACILITYFOREWORDSeveral very satis factory landmarks stand out in the map o f  TRIUMF achievements recorded in this annual report for 1977.The facility first attained full design intensity (100 ydj in an ex­ternal target in the middle of the year. This accelerator achieve­ment when combined with the later addition of appropriate shielding promises soon to provide the experimental capabilities for which TRIUMF was proposed, funded and designed. The director, Dr. d.T.^ Sample, and his very excellent group of machine engineers and physicists under the able leadership o f  Dr. Karl Erdman, are to be congratulated on this accomplishment.The experimental programme at TRIUMF constitutes the major part of this report. Some experiments are only^ beginning, either because they await full intensity or because the ideas for them have only just emerged, possibly out of initial work in other experiments at TRIUMF. Other experiments are fully under way. Still others have a.chieved their first major objective. Among the latter, the very rich body o f  data at TRIUMF on the fundamental interactions between neutrons and protons and between protons and protons in the whole range of in­termediate energy at TRIUMF constitutes a major forward step in our knowledge o f  these interactions. As a result of this forward step a major international conference on the nucleon-nucleon interaction was convened at TRIUMF in mid-1977 in large measure to provide the world with a first assessment o f  this new body o f  data.The TRIUMF Board of Management viewed the development of the project in 1977 with a great deal o f  satisfaction.E. W. VogtChairman o f  the Board of ManagementTRIUMF was established in 1968 as a laboratory operated and to be used jointly by the University of A1berta, Simon Fraser Uni­versity, the University of Victoria and the University of British Columbia. The facility is also open to other Canadian as well as foreign users.The experimental program is based on a cyclotron capable of ac­celerating two s i mu 1 taneous beams of protons, individually vari­able in energy, from 180-520 MeV. The potential for high beam currents— 100 yA at 500 MeV to 300 pA at 400 MeV— qualified this machine as a 'meson factory'.Fields of research include basic science, such as medium-energy nuclear physics and chemistry,aswellasapplied research, such as isotope research and production and nuclear fuel research. There is also a biomedical research faci1ity which wi 1 1 use mesons in cancer research and treatment.The ground for the main facility, located on the UBC campus, was broken in 1970. Assemb1y of the cyclotron started in 1971. The machine produced its first ful1-energy beam in 1974 and its full current in 1977.The laboratory employs approximately 190 staffat the main site in Vancouver and 12 based at the four universities. The number of university scientists and support staff associated with the present scientific program is about 170.CONTENTSPageINTRODUCTION 1OPERATION AND DEVELOPMENT OF FACILITIES 3Cyclotron 3Beam Line Development 7RESEARCH PROGRAM 9Introduction 9Beam Research and Development 11Part i c 1e Phys i cs 17BASQUE 17Precision measurement of p-p analyzing power at medium energies 21Gamma-ray studies 22Pion production 27Backward angle pion production from the D(p,ir+ )t reaction 29p-p Bremsstrah1ung at 200 MeV 30Nuclear Physics and Chemistry 31Pi scattering and total cross-section measurements 31Tr"-3He: Strong interaction shift 33Measurement of pionic X-ray energies, widths and shifts 3^Elastic scattering of protons from 9He 35Nucleon quasi-e1 astic scattering in nuclei 38Polarized (p,2p) reaction 39The (p,2p) reaction on 9He and 3He 1^The characteristics of fragments emitted from silver with200-500 MeV protons ^2Intermediate-energy fission 44Nuclear spectroscopic studies of short-lived radiactive productsof high-energy reactions 46y- capture in fissile nuclides 47Meson cascades in elemental targets 47Magnetic hyperfine splitting in polarized 209Bi atoms 48Research in Chemistry and Solid-State Physics 49Muon spin rotation in solids 49Muoniurn chemistry 52Applied Research 56Biomedical experimental program 56Proton radiography 58Isotope production 59Ferti1e-to-fissi1e conversion (FERFICON) 61Theoretical Program 62STATUS OF EXISTING FACILITIES 69Ion Source and Injection System 69Safety 71Remote Hand ling 72RF System 73Vacuum System 75M9 Channel 75Control System 76Instrumentation 78v i iPROGRESS TOWARDS ULTIMATE PERFORMANCE 80100 yA Task Force 80Separated Turns Task Force 81FACILITIES UNDER DESIGN AND CONSTRUCTION 82Ml 1 Channel 82Medium Resolution Spectrometer 82Beam Line IB 83Thermal Neutron Facility 83Targets 86Shielding and Activation 87Data Interface Task Force 87ORGANIZATION 89APPENDICESA. Publi cat ions 91B. Staff 3bC. Users Group 95D. Experiment Proposals 97v i i iINTRODUCTION1977 saw continued development of the ex­perimental program with more than four times the microampere hours of 1976 pro­vided for experiments. Nevertheless, development of the cyclotron and beam lines continued, with the following h i gh1i ghts:1) In July a beam current of 114 yA was delivered to the T2 target of beam line 1 for approximately 45 min.2) Several shifts were provided at cur­rents of approximately 30 yA.3) Experience enabled an increase in current from the polarized ion source to 90 nA at 78% polarization.4) Machine availability was increased to 82%.5) The medium resolution proton spectrom­eter was commissioned for use at a fixed angle of 22.5° and measurements were begun for several experiments.Integrated beam current was restricted to keep radiation exposure of employees well below current guidelines. This proved to be the controlling factor in decisions concerning maximum beam current. Remote handling capabilities were developed dur­ing the year with a corresponding relaxa­tion in integrated current, and the Safety group responded to the demands of increased beam by developing procedures for both routine and emergency situations.The experimental program expanded dramat­ically with the initiation, and in some cases completion, of experiments by manygroups in fields ranging from particle physics through nuclear physics and solid- state physics to biophysics, illustrating the richness of the new field of inter­med i ate-energy physics. Twenty-two papers were presented by TRIUMF scientists at the Vllth International Conference on High Energy Physics and Nuclear Structure at Zurich.The applied science program at TRIUMF was strengthened in 1977“78 because of in­creased beam current. The biomedical pro­gram— aimed at clinical experiments in cancer therapy— produced measurements of cell survival from negative pion exposure, and pharmaceutical grade 123l was produced for use in animals and a few selected human patients. An extensive program of measure­ments on conversion of common heavy iso­topes to nuclear fuel was initiated under contract with Atomic Energy of Canada, LtdThe importance of the TRIUMF Experiments Evaluation Committee increased during the year because 'second generation experi­ments' were presented by groups previously concerned with more direct measurements, possible in many cases by use of equipment adapted from low-energy nuclear physics laboratories in Canada. The new generation of experiments demands new instrumentation approaching in cost and sophistication the level of high-energy physics. TRIUMF scientists and management wish to thank R.E. Azuma, J.M. Cameron, B. Margolis,D.F. Measday, B.D. Pate, H. Primakoff andD. Wilkinson for their valuable service during their term on EEC. We welcome A. Astbury, A.E. Litherland, A.W. Thomas, J-M Poutissou and L. Yaffe as new members of the committee.When the National Research Council assumed the responsibility for financial support of TRIUMF operations, the legal descrip­tion of the funds changed from 'grant' to 'contribution1, implying much closer accountability. Accordingly, the National Research Council established the Advisory Board on TRIUMF to monitor TRIUMF needs and expenditures. At the same time fund­ing for the TRIUMF facility and for experimental groups increased in marked contrast to the Federal budget in general.Fund i ngOperat i ng Cap i ta1Research grants1976/77$ k ,650,000 2 , 130 ,000  983 ,8 001977/78$5 ,3 6 0 , 0 0 0  1,702,000 1 ,1 1 3 , 6 0 0The establishment of a new granting agency to replace the NRC Office of Grants and Scholarships was announced; the effect of the creation of the Natural Sciences and Engineering Research Council cannot be assessed at this time.J.T. Sample Di rector2OPERATION AND DEVELOPMENT OF FACILITIESCYCLOTRON1977 saw a further increase in the ope­rating current levels at TRIUMF, both with the unpolarized and polarized beams, a successful demonstration of the 100 yA design capability of the cyclotron, and a major shutdown in the meson hall for the installation of the 100 yA beam dump, the thermal neutron facility (TNF).The total microampere-hours of beam in­creased by about a factor of four over 1976, with the current levels still being intentionally kept down to reduce cyclo­tron activation while the remote handling capability of the major cyclotron compon­ents is being implemented. Figure 1 shows the total number of microampere- hours of beam delivered per month in the years 1976 and 1977- Typical operating current levels for meson production were 5~10 yA, with a number of shifts at 30- 50 yA to provide the necessary meson flux for the biomedical program. On July 29 TRIUMF achieved another milestone when a beam of 114 yA at 500 MeV was delivered to the T2 target position. Currents in excess of 100 yA were delivered for a total of about 45 min.During the year the output of the polar­ized source was improved substantially, and during a run in December typical cur-Fig. 1. Cyclotron beam current.rents of 600 nA source output and 90 nA on the experimenters' target were ach i eved.There were three major shutdowns for cyc­lotron and experimenta1 facility upgrading during the year: a seven-week shutdown in the spring primarily for resonator work in the cyclotron, a two-week shutdown in July to improve the RF system diagnostics and a seven-week cyclotron shutdown in the fall for the meson hall work. The fall shutdown was the first experience in coping with reasonably high radiation levels both in the cyclotron and on a number of components along the beam lines. In the three months prior to the shutdown over 6000 yA-h of beam was accelerated. The residual activity in the cyclotron was about as expected from extrapolation of lower operating current levels, with typical levels of 10 mrem at the tank centre and 50 mrem at the tank edge. The installation of the 60 3-in.-thick lead shields around the tank periphery, an operation which is now fully remote, re­duces the radiation levels by a factor between three and five. During the six weeks of cyclotron tank work the total dose to personnel was 7-9 man-rem with a 54 mrem average dose and 10 personnel re­ceiving the TR I UMF-i mposed shutdown limit of 300 mrem.The details of the work accomplished during these shutdowns can be found in other sections of this report.Operation and performanceThe cyclotron operation has not changed substantially from 1976. The 24 h/day,7 day/week operation is handled by five crews of operators, three men per crew— a shift supervisor, safety officer and operator. The operations staff are gradu­ally being given more of the responsibil­ity for the day-to-day operation of the various systems in the cyclotron and beam line areas. The groups responsible for these systems are then able to concen­trate their efforts on maintenance and3long-term improvement programs. Also the operators are now trained to handle most cyclotron and beam line tuning situations without assistance from the beam physi­cists. The beam physicists are called on for special beam tunes, e.g. new energies, dispersed focus at the experimenters' target, or higher current operation.During the year considerable effort and beam time was spent in reaching the goal of 100 pA operation. This effort re­sulted in improvements in ion source stability, a better understanding of the injection line optics, more experience in high current operation in the cyclotron and beam lines, improvements in non­intercepting beam diagnostics and variable duty cycle pulsing and the implementation of more machine protect interlocks. From the cyclotron performance point of view this effort has resulted in improved reliability of beam operat ion at the 10 pAlevel to the point where it is as straightforward as 1 pA operation in 1976-The performance of the cyclotron is sum­marized in Table I and Fig. 2. The machine availability for the year was 82.7%, an improvement of 5% over the corresponding figure for 1976.Downtime and cyclotron improvementsOne of the significant improvements in the cyclotron operation has come about by having a better understanding of the RF behaviour in the cyclotron resonator sys­tem. This has resulted fromthe installa­tion of further diagnostics, thermocouples and pick-up loops on the resonator strongbacks and remote adjustment of the resonator alignment by means of ground- arm tuning. During 1976 one of the RF problems was overheating of the centre region quadrants. This was cured byTable I. Summary of Machine Performance 1977hoursScheduled operating time 4779Injected beam Unpolarized 1988Polarized 1230Cyclotron Tune-up and development 673pA hours 8773Beam line 1 Tune-up and development 147Experiment 2165Beam 1ine 4 Tune-up and development 348Experiment 2460Downtime - System failures 828RF system 268ISIS and P0LISIS 247Vacuum 40Magnet 18D iagnost i cs 62Beam 1i nes 110Controls 20Safety system 14Servi ces 49Machine availability (average) 82.7%4Fig. 2. Beam operation in 1977.replacing the aluminum quadrants with copper ones and by monitoring the quad­rant temperatures. When the thermo­couples on the resonator strongbacks were installed it was found that the strong- back temperatures could rise above 200°C. This heating is due to RF leakage into the beam gap caused mainly by misalign­ments of the resonator system, in partic­ular in the region of resonator #8 (radius 2k0 in.) where the beam gap im­pedance is low. Using ground-arm tuning and the temperature information from the thermocouples, the resonators can be adjusted to minimize the leakage and heating. More details of these effects are contained in the RF report. The only serious heating problem in the resonator system occurred during start-up after the summer shutdown. This time several resonator tips at a radius of about 100 in. were found melted. About one-half of the downtime attributed to RF system occurred during this failure.This problem was hopefully eliminated during the fall shutdown with the addi­tion of water cooling to the dee gap probe housings.The ISIS and POLISIS systems were another major source of downtime due to failures although there was an improvement of about 50% over the previous year. A good part of the downtime is source filament failures, both in the unpolarized and polarized sources, during operating periods. The higher current operation from both sources has decreased the fila­ment lifetime to the point where failure can occur between maintenance periods. Improvements have been made to speed up source changes.During the three cyclotron shutdown peri­ods many improvements were made to the cyclotron systems towards improved reli­ability and high current operation. Details of this work can be found in the various group reports. Some of the sig­nificant improvements are summarized below:Remote hand ling- The remote radiation survey of the cyclotron tank was commissioned.- The equipment for the remote installa­tion and removal of the lead peripheral shields was commissioned.- The service bridge trolley for the in­stallation and removal of lower reso­nators was essentially commissioned.RF- The electrical contacts between reso­nator sections were improved and made remotely handleable.- The lead vibration dampers were replaced with copper ones.- Remote ground-arm tip adjustment was installed on eight resonators.- Water cooling was added to the dee gap probe housings.- The levelling arm adjusters were made compatible with remote handling.Probes- Two new centring probes operating in the radial range from 17 in. to 80 in. were i nsta11e d .- A non-intercepting capacitive probe was insta11ed.- The beam scrapers and stops near the cyclotron median plane were improved.- More monitors to detect the spilled beam from the scraper foils were in- sta11e d .ISIS- The control and interlocks for the vacuum, beam line components and cur­rent protect systems were upgraded.- Several water-cooled collimators were installed in the beam line to protect components and wiring from beam damage.- The beam monitor readout system was i mproved.Beam time to experimentsTable II shows the number of 12 h beam shifts scheduled to experiments during1977.5Table II. Beam Time to Experiments 1977Area/ Beam Line Exper i ment Short Title SpokesmanNumber of 12-hour sh i fts schedu1ed(P) polarized beamBEAM LINE 1M8 61 Biomedical L.D. Skarsgard 1061 ,54 SE scattering R.R. Johnson 3153 Heavy fragments D. Gill 14M9 M9 development - - 657 u -> ey P. Depommier J-M Pout i ssou6052 IT -r ev D.A. Bryman 22 & 24 (parasi tic wi th 57)13,51,80,89 Pionic X-rays R.M. Pearce G.A. Beer S . Ka p 1 a n2742a TT3He G.R. Mason 641 b EEREE0 charge exchange M.D. Hasinoff M. Salomon6(parasi tic with 42a)60 Muonium in insulators J.B. Warren 946,71,73 Muon studies G.T. Ewan J. Brewer18M20 35,71,78 ySR J. Brewer 151Beam 1i ne 1 10 pp -*■ ird G. Jones 64 (P)75 pd TT t W.C. 01 sen 18 (P)BEAM LINE 4A26,27,40 np scattering D.A. Axen D.V. Bugg80 (P) 113,6,11 Fragments F i ss ion Gas jetR. G. Korte1i ng B.D. Pate J.M. D'Auria4515 Quasi-free scattering W.J. McDonald 1348 FERFICON 1 .M . Thorson 2387 Proton radiography E.W. Blackmore 11BEAM LINE 4B24 (P)14 Proton elastic scatter i ngJ.M. Cameron W.T.H. van Oers24 Polarization pumping G. Roy 18 (P)58 Polarized (p,2p) P. Ki tch i ng 9 (P)59 (p,2p) on **He W.T.H. van Oers 1466 pp bremsstrahlung J.G. Rogers 5 (P) 30MRScommi ss ion i ng - J.G. Rogers 156BEAM LINE DEVELOPMENTThe beam line work this year has been dominated by activities required to per­mit high-current operation. By the end of the year beam line 1A, which had ope­rated with more than 100 yA during tests, had been rebuilt and extended from the vault wall to the thermal neutron facility (TNF) and was ready to receive high currents regularly; beam line 4A had operated with 2 yA and had shown that it could accept 10 yA.The beam line layout is reproduced in the frontispiece. The beam line 1A copper temporary dump, which had accepted 100 yA, was removed from the T2 shield and the beam line extended to the TNF at the east end of the meson hall. The line between the vault wall and T2 was completely re­built, the iron shield vessels for a 'thin' (about b g/cm2) meson production target T1 and associated collimator were installed, and the opportunity was taken to install the first dipole 1BV2 of beam line IB. This line is intended for low- current operation in partnership with the proton hall and should be completed in 1978. In addit ion it was necessary to re-configure the controls and safety sys­tem, and to double the shielding thick­ness to 12 ft (16 ft downstream of the targets). The beam line extension starts with two collimators immediately after the T2 target; these are intended to intercept typically 11% of the T2 scattered beam that would otherwise strike the beam pipe. These are followed by a radiation-hard quadrupole triplet, two retractable pro­file monitors, a helium-cooled window andthe TNF itself. Three massive iron scrapers are used to intercept halo (1.3% of the T2 beam) from the collimators. The beam optics is designed to provide a large spot size at the TNF and windows, to keep the power density low, while pre­serving a small spot at T2. A focus-to- focus condition is used since the TNF spot w i 11 then not depend on the presence or absence of a target at T2. The quadru- poles are placed close to T2 to collect as much beam as possible. A computer pro­gram, written to assist in the collimator design, confirmed that a conical entrance and exit aperture are desirable to reduce spills. Even with the collimators shown in Fig. 3, 0.2% of the beam on T2 can hit the quadrupoles.All components around, or downstream of,T2 are radiation hard or easily replaced remotely. Major items have been removed and resinstalled by the Remote Handling group and the operation video-taped for future reference.The opportunity was taken to install the first dipole IVBV2 of beam line IB; this line is intended for low-current opera­tion in partnership with the proton hall, and should be completed in 1978.A turbomolecular pump has been installed near ABV2 and the vacuum in beam line 1A and secondary channels upgraded to 10-5 Torr to permit windowless operation from stripper foil to the window in front of the TNF. The roughing and exhaust system is now common for the beam line andFig. 3. Extension of beam line 1A. Collimator A can be removed and different inserts installed. The monitors 1AM10 and 11 may have multiple heads to measure beam profile, intensity or position and halo. Quadrupoles 14, 15 and 16 are radiation hard and all compon­ents can'be reinstalled remotely.EXTREMERAYSSCRAPER SCRAPERTARGET SCRAPER(TYP 10cm long I cm high)SCALEPROFILE MONITOR IAMIO (RETRACTED)COLLIMATORI AM 11 MONITOR (RETRACTED)7secondary channels and can be extended to include new channels.The beam line 4A dump area is becoming one of the most radioactive accessible locations on site as more high-current radiochemistry experiments are being per­formed. The radiation handling in this area has been improved but remote handling improvements still need to be done. A carbon beam stop was installed in the 4A dump; the beam stop is separated from the beam line vacuum by an edge-cooled copper- plated stainless steel window, and the activation products are pumped separately. The short-lived activity produced in car­bon allows entry after the beam is turned off without the necessity of an insertable dump shield. The temperature and pressure rise at a current of 2 yA showed that the new dump could adequately accept the de­sign aim current of 10 yA. The dump con­tains a Cs cell for the manufacture of 123I. Beam line ^A has a windowless vacuum system up to the isotope facility near the dump; however, window valves are inserted whenever the liquid deuterium target is used. The scattering from this target limits currents to 0.2 yA, ade­quate for polarized beam; however, a col­limator design study is under way to allow neutron experiments at currents of 1 yA.Additional diagnostic devices installed this year include a multiple plate sec­ondary emission monitor in front of the beam line 4A irradiation facility. The background current is equivalent to about 1 nA beam, and it is possible to obtain a more accurate measure of integrated beam during a bombardment than is obtainable from the stripping foil. A carbon wire secondary emission profile monitor has been wound on an aluminum oxide frame, similar to a Los Alamos design, and in­stalled in front of T2 where the beam spot is k x 10 mm, and has operated success­fully at currents in excess of 100 yA. Secondary emission halo and halo protect monitors have been used to give warning of rnis-steered beams before losses were registered on the safety spill monitors.The capacitive pick-up monitor in beam line 1A is operated in a manner to give a heavily damped oscillation; the crossover of this gives a beam-related timing pulsefanned out to experimenters. The signal is used in the control room to identify the 10 ysec 'hole' in the beam when ope­rating in the 33% duty cycle mode. The time of flight from the ISIS pulser to the beam line capacitive probe gives use­ful information on cyclotron isochronism and RF voltage fluctuations. A toroid, made of Permalloy tape, has been tested with beam and gave a voltage pulse of 23 mV/l yA(dc) after amplification; the noise level was 10 mV and the rise time 0.6 nsec.The magnet design code G-FUN has been brought into operation, and design studies have been started on a high flux muon channel and a low-energy SE channel H 13. Calculations are continuing on the high-energy meson channel Mil to obtain a high-density spot at the meson focus. It has been decided to develop a methane target, not water, for the T1 location to provide the optimum ratio of meson pro­duction to beam spill.A study o f axi-symmetric high acceptancepion and muon channelsThe (3-ray spectrometer design of Slatis and Siegbahn [Ach. F. Fysik J_, 399 (19**9)1 has been adapted to provide a high flux pion channel [Abazov e t a l . , JINR report P13-8079 (197*0]- A systematic investi­gation of the properties of such channels has been undertaken; preliminary results have been reported [TRIUMF internal reports VPN-76-2 and VPN-77-2] .For a wide range of coil shapes and radii channels can be designed to have a peak solid angle of acceptance of ~1 sr, an integrated solid angle of acceptance ~5 (MeV/c)sr for momenta near 100 MeV/c and a final beam spot size of the order of the source spot size.For a muon channel three coaxial source coils could be used to produce two Larmor periods of muon orbits. At the first axis crossover a degrader would be located to separate the pion and muon momenta so that all pions would subsequently be rej ected.These general investigations are continu­ing with the goal of choosing parameters for a practical system.8RESEARCH PROGRAMINTRODUCTIONThe TRIUMF research program expanded in many fruitful directions in 1977- With the large increase in available microamp­ere hours of beam came a large increase in meson flux which in turn allowed the experimenters to proceed with a number of exciting research programs. The program which aroused the greatest ferment in theoretical particle physics was that on the rare decay modes of the muon, partic­ularly the y -* ey decay which had earlier been forbidden beyond the possibility of experimental observation. The TRIUMF measurements in 1977 indicated an upper limit of 1.9 x 10~9 fractional decay of the muon in this mode. Construction is proceeding on an experimental detection system which is designed to push this limit down two orders of magnitude below this value. It is to be noted that several theoretical papers have appeared predicting fractional decays in the 10-8 to 10-10 range.Another important result obtained in the TRIUMF research program is particularly fascinating because it is presently unex­plained and one really can't be sure whether the answer lies in particle phys­ics or in nuclear physics. Continuing their definitive program in pion produc­tion by polarized protons, the experi­menters have turned their attention from the fundamental reaction pp -*■ d7r+ or pmr+ to the more complex situation of pA -> V SEI These represent the first measurements of the analyzing power of pion production ending in specific nuclear final states, and the results were very surprising.The angular distributions of the analyz­ing power for several low-lying states in beryllium and carbon turned out to be very similar, indicating that some basic, simple mechanism is invoked. The magni­tude of the analyzing power, however, reached a negative peak of unity— much larger numerically than the value of -0.5 from the fundamental reaction. Predic­tions of the pionic stripping models are quite incompatible with these results.The fundamental work at TRIUMF on nucleon- nucleon scattering was continued in 1977with several important contributions.One was a precision p-p double scattering experiment to normalize the absolute values of the p-p polarization to ±1.5%. The results obtained in this experiment were consistent with another double scattering experiment involving liquid helium (Experiment 2 k ) . The previous data of the nuc1eon-nuc1 eon group on the p-p Wolfenstein parameters were then used to set good values of the ir°n coupling constant (14.25) and the relevant phase shifts. Analysis of the n-p data on the Wolfenstein parameters allowed a decision to be made on a long-standing theoretical ambiguity in the n-p phase shifts at 325 MeV.In the interaction of pions with nuclei informative contributions continue to come from pion elastic and total scatter­ing experiments at low energy. It appears, for example, that the possibil­ity of complete disappearance of the pion in the nucleus has an important effect on the elastic scattering cross-section and that the Coulomb amplitude plays an important role well past 90°. The strong interaction shift in the pionic 3He X-ray spectrum has also been measured both in magnitude and width.In more traditional nuclear physics several long-term programs bore fruit in 1977- Backward angle studies were made both of elastic scattering of protons by 9He and of the p^He -*■ 3Hed reaction.Strong backward peaking in the latter re­action suggests that deuteron exchange is an important mechanism here. Investiga­tion of the reaction pd dp using the polarized beam resulted in unexpectedly large asymmetries at backward angles. Comparison of the quasi-elastic scattering of nucleons in the react ions (p,pn) and (p,2p) has also yielded some unexpected results at TRIUMF energies. For example, the cross-sections observed for 12C(p,pn) are larger than those expected from the 12C(p,2p) cross-sections when combined with the known difference in the pn and pp cross-sections. The difference is (35±9)%.9In nuclear chemistry, the various mecha­nisms responsible for the emission of fragments from heavy nuclei bombarded by protons are being studied, as is inter­mediate energy fission and also the radiations emitted by the exotic short­lived nuclei formed in intermediate- energy reactions.The ySR group at TRIUMF has been very active in chemistry and solid-state phys­ics. The close association with the group from the University of Tokyo has con­tinued very successfully. The research reported last year on the relaxation of positive muons in ultra-pure Fe crystals was developed further with a borrowed single crystal of even greater purity.The result was an even slower relaxation of the y+, which again levelled off at low temperature, in support of a general model of quantum diffusion of y+ in metals. The combined groups have also applied the y+SR technique to various magnetic alloys, such as NjCr and PdMn and to semi-conductors (Si) and insulators (Si02). In research in chemistry the TRIUMF group has obtained further data on the activation energy for muoniurn in the halides, in the gas phase. Work inliquid phase chemistry has benefited from the use of a new, very thin target cell, and results have been obtained for an extensive list of liquids.In the area of beam research and develop­ment the most important milestone was the achieving of a proton beam of over 100 yA at an energy of 500 MeV transmitted down beam line 1. This achievement was the result of much careful development in the ion source and injection line, in improv­ing the transmission in the cyclotron and in reducing the losses in beam line 1. More effective techniques were also developed for the measurement of the variation of beam intensity with radius in the cyclo­tron and in the measurement of the phase (with respect to the RF) with which the H" ions cross the resonator gap. The lat­ter technique makes use of the H~beam which is accelerated to the magnetic edge of the cyclotron and is then decelerated— even­tually to the centre. In investigations with the polarized beam some losses in polarization (3_7%) were observed at some radii, but the cause of this loss of polar­ization is not yet known. In any case it is not important because polarization moni tors are used in the nuclear experiments.10BEAM RESEARCH AND DEVELOPMENTThe major 'beam development1 this year was, of course, the achievement of a 100 yA beam to the T2 target in July. However, since the necessary beam dynam­ics tuning of the injection line, cyclo­tron and beam lines was complete at the beginning of the year, the reader will be spared further reference to it in this section.Apart from 100 yA there have been no major improvements in performance to report this year. However, there have been a number of developments which should make possible significant improve­ments in the future. Chief among these have been the successful commissioning of the centring probes and low-energy beam selection slits; with these we may reasonably hope to improve the beam quality and energy resolution signifi­cantly. A new probe head has made possible much cleaner measurements of beam transmission between 60 and 520 MeV; the amount of electric stripping it has revealed emphasizes the advisability of reducing the beam energy for pion pro­duction to 450 MeV. TRIUMF's excellent capabilities as a decelerator have been used in earnest for the first time, firstly to make phase measurements more accurately, and secondly to detect small losses in polarization. Tunes have been improved for existing beam lines and found for new lines. The feasibility ofextracting beams in the 65-180 MeV range has been confirmed. And finally we have dared to dream of the future, and have looked at possible second-stage accelera­tors which would convert TRIUMF into a kaon or anti-proton factory.Central regionHere the successful operation of the two centring probes has revolutionized the experimental situation, which had been essentially static since early 1975. At that time exploratory runs were made with the 'low-energy' differential probes, but were discontinued on discovery of damage to the probes by RF leaking into the beam gap. The two centring probes consist of 5 mm wide fingers which can be moved along the east or west dee gaps.No attempt is made to pick up signals directly from these probes, but as they move the turn pattern of the beam is re­vealed in the shadows they cast on fixed current-measuring probes at larger radi­us. The first successful run with both centring probes was made in November.Turns were identifiable without difficulty out to the maximum probe radius of 78 in. The turn separation indicated Vj cos <j> =75 ± 1 kV (after allowance for dee gap transit time effects), in line with other estimates of the dee voltage Vj near the centre at that time. The coherent centring error proved to be small (Ar < 0.1 in.) inside 40 in. radius (see Fig. A), but from 40 in. to 78 in. grew to an undesirably large 0.3 in. (At 162 in.0.4-§ °-2wu5 0.0CDSWFig. 4. Centring error u along the dee gap, as -0 . 2determined from centring probe runs.— 1—20 0 00 0 • 40 60 1-------- 1---80RADIUS (in.)1 1shadow measurements with the HE probes showed that A r or 0.3 in.) This suggests that the injection conditions are fairly well optimized for centring along the dee gap but that first harmonic magnetic field errors may need to be tuned out at larger radii. Systematic studies of the effects of the inflector, deflector and harmonic coils for selected RF phases next year should make it possible to meet the centring tolerances out to 78 in. First harmonic field errors are expected to cause significant centring errors out to 150 in.; to correct these it will be necessary to either shift or extend the centring probes to larger radius.Slits and beam qualityThis year also saw the first operation of the four pairs of beam selection slits mounted in the 2 to 4 MeV and 15 to 35 MeV regions. The inmost slits set with a 1 mm gap were found to select a phase interval of 17° FWHM. With three pairs of slits set around the beam, scan­ning with the fourth pair revealed distinctly separated turns out to the maximum slit radius. The incoherent radial amplitude was three times smaller than that measured previously with no slits. in December it was found possible to reduce the energy resolution seen at the MRS from 1.5 to 1.2 MeV by using the slits in conjunction with harmonic coils to control the coherent radial amplitude. To reduce the energy spread further will require firstly, tuning out first harmon­ic field errors out to 150 in., and secondly, stabilizing the dee voltage, which shows excessive fluctuations at about 4 Hz due to mechanical vibration of the resonators. With the slits in, the latter effect also gives rise to large 4 Hz fluctuations in the intensity of the accelerated beam. Progress in stabiliz­ing the dee voltage is reported onp. 81 .Transmission and 450 MeV extractionReplacement of one of the vertically staggered five-finger HE probe heads by one consisting of two radially staggered plates has led to a reappraisal of the beam transmission through the cyclotron. The new head, which col 1ectsthe stripped electrons more efficiently, indicatesthat at least 8% of the unbunched dc beam from ISIS, and at least 33% of the bunched beam, is accelerated to 500 MeV. Previous measurements were also confused by the differing collection efficiencies of the different fingers; these gave rise to apparent variations in current with radius— in reality due to changes in the vertical position of the beam. With the new head these variations are absent; with noise below the 2% level the most prominent feature of the trans­mission curve is the drop-off due to electric stripping starting at 290 in. (400 MeV). This loss amounts to 12% by 500 MeV and 25% by 518 MeV, nearly twice as large as originally anticipated, due to the low dee voltage (~60 kV) at these rad i i at present.The two radially staggered plates of the new probe head also provide information on the radial variation of current density in the cyclotron. In fact an individual turn pattern has been revealed out to 160 in.In order to avoid the irradiation of the cyclotron by electric stripping losses while work is still required in the vacuum tank, and yet permit higher cur­rents to be run, it has been proposed that the high intensity proton beam (beam line 1) for pion production be ex­tracted at a lower energy than the presently standard 500 MeV, at least on a temporary basis. This is advantageous because the pion production cross- section varies approximately linearly with energy while the electric stripping varies exponentially. Figure 5 shows how the beam loss in the cyclotron varies with energy if the current is ad­justed to keep the pion production constant. Because of other beam loss mechanisms, such as gas stripping, it is not necessary to lower the energy to 400 MeV to reduce the electric stripping losses effectively to zero. For 10% losses due to other effects (close to the present situation) the optimum energy would be 456 MeV; the ion source current would have to be increased by 28% to maintain the pion flux, but nevertheless the beam loss in the cyclo­tron would be reduced by 26%. Reduc­tion of the gas stripping losses through improvements to the vacuum would make it12Fig. 5. Beam loss in the cyclotron versus energy, with the beam current adjusted to maintain a constant flux of 200 UeV/c EEG  in M8.possible to reduce the electric stripping losses even further. As a first step towards lower energy operation of beam line 1, the line has been tuned up at A50 MeV, with spills a factor two lower than at 500 MeV.Phase measurements using decelerating beamTwo methods have been used to measure the RF phase angle 4> as the beam crosses the dee gap. One method utilizing trim coils ganged in pairs and triplets was des­cribed in last year's report. A more precise method involves timing external beam bunches relative to the RF wave, us­ing a scintillation counter telescope to detect protons scattered from the AVM2 beam monitors. Although this involves changing the stripper position and beam line settings, a complete scan from 180 to 520 MeV in 10 MeV steps can be com­pleted in about an hour. The timing is accurate to about 2°F; however, until re­cently, the technique has only been capable of giving relative results, and has relied on theoretical estimates of the flight-times for different energies. This drawback has now been removed in a novel way by timing protons arising from a decelerating component of the internal beam 'simultaneously' with those from the normal accelerating component. To dothis, part of the beam is allowed to by­pass the stripping foil and run +90° out of phase at full energy (— 525 MeV); it then passes into the decelerating half of the RF cycle and returns to low energy with a mirror image phase history rela­tive to +90°. This reflection symmetry is clearly exhibited in Fig. 6, where the phase histories for the two components have been determined independently by the relative method. Because of this symme­try the absolute phase (f>a of the acceler­ated component can be determined directly from the phase difference 6<j> between the two components by <j>a = 90° - 6<j>/2. Abso­lute values of <j>a calculated in this way are also plotted in Fig. 6 (crosses); they are in good agreement with the rela­tive values (squares) which have been uniformly phase shifted to best match them. The phase oscillations observed closely match those predicted from the magnetic field measurements.Polarization lossesThe BASQUE group has measured the scat­tering asymmetries e/\, eg of the acceler­ating (A) and decelerating (D) beam components at ten energies between 210 and 520 MeV. An initial run with a B- type foil (0.5 in. high x 0.1 in. wide) showed ep > e/\ at some energies, indicat­ing variations in polarization across the beam. A special 1 in. high x 0.20 in. wide foil was therefore installed to give a better average sample of the beam. At A83 MeV and above eq was then found equal to c/\. However, from A67 down to 307 MeV £0 is 10% lower than e^, and at 250 andFig. 6. Phase histories of accelerating and decelerating beams, obtained by timing an external beam.13210 MeV 20% lower. There thus appears to be one 3-5% loss in polarization at 280 ± 30 MeV and another at 475 ± 7 MeV. Whether these are resonant depolarization effects, or are associated with the vari­ations in polarization across the beam, remains to be clarified.Extraction of 65 - 180 MeV beamsA request for a 70 MeV proton beam for isotope production has led to a general study of the possibility of extracting beams below the present l83 MeV limit (modifications to the stripping mechanism could lower this limit to 168 MeV). Cal­culations have shown that useful beams could be extracted through the sides of exit horns 2 and 5 over the range 65 to 200 MeV. Figure 7 shows a possible de­sign in which the 65-100 MeV and 100- 180 MeV beams are steered into two separate beam lines, each with its own combination magnet. The stripping foils would be located near the resonator levelling arms at about 90° to the dee gap. An experimental test has been made on the 76 MeV beam, in collaboration with the Experimental Facilities group, con­firming the calculated trajectory and magnification. The detailed design of the 65-100 MeV extraction system is now under way (see p. 60).Primary beam linesIt is difficult to measure beam emittance at 500 MeV with the resolution obtainable at lower energies using slit systems. Published methods using beam profiles taken at different quadrupole settings either assume the emittance to be ellip­tical or require greater resolution than our multi-wire ion chambers can provide.A method has therefore been developed suitable for these profile monitors which gives the density distribution in phase space without any assumptions of ellipti­cal shape. At a given quadrupole setting adjacent wires on a monitor define adja­cent parallel bands in phase space; the fraction of beam in a particular band is proportional to the signal on the cor­responding wire. Altering the quadrupole strength alters the slope of the bands and the wires sample different slices through the emittance. The emittance plane is divided into a grid and enough measurements are made that the problem is overdetermined, the beam intensity in each element being estimated by a least squares method; measurements made in turn with different quadrupoles and using several monitors can be combined to im­prove the resolution. In practice it is often necessary to alter the quadrupole settings upstream to pre-calculated values to permit a wide range of slopes to be obtained. The measurement is made where the beam line is achromatic. A result is given in Fig. 8; the 'noise'Px1.50.5 -0.5  -1.5  -2.5-3.5 ---------------0.7 0 0.7 1.5 2.2 3.0 3.7 <1.5 5.2 (mm)Fig. 7. Trajectories of extracted proton Fig. 8. Intensity distribution ofbeams for beam lines 2A (400-520 MeV), horizontal emittance (B-foil).2B (100-180 MeV) and 2C (65-100 MeV).(mrad)2 1 3 -1 -2 3 -1 02 6s "X 2 -1 0 -1 -1-1 C9 11 5 -1 0 1-1 0s 9 9 & 1 1-1 1 2 -1 1 3 3RESONATORS65-100 MeV14is a few per cent of the total beam.Tests with two different 500 MeV tunes gave very similar values for the area and shape of the vertical emittance leaving the foil (2EE mm-mrad for 95% of the beam).Increased computerization of the emit- tance-measuring techniques for beam line 1 has enabled results to be examined minutes, rather than hours, after the measurements. The computer has also been invoked to allow rapid optimization of the steering in beam line 1, using an interactive least squares fitting code.With the rebuilding of line 1 and its extension to the TNF this fall, a variety of new tunes have had to be calculated—  eight different 500 MeV beams and four at lower energies in steps of 50 MeV down to 300 MeV. The 500 MeV cases involve vari­ous combinations of T1 present or absent, vertical (regular) or horizontal (medi­cal) spots at T2, and 09 off or on for ir+ or ir” beams in Mil. REVM0C was used to select settings to keep the spill tolerable and still retrieve acceptable spot sizes at TNF.Kaon and antiproton factoriesThe world's three meson factories are clearly in an unrivalled position to act as injectors to a future generation of high-current accelerators in the GeV range. These would perform the same functions for kaons and antiprotons that the meson factories are doing so success­fully for pions and muons. Preliminary studies have therefore been made of accelerator designs which would boost a beam from the TRIUMF cyclotron to several GeV. The following guidelines have been observed:- TRIUMF would continue to deliver pro­tons to the proton and meson halls, and in particular the biomedical facility would not be appreciably affected.- The site would be limited to the present one plus that adjoining.- The most interesting particles for in­tense production would be kaons and anti protons.Two specific designs have been considered. In the first of these J.R. Richardson hasproposed a two-stage system consisting of 8 GeV and 40 GeV proton synchrotrons (PS) in tandem. Taking a time-wise fraction of a 400 yA beam from TRIUMF 35 yA of 8 or 40 GeV protons could be produced. The synchrotrons would be fairly conventional and would present few design problems.The challenges would arise in matching TRIUMF, which relies on CW operation to provide high-intensity beams, to a syn­chrotron, which is essentially a pulsed machine. The first synchrotron would therefore be fast-cycling at 60 Hz and would act as an 8 GeV booster for the second 40 GeV ring. Three extraction schemes from TRIUMF have been considered:- Conventional proton extraction by stripping foil (giving minimal inter­ference with cyclotron operation).- Pulsed extraction of 100 turn 'stacks'.- Resonant extraction of H_ at v r = 3/2 (430 MeV); this would circumvent Liouvillean restrictions on filling the synchrotron phase space.The second proposal is for a ring cyclo­tron to accelerate 100 to 400 yA proton beams to 5 GeV— an adequate energy for kaon (but not antiproton) production.This machine (see Fig. 9) would be isochronous like TRIUMF with CW operation,Fig. 9. S GeV isochronous ring cyclotron for kaon production.so there would be no matching problems. Extraction from TRIUMF would be by con­ventional stripping foil and whatever beam was extracted would be accelerated to full energy in the ring. Here it is the ring cyclotron which presents the challenge. The most relativistic cyclo­tron yet operated has been the Analogue II electron model with 3 = 0.88, y = 2.1. Since the radial tune v r ~  y several in­teger and half-integer resonances would have to be crossed in accelerating pro­tons to 5 GeV (y = 8-3)- However, these need not be damaging if they are crossed quickly enough, and several designs for super-GeV cyclotrons have been published. Such a resonance would in fact be used for extraction. A 16-sector design is pro­posed with 12 SIN-style accelerating cavi­ties giving an energy gain of 6 MeV/turn. The maximum radius Rm would be 20.5 rn and the total magnet weight 3200 t (less than TRIUMF) using normal magnets. With super­conducting magnets the machine could be scaled down to Rm = 8.2 m (10% larger than TRIUMF) with a magnet weight of perhaps only a few hundred tons.ComputingA major addition to our computing arsenal this year has been 0PDATA, an interactive program of general applicability whichhas been written to make possible the algebraic manipulation of data arrays. It permits power spectrum analysis, integra­tion, differentiation, smoothing, and least squares fitting by functions which can be dynamically specified by the user. It has been particularly useful in pro­cessing data from the cyclotron probes. With the assistance of the Controls group this is as far as possible digitized and transmitted to the UBC Computing Centre; the use of 0PDATA then allows rapid and comprehensive analysis of the data. This is proving especially important in analyzing the centring probe data.Most of the beam development projects described above involved some computing. In many cases special codes were written, as for emittance measurements, depolarizing resonance studies and ring cyclotron design. In other cases im­provements were made to existing codes, as with our Monte Carlo particle track­ing code (now REVM0C 3) and our inter­active version of TRANSPORT (INTRAN).The CERN program library is also now available on tape; the CERN MINUIT code for function optimization and analysis of parameter errors and correlations has been converted to interactive double precision form.16PARTICLE PHYSICSExperiments 27, 40 BASQUEThe BASQUE group has completed the mea­surement of the spin correlation param­eters P and in neutron-proton elastic scattering at 210, 325, 425 and 495 MeV. Also completed was a proton-proton double scattering experiment at 24° lab in the energy range from 266 to 440 MeV which provided an absolute calibration of the polarimeter used to monitor the inci­dent beam polarization. With this abso­lute normalization available the analysis of the proton-proton elastic scattering experiments of the previous year was finalized. Experiments to measure the A and R parameters in np elastic scattering are in progress.Results of the double scattering experi­ment are shown in Fig. 10 [Amsler e t a t . ,  J. Phys. G, in press]. The accuracy of the present data is ±1.5%. In order to constrain the form of the fit at the ends of the range, values at 98, 1401, 601 and 702 were included. The solid line represents the fit to the measured asym­metries using a power series for P(24°) as a function of energyP (E,24°) = £  an (E-400) n=0nwhere a0 = 0.38605 ± 0.034682«! = 2.9129xl0-lt ± 5.4982xl0-5ct2 = 1.0803xl0"7 ± 5.2824xl0“7a 3 = 4.0962Y 10-9 ± 8.6202xl0"10a4 = -7.7334xl0‘12 ± 8.1 073>< 10“12The pp phase shifts obtained with previ­ous measurements of D, R, R' and P in pp elastic scattering [Axen e t a t . , Lett, al Nuovo Cimento 20^ , 151 (1977)] and the above normalization are listed in Table III [Bugg e t a t . , J. Phys. G., in press].Data at 150 MeV have been added to obtain a good value for g2 , the T T ° n  coupling constant. These phase shifts are com­pared with predictions from Vinh Mau e t  a l . in Fig. 11. In his latest work Vinh Mau has introduced an empirical short- range interaction below 0.8 fm fitting S and P waves. This interaction somewhat overdoes the required corrections toF waves but gives agreement with experi­ment for 1D2 . The central, spin-orbit and tensor combinations of F waves are shown in Fig. 12 and compared with the predic­tions of Vinh Mau, both with and without empirical short-range interaction.The measurements of P and Dt in np scatter-ing at 210, 325, 425 and 495 MeVare shown in Fig. 13 along with fits obtained from a preliminary energy-independent phase- shift analysis. Prior tothis work a long­standing ambiguity existed in the np phase- shift analysis at 325 MeV. The MAWIX analysis found a solution with e"i ~  7° and 3Sj x  9° while the later MAWX analysis of essentially the same data set found a solution with eTj = 21° and 3S^ ~  -11°.The BASQUE group results [Amsler e t a t . ,  Phys. Lett. 69B, 419 (1977)] clearly re­solve the ambiguity in favour of the MAWIX solution and are in good agreement with a prediction of Fj = 6.8 (using the Hamada-Johnston potential) and a predic­tion of 7.1° by Vinh Mau.T  labFig. 10. Fit to P(E, 24° lab) and the experimental p o in ts .17Fig. 11. Phase shifts from this analysis compared with the predictions of Vinh Mau et at. where the solid line includes normal exchange forces and the broken line the empirical short-range terms.18Table III. Phase-shift solutions with g;Inelasticity parameter n = cos2 = 14.25 and H waves and 01+ constrained by theoretical values.OTEnergy (MeV) 150 210 325 380 425 5154.87 ± 0.49 -1.41 ± 0.50 -13.46 ± 0 .83 -15-04 ± 1.09 -19.66 ± 0.69 -23 .44 ± 1 .70so 1*1.79 ± 0.51 4.78 ± 0.51 -9.34 ± 0.51 -13.76 ± 0.66 -18.26 ± 0.53 -19.98 ± 1.37-17.56 ± 0.16 -22.45 ± 0.18 -30.20 ± 0.52 -33.82 ± 0.56 -35-26 ± 0 .36 -42.60 ± 0.86P2 14.05 ± 0.10 16.01 ± 0.16 17.05 ± 0.25 17.09 ± 0.36 18.47 ± 0.21 18.98 ± 0.55I2 -2.81 ± 0.05 -2 .89 ± 0.11 -2.65 ± 0 . 1 8 -1.29 ± 0.28 -2 .52 ± 0.22 -0.18 ± 0.55pNO 1.12 ± 0.24 0.97 ± 0.25 0.92 ± 0.35 -0.40 ± 0.44 0.20 ± 0.25 -1 .55 ± 0.493D2 5.20 ± 0 . 1 6 7-31 ± 0.19 9.64 ± 0.18 11.16 ± 0.20 12.09 ± 0.22 14.29 ± 0.35pN p -2.19 ± 0.16 -2.59 ± 0.16 -3.23 ± 0.47 -1.49 ± 0.61 -2.51 ± 0.18 -0.41 ± 0.21pUSP 1.02 ± 0.13 1.68 ± 0.15 2 .85 ± 0.11 3 .09 ± 0.14 3.58 ± 0.13 4.67 ± 0.15I1* -0 .87 ± 0.005 -1.17 ± 0.009 -1.54 ± 0.017 -1.64 ± 0.033 -1.68 ± 0.06 -1.72 ± 0.18X 0.24 ± 0.026 0.30 ± 0.038 0.66 ± 0.07 0.51 ± 0.09 0 .76 ± 0.09 -0.02 ± 0.15G„ 0 .82 ± 0.06 1.04 ± 0.09 1.24 ± 0.11 CO Jr- 1+ O 2.17 ± 0.14 2.73 ± 0 .18*H 5 -0.54 ± 0.026 -0 .89 ± 0.038 -1.11 ± 0.07 -1.42 ± 0.09 -1.28 ± 0.09 -1.88 ± 0.14pD H 0.14 ± 0.027 0 . 1 6 +  0.038 0.54 ± 0.07 0.42 ± 0.09 0.67 ± 0 .09 0.19 ± 0.11(-0.241) (-0.377) (-0.607) (-0.689) (-0.749) (-0.858)k6 (0.048) (0 .088) (0.174) (0.216) (0.249) (0.311)X6 (0.196) (0.292) (0.488) (0.587) (0.665) (0.830)6 (3Pi) - - 4.17 ± 0.41 - - -0 ( ^ 2) ” - - 8.19 ± 0.52 10.28 ± 0.39 19.43 ± 0.46X2 224.08 79-36 171.16 119.93 226.45 242.79Degreesof freedom 190 62 171 113 178 193Fig. 12. Central, spin-orbit and tensor combinations of F-wave phase shifts from this analysis compared with the predictions of Vinh Mau et al.LAB ENERGY (MeV)1960  9 0  120 1509 cm9 cm9 cm9 cmFig. 13. P and Dy in n-p scattering with9 cm9 cmP 4 2 5  MeV np9 cmP 4 9 5  MeV np9 cmfrom preliminary phase-shift analysis.20Experiment 24Precision measurement o f p-p analyzingpower at medium energiesBecause of the importance of obtaining a good absolute normalization for polariza­tion experiments, and to avoid some of the difficulties associated with the techniques used until now, a novel double scattering technique has been used to obtain accurate p-p analyzing powers at 499, 308 and 205 MeV. A schematic dia­gram of the experimental configuration is shown in Fig. 14. The beam polarization P0 is monitored by p-p elastic scattering from a thin CH2 target at 17°. The ob­served left-right asymmetry in this po1ar imeter i sEl P 17>where Pj7 is the p-p analyzing power at 17° in the lab. The unscattered proton beam then passes through an 8 cm long liquid 4He target. Protons scattered at 15° form a secondary polarized proton beam which is then scattered from a second 2 cm long CH2 target. The liquid ^He target provides an interesting effect that we refer to as 'polarization pumping'. Since for spin-0 nuclei the depolarization parameter D is unity, the outgoing polarization of the elastically scattered beam can be writtenn po + ^He+ Po^HeThe sign of P0 is positive or negative depending on whether the beam polariza­tion is parallel or anti-para11e 1 to the normal to the scattering plane. The quantity Aj-|e is the p-^He analyzing power at 15°. Helium has a large analyz­ing power at these energies and the large separation (20 MeV) of the firstexcited state allows inelastic scattering to be eliminated. Polarization pumping produces almost 100% polarized beam by scattering from the He target. For exam­ple, with P0 = 0.70 and A^ |e = 0.70, secondary beam polarization is Pj =An additional advantage is that the ef­fects of uncertainties in PQ and A|-|e are reduced by a factor of about 4. The left- right asymmetry of the scattering on the He target was also measured:the0.94.£2 Po ^HeThe final scattering was detected in the '£3' polarimeter where proton-proton elas­tic scattering at 24° in the lab was mea­sured. The angle of 24° was chosen to compare with the previous high precision results also obtained at TRIUMF. The observed left-right asymmetry is given by£3 - p lp24 240 + ^He \ ^He /1 + PCombining observations for £1, e2 and £3, and using phase-shift predictions forthe ratio solve for324/P17 it is poss i b 1e to24 •2 4El 2 —  n E2 \ n£ 3 ( l + £ 2 )El1 / 2In the experiment, data were obtained with incident beam polarization up, down and off in order to provide good control over possible systematic error due to instrumental asymmetries. In addition, contributions from carbon in the CH2 targets and from the walls of the liquid helium target were measured in separate runs.Two methods of analysis are being used to extract the desired p-p analyzing powers. In one method consecutive runs with spin21up and spin down are grouped and averaged to eliminate the effects of possible instrumental asymmetries. Values of n have been obtained from the BASQUE phase- shift analysis. Preliminary results are given in Table IV. The energy quoted is at the centre of the CH2 target in the £3 po1 a r i mete r.Tab 1 e IV. (Preliminary results)Energy ?2k ± AP24 n205 0.294 ± 0.003 0.856308 0.354 ± 0.005 0.833499 0.412 ± 0.013 0.817The error quoted is due only to counting statistics. The effects of all possible systematic errors are being investigated in detail so that these data will provide a reliable calibration standard. System­atic errors will be comparable to or smaller than the statistical errors.The second method of analysis is still in progress. It uses chi-squared minimiza­tion procedures to check the consistency of the complete data sets at each energy and estimate correlations between possible errors. The preliminary results are in good agreement with the BASQUE experiment at TRIUMF, and together they represent the most accurate data in the energy range 200-500 MeV and will provide excel­lent input for phase-shift analyses.Experiments 5 7, 41B Gamma-ray studiesStudy of the radiative decay of the pion, EEX e vey, which was described in the 1976 annual report, was discontinued this year in favour of the neutrinoless muon decay y+ -* e++y (Exp. 57). This latter experiment had been given a lower priori­ty due to the lack of a clean, high- intensity y+ beam at TRIUMF, but at the beginning of 1977 it was decided to make it first pr ior i ty.The hindrance of the y -> ey decay is very important in the theory of the weak in­teract i on, espec i a 1 1 y in the context of the new gauge theories of the unifiedweak and electromagnetic interactions.In December 1976 and January 1977 several theoretical papers appeared which pre­dicted branching ratios for the y -* ey decay at the level of 10_10— 1 0-8 , well within the reach of present experimental techniques. Some of these papers were no doubt instigated by the rumoured ob­servation of 6 unexplained events in a SIN experiment to search for this rare muon decay.Since the experimental apparatus and techniques for the rr evey and y -> ey decays were so similar, the emphasis of the TRIUMF program was changed to a study of the muon decay reaction.Initially a 4.1 MeV y+ beam of 'surface muons' from the stopped ir/y channel (M9) was chosen as the source of decay muons. However, the flux of y's was only 105/sec/10 yA protons, and so it was decided to use a low-energy beam of 30 MeV EEX I This choice of a pion beam provided both advantages and disadvan­tages. By using a stopping pion beam as a source of decay muons, it was pos­sible to check the efficiency for detecting low branching ratio processes such as EEX  e+vey and rr+ -> 7r°e+ve ; it was also possible to use the tt+ -* e+ve reaction as an energy calibration line for the Nal during the course of the ex­periment. Also, simply by reversing the polarity of the magnets the decay y's from the ( tt- , it0 ) reaction on the H in the scintillator target could be ob­served without any changes in the experimental geometry or logic. The background produced by pions scattered into the electron scintillators (5,7,9 or 6,8,10) was eliminated by a prompt coincidence between these counters and the beam-defining counters (1,2,3)— see Fig. 15“ which generated a 10 ysec veto for all subsequent events.Figure 15 shows the experimental configu­ration used in the February experiment which utilized a symmetric e-y geometry for both Nal counters. The scintillators5,7,9 or 6,8,10 were used to define electrons which entered the Nal detectors following a pion stop (1 -2• 3 * by more than 30 nsec. Figure 16 shows a histogram of the time difference between the two Nal detectors for all ey events above 30 MeV at a EEX stopping rate of22L E A DIRON1 0 0 MeV n  + cMl NA3 6 0  X  3 6T I N A46 X 516 0 0_J 50 0LdX2< 4 0 0Xo\CD 3 0 0\ ~23O 200OI00TINA-MINA (**8) TIMINGTIME SPECTRUM (TINA-COUNTERS)RUN 69  Feb/78SIGNAL/NOISE -  5 / I5 channels^ 4  nsecACCIDENTALCOINCIDENCESIOO IIO I20 I30 I40  150 I60 I70 CHANNEL N U MB ERFig. 15. The saintillation counters Nos. 1-10 (thickness not to scale) were used to identify charged particles.F ig . 16. Histogram o f the time d iffe rence o f  the two Nal detectors fo r  a l l  ey events above 30 MeV at a stopping ra te  o f 2 x 105/sea.2 x 105/sec. The ratio of rea1/accident- al events within the 6.7 nsec window accepted for analysis was 5:1. Most of the events come from radiative muon decay (B.R. —  10_l+) where both events have <k0 MeV.Figure 17(a) shows a two-dimensional plot of the electron energy in TINA and the y energy in MINA for all ey events falling within the coincidence timing window;Fig. 17(b) shows an equivalent random co­incidence timing scatter plot. The most(D>-60 ocrANUZ  50w  z£2 40oX  Q_3040 50 60 70 40 50 60 70ELECTRON ENERGY (MeV)Fig. 17. (a) Energy scatter plot of e-y data. The rectangle encloses the region(53 + 3 MeV) where the -+ e+y events are expected. The triangles (h). and circles (o) identify events corresponding to ir+ -*■ e+vey decay or events associated with the incident beam, (b) Scatter plot for random e-y coincidences.~r©A1 © (a) REAL &  B A C K G R O U N DA111 1 1 i 1 0 1A22 1 211 in 2 11 21 (ft 1 12 4 2221 121 21 H  & 21 12112311 12 1111 X2422141 21311 2 <2' 1 < j)123225221211 1 11 1 ' 1  1 ^ 1 1"2131 1233121 21 2 11 12123324.2 23222 1121 2 1244 4453211124112 1 11111 111 47132433211221143 32 111 122532 214 2 3111411142 2 1 1545477374213312223412 3 12 6 444534272 6211342141131 221©A©©A© © AA©.©QX%1 11 11 1 1 1 12 2  11 11 1 31 1 1121 211 2 111 1 1 1~r(b) BACKGROUND2 1 11 11 1 111 11 1 11iA1 1211 1 2211 1 1  11 1 2 11111 1 11 2 12 2 141 1 2 12  21111 121112212 211 1211111 1 22 1 21 24 1121 11 111A23important source of background for this experiment comes from a random coinci­dence between a positron from normal y decay and a photon from radiative muon decay. Events for which Ey > 50 MeV and Ee < 50 MeV are due to random coinci­dences between positrons from normal y decay and neutrons or cosmic rays which escaped detection by the anti-coincidence shield. The counts on the high-energy electron side (Ee > 50 MeV) are due either to ir+ -> e+vey decay (within 100 nsec after a pion stop) or to beam- related events (counter 3 fired within ±100 nsec of the event).During the February run a total of 3.61 x 1010 pions were stopped and no events were observed above background.This yie1ds an upper limit of 3-6 x 10-9 (at 90% confidence level) for the branch­ing ratio p -x ey/y -*■ evv", and these results have been published [Phys. Rev. Lett. 39, 113 (1977)].In June and August further data were re­corded, again using a 30 MeV EEX beam. However, in these runs an asymmetric geometrical configuration was adopted in which one of the Nal detectors (TINA) was optimized for electrons and the other for photons (MINA). This asymmetric configu­ration was chosen so that the p -*■ ey experiment (Exp. 57) and the ir+ e+ve experiment (Exp. 52) could take data simultaneously. In the June run 5 x 1010 pions were stopped, and 1 real event and 1 background event were observed. In the August run 1.1 x 1011 pions were stopped;3 real events and 3 background event were observed. Hence a total (including the February run) of 5 real events and 5 back­ground events were observed, and thus the upper limit on the pey branching ratio is <1.9 x 10~9 at 90% confidence level.On connaTt l'int£ret qui s'attache h cette disintegration, trSs importante pour les interactions faibles, surtout dans le contexte des nouvelles theories de jauge. Cette experience itait I notre programme depuis longtemps, mais au debut de 1977 nous avons decide de la mettre en toute premiere priorite. Au cours d'une premiere serie de mesures en fevrier, nous avons utilise les deux cristaux d'iodure de sodium, mis au pointpour 1'experience v+ -* e+vey, dans une configuration symitrique (coincidences e+-y et y-e+ ) . Par la suite, nous avons recueilli les donnies sur p+ -> e+y en parallele avec 1'experience it+ •+■ e+ve .On travaillait alors de fa^on non sym€- trique: 11un des detecteurs INa itant optimise pour les positrons (TINA),1'autre pour les photons (MINA). Nous avons d'abord pensd utiliser un faisceau de muons de surface (energie cinetique de b MeV). N'ayant pas riussi h obtenir une intensitd suffisante, nous avons de­cide d'utiliser un faisceau de pions de basse energie. Ce choix presentait des inconvenients et des avantages. Avec des pions, on s'attend a observer des 6v£ne- ments parasites pouvant eventuel1ement simuler des des i ntegrat ions p+ -*■ e+y. En jouant sur la difference entre les vies moyennes du pion et du muon, et en fais- ant usage de la logique e 1ectronique, il est possible de rdduire cette source de bruit de fond S un niveau ndgligeable compte-tenu de la sensibilitd visde de 10-9 pour le rapport Ruey - y+ e+y/y+-> e+\)eV y . Par contre, 1 utilisation d ' un faisceau de pions facilite I'etalonnage en energie des detecteurs: on peut obser­ver les positrons de 70 MeV de la disin­tegration ir+ -> e+ve ; en renversant la polaritd du faisceau, on peut observer les rayons y du E E 1  suivant l'echange de charge'des E E G  dans la cible, et ceci sans avoir h changer la geomitrie de 11exper i ence.La figure 15 montre Is disposition des diffirents compteurs. La figure 17 montre les ivdnements observes dans la region d'intiret, centree autour de 50 MeV pour positron et photon. Pour plus de details, on consultera les publi­cations [Depommier e t a t . , Phys. Rev. Lett. 39., 113 (1977); Communication £ la Conference Internationale 'High Energy Physics and Nuclear Structure', Zurich, contribution P4 (1977)].Un premier risultat, faisant usage des donnees de fevrier seulement, a donni une limite superieure Ryey < 3-6 x 10~9 (avec un degri de confiance de 90%). L'analyse des donnees de juin et aout n'est pas terminie, mais le risultat devrait etre une limite superieure de 11ordre de 2 x 10-9.2bNous etudions actue11ement la possibility de rdaliser une nouvelle experience y+ -> e+y en vue d'abaisser la limite superieure sur RueY ^ un niveau de 1 1ordre de lCT11.Programmes d 'acquisition de donnees et de simulation des experiences. La decision rapide de passer h 1'experience p-ey en janvier dernier nous a obliges a refaire un programme d 1acquisition de donnees nomme MEG3M adapte aux nouvelles condi­tions d 1experience. Ce programme permet d 'enregistrer jusqu'S 1000 evenements par seconde sur bande magnetique tout en faisant de i'analyse en ligne. De plus nous avons re^u cette annee notre derouleur de bande et nous sommes mainte- nant inddpendants de tout autre groupe pour la prise des donnees.L'analyse se fait maintenant en deux etapes:a) un premier depoui11ement des bandes a 1'aide de i'ordinateur de type Eclipse du groupe de controle de TRIUMF;b) une etude plus detail lee des evene­ments en coincidences sur 1'IBM du Centre de Caicul de UBC ou la CDC du Centre de Caicul de 1'University de Montrea1.Finalement, S la suite d 1une collabora­tion avec G. Opat [TRIUMF report TRI-77-A] nous avons maintenant des programmes SIMUL9 et M0NTE-PI0N, qui nous permettent de faire une comparaison directe entre un caicul de Monte-Carlo et les resultats des experiences.Aprfes modification, ces programmes pour- ront servir S simuler les conditions de la future generation d 1experiences et S tester differentes configurations.During a 5-day run in March a measurement of the Panofsky ratio in 3He (Exp. Alb) was performed. The experiment was con­ducted parasitica11y while the University of Victoria group was measuring the pionic X-rays from 3He. A liquid 3He target (1.9 cm x 10.6 cm <j)) was used, and the tt" flux from the M9 channel was typically 2 x 105/sec. The measured rr~ stopping rate was 5 x lOVsec; however, it was estimated that only about 10% of the tt" registered as stops were actuallystopping in the 3He content of the target. This estimate was based on a comparison of the measured y branching ratio with that published by Truol et al. [Phys. Rev. Lett. 32_, 1268 (197A) ].The high-energy gamma-rays were observed in the TINA detector (18 in. $ x 20 in.) and a resolution of A . 5% at 135 MeV was obtained using a 6 in. <j> collimator. Neutrons were eliminated by a time-of- flight cut between the Nal signal and the beam-defining scintillator (S3) over a f1i ght path of ~3 m.Figure 18 shows a 2D contour plot of the energy vs T0F for one run (^20% of the data collected). The gamma rays from radiative capture are visible as a seriesof islands at EY 110-1A0 MeV wh i1ethose from rr° decay are visible as a rectangle from 53_86 MeV. The time scale has arbitrarily been set to 0 nsec for the y peaks. A clear separation of the neutrons and y's can be seen: the neutrons from He target take at least 12 nsec longer to reach the target. The curved contour enclosed in the dashed curve ex­tending from -12 to +8 nsec is a back­ground source of neutrons arising from the previous proton burst striking the production target (and beam dump) A3 nsec earlier. This was confirmed by collect­ing data with the first bending magnet of the M9 channel turned off.A sample energy spectrum of y-rays in TINA is shown in Fig. 19. These data have been corrected for small gain shifts which occurred during the run. The data near the bottom of the figure are esti­mates of the 1T2 neutron' and 'target- empty' backgrounds which have been appro­priately shifted and normalized with respect to the raw data. In order to ex­tract the Panofsky ratio these backgrounds were subtracted from each run and then the remaining data was fitted with four lines: a yT line, a radiative break-upline for the ynd + ynnp channels, a tt0 line, and a low-energy background line as shown in Fig. 20. The analysis of five sets of data such as that shown in Fig. 20 results in Panofsky ratio for 3HeW(u~3He yydju W(ir-3He +  yT) = 2.83 ± 0.07.25TIME OF FLIGHT (nsec)This value can be compared with the earlier measurements of Zaimidorogo e t a t .  [Soviet Phys. JETP 2J_, 848 (1965); 24., 1 11 (1967)] 2.28 ± 0.18 and that of Truol e t  a t . [Phys. Rev. Lett. JfL, 1268, 1974)]2.68 ± 0 .13, which differ by considerably more than their stated errors. Our result clearly indicates that the Russian value obtained by measuring the recoil T in a cloud diffusion chamber is in error.There have been several theoretical cal­culations for P3 and a detailed review of the theoretical picture will not be presented here. Calculations using the elementary particle model for 3He and the partial conservation of the axial vector current (PCAC) have been performed by Ericson and others [Nucl. Phys. B3_, 609 (1967); M l ,  621 (1969); and Phys. Rep. 5£ ,E N ERGY (MeV)Fig. 18. Contour plot of y energy vs. TOF. The superimposed dashed lines indicate the shape obtained for data taken with the B1 dipole off.59 (1976)]. They obtain P3 =* 1.9 - 2.1 although an earlier calculation [Ericson and Figureau, Nucl. Phys. ]33_, 609 (1967);B 11 , 621 (1969)] which neglects p ex­change, NN correlations and N intermediate states gives a value of 2 .70, in better agreement with experiment. Calculations based on the impulse approximation have also been made [Phillips and Roig, Nucl. Phys. A234, 378 (1974) and Goulard e t a l.  preprint (1978) Univ. de Montreal]. These calculations are somewhat sensitive to the amount of D state in the 3N wave function and yield values in the range2.5 " 3-0. These I.A. calculations are in good agreement with our experimental results, and thus it appears that the pro­ponents of the PCAC approach for 3He should re-examine the corrections to their original 'simple' calculation.G3 INSHIFTED PHOTON SPECTRUM. RUN 169 300 ----1---- r~.---1---- 1---- T-- — I—300 - .i/i '1  2 0 0  - ot_> ' • •100 - •'••v ■ f '10 30 50 70 90 110 130 150PHOTON EN ER G Y  IMEV1Fig. 19. Gain-shifted photon spectrum of run 169. The data given below are estimates of the 'T2 neutron' and 'target-empty' back­grounds, appropriately shifted andnormalized with respect to the target-empty run.PHOTON EN ER G Y  (M EV )Fig. 20. Contributions to the fit of Fig. 19 by the four lines: the low-energy background, the it0  photons, the break-up channels and the 136 MeV photons, all folded with the experi­mental response function.26Experiment 10Pion production by proton bombardment of hydrogen and other light nuclei1) PPdiT+pmr4Using a 50 cm Browne-Buechner magnetic spectrograph for detecting the pions in a conventional single arm experiment (to­gether with a proton beam polarimeter—  based on the known analyzing power of the pp elastic scattering reaction— situated downstream of the pion production target), a comprehensive set of differential cross-section and analyzing power data for both the pp -> dir and the high pion energy end of the pp -> prnr reaction has been obtained. The analyzing power data in particular provide unequivocal evi­dence for a significant d-wave component over much of this energy range. These data were presented in an invited paper at the Nuc1eon-Nuc1 eon Conference held at the University of British Columbia in June. Only the pions from the pp -* drr reaction have been analyzed thus far. A sample of the analyzing power data for a number of incident proton energies is illustrated in Fig. 21. The data at 422 MeV are in very good agreement with those of Dolnick [Nucl. Phys. B22, 461 (1970)].Almost no experimental data are currently available on the three-body final state.An initial perusal of the data indicates that the analyzing power for the pp -* pnir reaction is very similar to that for the two-body state. Very little dependence on the energy of the pion is evident.The data-taking phase for these reactions■422 MeV 375 MeV350 MeV<!> DolnickFig. 21. Analyzing power for pp -> di\+ .is now complete, with emphasis now directed to completing the analysis of the data.2) pA •> VEE reactionsThe dependence of the production reaction on the polarization of the incident pro­ton as well as the obvious one of extend­ing the range of proton energies over those measured at other facilities is being pursued.Again, the 50 cm Browne-Buechner broad- range spectrograph has been employed in this work to date. By employing suitable 'cuts' in the off-line analysis of the data, differential cross-sections as low as 5 nb/sr could be detected (the princi­pal cut involved the propagation time of the particle through the apparatus, a very effective way of separating the pions from the heavier reaction products). The reactions investigated so far are:12C (p ,rr+ ) 1 3C and 3Be (p , tt+ ) 13Be at Tp = 200 MeV with some data from the latter reaction at 237 MeV as well, and 2H( P ,tt+)3H at 305 and 330 MeV. The typi­cal energy resolution of the system was about 1.5 MeV, a figure dominated by the energy spread of the incident proton beam with a somewhat smaller contribution from the spectrograph hodoscope bin size.The initial results of this program (rep­resenting the f i r s t  measurements* of pion production from nuclei using polarized protons) were presented in a contributed paper to the Seventh International Conference on High-Energy Physics and Nuclear Structure at Zurich in August.The experimental analyzing powers for the pion production reaction feeding any of the low-lying states of 10Be (or 13C) are illustrated in Fig. 22. The similarity of the data for the various states as well as the magnitude of the asymmetries observed suggest that a rather simple, basic mechanism is involved. Predictions of the pionic stripping models [Noble, Nucl. Phys. A244, 526 (1975); Young and Gibbs, Phys. Rev. C J_7, 837 (1978)] which*More specifically, these are the first measurements yielding information con­cerning the analyzing power of the pion production reaction leading to specific nuclear final states.27L A B O R A T O R Y  ANGLE LA BO RA TO RY ANGLEb +p —5- bd)$3 excited states unresolved20 40 60 100 120 140L A B O R A T O R Y  ANGLELA BO RA TO RY ANGLE (DEGREES)Fig. 22. Analyzing power CA^J vs. laboratory angle for the (p,v) reaction.have been obtained to date, however, are quite incompatible with such results. Predicted analyzing powers are generally <0.4 in magnitude with both positive and negative values expected, depending on the characteristics of the nuclear state excited. Clearly, more experimental in­formation is required. The extent of the universality of the angular structure ofthe analyzing power upon both the nature of the nucleus bombarded as we 11 as the value of the proton energy must be elucidated.The experimental set-up was removed from its position in beam 1ine 1 in September to make room for the beam line 1 expan­sion. The group proposes to set up again in beam line IB in the spring of 1978.28Experiment 75Backward angle pion production from the D(p, n*)t reactionThis experiment was successfully com­pleted in 1977- The experiment was set up in beam line 1 at the same target loca­tion as the Exp. 10 (p,ir) system. Much of the data acquisition system of Exp. 10 was used in taking data.The pion detection system was a simple 3-counter telescope which consisted of two small passing counters, the second of which defined the solid angle (2.8 msr), and a calibrated pion stopping counter of NE 102 A; dE/dx and total E informa­tion were used to identify the pions.The reaction was studied at proton ener­gies of 400, 425, 443, 470 and 500 MeV and at laboratory angles between 120 and 160°. The 470 MeV energy was chosen to check a previous measurement of thisreaction [Dollhopf e t a t . , Nucl. Phys.A 2 17, 381 (1973)], where a significant backward peaking of the differential cross-section was found. The polarized beam from TRIUMF was used for these measurements so that the analyzing power as well as the cross-section was measured. The beam polarimeter was the same as used by the Exp. 10 system.The results of the preliminary analysis of the 470 MeV data were presented at the Seventh International Conference on High- Energy Physics and Nuclear Structure, Zurich. Figure 23 shows a comparison of the TRIUMF results with the Dollhopf results. There is clearly a disagreement between the two. A theoretical prediction [Fearing, Phys. Rev. C JJ_, 1210 (1975)] agrees more c 1ose1y with the TRIUMF resu1t .The analysis of the data taken at the other energies mentioned above is continu­ing and should be complete by mid- 1978.Fig. 23. Cross-sections and asymmetries for the reaction 2H(p,-n)3H measured at large angles. P IO N  AN G LE  (c m )29Experiment 66p-p bremsstrahiung at 200 MeVThe details of the apparatus for this ex­periment are described in the 1976 Annual Report (see, for example, Fig. 17 of that report— modified as described there). The data-taking phase was completed in 1977 and some analysis of the data has been done, particularly at the 17°"17° angles for the two proton counters in Harvard geometry. The incident proton energy (lab) was 200 MeV, and some of the data are shown in a coincidence scatter plot in Fig. 2b, where E3 and represent the energies of the two protons. The locus of the p-p bremsstrahiung events is clear­ly shown, indicating the prominence of the events above background. The (p,2p) background from the deuterium in the gas can just barely be made out as a line parallel to the upper part of the brems­strahiung 'ellipse'. Other contaminants give similar background. The background due to accidental coincidence events was determined from data in which the protons originated in adjacent RF eye 1e s .The absolute cross-section was determined a) by indirect measurement of the beam by a Faraday cup, b) by simultaneous compari­son with the pp elastic events produced in the hydrogen target. The methods agreed to 5%. The preliminary results are shown in Fig. 25, where the differential cross- section is shown as a function of the angle of emission of the gamma ray. This represents about 2/3 of the available data. The work by H.W. Fearing on the theoretical approach of the soft photon approximation (SPA) is discussed in the section 'Theoretical Studies' of this re­port. The curve labelled OBE is the one- boson exchange model calculation of Szyjewicz and Kamal [AI PCP #k\ (1978), p. 506]. This is an improved version of the earlier calculation of Baier, Kuhnelt and Urban [Nucl. Phys. B 11 , 675 (1969)]. The comparison with SPA is quite good ex­cept at 6y = 0° and 180° where the SPA is low. According to Fearing these are the regions where off-shel1 contributions might be expected to enter. In any case these experimental results represent an interesting challenge to theorists, and it is to be expected that some important results will emerge.48tE4 321600 16 32 48M p WFig. 24. A scatter plot of the ppy data. E 3 and E 4 are the kinetic energies of the two detected protons in arbitrary units.P re lim in a ry  Data Only(deg)Fig. 25. Preliminary ppy cross-sections for 16.3° compared with soft photon approximation (SPA) of Fearing and one-boson-exchange model (OBE) of Szyjewicz and Kamal.30NUCLEAR PHYSICS AND CHEMISTRYExperiments 1. 54Pi scattering and total cross-section measurementsThe group's early positive pion elastic scattering experiments indicated that the angular distributions were very sensitive to true pion absorption where pions are not present in the channel afteran inter­action [Johnson e t a l., Nucl. Phys. A, to be published]. The major effect of true positive pion absorption is to fill in the Coulomb nuclear interference minimum. Since the interference is constructive in ir" elastic scattering, study has begun on tt” elastic scattering at pion bombarding energies between 30 and 50 MeV to see what effects can be attributed to true it- absorption. This then offers calcula­tions a stringent test; agreement of cal­culations with both positive and negative pion elastic scattering cross-sections will indicate a proper treatment of the very important Coulomb effects. After all, it is basically the same experiment and the it- calculation should give as superb agreement as the tt+ agreement with just a change in the sign of the charge. The apparatus, however, had to be changed. The stopping detector was replaced by a stack of p 1astic detectors of varying thick­nesses that gave energy loss as well as range information. An additional passing counter after the last counter that stopped pions was used to reject electrons and energetic muons. Additional muon contami­nants were separated according to time-of- flight information as well as energy depo­sition in passing and stopping counters.The cross-section was calculated using the incident pion flux as measured by an ion chamber as well as scintillation counters placed downstream of the target. The results are displayed in Fig. 26.These data are the combined results of several runs and consistently show the minimum in the angular distribution. The open circles are the results of Marshall e t a l. [Phys. Rev. C J_, 1685 (1970)]. The solid curve is the Coulomb scattering cross-section. Notice that the Coulomb- nuclear interference is now constructive and the forward angle cross-sections are strikingly different from the tt+ forward angle cross-sections. By comparing thepositive and negative cross-sections it can be seen that the Coulomb amplitude plays an important role well past 90° for this combination of energy and target nucleus. In particular, the nuclear am­plitude becomes repulsive at back angles, and consequently the EEl cross-sections are less than the ir+ cross-sections until the Coulomb effects are no longer man i fest.The EEX data were used to obtain phase shifts, and these phase shifts in turn were used to calculate the EEb elastic angular distribution. The results are consistent. Likewise, calculations of EEl carbon elastic scattering are consistent with the data and are shown in Fig. 26. The solid curve is the calculation with2 0  4 0  6 0  8 0  1 0 0  1 2 0  140SCAT TER ING  A N G L E  D EG , C MFig. 26. Tla  elastic scattering cross-section at 1^=29 MeV. The forward angle Coulomb nuc­lear interference is constructive while the interference is destructive at the minimum.31P R O T O N  E N E R G Y  I N  M e VFig. 27. Proton spectra resulting from pion absorption. The dashed lines indicate a region correspond­ing to the it"D"-+2p reaction while the dotted region represents the Tl " a  "+aHe p kinematics.an absorption term proportional to p2 in­cluded. The dashed line is the same cal­culation excluding the p2 term.This work is continuing on other nuclei.The true absorption terms of the elastic scattering cross-section calculations were assumed to follow the AAN U 2p reac­tion cross-section energy dependence.Pion absorption on ^ C a  was studied in a poor resolution experiment using the TRIUMF biomedical pion beam line and these experimental results compared with the energy dependence of pion absorption on deuterium at pion bombarding energies of 30, 40, 50 and 60 MeV.Particle-counting telescopes were placed at ±82° in the laboratory. This corre­sponds to a centre-of-mass angular sepa­ration of 180° for the EEX F -* 2p reaction at a bombarding energy of 40 MeV. Each telescope consisted of a plastic passing counter and a Nal stopping counter with a thickness adequate to stop 180 MeV protons. The resolution of the reflec­tion geometry detector was about 7 MeV FWHM, primarily due to the thickness of the calcium target, and determines the overall resolution of the experiment.The energy calibration of each telescope was made using the peak position of the pion elastic peak at 20, 30, 40, 50 and 60 MeV. The energy uncertainty was ±2 MeV at 100 MeV. The proton-to- scattered-pion ratio was typically 0.6, and no distinct deuteron peak was ob­served at any of the pion bombardingenergies. The proton spectra for 30 and 50 MeV are shown in Fig. 27. The proton coincidence events from the reaction Lt0Ca )EEX , 2p) 38K were used to determine 38K excitation spectra for each bombarding energy. Figure 28 gives a typical exci­tation spectrum. Both singles and coin­cidence cross-sections have about the same energy dependence as the rrD 2p cross-section so that the true absorption elastic scattering calculation assumptions seem well founded. Additional analysis of this data is proceeding and a higher resolution experiment is being prepared.E XC I T AT ION  ENE RGY  ( M e V )Fig. 28. aaK excitation spectrum for k0Ca(Tr+,2 p )3aK at = 60 MeV.T = 50MeV.32Experiment 42an3He: Strong interaction shiftDuring a successful run in March pionic X-ray energies, Loientzian widths and relative intensities were measured for the K transitions in pionic liquid 3He. The experiment was performed using the M9 channel tuned for 96 MeV/c negative pions produced in a 10 cm long beryllium target bombarded by 10 yA of 900 MeV protons.The liquid 3He target (loaned to TRIUMF by the National Aeronautics and Space Ad­ministration of the USA) is seen in cross-the direct pion beam. Pions stopping in the 3He target were signalled electronic­ally by the usual l-2*3*^ coincidence among the plastic scintillators constitut­ing the telescope. Of the 5 x 101* stops/ sec, only about ten per cert were in the 3He itself, with the remainder being in the mylar windows, target frame and scin­tillation counters. X-rays emitted dur­ing the atomic cascade of the pions were detected with a Kevex Si (Li) detector (80 mm2 by 5 mm thick) having an in-beam resolution of 181 eV FWHM at 6.A keV.The data were stored in a Nuclear DataFig. 29. Plan view of the it3#e experiment.section in Fig. 29; the helium target volume is pill shaped, 20 mm thick by 106 mm in diameter, and is cooled to 2°K by superfluid ^He. The cylindrical lead collimator and borated gypsum blocks en­sured that the pion beam was confined to the liquid helium volume and also served to shield the Si(Li) X-ray detector fromND2A00 A096 channel pulse height analyz­er, with half of the channels being used to record the pionic 3He X-ray spectrum and the other half to record a 57Co source spectrum.In Fig. 30 is shown the pionic 3He X-ray spectrum which was obtained by combiningFig. SO. Summed spectrum of X-rays from the tt experiment. CHANNEL NUMBER33Table V. Summary of EE 3He X-Ray Results (all energ ies in eV)Trans i t i on Ka KeInstrumental resolution 221 ± 9 234 ± 9Lorentzian width T 66 62CT (statistical) 4.1 7.06T (tota1) 12.1 13.4Calculated electro­magnetic energy 10646 12613Experimental energy 10673 12640Strong interaction shiftAE of the Is level 27CAE (stat i st i ca1) 2.4CAE (total) 5-0data from 22 separate runs over a totalnet acquisition time of 17-3 h. From ananalysis of this spectrum, the p ion-nucleus interaction is found to result inan attractive shift of the Is level of 27 ± 5 eV and in a Lorentzian width of 65 ± 12 eV. The intensities of the Ka , Kg, Ky, and Kg transitions were found to be in the ratios of 1, 1.05, 0.22 and0 .08, respectively.Experiment 80Strong interaction effects in pionic atoms1) 2p-1s trans i t i onDuring 1977 measurements of the pionic 2p-ls X-ray transitions in 19F and 23Na were completed using the 100 MeV/c pion beam at the M9 channel. The result of the analysis of the two summed spectra to obtain the Is strong interaction shifts and widths is summarized in Table VI.Also shown are comparisons with previous measurements made at Berkeley and CERN[Jenkins e t a l . , Phys. Rev. Lett. Y]_, 1 (1966); Backenstoss e t a l. , Phys. Lett. 25B, 365 (1967)]. The considerable im­provement in accuracy of the TRIUMF mea­surements resulted from better statistics and resolution as well as more favourable peak-to-background ratios. Uncertainties due to the effects listed in Table VII were carefully determined to arrive at overall precisions in energies and widths about four times better than those of previous measurements.2) 3d-2p transitionsSpectra have been obtained in the weak broadened 3d-2p transitions in 2 g/cm2 targets of 30Zn, 32Ge, 33As, 3i+Se and 35Br. A preliminary analysis of the summed spectra of 30Zn and 32Ge, both of which were long measurements in compari­son with the higher-mass targets, yielded energies and widths in good agreement with a recent CERN experiment [Abela e t a l. , Z. Physik A282, 93 (1977)] with targets of Z < 33- The trend with Z is as expected by Ericson [Proc. Banff Summer School, 102 (1970)]. The statis­tical accuracy of the survey spectra from the remaining three targets is poor; how­ever, analysis is currently in progress in preparation for a further run.Table VII. Contributions to the Uncertainties in the Measured X-ray Energies (E) and Widths (r) in keV.irf irNaAE AT TE ATstat i st i cal 0.. 1 1 0.,45 0..23 1 ,.07line fitting parameters 0. 03 0..05 0.,06 1.06unresolved y 1s 0. 03 0.,30 0.,06 0,.50fitting reg i ons 0.,10 0.,50 0..01 0..07Compton edge 0.,06 0..08energy calibration 0.,05 0.,01 0..10 0..02total uncertainty 0.,16 0.,74 0..27 1. 19Table VI. Energies, Hadronic Shifts and Line Widths of Pionic X-ray Transitions in 19F and 23Na. (All values are in keV)FIuor i ne Sod i urnEX-ray e r EX-ray e rTRIUMF 195.17(0.16) -25.68 10.12(0.74) 275.75(0.27) -51.40 12.0 (1.2)CERN 195-9 (0.5) -25.0 9.4 (1.5) 276.2 (1.0) -51.0 10.3 (4.0)Berke1ey 196.5 (0.5) -24.4 4.6 (2.0) 277.2 (1.0) -50.0 4.6 (3-0)3^Experiment 14 p-4He elastic scatteringl) Backward angle p-4He elastic scatter i ngThe elastic scattering of protons from light nuclei at backward angles is not well understood in the intermediate-energy region. Various models have been studied, including nucleon isobar exchange [see, for example, Weber and Arenhovel, Phys. Lett. C, to be published], multiple nucleon-nucleon scattering [Gurwitz e t a l. , Ann. Phys. 98_, 3^6 (1976)], and multi-nucleon exchange (e.g. triton ex­change for p-4He scattering) [Lesniak e t a l. , Nucl. Phys. A267, 503 (1976)] , but definitive conclusions are not yet possible.Extensive measurements of p-4He elastic scattering have been performed in the backward region in order to provide data, especially analyzing powers, which will assist in clarifying the details of the reaction mechanism and will also aid in testing recent theoretical predictions. Differential cross-sections have been measured for ten energies between 185 and 500 MeV from l4A° to 168° in the labora­tory system. Analyzing powers were also measured for seven of the ten energies. Experimental details are given in the 1976 University of Alberta TRIUMF prog­ress report and in a preprint submitted for publi cat ion.The p-^He differential cross-sections are presented as a function of cos 6c.m. ar|d 6c .m . in Fig. 31- The statistical uncer­tainties in the points are between 1 and 3%; normalization uncertainties are an additional IX . The straight lines in the figure represent an exponential fit to the data as a function of cos 6c m _ The analyzing powers are shown in Fig. 32.The crosses in part a) of the figure are previous data at 1^7 MeV [Cormack e t a l. , Phys. Rev. 115, 599 (1959)]. The error bars in that figure represent the statis­tical uncertainty in the measurements.The differential cross-sections do not show the marked backward peaking observed at both lower and higher energies. The possible structure in the cross-sections and the 180° excitation function suggested for energies around 2k0 MeV [Lesniak e ta l . ]  was not observed in the data. The p-4He analyzing powers are large and negative, and show strong dependence on both angle and energy. Thus, these mea­surements may be most valuable in differentiating between different models in this reg i o n .2) Backward angle study of p + 4He -> 3He + dRecent data obtained at TRIUMF for p-4He elastic scattering cast doubt on triton exchange as the dominant reaction mech­anism at large angles. The possible contributions of other more complex reac­tion mechanisms are also unclear. In order to provide additional information about the large momentum transfer reac­tions of nucleons on light nuclei, the group measured the differential cross- section and asymmetry for the reaction p + 4He ■+ 3He + d at energies between 275 MeV and 500 MeV. Details of the ex­periment and the complete results can be found in Cameron e t a l. [submitted for publication; contribution to 7th Int.© c m (deg rees)155 160 165 180cos © c mFig. 31. p + 4He -*■ p + 4He differential aross- seotions. The lines are only to guide the eye.350- t  '/  T e r r o rI  1 1  to +0.15-1 ' I 1 ... 1 ' I .......... 1 " l ... I—-- • 2 0 - JL -'T T  i  z  H J - I - I _- • 4 0X-VzI H HH W 1H H H H -  1 I --1  1-- • 6 0 ©  185 MeV1 . ._1 1 .©  200  MeV .........1 l t“ ©  2 2 5  MeV1 1 1"  ©  2 50  MeV ... ! 1 1-5  140 150 160 170 180 150 160 170 180 150 160 170 180 150 160 170 180O Proton Laboratory  Angle ( degrees)Proton Laboratory Angle (degrees)Fig. 32. p + 4He -+ p + 4He analyzing powers; the crosses in (a) are previous data at 147 MeV.Conf. on High-Energy Physics and Nuclear Structure, Zurich, Abstract vol. p. 19A (1977)] •The experiment was performed at large angles, the deuteron being detected in the range 1^0° 9]ab -£ 170°. Differen­tial cross-sections are backward peaked, in sharp contrast to the p-^He elastic scattering cross-sections which are flat or tend to fall towards 180° in this en­ergy range. In addition, the 1+He(p,d)3He cross-sections show unexpected similarity to those for p-3He elastic scattering both in magnitude and shape. The back­ward peaking suggests that deuteron ex­change is an important reaction mechanism for both processes. It is hoped that this experiment and the possibility of comparing results to the asymmetry data will stimulate more extensive theoretical calculations and provide a reliable foun­dation with which to describe nucleon scattering on light nuclei.Study of pd dpThe cross-section asymmetry (A) has been measured for elastic proton scattering off deuterons in_^the backward hemisphere with polarized (p) incident protons ]xi -> dp; A is a measure of the spin de-the react i on as expressed by/ dot do A  /dat + dat\\d£2 dC2 A dil dfi /where the arrow indicates the spin direc­tion of the incident proton relative to the reaction plane. Data were obtained over the angular range 0p(c.m.) ~  110 to 1700 at two incident energies, Ep = 316 and 516 MeV. The results of a prelimi­nary data analysis are shown in Fig. 33-A0.40.2.  dcrt-dcri do-f+dcr*•"p+d —  d + p .  Ep= 316 MeV 0 Ep= 516 MeVO OO.* 0•1--- 1--------1--------»_ 1____ 1_____1_____1_____1-------120 140 160 19 c.m.Fig. 33. Measured asymmetries in p-d large angle elastic scattering.18036This experiment was undertaken in order to study the dynamics of nuclear reac­tions at larger momentum transfers (Q). The long-standing question is whether the nuclear wave function can supply the high momenta needed or if these have to be provided for externally through peculiar­ities in the reaction mechanism. The pd ■+ dp reaction is the simplest one where this can be studied and its diffe­rential cross-section (do/dfi) has been measured for a range of incident energies up to several GeV. The interpretation of the Ep and Q. dependences seems to require a change of reaction mechanism around 300 MeV. A nucleon exchange (NE) diagram [Remler and Miller, Ann. Phys.82, 189 (197*01 seems to be predominant below 300 MeV and is superseded by a nucleon-pion exchange (NE+PE) triangle diagram [Craigie and Wilkin, Nucl. Phys. Bl4, 477 (1969); Barry, Ann. Phys. 73,482 (1972)] [Fig. 3*+ (a) ] . The spin de­pendence in these reaction model approaches is very different. The NE diagram contains no explicit spin depen­dence, and the observation of asymme­tries indicates the presence of second- order effects; the interference between single scattering [SS, Fig. 34(b)] and NE is found to be an important origin of A for Ep < 300 MeV. The NE+PE diagram, on the contrary, contains potential sources of spin dependence to be that of the pp -+ dir vertex [see Fig. 34(c)].This reaction model implies [Kolybasov and Smorodinskaya, Sov. J. Nucl. Phys.17, 630 (1973)] certain similarities between the pd -+ dp and ]3p + d reactions which can be used to gain more detailed information about the importance of PE.The result of the present investigation is that the pd -> dp asymmetry at 316 and 516 MeV is much too large to have the pp ■+ dir vertex of the triangle graph as its single source. The present data and those of other experiments [Postma and Wilson, Phys. Rev. J2J_, 1229 (1961) ; Adelberger and Brown, Phys. Rev. D 5_,2139 (1972); Dolnick, Nucl. Phys. B23,461 (1970); Lapidus, Prov. VI Int. Conf. on High-Energy Physics and Nuclear Structure, Santa Fe (AIP, New York, 1975)1 (at Ep = 146, 198, 425 and 630 MeV) are used to compose a contour of A vs Ep and 0p (see Fig. 35). The asymmetry shows different character above and below «300 MeV; for instance, the maximum loca­tion of A (0) changes from 0p ss 155 to 0p wa 145° when pairing 300 MeV. There is a monotonic increase of the maximum A from Ep «  300 to Ep «  500 MeV but very little variation in the low-energy domain. The onset of PE exchange contributions could be a natural explanation of the changes taking place at «200 MeV. This approach, however, would require addi­tional sources besides the pp -+ dir vertex. The large asymmetries observed may be of second-order origin like the case for lower energies. The interference from SS-PE contributions [see Fig. 34(d)) (and possibly from the NE diagram at the low energy part of the range Ep > 200 MeV) could be the main source of the observed asymmet r i e s .Fig. 34. Contributions to p-d baok-angle elastic scattering discussed in text.Ep (MeV)Fig. 35. Contour^diagram of A vs Ep and 6p for the reaction pd ■+ dp.37Experiment 15Nucleon quasi-elastic scattering in nucleiCounter experiments have been completed which compare 12C(p,pn) and 12C(p,2p) at Ep = 200 and 400 MeV over a limited range of kinematic conditions. The 400 MeV data have been analyzed to yield binding energy values for the s- and p-state nucleons and distorted momentum distribu­tions. Figure 36 shows some results for the 400 MeV data. An estimate for the neutron detector efficiency was made by measuring the ratio of (p,pn) to (p,2p) events for deuterium. The results were in good agreement with values predicted using a modified version of Stanton's Monte Carlo code LJames e t a l .  , Nucl. Instr. and Meth. 142, 443 (1977); Stanton,COO-145-92 (Feb. (Nucl. Instr. and On the basis of found that the for 12C(p,pn) areOhio State Univ. report 1971); Edelstein e t a l.Meth. J00, 355 (1972)]. this calibration it was cross-sections observed larger than those expected from the 12C(p,2p) cross-sections and the known difference in the pn and pp cross-section by (35±9)?o. There are also small differ­ences in the shapes of the distorted mo­mentum distributions for p-state neutrons and protons in 12C which are not understood.In order to check this result and to ex­tend the energy range of the calibration an experiment has been performed to mea­sure the absolute efficiency of the neutron counters. The BASQUE neutron beam and LH2 scattering target were used, and n,p scattering in the LH2 target was200 200100 100co100ok-o100LLi~oIG■oG“O100 100L R = 90MeV 85MeVEi = 108MeV84MeV Ei = 77MeV102M eV78MeV Ei = 69MeV7  E, = 96MeV6L degrees61_ degrees0Fig. 36. The distributions in (a) correspond to the removal of a p-state nucleon from 12C while the distributions in (b) correspond to the population of states with excita­tion energies near 20 MeV (the energy for removing the nucleon from being about 40 MeV). The curves represent FWIA predictions for the (py2p) (solid line) and (pypn) (dashed line) reactions.38observed using a pair of neutron counters set at conjugate angles. The apparatus detected conjugate protons and scattered neutrons separately. The data are nearly analyzed now, and it appears that they will be in agreement with the predictions from the Monte Carlo code.Experiment 58 Polarized (p,2p) reactionThe complete set of data on 160(p,2p) and 12C (.,2p) at 200 MeV has now been analyzed. The 160 data agree with the group's DWIA calculations using optical model param­eters derived from the prescription of Seth [Nucl. Phys. Al38, 61 (1969)]. (See Fig. 37(a).) This prescription was ob­tained from measurements made on nuclei with A 40 and gives optical model parameters for 160 which yield total reaction cross-sections too large by a factor of 2 at 100 MeV and 1.5 at 50 MeV. When optical model parameters which give an approximate fit to 150 elastic scatter­ing data and correct total reaction cross- sections are used in the DWIA code the predicted ls0(p,2p) cross-sections are too large by a factor of 3- (See Fig. 37(b).) The group has been unable to find optical model parameters which simultaneously give agreement with (p>,2p), elastic scattering and total reaction cross-section data. This anomaly is not understood at the present time.The 12C(p,2p) data will be combined with measurements made as a part of Exp. 15 to compare 12C(p,2p) and 12C (p,pn) at 200 MeV incident energy.During the summer 10 shifts of polarized beam time were used to look at the 2S state in 40Ca. This state is separated by 3 MeV in energy from the ID states on either side of it. Because this energy separation was about at the limit of the energy resolution achievable with the sodium iodide crystal detectors, kinemat­ic conditions were chosen such that the recoil momentum was kept close to zero. This configuration enhances the S states and suppresses the D states. The asymme­try and cross-section were then measured as a function of c.m. proton-proton scattering angle to see if the asymmetry is the same as in free proton-protonEnergy (MeV)Fig. 37. (a) Measured asymmetries as a func­tion of the energy of one of the outgoing protons for the reaction l^0(p,2p) with the angles of the outgoing protons 0!=e2=30°. The full lines are the results of DWIA calcula­tions done with optical model parameters derived from the prescription of Kiran Seth. The dashed lines are the results of DWIA cal­culations with optical model parameters derived from fitting 1 5 0  elastic scattering and total reaction cross-sections at 100 and 50 MeV. (b) Measured cross-sections (in \ib per sr2 per MeV) for the reaction ^&0(p,2p) with 0i=02=30°. The full and dashed lines are as in (a), except that for the dashed lines the DWIA cross-sections have been divided by 3.scattering (the 'Maris' effect asymmetry should be zero for S states). Thus the experiment was a comparison of proton- proton scattering inside the 40Ca nucleus with free proton-proton scattering.Preliminary results [see Fig. 38(b)] indicate that the 2S asymmetry is quali­tatively similar to that observed from free hydrogen. The observed asymmetries39Angle (degrees)Fig. 38. (a) Measured asymmetries forl°0(p,2p) as a function of the angle of one of the outgoing protons with the other angle held fixed at 30°. The energy difference of the two outgoing protons is 80 MeV. The full and dashed lines are as in Fig. 37(a).(b) Measured cross-sections for 2p)under the same conditions as (a). The full and dashed lines are as in Fig. 37(b).of the two ID states are opposite in sign, in agreement with the predictions of the 'Maris effect1, and there are in­dications that the 1p3/2 state has been observed [see Fig. 39(a)]. It will also be of great interest to see if the 40Ca data show the same normalization anomaly noted in 160, i.e. no single set of optical model parameters could simultane­ously fit the 160(p,2p), elastic scatter­ing and total reaction cross-sections.There is much more data on 40Ca elastic scattering and total reaction cross- sections than there is on 160, and sokOFig. 39. (a) Events observed as a function ofmissing energy (incident energy less the sum of the energies of the outgoing particles) for the reaction l*°Ca(p32p) with the angles of the outgoing protons Q\=30°, 02=64°. The diffe­rence in energies of the outgoing protons was such that the recoil momentum was ~100 MeV/c. Hence the 1=0 states are suppressed relative to 1^0 states.(b) Events observed for the reaction >*0Ca(f>,2p) under the same conditions as (a) except that the difference in energies of the outgoing protons was such that the recoil momentum was ~0 MeV/c. In this situation 1^0 states are suppressed relative to 1=0 states.the optical model parameters for l+0Ca are much better determined. It will be interesting to see how the DWIA calcula­tions using these parameters compare with the results of the analysis of the L+0Ca(^,2p) data.It should be mentioned that Daphne Jackson's group at the University of Surrey is making a theoretical investiga­tion of quasi-elastic scattering of polarized protons, including for the first time spin-orbit distortion effects. Pre­liminary results from this group also suggest that quasi-e1astic processes may be a good way of investigating off-shell effects in nuc1eon-nuc1 eon scattering.Experiment 59The (p,2p) reaction o n 4He and3HeDuring the past year the investigation of p-p quasi-free scattering on 4He was ini­tiated. Using a 96-5 mg/cm2 liquid 4He target, energy-sharing spectra at 500 MeV incident energy were measured at coplanar symmetric angle pairs 0[_ = 9w = 40° and 0L = 6R = 58°. The energies of the out­going particles were measured with Nal(TL) detectors, passing counters (plastic scintillators) provided dE/dX values and time signals, and multi-wire proportional chambers measured the emission angles.recoil cross-sections measured at these energies have been included in the figure. The TRIUMF data appear to resolve the discrepancy between the two results in favour of the SREL data. Roos [Phys.Rev. C 3_, 2437 (197**)] and Frascaria e t a l. [Phys. Rev. C J_2, 243 (1975)] have analyzed the 1*He(p,2p)3H data from six experiments between 65 MeV and 590 MeV in the distorted-wave impulse approximation. The calculation agrees only with the 590 MeV data whereas, if the calculation is renormalized by a factor 0.5, it agrees with the other five data points. Thus, our corroboration of the 590 MeV result shows that these calculations can­not attain consistency over the entire energy region (either due to an improper choice of optical potentials or due to a failure of the DWIA to describe the reac­tion mechanism). Planned measurements of the energy-sharing distribution and the symmetric angular distribution at 350 MeV will provide valuable information on the energy dependence of the discrepancy between the theoretical and experimental quasi-free cross-sections.The energy-sharing distribution at the quasi-free angles 0|_ = 0w = 40° contains the point of zero recoil momentum.Through measurements in three consecutive energy bites— corresponding to different combinations of copper degraders in front of the stopping counters— it was extended to momenta in the 300 MeV/c region, fur­ther out in the tail of the single-particle momentum distribution than in any previous 1+He(p,2p) experiment. The preliminary results from the first two energy bites are shown in Fig. 40. The measurement at angles 6|_ = 0r = 58° constitutes a second data point on the symmetric angular dis­tribution at 500 MeV, which will be fully measured in a next experiment. Informa­tion about the momentum distribution of the p+3H system in ^He will be extracted using both PWIA and DWIA calculations.Since the data extend well into the tail of the momentum distribution, they should serve as a sensitive probe of the ^He single-particle ground state wave function.Earlier data on the 1+He(p,2p) reaction above 200 MeV are available from the 590 MeV experiment at SREL [Perdrisat e t a l. , Phys. Rev. 187, 1201 (1969)] and the 460 MeV Chicago experiment [Tyren e t a l. , Nucl. Phys. 79., 321 (1966)]. The zero_QE\—cjpq (MeV/c)1.01.4_1 1 ■ ■ _ ■ ~ ---  ■4He (p ,2p) 5H at 500 MeV1.2 -1 A l I I j 5 IsL e sw = 4 0° x SREL1.0 T Chicago0.8 “ I{0.6 - 5 5 S o0.4 1 2  o0.2 n n~i i 1 1 .. . 1.220 240tL (MeV)Fig. 40. The energy-sharing distribution of the ^He(p,2p) reaction for 500 MeV incident protons at quasi-free scattering angles di=Qp=40°. The momentum of the struck pro­ton in the initial p+3H system is indicated along the top of the figure. The results shown are from a preliminary analysis which does not yet include data at higher momentum values.41Experiment 3The characteristics of fragments emitted fromsilver with 200 - 500 MeV protonsThis study is designed to collect experi­mental information on the processes lead­ing to the emission of fragments (A >  A) in medium-energy reactions by detecting the fragments directly. This information can be used as a basis on which to formu­late the possible mechanisms involved in fragment emission and also should lead to a better understanding of energy equili­bration in the residual system after an initial energetic interaction.Standard AE, E and TOF measurements are used to detect and identify these frag­ments. A 5_detector 1AE , E 1 telescope has been used to measure a wide range of particles and energies simultaneously.The low energy cut-off, due to the first12.9 y detector, is well below the Coulomb barrier for particles through Ne. However, range limitations of the total 1600 y detector stack limit the higher energy portions of the spectra for iso­topes up to and including 7Be. The 12.9 y detector is capable of giving adequate isotopic separation through the Be iso­topes but is only able to give element separation for B and above. It is there­fore necessary to use TOF techniques to separate the isotopes of these heavier elements.The first stage of this project is essen­tially complete. This includes a general survey of fragment emission from a medium mass target, A g , with 210, 300 a n d'480 MeV protons. Double differential cross-sections were measured at 20°, 90° and 160° at the three energies, and iso­topic resolution was obtained for He-Be with elemental resolution for B-Na. These measurements have given a general indica­tion of the features of fragment emission in medium-energy reactions but also they have given specific information about the fragmentation process which was unexpected.The most dominant new result is that the data have clearly identified two or more different processes involved in fragment production. In line with the convention­al notions of the cascade-evaporation mechanism, one can identify a fraction of the particle emission due to a statisticalisotropic evaporation process resulting from the de-excitation of the excited nuclei produced by the initial cascade. With a new evaporation calculation based on the simple Weisskopf evaporation formalism and which includes the general features of the excited nuclei predicted by cascade calculations and which appro­priately corrects for kinematics and tar­get thickness, appropriate sections of the particle spectra can be reproduced with surprisingly good fits considering the crude assumptions of the calculation. This is done with only three parameters: a fractional Coulomb barrier determined from the fall-off in cross-section at the lower energies and determined to be 0.90, a mean excitation energy given by cascade calculations to be 75 MeV, and a Fermi level density parameter determined from the data to be 20 MeV-'*', in line with published values. Although this is not an absolute calculation, it does scale as a function of angle and bombarding energy. It can also be used to determine the rela­tive probabilities for the different fragments measured. Figure Al shows the case for ^He produced by 300 MeV protons on Ag. It is clear from the figure that there is a major part of the cross- section which cannot be explained by this mechanism. The 4He case is very illus­trative because it clearly shows both processes to be important. Other cases tend to have one or the other dominating: for example, 3He and 7Be are almost ex­clusively produced by other mechanisms. Since there is this significant difference f r o m  i s o t o p e  to isotope, it is i m p o r t a n t  to resolve each isotope before making any comment on the relative importance of the traditional evaporation mechanism in the production of the isotope.When the results are anal yzed by plotting cont ours of constant re 1 a t i v i s t i c a11y invariant cross-section versus the t r an s­verse mo me nt um per nucleon and the rapid­ity variable y = 1/2 An [ (,E + P n ) /(E - P n ) ] ,  several points can be deduced which are model independent:(a) Since circles in this display (see Fig. A2) indicate isotropic emission from a system of rapidity centred at the origin of the circle (within minor modifications due to distributed emitting velocities), it can be shown that in fact the region ofA2ENERGY [MeV]Exp. 41. Energy spectra for 3fle fragments at 20, 90 and 160° from 300 MeV p on Ag. Also shown are an evaporation calculation and a calculation which, while difficult to inter­pret physically, fits the non-evaporative parts of the spectra.of invariant cross-section attributed to evaporation is consistent with isotropic emission. As the cross-section decreases to where the evaporation calculation can no longer predict the values, the contours start to deviate from pure circles imply­ing some non-isotropic emission. Although the ^He case seems to indicate agreement with circular contours for all values of the cross-section, closer inspection of the data reveals a decided deviation at the lower contour levels. In addition, the values for some fragments, such as 3He and 7Be, deviate substantially in all regions of cross-section.Fig. 43. .Invariant cross-section (in nb/(sr'MeV) (MeV/c)) versus source rapidity ("=£! of evrltting source), as defined by fitting symmetric distributions from moving sources to data points of the given invariant cross- section (as in Fig. 42). The dashed 4He extension is for an isotropic distribution fit to 90° and 160° data.yFig. 42. Sets of data points of constant in­variant cross-section in the y, px c/mc2 plane for 3He and 4He fragments from 300 MeV protons incident on Ag; px is the transverse momentum of the fragment, m is its mass, and y = 1/2 iIn ((E+p„c)/ (E-p„c)) is its rapidity where E is the fragment total energy. Fits for isotropic emission from sources moving in the beam direction are shown with labels indicating in­variant cross section in nanobams/((MeV/c) (MeV/sr)). Solid circular curves are fits to 20° and 160° data points; dashed circular curves are fits to 90° and 160° data points.(b) If a plot is made of the log of the invariant cross-section versus the rapid­ity about which the cross-section is symmetric (see Fig. 43), it becomes clear that as the cross-section decreases the emitting mass involved in any dominant statistical process must decrease. These plots are consistent with a notion that"s o u rce  r a p id i t y "43average momentum transfer of — 1 /2 of the maximum is taking place to masses ranging from the target down to the mass of the emitted fragment. This would imply that fragment emission can take place at each step from the initial interaction of the incoming proton to the final statistical configuration when the energy and momen­tum of the proton has been equilibrated throughout the target nucleus. That is, there is a constant and smoothly varying probability of fragment emission during the time it takes the nucleus to equili­brate the deposited excitation energy and momentum. If this can be verified by further analyses of the data and experi­mentation, it would be a step in the understanding of not only the process of fragment emission but also of the energy deposition and equilibration processes.These results have made it just that much more important to resolve individual iso­topes of higher masses. This work has begun, and we have already been able to show that, for example, 12-15C have similar spectra but that 10-11C are de­cidedly different in that they have components of high-energy tails not ob­served in the heavier carbon isotopes. Furthermore, it also becomes important to collect more angular information so that the non-isotropic components can be resolved. In addition, the measured energy range must be extended for the lighter nuclides (A 7) so that the data can be obtained to indicate limiting rapidities for these isotopes. At the same time, a thicker telescope would per­mit the measurement of the H isotopes over a sufficient range to be useful for studies of relativistic heavy ions where some of the current suggested models (coalescence or thermodynamic and fire­ball models) rely on the shapes and mag­nitudes of the hydrogen spectra at inci­dent energies per nucleon of A00 MeV and above.kkExperiment 6Intermediate-energy fissionProgress in this experiment during 1977 was a 1ong two 1i nes:The energies and differential time of flight were measured to good statistics for the systems A u , Bi, Th and U plus 235 and A80 MeV protons. These data were taken for correlated fission fragment pairs, when the correlation angle was (i) 180°, (ii) near the peak of the angu­lar correlation function (measured in each case), and (iii) at a correlation angle near the forward extreme of that function. In addition, the angular dis­tribution of fission fragments was mea­sured with respect to the beam direction. The data collection program is almost complete. The data are being analyzed to extract fragment mass distributions, total energy release distributions, fissioning system momentum distributions and fission moments of inertia for com­parison with theory. Figure kk shows the distribution of fissioning system c.m. momentum measured for U + 235 MeV protons, compared with that calculated via the VEGAS intranuclear cascade code.Fig. 44. Experimental configurations employed. The telescope used for measurement of evapo­rated particles consisted of 27, 500 and 250 y thickness transmission detectors. Fission fragments were measured by heavy ion detectors.Fig. 45. The distribution of fissioning sys­tem a.m. momentum measured via the fission fragment-fission fragment angular correlation, compared with the a.m. momentum distribution calculated via the VEGAS code for reaction products at the end of the intranuclear cas­cade (a) for Au+480 MeV protons, (b) for U+480 MeV protons.T 13 12 l 1 n I 1 ! 1* i j j  2 l f 3ll* i* l 1 11 !i 1 1 i Mit LThe energies and angular distributions have been measured for evaporated light charged particles observed in coinci­dence with fission fragments from the above fissioning systems. This year emphasis was placed on measuring binary fragment-charged particle coincidence events (rather than the trip1e fragment- fragment-charged particle events studied last year). Charged particle spectra have been measured at a constant angle of 135° to the beam direction, in coin­cidence with fission fragments observed at 180°, 120° and 90° tothis direction.Data-taking in this program is approxi­mately 50% complete. Some dataare shown in Figs. 45 to 47. Comparison of the data for a bismuth target with those for a uranium target reveals no strong dif­ference in the angular distribution of the recorded alpha particles with re­spect to the fission axis. This is in conflict with the expectations of the stat i st ica1 model.Fig. 47. The energy spectra of He isotopes emitted (a) at 135° from a Bi target, (b) at 112° from a UF4 target, in coincidence with fission fragments. The fission detectors were located (a) 60°, 90° and 180° (b) 45°, 90° and 180° with respect to the position of the He particle telescope.f is s io n  fra g m e n t EFig. 46. Light particle-fission fragment co- incidences from the interaction of 500 MeV protons with bismuth. Shown is the energy of the fission fragment vs the difference in time of flight between the fission fragment and the coincident light particle. The telescope and heavy ion detector were at 135° and 45° with respect to the beam.He -  ISOTOPE ENERGYExperiment 11Nuclear spectroscopic studies of short-lived radioactiveproducts o f high-energy reactionsThe emphasis here is directed towards studies of short-lived nuclides not easily performed at ISOL facilities, yet feasible with techniques developed here coupled with unique characteristics of TRIUMF,i.e. high intensity, variable energy pro­ton beam. The techniques developed and in use include a gas jet recoil transport system for transporting simultaneously a broad range of short-lived (~ seconds) products, roughly independent of Z, from thin targets (allowing use of isotopical- ly enriched target materials). The gas jet can form very thin sources useful for alpha and beta spectroscopy studies. De­tection systems have been assembled to allow initial Z identification (X-ray-y, X-ray-a coincidences), Q.g measurements (AE-E plastic scintillation telescope), half-life measurements (tape transport system) coupled with appropriate computer- based, multi-parameter data acquisition systems. A TOF mass identification sys­tem is being installed and a gas phase thermochromographic chemical separation cell is under design for Z identification. The gas jet production cell has been uniquely designed to handle up to six targets in the high radiation fields.These systems in l977 were devoted to studies of the Qg valu es of high neutron- ex ce ss prod ucts resulting from high- energy proton-induced fission of uran ium and to measurements of the spallation yields of known, shor t-lived alpha emitters in the rare-earth region.In the Qg studies the AE-E plastic tele­scope, operated in coincidence with specific gamma rays from known fission products, was used to measure new Eg values from about 15 isotopes including 100-104Nb; 104-1060.  and 115-118A g .values for comparison with mass formula predictions were deduced for those nuclides in which information was avail­able on their decay schemes (see Table VIII for preliminary results). In addition half-lives were measured for new isotopes 105Nb (T 1/2 = 1.4 ± 0.2 sec) and llsRh (T 1/2 = 1.6 ± 0.2 sec) through the growth of their daughter activities.In the measurement of spallation yields of known short-lived alpha emitters data has been obtained from the irradiation of a variety of targets (Tb, Ho, Tm, Ta, Re, Ir, A u , Pb and Bi) with 480 MeV protons. Radioactive products were transported with ethylene clusters in the gas jet system as this provided minimal material deposits and optimal resolution of ob­served alpha peaks. Species, e.g. 155Yb, with a AA (difference between target and product nuclide) as high as 36 and with a calculated cross-section from the Si1berberg-Tsao code as low as 0.3 yb have been observed. These data are being transformed into absolute cross-sections for comparison against various calcula­tions, e.g. Julian code. The transit time of the gas jet system was studied by operating TRIUMF in a pulsed mode, and values from 0.7 to 1.25 sec were obtained as a function of the flow rate. Thick target-thick catcher studies, to estimate the effective target thicknesses for heavy spallation products, indicated that the recoil range increased linearly withAA of the product.Table VIII1 sotope °-B (MesV)" N b m 3 36 + 0 .05i°°Nb (high spin) 6 57 + 0 .0 8100Nb 6 17 + 0 .15101Nb 4 5 ± 0 .1i0 2Nb (h i gh spin) 7 2 6 + 0 .1102Nb ( » ) 6 63 + 0 . 1114Ag 4 78 + 0 .15115^gm (>)4 48 + 0 .1116Agm 5 4 + 0 .1117Ag 4 2 8 + 0 .0 8118Ag U ) 5 5 + 0 .346Experiment 89p~ capture in fissile nuclidesThis experimental program is intended as a comprehensive study of the interaction of muons with fissile nuclides. The primary goal is to use the muons to probe the fission barrier, in particular the double-humped barrier that produces the so-called shape isomeric state. The specifically measurable parameters are the energy of the back-decay y rays (which will give the ground-state energy of the isomer), and the forward (fission) and backward decay rates (which are sensi­tive functions of the barrier shape).Theoretical estimates [Bloom, Phys. Lett. 48B, 420 (1974); Bloom, private communi­cation; Leander and Moller, Phys. Lett.57B, 245 (1975); and Moller, private communication] and recently reported mea­surements from Dubna [Ganzorig e t d l . ,JI NR preprint E 1 5~9365 and abstract to 7th Int. Conf. on High-Energy Physics and Nuclear Structure] and from CERN [Fromm e t a l . , Nucl. Phys. A278, 387 (1977)] are very encouraging in their indication of the feasibility of studying the fission isomer using the intended approach. However, the body of experimental results to date is primarily on 238U and is either of very low statistical precision or has significant internal inconsis- tenc i es.In pursuing its primary goal the present work will analyze inter-correlations in the time and energy spectra of X-rays, y rays, and fissions associated with muon stoppings, thereby producing also a set of internally consistent and more precise measurements of a number of y-- capture parameters. The total muon flux and beam spill characteristics make TRIUMF ideally suited for these measure­ments .Experimental preparation was begun this year. A multiplate fission chamber was designed, constructed and tested. The chamber is of a modular design consisting of a stacked sandwich of alternating layers of avalanche chambers and thin U targets. It contains a total of ten targets, each 6.25 cm diam, and with a U thickness of 5 mg/cm2 , giving a total U mass of 1.5 g. The ratio of U mass: total mass (including counter end windows)is approximately 0.3- The chamber was tested in a short preliminary run in September. It gave a time resolution under beam conditions of 3 nsec (FWHM). A flat discriminator plateau was obtained for the net y~-correlated fission rate, indi­cating that the counting efficiency equalled, or approached, its geometric value of 4EEI In the course of these tests the time distribution of fission follow­ing y" capture was measured, and a pre­liminary analysis of the data gave the fol1ow i ng resu1ts:1. if (mean life of y" and 238U measured by fission) = 76.6 ± 1.3 msec;2. prompt fissions/delayed fissions =6 .6%.These results are in excellent agreement and of comparable precision with earlier measurements. No short-lifetime com­ponent was observed and this preliminary data analysis set an upper limit of 2.4% (2o) for such a component.Experiment 108Meson cascades in elemental targetsThe X-ray intensities in mesic atoms are not yet completely understood. In the case of kaons the intensities of kaon X-rays per stop have been observed [Godfreyand Wiegand, Phys. Lett. 56B, 255 (1975); Godfrey, LBL thesis 3857, May 1975] to vary with Z in a way similar to the periodic table. In the case of pions there have been three unpublished studies: the LAMPF work [Hargrove and Leon, LAMPF Proposal, February 1975], an early study [Kunselman, LRL report 18654 (1969), unpublished] which shows variations over a small range of Z, and recent TRIUMFwork which is described below.In August pionic X-rays were measured for fifty-seven elements between approximate­ly 10 keV and 500 keV. Typically two or more transitions with principal quantum numbers between 1 and 11 were seen for each element. The targets were packaged in elemental form in 10 cm diam discs, some with thin mylar windows, depending on their physical properties. The discs were mounted, eight at a time, in a remote- controlled target wheel which was situ­ated in the M9 100 MeV/c ir~ beam. X-rays were detected in a hyperpure Ge detector47gated by a stop signal from a typical scintillator telescope. The detector and target apparatus were obtained from Lawrence Berkeley Laboratory.In analysis of the data thus far prelimi­nary results have been obtained for the 6-5 transition which was observable for 30 < Z < 75- The X-ray yields have been corrected for counting system dead time obtained from a pulser, for detector effi­ciency variations, and for self absorption in the 2 g/cm2 target.Experiment 46Magnetic hyperfine splitting inpolarized 209Bi atomsMagnetic hyperfine splitting in muonic X-rays is known as a sensitive measure of the spatial distribution of nuclear mag­netic moments. Such a measurement is particularly interesting in 209Bi in the light of mesonic exchange current effects on orbital magnetism [Yamazaki e t a l. , Phys. Rev. Lett. 2S_, 547 (1970)]. To date, all experiments of this kind have been made by looking at the broadening effect in the muonic X-ray spectrum, since the magnetic hfs is comparable to the Ge(Li) detector resolution.The proposed new technique [Nagamine and Yamazaki, Nucl. Phys. A 2 19, 104 (1974)] is to use polarized targets and polarized negative muons to selectively populate one of the two hf components of the 2pj/2 level. Thus an enhanced line intensity can be induced in one of the two extreme hf lines (F=5 -*■ F=4 or F=4 -> F=5) , by a relative change of polarization direction. In this way a precise number for the hf splitting can be obtained without having to improve the detector resolution. Polarized 209Bi targets have been realized by the Tokyo group [Koyama e t a l. , Hyperfine Interactions 5_, 27 (1977)] using a ferromagnetic BiMn compound. In an exploratory data-taking run at TRIUMF a large BiMn crystal of 25 mm diam and 15 mm thickness was successfully cooled by the dilution refrigerator for 30 h down to 95 mK in a 7 kG external field, corresponding to better than 50% polariza­tion.However, it was not possible to accumu­late a sufficient number of events to complete the experiment in the allotted time and with the proton beam current available. In addition the Ge(Li) detec­tors were damaged by neutrons from S E i  capture in the collimator and in the ranging material which was used to puri­fy the m beam. However, a shift of the centroid of the 2pj/2 level due to re­versing the target polarization was observed. The magnitude of this shift confirms that given the planned improve­ments in intensity and purity of the beam, the polarization method will pro­vide more accurate values of the hf splitting constants than conventional techn i ques.48RESEARCH IN CHEMISTRY AND SOLID-STATE PHYSICSExperiments 35, 60, 71, 91 Muon spin rotation in solidsI nt roducti onMuon spin rotation (ySR) is still a rela­tively new field, despite its rapid growth in the last few years; thus, while the basic techniques of ySR have been described in previous annual reports some introduction to its applications in condensed-matter physics is appropriate here. Briefly, the y+ plays the role of a positive impurity ion in a crystal, taking up an interstitial or substitution­al position and sometimes (in nonmetals) capturing a single electron to form muonium (y+e~ or Mu); in contrast, the y~ is captured into a close orbit about a nucleus at a lattice site, creating in effect a somewhat enlarged substitutional nucleus of charge Z-l. Thus these two probes provide quite different informa­tion, and will be discussed separately.y-SRThe information available from y“SR is analogous to that obtained from NMR or PAC with (Z-l) impurity nuclei (e.g., in MnO, y-0 looks like a 16N nucleus substi­tuted for 160). The motivation for using muons in such studies lies in the dis­tinctive differences between (y_Z) and (Z — 1) : First, there may not be an iso­tope of (Z-l) suitable for use with NMR or PAC, or there may not be a way of implanting it into the lattice nondestruc- tively; in these cases y"Z provides unique information. Second, the y"Z 'pseudonucleus' has a different size and magnetic moment distribution, especially for Z < 50, than the corresponding (Z-l) nucleus; in cases where (Z-l) can be studied, this provides a unique opportun­ity for study of the spatial variation of crystal hyperfine fields at the lattice sites, the so-called 'hyperfine anoma1y '.y+SRThe behaviour of the y+ in solids is es­sentially that of a light isotope of hydrogen; if there were another H isotope of similar mass (m^/9) with which onecould perform NMR and EPR experiments on a single nucleus at a time in a macro­scopic metallic sample without an applied RF field, there would perhaps be little excitement over the applications of y+SR in solid-state physics. However, there is no such isotope; moreover, NMR requires application of an RF field penetrating deep into a sample containing ^1018 nuclei. Thus y+SR is useful in many situations where proton NMR provides com­plementary information, and in more situ­ations where no comparable probe is ava i1a b 1e .In any observation of microscopic phenom­ena none of the interactions of the probe with its environment can generally be neglected. If the y+ senses the collec­tive effects of a large number of atoms (e.g., the Lorentz field in a magnetic metal), then it truly samples the intrinsic properties of the crystal; more often— and usually more interesting — the y+ senses local effects (e.g., the hyperfine field due to a contact inter­action with screening electrons) which are in turn influenced by the presence of the y+ . In these cases it is the 'extrinsic' behaviour of the muon-lattice system which is studied.The self-consistent problem of probe- lattice coupling is certainly not unique to y+SR. In fact, the simplicity of the y+ probe is unparalleled; the muon is a Dirac point-charge with spin 1/2, no nuclear quadrupole moment, and no polari- zable core electrons; it is used in the ultimate dilute limit (one at a time) where probe-probe interactions are total­ly absent. Thus the y+-lattice system is a testing ground for theoretical models of impurity states. An improved understanding of such couplings allows more confident extraction of the intrin­sic crystal properties from the experi­mental data. More important, it leads to a deeper understanding of the effects of impurities in crystals, which are of practical significance in solid-state physics. There is, after all, no such thing as a pure crystal in the real world, and many of the most distinctive properties of sol ids (e.g., the electrical^9properties of semiconductors or the mag­netic properties of metals) are qualita­tively affected by impurities.As the worldwide effort in y+ SR expands (the number of groups working in this field has approximately tripled in the last two years) it becomes more and more obvious that muons can be used to study virtually any solid. However, ySR is ex­pensive; we are thus obliged to restrict the scope of our studies. Our primary objectives have been threefold. First, we have initiated selected 'pilot studies' on systems which seem promising. Second, we have closely examined those systems which promise to yield the clearest and most complete understanding of the y+ - lattice interaction— where the muon goes (substitutional or interstitial sites; defects?); what it does when it gets there (diffusion?); how electrons and lattice ions respond to its presence (screening, bound states, distortions). Third, we have exploited situations in which it is already possible to extract information about the intrinsic properties of the crystals from y+ SR data, and in which no other probe can provide the same informa­tion.Progress in 1377 y~SR (Experiment 71)TRIUMF does not yet have a polarized y" beam of very high flux. The best is M 9 , which produces ~100 y_/sec*cm2 at 10 yA when tuned to minimize e” contamination. Experimentally, y"SR is intrinsically rate limited in two ways: The asymme­tries are always lower than in y+ SR (~6% maximum), requiring higher statistics, and a large fraction of the muons (up to 95% in high-Z elements) capture instead of decaying and are thus lost to y“SR.In the more difficult cases it takes ~100 times as many y- as y+ to obtain the same statistical precision. Fortu­nately, this is not always necessary, and useful information (especially pre­cession frequencies) can be extracted from data with low statistics. Neverthe­less, y"SR is only practical at beam intensities of >10 yA.In 1977 the number of available shifts at 10 yA was limited by shutdowns, acti­vation limits, and the requirements ofthe y->ey experiment. Thus y_SR has again been postponed in favour of y+ SR, which can be applied more efficiently at low rates.y+SR in ferromagnets (Experiments 71, 78)Our continued y+ SR studies of Fe, Co and Gd have been reported at several symposia and conferences (Symp. on Chem. and Phys. Appl. of Positron and Muon Spectroscopy, ACS meeting, New Orleans, March 1977;Int. Symp. on Meson Chemistry and Meso- molecular Processes in Matter, Dubna,USSR, June 1977; IVth Int. Conf. on Hyper­fine Interactions, Madison, N.J., June 1977; Conf. on the Physics of Transition Metals, Toronto, August 1977) and in several papers. This effort has contrib­uted to an improved understanding of how the y+ behaves in metals. First, studies of the local field at the y+ in Co and Gd have shown that the dipolar field component is classical (that is, without exotic enhancements) and that the muon occupies the octahedral interstitial site. From this conclusion the data were further reduced to give the temperature dependence of the hyperfine field B^f, which in these metals deviates from that of the saturation magnetization Ms in a sense opposite to the deviation in Ni, as can be seen from Fig. 48. This be­haviour is indicative of the mechanisms involved in y+ screening and contactT /TcFig. 48. Deviation of the temperature de­pendence of the hyperfine field at the y+ from that of the saturation magnetization for several ferromagnets.A(T) = (Bhf(T) -Ms (0) )/(Bhf(0) -Ms (T) .50TEMPERATURE (K)lO O rO O  o O O  O rOCJ —O O o/i.+ in Fe10-!7meVidfe2 i.oh/ fj / * "<X<'° ♦—  56 meV0.1 ■0.01 0 10 20 30 4 0oCM4  CECM-Vitry §  NR IM -Tokyo10'10'10'10'ozCL50l /T  x 10s (K '1) ,  INVERSE TEMPERATUREFig. 49. Temperature dependence of the y+ relaxation rate in Fe single crystals.Fig. 50. Knight shift as a function of susceptibility for y+ (open circles) and ^ M n  (solid circles) in paramagnetic MnSi.interactions with polarized conduction electrons. The values of (,T=0) inthese metals continue to stimulate theo­retical activity. A second clarification has come from our study of y+ relaxation in ultra-pure Fe crystals. Last year we found relaxation rates in pure Fe single crystal which were much slower than those seen in a different study at SIN. Since a y+ at rest would relax very rapidly in local dipolar fields, slow relaxation reflects 'motional narrowing'; our results were attributed to easier diffu­sion resulting from the higher purity of our Fe crystal. Accordingly, we borrowed an ultra-pure single crystal of Fe from VITRY in France and repeated the measure­ments, finding still slower relaxation! Relaxation rate data for y+ in Fe are summarized in Fig. ^9. In both cases the relaxation levels off at low temperature; this is taken as evidence for diffusion by quantum tunneling, which joins with extensive new data on y+ diffusion in nonmagnetic metals to support a general model of quantum diffusion of y+ in metals. In this model y+ diffusion is extremely sensitive to dilute impurities, and ultra-pure crystals are essential; however, the model predicts that it is impossible to observe quantum diffusion of protons in similar metals because of even more exaggerated sensitivity to im­purities. In Dubna the opinion was ex­pressed that the y+ was the o n ly probe that would ever allow direct experimentalobservation of this type of coherent quantum diffusion— a controversial phenom­enon in the theory of hydrogen in metals.y+SR in magnetic alloys (Experiment 71)In the last few months of 1977 we studied several new systems with the y+ . In N i Cr the temperature dependence of B^f was measured and compared with that in pure Ni, which shows anomalous behaviour compared to Fe, Co and Gd (see above). In PdMn the temperature dependence of the y+ relaxation time was used to observe the 'spin glass' ordering phenomenon. This work is closely related to earlier studies of giant moments and RKKY interactions, and represents one situation in which the y+ directly probes 'intrinsic' properties. In the 'itinerant' helimagnet MnSi the y+ Knight shift and relaxation rate were measured in the paramagnetic phase between 28 K and 300 K, and H^f was mea­sured in the ordered phase. A very large Knight shift of -30% was found at 30 K.As can be seen from Fig. 50, Ky is found to vary linearly with the susceptibility X ,  in agreement with NMR studies of Kfg; however, unlike K^, Ky extrapolates to 0 at x=0, suggesting that the y+ inter­acts o n ly with the itinerant electrons.NMR has been unable to explore the same temperature region in MnSi.51li+ SR in ant i ferromagnet i c insulators: MnO (Exper iment 71)The y+ Knight shift and relaxation rate were measured in the paramagnetic phase of this typical antiferromagnet and found to be small, in contrast with dramatic effects recently observed at SIN in a-Fe20 3 (rust) .y+SR in semiconductors (Experiment 91)A brief study of y+ SR frequency spectra in Si at various temperatures and fields led to the refutation of an earlier re­port of temperature-dependent frequencies for the ground state US) of the bound Mu atom in Si. We also observed Mu (IS) at A.2 K, where groups at SIN and SREL earlier reported a disappearance of the precession signal; y+SR frequency spectra for several magnetic fields at h .2 K are shown in Fig. 51- We now think that Mu (IS) is a relatively simple, predict­able system in Si, and can proceed to a study of excited, 'sha11ow-donor' states Mu*, which should have some bearing on the electrical properties of hydrogen impurities in Si crystals.y+SR in insulators (Experiment 60)The diffusion constant of Mu in Si02 was measured in a study of the behaviour of y+ and Mu on powdered insulators. At room temperatures the diffusion constantFig. 51. Field dependence of Mu and Mu* signals in Si at 4.2 K.is D = (2.2 ± O.A) x 10-7 cm2/sec. In larger quartz crystals we found a split­ting of the low-field (A.5 G) muoniurn precession frequency, which can be taken as tentative evidence for an interaction between the crystal field gradient and the electric quadrupole moment (!) of the Mu atom.Experiment 35 Muonium chemistryGas phase studies1977 saw two major developments in the study of gas phase muonium (Mu) reactions: one experimental, the other theoretical. Experimentally, the first determination of an activation energy for a chemical reaction of muonium in any medium was made at TRIUMF for the gas phase reac­tions: Mu+F2and Mu+C£2 between 300 and 400 K. Theoretically, the first detailed calculation of a muonium reaction was performed by a group in Europe for the Mu+F2 reaction [Conner e t a l., Chem.Phys. Lett. k$_, 265 (1977)]. Connor showed that quantum mechanical tunneling dominates the Mu reaction at 300 K and predicted an apparent activation energy of 1.1 kcal/mole for the Mu reaction and 2.1 kcal/mole for the analogous H atom reaction. The experimental data summa­rized in Table IX is in excellent agree­ment with these predictions. Table IX is an up-to-date summary of Mu atom reaction rate data taken at TRIUMF in the gas phase and their comparison with analogous H atom results. In some cases several values are quoted for H atom rates in the table, reflecting the difficulty chemists have in observing H atom reactions directly due to the interference of several very reactive species simultane­ously present in most H atom experiments. Mu chemistry is one-atom-at-a-time chemistry and is therefore unemcumbered by these difficulties. In the case of the hydrogen halide reactions with Mu it is impossible to differentiate between the two possible reaction channels of exchange (Mu+HX MuX+H) and abstraction (Mu+HX -> MuX+X), and therefore the Mu atom values represent the total rate forboth channels. Dynamical and energyarguments suggest that the Mu+HCJL reac­tion is dominated by exchange ratherthan abstraction, in constrast to the H52Table IX. Reaction rate parameters for Mu and H in the gas phase.Muonium Hydrogen=act i on k(295K)a Ea (kcaI/mole) k (29 5 K) a Ea (kca 1 /mole) kMu/kH (295K)f2 1.4 ± 0.1 0.92 ± 0.23 0.20 ± 0.05 2.4 ± 0.2 5.2 - 100.09 ± 0.01 2.2 ± 0.1 13 - 19Cl2 5.1 ± 0.2 1.36 ± 0.21 1.7 ± 0 . 6 1.8 ± 0.3 2.1 - 4.80.41 ± 0.04 1.4 ± 0.2 1 1 - 1 41.15 ± 0.15 1.15+ 0.1 3-8 - 5-3Bf2 24 ± 3 - 2 .2 ± 1 . 5 1.0 ± 0.5 5-7 - 38H atom reaction typeHC1 <0.00003*+ + 0.000005b abst racti on 2(0.0021 ± 0.0002)c 3.1 ± 0 . 3exchange 000018 ± 0.0000l8d >4.0HBr 0.9 + 0.10 abstract ion 0.21 ±0.02 2.6 ± 0.1exchange 40..0023 5 - 6HI 2.53 + 0.13 abst ract i on 0.86 ±0.39 1.2 ± 0.4°2 16.0 + 0.7eis(0 .013-0 .020)c ~ 1 .9 3-5 - 5-3 350 - 440 1-9 - 5-7^k(x 1010 £/mole-sec)Upper limit on 1y ^There exists a stoichiometric ambiguity of a factor of 2 Upper limit (i.e., <3-6 x 105 £/mole-sec) eProbably spin exchange, not chemical reactionatom situation. All of the systems in the table as well as I2 and H2 will be the subjects of further study in 1978.As a preliminary step in the understand­ing of Mu formation processes, an experi­ment was performed to measure the Mu and y+ asymmetries in xenon-doped neon gas. The results are shown in Figs. 52 and 53- Two processes are evident from this ex­periment: a) epithermal Mu formation (Fig. 52; the non-zero y+ asymmetry at high xenon concentration is probably due to p+ scattered into the walls of the gas target, but it may also be due to the formation of Ney+ molecular ions), and b) a thermal Mu formation process (since y+ + Xe Mu + Xe+ is exothermic by about1.4 eV). The rate of the latter was de­termined (Fig. 53) to be 2.5 x 10-11 cm-1 atom-1 sec-1 (1.5 x 1010£ mole-1 sec-1). Incomplete results from xenon-doped helium indicate that this rate is even slower in He. In 1978 an attempt will be made to resolve the question of the non­zero y+ 'background' at high Xe concen­tration and to further investigate the role of the ionization potential of the target gas in Mu formation.Finally, it should be noted that all the above studies of muons in low pressure gases are possible due to the availabil­ity of surface muons from M20 and M 9 . At the present time, this program at TRIUMF is unique in the world.Liquid phase chemistryMeasurement of 'hot atom' fractions (indicative of epithermal Mu reactions) in pure liquids has been hampered by sys­tematic errors due to variations in the density of thick liquid targets. In 1977 a very thin target cell was designed for use with 'surface' muons which eliminated this problem. Results are shown in Table X and compared with density- corrected values from other laboratories. These data indicate that epithermal reactions of Mu occur over a very short time scale and probably a very small energy range, that there are certain identifiable systematics such as suppres­sion of Mu reactions by TI bands in the target molecules, and that there is no direct dependence of the reaction proba­bility on the strength of the bond being broken. The role of the 'spur' at the53Tab l e  X.  Compar i son o f  d a t a  o b t a i n e d  on Pres  f romTRIUMF u s i ng  s u r f a c e  muons w i t h  d a t a  f rom LBL ( c o r r e c t e d  Pr e s , 0 ° mode) ,  J INRa ( c o r r e c t e d  p res> ° °  mode) and SIN (0°  mode) where  pos-  s i b l e . bTargetLiquid TRIUMF LBL J 1 NR SINCC 1 4 1 1 1 1CHC1 , 0.86+0.04 0.85±0.04 0 .80±0 . 06D O h 0.61±0.02 0 . 5 9 ± 0 . 0 2 c 0.62±0.04 0 . 6 2 ± 0 .01d Oh 0.57±0.04 0 . 59± 0 . 02 0.58±0.03C H 30H 0 . 56±0.04 s I n 9 6 s I s O 8 0.58±0.05 0.6110.01)8 D p (O8 D h D 0.6l±0.04 0.64±0.01C ~C 6h 12 0.68±0.04 0 . 6 7 ± 0 .02 0 . 6 8 ± 0 .058 b 8 H D os 0.47±0.03 0.48±0.05C6H6 0 . i2±0.02 O OO 1+ 0 0 0 0 . 1 5± o .03C S 2 0 . 16 ± 0 .03 0.1 1± 0 . 0 1)ryp ( h rs 0 . 5 4 ±0.05Si )8 D p(u 0 . 5 4 ±0.03S 5H 3 2 0.64±0.04C7H16 0.65±0.04C1 0H12 0.67±0.052,2,4tr imethyl -pentane 0.61±0.05aJINR is  t he  J o i n t  I n s t i t u t e  f o r  Nuc l e a r  Res ea rch ,  ^Dubna,  USSR.The e r r o r s  quoted  a r i s e  f rom t he  u n c e r t a i n t y  due t o  t he  s t a t i s t i c s  o f  t h e  e xpe r imen t  and do not  t a k e  a c ­coun t  o f  o t h e r  p o s s i b l e  sources  o f  e r r o r .These d a t a  were  o b t a i n e d  as l i m i t i n g  in  v a l u e s  in  t i t r a t i o n  cu r ve s  and t h e r e f o r e  r e q u i r e d  no d e n s i t y  c o r r e c t  i o n s .end of the y+ ionization track is unclear in these processes. In 1978 it is planned to extend epithermal reaction studies to the gas phase where this 'spur' is not present.Exciting results from SIN indicate that thermal reaction rates of Mu in liquids can be directly determined by the MSR method using carefully prepared (02-free) samples. Their technique has been modi­fied for use with the thin surface muon liquid target at TRIUMF. This compensates for the large y+ spot size on M20 by allowing the use of thin targets of large cross-sectional area. In 1978 this tech­nique will be used to directly explore thermal reactions of Mu in liquids which can be compared with values obtained by an earlier, indirect method.XE CONCENTRRT1 ON inTOM-CIT3) X 10~'6F ig . 52. Dependence o f 'fre e  v+ ’ asymmetry ( t r ia n g le s )  and twice the muonium asymmetry (squares) upon the concentration o f  Xe im­p u r it ie s  in  Ne.p+ IN XENON DOPED NEONXE IN RTOM-CM"3 X 10~16F ig . 53. Dependence o f the 'f re e  y+ ' re la xa tio n  ra te  upon Xe concentration  in  Ne.54TIME INSECiFig. 54. .Two-frequency muonium precession signal (background and muon lifetime removed) in single crystal Si02 at 4.25 G.Solid state chemistryA search for muonium-1ike precession sig­nals with split frequency in a moderate magnetic field has produced tentative evidence for the existence of a CO2 muonic radical at 77 K. While indirect evidence suggests that muonic radicals are formed in many chemical reactions, their charac­teristic precession signals have not yet been directly observed. In 1978 this search will continue in both solids and 1 i qu i ds.A check for a biased Mu formation proba­bility in d- and 1-quartz due to indirect coupling between the helical muon and the helical crystal has to date given nega­tive results. This experiment did, how­ever, lead to a totally unexpected result shown in Fig. 5^ t— a beating in Mu at low field! At first this was laid to an instrumental artifact, but upon further investigation this possibility was elim­inated. Presently, the beating is attributed to the electric quadrupole moment of the triplet Mu in the Is case. It should be easy to check this possi­bility, and this will be done early in 1978.55APPLIED RESEARCHThe importance of research at TRIUMF directed towards practical applications continued to grow in 1977- In fact, a selection had to be made amongst a number of exciting possibilities because of the limits on technical and scientific man­power. Solid progress was made on all the research lines which had previously been established, including the Et  therapy program, proton radiography, ferti1e-to-fissi1e conversion. One indi­cation of the importance of applied work at TRIUMF is the successful project in­volving both theoretical and experimental studies on the bringing out of a 70 MeV simultaneous beam for the exclusive pro­duction of radioisotopes for important medical and possible industrial applica­tions.Irradiation facilities were installed in beam line for production of pilot quantities of radioisotopes from solid targets irradiated with beam currents up to 1 yA and with proton energies between 180 and 500 MeV. Design has proceeded for the corresponding facility to be in­stalled in beam line 1 immediately ahead of the TNF target where beam currents will extend to 100 yA.Negotiations continued this year with a commercial agency for the commercial dis­tribution of radioisotopes produced at TRIUMF for application as radiopharma- ceut i c a 1s .Planning, begun in 1975, continued on utilization of the TNF thermal neutron flux for neutron activation analysis of a variety of materials. The interested users (represented in the PANARA group) consisted of local commercial chemical analysis companies, Federal and Provin­cial government laboratories, and depart­ments in the four TRIUMF universities. Planning of the necessary technical installation at TRIUMF and of the organi­zation of the analysis activity proceeded, and resulted in an application for fund­ing being submitted to the Federal government.Experiment 61Biomedical experimental programDuring the l8 months of operation prior to l977 most of the experimental effort in the biomedical program was directed towards understanding the properties of the beam line and optimizing its operat­ing parameters. In l977 substantial prog­ress was made in developing methods whereby the pion beam can be tailored to provide the particular properties required for a specific radiotherapy treatment. Studies of the biological effects of pions have also been extended.It is a characteristic of charged particle beams that the particle range must be modulated in some fashion in order to pro­vide the uniform dose that is required throughout the tumour volume in cancer radiotherapy. A simple, flexible tech­nique has been developed to generate the desired depth dose profiles using dynamic momentum control of the TRIUMF biomedical beam. In effect, the tumour must be irradiated using a series of beam tunes with different momentum distributions (and therefore different ranges). The mathe­matical problem of combining these tunes is handled by the method of linear pro­gramming. Using a beam intensity monitor, the system can be operated automatically with an unstable beam (see Fig. 55)- A depth dose profile uniform to ±1% over the range 19-5 cm to 25-0 cm in water has been generated using this system as shown in the upper portion of Fig. 56.The biological properties of this modu­lated beam were determined by measuring the inactivation of Chinese hamster ovary (CH0) cells as a function of depth. The results are shown in the lower half of Fig. 56. Because the proportion of dose which arises from 'star' events increases with depth in the stopping region of a EEb beam, it is to be expected that the biological effectiveness of the beam will also change in this region. Since the densely ionizing radiations arising in the stars are more lethal, the relative bio­logical effectiveness (RBE) of the beam increases with depth through the stopping region. It can be seen that although the56Biomedphysical dose is constant through the depth range 19.5 cm to 25 cm, the result­ing cell inactivation increases towards the distal side of the stopping region, where the star fraction is greatest.Fig. 55. Block diagram for the computer control of the uniform dose irradiation.Fig. 56. Dose and cell survival profiles for an extended peak (7 cm) EEb  beam. The tt- energy range is approximately 77 to 98 MeV.From a series of such survival measure­ments one can calculate RBE values at particular survival levels and for differ­ent positions in the y~ dose distribution. Table XI shows RBE values for this flat- top dose distribution at various depths, evaluated at a cell survival fraction of0.5 and 0.1. These measurements were carried out at dose rates of approximate­ly 1 rad/min and the cells were irradiated in medium containing 25% gelatin at 0°C. While dose-rate effects are minimized at this temperature, definite RBE studies must await 100 yA operation.Studies of the E E G  damage in mice (in par­ticular mouse skin) is another important part of the pre-clinical research program, and it too requires 100 yA operation.It is hoped that these components of pro­posal #61 will proceed during 1978 to the point where patient treatment can com­mence in 1979- This will require extended periods of operation at 100 yA.Table XI. RBE Values: EEi 7 cm peakPos i t i on Depth(cm)*RBE0 .5 *RBE0 .iX-rays _ 1 .0 1.0P 1ateau 5-15 1 .0 0.95Proximal peak - a 20.0 1 .15 1 .05Peak centre - b 22.5 1 -25 1.15Distal peak - c 25.0 1.3 1 .25Downstream - d 27-0 1.^5 1 .35-'Uncertainties in these preliminary RBE values are approximately ±15%.57Experiment 87 Proton radiographyA general description of the aims of the proton radiography program and the ex­perimental arrangement used for the ini­tial series of measurements was presented in the 1976 annual report. The technique is to produce a pencil beam of 200 MeV protons which is scanned over a test object in a raster fashion, and to de­tect the transmitted protons with a counter telescope of plastic scintilla­tors. By using supplementary absorbers the counter telescope can be arranged to cover the region at the end of the proton range curve where small changes in the density or thickness of material of the test object produces large intensity changes in the transmitted protons.are correlated to changes in the RF volt­age on the cyclotron resonators. Attempts to improve the cyclotron stability with improved feedback systems on both the mag­netic field and RF voltage are in prog­ress. This work will benefit other users requiring good energy stability.An improvement in the data handling and display of experimental information is under way using the Eclipse computer which is part of the data interface sys­tem being commissioned at TRIUMF. As a check on the resolution of this technique one of the test objects scanned is a plastic plate with holes of varying depths and diameters. A projection of one scan across a series of holes of dif­ferent diameters is shown in Fig. 57. The 1/16 in. diam hole is easily seen.During 1977 much of the effort on this program has concentrated on studying the factors affecting the spatial and densi­ty resolution of this proton radiography technique. It has turned out that the experimental arrangement is useful as a diagnostic of the cyclotron performance, in particular its energy stability. A 100 keV change in the proton energy is equivalent to a density change of about 0.1%. Energy fluctuations of this order are present in the extracted beam from the TRIUMF cyclotron. These energy fluctuations have been correlated to changes in the cyclotron magnetic field at the 10 ppm level. Intensity fluctua­tions are also a problem as this experi­ment usually runs with a fraction of a nanoampere of beam obtained by inserting a wire stripper into a circulating beam of 1-10 yA. The intensity fluctuationsFigure 58 shows a scan over a small mouse mounted on an absorber equivalent to 10 in. of water. This display of the data does not show the details of the in­formation available in the scan, and the presentation of the scan data is another area requiring development. A signifi­cant improvement in the experimental arrangement should result when the equip­ment is moved to the new experimental< VS Y VS RHOCPOINT SIZE- 9 0 0HORIZONTAL POSITION- 3 0 0  3 0 0  9 0 0X DRC- VRLUEFig. 57. Scan across holes in a Perspex plate. Fig. 58. Proton radiographic scan of a mouse.58area in beam line IB. Techniques using high-speed X-ray film as the proton de­tector will be tried with this set-up.An extension of the scanning techniques to axial scanning, as is done in 1CT1 computerized tomography with X-rays, will also be investigated.Experiment 11 Isotope productionEfforts to utilize the capabilities of TRIUMF for medical radioisotope produc­tion have intensified and broadened this year. In addition to further development of the 123I program, a solid target ir­radiation facility for millicurie level activity has come on line, spallation 52Fe has been chemically separated, and a design has been completed for a new 65 to 100 MeV beam to be exclusively devoted to isotope production.Early in the year routine quantities up to 10 mCi of 123I were used to tag ortho- iodohipurate for possible kidney diagnos­tics. With the ability to routinely pro­duce, purify and tag 123I in hand, a proposal was drafted to Health and Welfare Canada for support of a pilot operation at the level of 300 mCi per week. The objective is to exercise a completeisotope supply system for a small group of clinics in Canada. A schedule will be based on one 12 h shift of 10 pA at 500 MeV per week on a 20 g/cm2 caesium target in the beam line AA dump. The de­sign (Fig. 59) has been bench tested and will come into operation in 1978. In addition to Vancouver General Hospital, co-operating clinics are W.W. Cross Cancer Institute, Edmonton, the Health Sciences Centre, Winnipeg, and the Hospi­tal for Sick Children in Toronto.With the commissioning of the high cur­rent dump in beam line 1 there has come the need to explore a wider variety of reactions for possible high-level produc­tion. A small irradiation facility (Fig. 60) was constructed on beam line AA to generate quantities of activity which could be handled manually. Thirty solid targets in air can be individually posi­tioned in the beam. Incident proton flux is obtained by integration of a precision secondary emission chamber.With this facility it has been possible to produce 52Fe from natural nickel spallation and chemically separate this activity from by-products.Finally, an effort is being made to ex­ploit the multiple, simultaneous beams feature of TRIUMF for isotope production.59Fig. 60. Multi-sample irradiation station.In collaboration with the Beam Develop­ment group, orbit calculations have been completed which indicate the feasibility of extracting variable energy beams from 100 to 65 MeV through a special port in exit horn #2. The emittance of these beams is large due to defocusing in the 7.6 m trajectory through the valley field from the stripper to the tank wall. Us­ing a 0.003 cm carbon stripping foil the predicted phase space ellipses are given in Table XII. The large beam spots are not a disadvantage for isotope production with natural targets, especially where low power densities are necessary. The calculations have been checked by extract­ing a 76 MeV beam to horn 2; the agree­ment of position is within 1 cm and the vertical matrix elements are within ±20%. Authorization has been received to prepare the extraction port and stripping mecha­nism for operation in 1978. This beam will be used exclusively for isotope pro­duction using the p,xn reaction on targets positioned in the cyclotron vault.Table XII. Phase Space at Horn 2,99% ContourExperiment 48Fertile-to-fissile conversion (FERFICON)The measurements of neutron leakage from lead, thorium and uranium targets into a surrounding water moderator by thermal flux mapping (described in the 1978 annual report) have been essentially com­pleted during the year. Table XIII shows the results as neutron sink rates in the H2O moderator per incident proton esti­mated from the known absorption cross- section for water and the volume integral of the flux distributions. A full report will be published shortly.Following assembly of the experimental apparatus, measurements have been started on the second phase of the FERFICON pro­gram, namely the mapping of fertile-to- fissile conversion reaction rates by high resolution y-spectroscopy of the X- and y-rays emitted during the conversion g-decays. The conversion reaction rates, as well as fission and other non-elastic processes such as (n,2n), are being mapped as a function of longitudinal and radial position within the thorium and depleted uranium targets for a range of target diameters. Some preliminary spec­troscopy results are shown in Fig. 61 identifying the y-lines associated with the conversion reaction products as well as some other reaction products.Energy X,cm Y,cm dx,mr dy,mr65 ±2.3 ±6.0 7.0 7-570 2.0 k.O 11.0 k .580 2.0 2.0 17.0 3-090 2.0 1 .0 19.5 2.5100 1.5 1 .0 19.5 2.560Table XIII. FERFICON Water Bath Results. Neutron captures in water per 480 MeV proton incident.TargetHigh dens i ty data setLow dens i ty data setPreferred va 1 ueU-l 10.9 11.1 11.1 ± 0.7U-7 15.6 14.5 15-5 ± 0.9U-19 17.1 17-7 17-5 ± 1-0U-37 17.1, 18.8 18.0 ± 1.0U-37 i 18.3 18.3 ± 1.0Th-1 10.0 9. 1 9.8 ± 0.6Th-7 9-8 10.1, 11.5 10.1 ± 0.6Th-19 11 .4 11.7 11.6 ± 0.7U02 12.2 11.6, 11.7 12.1 ± 0.6Pbl-U6 12.0 12.0 ± 1.0Pb1-U36 13.4 13-4 ± 0.7Pb7-U30 12.7 12.7 ± 0.7Pbl-Th6 8.7 8.7 ± 0.9Pb1-Th18 7.6 7.6 ± 0.8P b 7 _ T h 1 2 9-3 9.3 ± 0.6Pb — 1 (d=3 - 84 cm) 6.7 6.7 ± 0.5Pb-7 8.8 8.8 ± 0.6Pb-1 (d=10.16 cm) 9-2 9.2 ± 1.08Fig. 61. FERFICON target conversion y-spectra. Spectra are 5 min counts of a thorium foil taken at ^5 h intervals start­ing 19 h after the end of a short bombardment by 11 iiC of 480 MeV pro­tons. The 57 mg am~^ thick foil was imbedded in a 19-element thorium target (18.3 am equiva­lent cylinder diameter and 30.5 am length) dur­ing bombardment. The bottom spectra was taken first with logorithmic scale shown; succeeding spectra are progressive­ly shifted up one decade each. The fertile-to- fissile conversion (n,2n) and one of the many fission products are identified on the figure. ENERGY keV61THEORETICAL PROGRAMThe theoretical group at TRIUMF exists to provide a focus for an active program of theoretical research in medium-energy physics at TRIUMF. It is hoped that the presence of such a group and in particular the stimulation provided by interchanges between experimentalists and theorists will lead to better and more efficient research progress at the laboratory.The group is presently quite small, but there are plans for eventual expansion. Permanent members include H.W. Fearing and A.W. Thomas; R. Woloshyn joined the group as a research associate in August, and Y. Alexander, formally a UBC research associate, has been involved since December. Theoretical faculty of the TRIUMF universities including D.S. Beder,M. McMillan, E.W. Vogt (UBC), A.W. Kamal,H. Sherif (Univ. of Alberta) andC. Picciotto (Univ. of Victoria) partici­pate as wel1.Members of the group were active in plan­ning for the Nuc1eon-Nuc1 eon Conference held in Vancouver in June and in organiz­ing a Workshop on Nucleon-Nucleon Brems- strahlung held in conjunction with the conference. A number of theorists from other institutions were able to combine attendance at the conference with a longer visit at TRIUMF and as a result the summer period was an extremely active and stimulating time. Such visitors included R. Aaron, R. Landau, B. Loiseaux, J. Ng, J. Noble, A. Phillips, A. Rosenthal,H. Sherif, V. Vanzini and many others passing through for short periods of time.Specific areas of research which have been of interest in the past year include:Nudeon-nudeon bremsstrahlungWork has continued on soft photon (SP) calculations of proton-proton bremsstrah­lung in conjunction with the TRIUMF ex­perimental group (Experiment 66) and with an experimental group at UCLA (Nefkens e t  a t . ) , and a summary of the results was presented at the Nucleon-Nucleon Confer­ence [Fearing, AIPCP tth 1 (1978), p . A A6 ] . Such calculations are very useful for understanding the on-shell contributionsto the process and delineating those regions where the more interesting off- shel1 terms may be important.The ppy cross-section can be written as do ~  A2/k + 2AB + (B2 + 2AC)k + 2BCk2 + ..., where A and B are given by soft photon calculations. Typical results showing the contributions of the various terms for the 200 MeV equal-angle geometry of the TRIUMF experiment are shown in Fig. 62. At this energy the B2 term dominates unlike lower energies, where the A2 and AB terms are most im­portant. At 730 MeV in the somewhat different UCLA geometry the A2 term dominates for all photon energies below about 100 MeV. Above that energy the relatively constant B2 term becomes important, and at all energies the AB term is sma11.Comparison with experiments shows that the soft photon calculations generally repro­duce the data except near 0y = 0° and 180° for the TRIUMF experiment and exceptFig. 62. Contributions of individual terms in the SP expansion to the square of invariant ppy amplitude.62for k > 100-120 MeV for the UCLA experi­ment. In both cases the SP results are low and in both cases these regions are the ones where off-shell contributions might be expected to enter. Comparison with one-boson-exchange (OBE) calculations [Szyjewicz, AIPCP #41 (1978), p. 502] and non-relativistic and re 1 ativistica11y cor­rected HJ calculations [Liou, Bohannon, private communication] show that SP, OBE and relativistic HJ results are similar, differing by about one error bar for the TRIUMF experiment. The non-relativistic HJ calculation is quite different, indicat­ing that even at 200 MeV relativistic corrections are important.Preliminary calculations have been made in the SP model of the asymmetry in ppy using polarized protons. Indications are that there are sizable contributions to the asymmetry from purely on-shell terms even in the 'forbidden' configurations for which the asymmetry vanishes in the elastic process [see Moravcsik, AIPCP ffk 1 (1978), p. 515]- There are, however, geometries for which the on-shell contri­butions to the asymmetry are small but for which the potential for large off- shell contributions is present.(p, n) reactions in light nucleiWork has continued during the past year on a few further refinements of a dis­torted wave impulse approximation model of 19 788v reactions in light nuclei, particu­larly pd ■+ trr, and a paper [Fearing,Phys. Rev. C _16_, 313 (1977)] describing effects of proper wave functions which reproduce electromagnetic form factors and effects of distortion on the reso­nance position. On the experimental side TRIUMF Experiments 75 and 10 seem to be showing that the backward peak in pd -+ tir seen in an earlier experiment is in fact not there which thus removes the one major discrepancy between theory and exper i ment.Perhaps the most interesting new result deals with investigations (with R.H.Landau) of effects of using different pion distorted waves. In calculations so far Glauber distorted waves were used which were determined in the interior of the nucleus so that they reproduce for­ward elastic scattering, but of courseare incorrect asymptotically. Now the calculations have been repeated using wave functions based on a sophisticated multiple scattering approach. These have correct asymptotic properties and repro­duce elastic scattering at all angles, rather than just forward angles, and give a prediction of the wave function in the interior of the nucleus which can be tested in inelastic reactions. In a variety of other reactions such as pion photoproduction and pion charge exchange such wave functions seem to be too strongly absorbed in the nucleus, and a similar situation occurs in (p , EE ) . At lower energies, well below the resonance, differences in the cross-section calcu­lated with the two wave functions are small but at resonance and above the multiple scattering wave functions are much smaller inside the nucleus and the cross-section is strongly suppressed.The difference can be as much as two orders of magnitude in the extreme case, and the agreement of theory to data is completely destroyed. While various de­tails need further investigation, in particular the dependence of these results on various aspects of the DWIA model used for (p,ir), it is clear that (p ,EE( reactions provide information on wave functions inside the nucleus which is not available from elastic scattering.Finally, preliminary investigations have been made in the DWIA model of the asym­metry when polarized protons are used. General features of the experimental results (Experiment 10) suggest the rele­vance of this model, but at present some technical approximations required, in particular an approximation equivalent to the usual zero-range approximation, lead to zero asymmetry, and so must be relaxed for a realistic calculation.Radiative muon captureDefinite progress has been made in the program of calculating the higher-order 6(l/m2) terms in the radiative muon cap­ture effective Hamiltonian. Such terms are necessary for a correct calculation of the photon asymmetry observed follow­ing capture of polarized muons [Fearing, Phys. Rev. Lett. 35_, 79 (1975)] though the motivation for such an improved cal­culation has been lessened somewhat by63kJMeV)km(MeV)F ig . 63. The re la t iv e  capture ra te  as a func tion  o f km in  c lo su re  approximation (long dashed curve) and as corrected  ( s o lid  curve). The h o rizo n ta l l in e s  show the experimental bounds from Ha rt et a l.the result of a new SREL experiment [Hart e t a l . ,  Phys. Rev. Lett. 3£, 399 (1977)] which gives a measured photon asymmetry a = +0.9^ ± 0.50 in agreement, albeit with large errors, with the previous theoretical estimate a ~  0.80. Using an effective Hamiltonian comp 1ete to 0(1/m2) , the photon spectrum and asymmetry were calculated in both the harmonic oscilla­tor and giant dipole resonance models. Improved wave functions, calculated by a Hartree-Fock procedure in a harmonic os­cillator basis [Shao e t a t . , Phys. Rev.C 8, 53 (1973); Lomon, private communica­tion], were also utilized. All of these improvements gave rather small changes in the numerical results. Better photoab­sorption data [Ahrens e t a l . , Nucl. Phys. A251, ^79 (1975)] and a more accurate selection of average neutrino and maximum photon energies yielded improved results in the giant dipole resonance model, which now gives a photon spectrum closer to that of the harmonic oscillator model.In the usual closure approximation, muon capture rates are very sensitive to the values of the average neutrino energy or average maximum photon energy chosen.In an interesting auxiliary calculation it has been shown that corrections to the closure approximation results can be ob­tained by expanding about the closure value for the average energy and evaluat­ing the leading correction terms via a variant of the Thomas-Reiche-Kuhn sum rule. Figure 63 shows a comparison of the rates computed using both methods as a function of the average energy param­eter. One observes that for the modified closure approach the rate is nearly inde­pendent of the average energy, a distinct improvement over the standard closure approach where the strong dependence of the rate on km makes extracting informa­tion on the weak couplings difficult. The results of this latter work have been submitted for publication [Sloboda and Fearing, submitted to Phys. Rev. C].Effective Hamiltonians for nuclear problemsIn nuclear problems one often wants to find an effective non-re 1 ativistic Hamiltonian, given knowledge of a relati- vistic elementary particle Hamiltonian. Muon capture, radiative muon capture, and pion photoproduction in nuclei are exam­ples of such problems as is the (p,ir) reaction, which has stimulated so much discussion lately regarding the appropri­ate pion nucleon absorption operator. In simple cases one uses the standard Foldy- Wonthysen reduction but for more compli­cated cases, in particular those involv­ing second-order (i.e. two different) interactions or time-dependent interac­tions, there are additional subtleties which have been incompletely or incorrect ly discussed in the literature. We have worked out the general procedures for an arbitrary second-order interaction. The main qualitative feature that emerges is that the orders of the interaction become mixed among the orders of the S-matrix. Thus for a correct second-order inter­action Hamiltonian one must keep second- order contributions to the first-order S-matrix, i.e. terms corresponding to 'seagull' or 'contact' interactions. It is necessary also to be very careful with the 'energy ambiguity' terms, i.e. those proportional to time derivatives of the6Aexternal fields, which are actually higher order relativistic corrections than they appear. These general results have been used in the radiative muon capture calculations described above, and work is continuing to understand their consequences for the pion absorption operator appropriate for (p,ir) reactions.Phenomenology o f inclusive reactionsUsing the single scattering model of Amado and Woloshyn [Phys. Rev. Lett. 36.,1435 (1976)], Frankel has analyzed a large quantity of nuclear inclusive scat­tering data and shown that it obeys a scaling relation [Phys. Rev. Lett. 33,1338 (1977)]- That is, as a function of the proper scaling variable all cross- sections seem to have the same (exponen­tial) behaviour. We have argued that the existence of a scaling variable and the fast fall-off of the inclusive cross- section are the result of a more or less coherent recoi1 of the (unobserved) residual nuclear system [Amado and Woloshyn, Phys. Rev. C (to be published)]. A number of alternative models have been proposed for nuclear inclusive reactions, and we have suggested that measurement with polarized protons can discriminate between these models [Frankel and Woloshyn, Phys. Rev. C (to be published)]. It is expected that such experiments will soon be performed at TRIUMF.One-dimensional many-body problemWe have calculated the single particle momentum distribution for a one-dimen­sional many-body system with 6-function interactions [Amado and Woloshyn, Phys. Rev. C JJ5, 2200 (1977)], with the aim of testing the Hartree approximation and the asymptotic behaviour of the momentum distribution in a soluble model. Contrary to expectation, it was found that the transition from Hartree (exponential) behaviour to asymptotic behaviour (domi­nated by two-body correlations) occurs over a very small range of momentum—  almost independent of the number of par­ticles in the system. The calculation was performed in a novel way by exploit­ing the formal equivalence of the problem to that of evaluating a set of Feynman integrals.Near threshold n° productionCross-sections have been calculated for ( y , T r ° )  on 2H, 4He and 5Li for E^o up to 6 MeV, including both the direct process and E E W  production followed by charge ex­change [Vergados and Woloshyn, Phys. Rev.C J_6_, 292 (1977) and Koch and Woloshyn (to be published)]. The differential cross-section for ^He (y ,ir°) ^ He (and all J = 0 targets) is proportional to sin20. (Rescattering simply changes the peak value.) Over the energy range studied the inclusion of rescattering increases the peak value by only about 25%. On the other hand this reaction depends on the term in the photoproduction operator which is most sensitive to the tail of the A (12 32) contribution, and should therefore provide a good test for models of this term.For the 2H and 6Li cases charge exchange rescattering increased the cross-section by an order of magnitude, and qualitative­ly changed the shape. Preliminary experi­mental observations seem to confirm these results (at least qualitatively) [Tzara, Meson-Nuclear Physics, Pittsburgh (1976),p. 566)].Pion-nucleus interaction in theresonance regionKisslinger and Wang [Ann. Phys. 99., 37^(1976)] have formulated a theory for pion- nucleus scattering in which the isobar is treated as an explicit degree of freedom. This has led to a phenomenological model (the isobar-doorway model), incorporating the features of their theory. In the resonance region the )j vf0) reaction may provide a good test of the Kisslinger- Wang model, because (i) it is dominated by A-production, and (ii) it uses the same isobar form-factor as ir-elastic scattering. Preliminary results for 12r)j vRyR0) C indicate much less damping of the cross-section due to final state interactions than in DWIA. Future work will be aimed at extending the phenomenol­ogy to other reactions such as (p ,EE( and establishing connections to more micro­scopic theories of the A-nucleus inter­action.657i-nucleus scattering and reactionsFurther theoretical work on the inter­action of low-energy pions with nuclei has been carried out. Although the start­ing point for this work is the multiple scattering theory of Kerman, McManus and Thaler, a number of improvements have been incorporated into the theory. These include the incorporation of a three- body energy shift and the effects of the Pauli exclusion principle on the in­medium irN interaction (see Fig. 64).=  X +F ig . 64. In c lu s io n  o f P a u li e ffec ts in  the ca l­cu la tion  o f  3b$ sca tte ring  in  a nuclear medium. The c ro ss ind ica te s that the nuclear momentum must be g reater than pp.Considerable effort has been made to en­sure that the Pauli blocking of the nucleon momentum is correctly taken into account for any AAE configuration. This improvement, which would be essentially impossible to include in a co-ordinate space approach, does increase our comput­ing time by a factor of four.While the influence of the Pauli princi­ple on the elastic scattering cross- section is non-neg1igib1e , the small im­provement shown in Fig. 65 would not, by itself, justify the increased expense. However, recent theoretical work on the reactive content of proton-nucleus opti­cal potentials [Tandy e t a l . , Phys. Rev.C _HS, 1924 (1977)] has now been applied to the iT-nucleus case. Figure 66 shows the total cross-section for quasi-e1 astic pion scattering [a (it , AAE ) ] , im p l ic i t  in several standard models of ir-nucleus scattering. While space demands that the reader be referred to the original paper [Thomas and Landau, to be published] for a full explanation, we note that both the usual Kisslinger and separable potential ('E2-body') treatments ove re stim a te  the  (tt,ttN) c ro s s - s e c t io n  a t 40 MeV by more than an o rd e r o f  magnitude. Only when the constraints of elastic unitarity and the Pauli principle are included ('E3-body + Pauli') is a reasonable quasi-elastic cross-section obtained. The implications of this for other pion reac­tions [(it,it'), (tt,y)» etc.] remain to bestudied. Nevertheless, the fact that at 50 MeV the p-wave pion wave function in­side the nucleus is twice as big in the 'E3-body + Paul i1 + U (abs) ( see below) case as in the standard 'E2-body' case is highly suggestive.Last year we reported very strong evi­dence for the need for a term 'lj(abs)' in the low-energy Tr-nucleus potential, representing the effects of true pion absorption. This was particularly evi­dent in the 30 MeV ir+ 12C data taken at TRIUMF [Johnson e t a l . , Nucl. Phys. A296, 444 (1978)]. More recently the same group has succeeded in obtaining EEb  data at the same energy. In view of the very strong Coulomb interference at these energies, the ir+ and 77“ data together provide an even more stringent test of the theory. Comparison of the theory with the new tt~ data is shown in Fig. 26 (p. 31). The need for the absorptive term (included here in a quasi-deuteron model) is obviously confirmed.AA + l2C E la s tic , Pauli ExclusionFig. 65. E ffe c t o f  the mod ifica tion  o f  the trlV in te ra c tio n  by P a u li b locking  (see Fig. 64) on the tt+-12C d if fe re n t ia l c ro ss-se c t io n .66Fig. 66. The total cross-sections for the f7Tj Sevr reaction on 12C implicit in several theoretical optical potentials are compared with the little available data. Bearing in mind that above (30-40) MeV the points labelled 'experiment' give a lower limit for the true o^0-y(i\,i\N) ^ we see that only the calculation including elastic unitarity (E2-body^ and Eauli effects is near bhe data.Pionic atom shifts and widthsThe pionic atom measurements made by a University of Victoria group have led to some theoretical work. The EEb 3He case is particularly interesting, because of the very large width, 68 ± 12 eV (SIN 42 ± 14 eV), compared to a shift of 2 7 + 5  eV (SIN 4 4 + 5  eV). Of course, the fact that this shift is attractive also makes 3He a unique case. Finally, the small number of nucleons, and the very weak s-wave irN interaction, suggests that a multiple scattering (MS) treatment should work very well. Indeed, using several sets of EE, scattering lengths led to a MS result between 22 and 39 eV.[For details please refer to A.W. Thomas, 'The strong interaction shift in pionic helium-31, to be published.]However, when the current wisdom concern­ing the dispersive effect of absorption is included [e.g., see the review by Thomas, Proc. 7th Int. Conf. on High- Energy Physics and Nuclear Structure, Zurich (Birkhauser, Zurich, 1977), p.109], namely Re f(abs) ~  -jm f(abs)( one finds a strong interaction shift very near zero. The only exception is the rather old EE, analysis of Samaranayake and Woolcock, which still gives a result much smaller than experiment (~14 eV with a large error). It is extremely important to ob­tain accurate measurements of the Tr~d shift, and the EEl 3He shift and width, as soon as possible. The former should give a good value of the isoscalar EE, scatter­ing length (a major uncertainty in the MS calculation for 3He). Then the latter should deepen our understanding of the old problem of the 'dispersive effect of absorpt i o n '.While the optical model approach described above for elastic pion scattering is presently being used to calculate the shifts and widths of pionic atoms, one may also be able to learn something from simpler approaches. The oversimplified a-cluster model of Hufner, Tauscher and Wilkin [Nucl. Phys. A23J_, 445 (1974)] has been used to calculate the Is shifts and widths of 19F, 23Na and 21tMg (also for comparison with University of Victoria ex­periments). This model seems to predict a much greater isotope dependence for the width, 14 keV for 23Na, than the Ericson- Krell potential (18 keV)— cf. experiment11.3 ± 1-2 keV. A measurement of the 24Mg width would be very valuable.nD scatteringTheinitial investigations of this system using a relativistic three-body scattering theory [Rinat and Thomas, Nucl. Phys. A282, 365 (1977)] have been continued in several d i rect i on s:(i) Fayard e t a l . at Lyon have independ­ently confirmed the accuracy of the 1RPK' results [cf. Nucl. Phys. A258, 417 (1976)] within one per cent, so that there is now a standard test problem for any three-body program written for this system.(ii) The correction to the elastic differ­ential cross-section due to other EE, waves670 CMF ig . 67. Comparison w ith ttD data of the th ree- body ca lcu la tion s o f  R in a t, Eammel, Starkand, Thomas and Camporese (to  be pub lished) and the Glauber ca lcu la tion s o f  Eoenig and R ina t (Phys. Rev. C, accepted fo r  p ub lica t io n ).has been calculated. The results at 142 and 180 MeV are now in good agreement with experiment, while there is still a real problem at 256 MeV (see Fig. 67). (This interference effect was also calcu­lated using ttD amplitudes kindly suppliedby V!. Gibbs and B. Gibson of LAMPF. Their estimate of this c o rre c t io n  is in very good agreement with the three-body calcu­lation.)(iii) With considerable numerical effort the AAU cross-section has been calculated using the realistic deuteron wave func­tion of Holinde and Machleidt. The result is not qualitatively different from the calculation with much simpler wave functions— a result also found using Glauber theory [Rinat, private communica­tion] .(iv) Various polarization parameters have been calculated and will soon be published. Of particular interest is the apparent model dependence of the tensor polarization T2o(l80°) [see Thomas,AI POP #h\ (1978), p. 373].The (p,2p) reactionA program has been written to calculate the half-shell function for several realistic pp interactions. This off-shel1 dependence is currently being incorporated into a distorted wave code at the Univers- ty of Alberta, to test its importance in the TRIUMF geometry.68THE STATUS OF EXISTING FACILITIESION SOURCE AND INJECTION SYSTEMUnpolarized source and injection lineTwo main objectives were pursued during1977:1) establishing a reliable and reproduc­ible system for normal beam production up to currents of 25 pA extracted (100 pA at i nj ect i on);2) achieving the 500 pA required at in­jection for the 100 pA 500 MeV design goal in a safe and stable mode.At the lower current levels space charge does not yet play a significant role and a tune could be set up which was substan­tially current independent. However, of serious concern even at these lower cur­rent levels was the necessity to limit beam losses along the beam line. As a matter of fact, losses of more than 20 to 30 pA at 300 keV could have produced melt­ing of non-cooled elements along the 40 m long electrostatic injection line and had to be avoided. This was achieved during the first months of the year by setting up an automatic, hard-wired interlock system which would stop the beam at the source whenever excessive losses were detected.Losses were measured and controlled through two main systems:1) A system of sensing-protecting elec­trodes (skimmers) which are placed such as to screen quadrupoles and bending ele­ments from mistuned beam structures. The currents of the beam spills hitting these electrodes were added together and com­pounded into eight main signals corre­sponding to eight different regions of the injection line. These signals were then available for tuning and interlock purposes.2) In parallel, two non-intercepting beam current transformers, one at the begin­ning and the other at the end of the300 keV line, were used to monitor trans­mission. The time structure of the beamfrom the source was provided with a 10 ysec hole every millisecond in order to provide a convenient pulse for the transformers. In Fig. 68 the current as measured through the non-intercepting monitor is shown to be the same as the one recorded on a normal beam stop within a few microamperes. The difference between the two signals, directly propor­tional to the loss, was displayed on the main cyclotron console and used in the main interlock system.Additional interlocks that would prevent other abnormal situations, such as the beam hitting gate valves, poor cooling of beam stops or high voltage on optical ele­ments in poor vacuum conditions, were included in a general centralized system installed and commissioned during the spring shutdown. The insertion and read­out of the various beam stops and collim­ators were made more efficient through a sophisticated control system controllable from the main control room. Water cool­ing on beam stops and cooled collimators was replaced with freon cooling in order to reduce leakage currents and to make3F ig . 68. The beam transfo rm er reading as a func tion  o f  beam cu rren t.the accuracy of the current-reading sys­tem compatible with tuning and interlock requ i rements.At higher currents the tune depends on space charge and increasing the current at the ion source without retuning the optics generally involves a substantial loss in transmission. The iterative pro­cess of raising currents and retuning whenever losses are too high can turn out to be very long and may never converge to better than 90% transmission unless the beam is extremely stable. It was realized at the end of 1976 that the sys­tem was quite marginal for high currents. In addition to this impossibility of going gradually from low to high currents independently from space charge, insta­bilities produced by arcing between ion source and puller, and other instabilities in the ion source power supplies, were still present. Also it was realized that the injection line had to be carefully tuned such as to maximize the current ex­tracted from the cyclotron in order for the injection line tune to be matched to the cyclotron acceptance.A series of high current tests was scheduled to gain experience on the tech­nique of setting up a 100 yA extracted beam. In February 100 yA were extracted in a 1% pulsed mode. Space charge was not the limiting factor any longer but losses and thermal effects had still to be improved. During one of the CW highcurrent tests a serious setback was suf­fered when two quadrupoles in the verti­cal bending section would no longer hold voltage, and a week later also the upper part of the vertical section was leaking to ground. The damage was repaired during the spring shutdown.At the beginning of the summer a system of variable slits and a variable duty cycle electronic pulser were installed in the 12 keV ion source region in order to allow the gradual increase of the cur­rent without extensive retuning. The variable duty cycle pulser proved to be more useful since with this technique both the space charge and the emittance were current independent. The injected beam time structure could be changed from \% (10 ysec on, 1 msec off) to 99% (10 ysec hole every 1 msec) continuously through a special DAC input. On July 29 during the first 100 yA TRIUMF extracted beam test, it was shown that the current could be increased from 10 yA average (10% pulsed) to more than 90 yA (99% pulsed) in a matter of a few minutes (Fig. 69). Current in the injection line was of the order of 400 yA.During the July test the arcing in the ion source was still a severe limitation (3 arcs/min). The vacuum system in the ion source was overhauled during the fall shutdown and an additional freon-cooled baffle was installed above the ion source oil diffusion pump to prevent oilinin OCMOO6CJin OJULY 29,77F ig . 69. E x tra c tio n  o f  100 y4 from the cyc lo tron.70contamination. The arcing rate could then be reduced to one every 10 min or so. No other arcing effects, other than between source and puller, were observed. The beam at the ion source was gradually made more stable and reproducible. Cur­rents up to 500 yA can now be easily set up with emittances of the order of G s I O EE mm-mrad normalized.At present the high current operation still calls for the presence of a physi­cist on site when the tune is set up. Training of the operators, the improve­ment of diagnostics and a more detailed understanding of the beam optics and its dependence on the current will allow en­trusting the high current operation to the operators hopefully by mid-summer 1978.Polarized ion sourceEmphasis during the past year has been on increasing the polarized beam intensity and on improving the source reliability. The current out of the source increased from an average of 250 nA to 700 nA, and improved transmission through the beam line resulted in extracted currents in­creasing by a factor of four, from 30 nA to 120 nA, by mid-summer.Analysis of source operation indicated that a significant part of the source downtime had in fact been due to an in­ability of predicting and avoiding prob­lems because many of the essential parameters could neither be monitored nor altered without turning off the 300 kV power supplies and entering the ion source cage.For example, a relatively straightforward operation such as restarting the arc after it had extinguished could not be done remotely. Therefore it was decided to give priority to adapting the source to permit remote control of essential ele­ments. In addition to those items for which remote control already existed, it is now possible to remotely adjust and monitor the hydrogen pressure, the argon pressure, and the filament current. Monitoring of the cesium temperature and the internal proton current is also possi­ble. The ability to vary the cesium temperature remotely should be availablenext year. The arrival of the long- awaited replacements for the power sup­plies used with the spin-selecting sole­noids eliminated another obvious source of downt i m e .It has been found that careful optical alignment of the focusing electrodes and argon solenoid is essential for increas­ing current through the acceleration tube and matching to the injection line. In fact, tolerances are so critical that final alignment has to be done with the beam. The influence of the stray magnetic field in this region adds to the alignment problem. As this alignment procedure has to be repeated each time these devices are removed for cleaning, modifications which would permit remote positioning would certainly save time and are being considered. However, it is felt that the rigidity of the present system is inade­quate to achieve the desired reproduci­bility. A design contemplating a RF spin filter along with an improved optics box mounted on a rigid support structure has been proposed.SAFETYThe Safety Group consisted of four mem­bers during 1977 whose primary responsi­bilities were health physics and modifi­cation of the safety interlock system.The TRIUMF Accident Prevention Committee continued to review all industrial safety matters, and the newly formed Targets group took over the responsibility for hydrogen safety. There are five persons designated as safety operators concerned with safe operation of the accelerator and beam 1i nes.The TRIUMF Safety Advisory Committee met seven times and reviewed the thermal neutron facility (TNF) four times and spent much of the time on Safety Group radiation measurement review. In June the Committee met with the Accelerator Safety Advisory Committee of the Atomic Energy Control Board to review the operating licence. Considerable effort was devoted to reviewing the design of the TNF.71Radiation protectionThere were 30 beam spill monitors and six neutron monitors in use by the end of the year. Beam lines 1A , AA and AB were routinely operated at 20 pA, 1 pA and 20 nA, respectively. The current in beam line 1A was 8200 pAh in 1977 compared with 2070 pAh in 1976, but the residual radiation levels have remained at about2 to 10 mrem/h at 50 cm from most sections of beam line 1 due to improved tuning and the addition of some local shielding in the beam tunnel. The beam current limit in beam line AA could not be increased beyond 1 pA due to high beam spill caused by several targets and windows. The radi­ation field was about 20 to 50 mrem/h one hour after end of beam at 50 cm from several locations in beam line AA.The residual radiation field in the centre of the cyclotron vacuum tank was 7 mrem/h on March 29, seven days after eight weeks of 2690 pAh of operation. Lead shadow shields were installed on April A and re­duced the radiation field by a factor of3 at the centre of the tank and a factor of A at the outside edge. It is antici­pated that the shadow shieldswill be more effective as beam losses inside the cyclo­tron are reduced and directed towards the outside wall of the vacuum tank.There was a total of A35 individuals on the TLD and neutron badge service during 1977, and 2A5 individuals received a gamma dose greater than 20 mrem. The total exposure for the year was 25.1 man- rem which yields an average dose of102.5 mrem per person. The cumulative neutron dose for all individuals was zero as measured by the Canadian Radiation Protection Bureau neutron film badge service. The frequency distribution of accumulated gamma dose is shown in Fig. 70.Industrial safetyACCUMULATED DOSE (GAMMA) IN MREMFig. 70. Frequency distribution of accumulated gemma dose.TRIUMF increased its number of industrial first aid attendants from four to six.By the end of 1978 this number will prob­ably reach ten. This should ensure a first aid attendant being on site throughout the three-shift system, at the same time covering TRIUMF's expansion of new facilities and new work areas.Fire inspections are carried out semi­annually by the UBC Fire Department's Fire Prevention Division.The entire TRIUMF site is inspected on a once-a-month basis by the provincial Workers' Compensation Board in order to record and correct any industrial safety haza rds.REMOTE HANDLINGHighlights of the past year have been: CyclotronIn 1977 a total of 55 minor accidents were reported and treated by TRIUMF's six first aid attendants, with a total loss of 35 man days. Unfortunately, not as low a record as 1976; however, the severity of the injuries was by far lower. In fact, 90% of the accidents were mainly of the band-aid type requiring minor attent ion.A complete 'hands-off' iteration of shadow shield handling (removal of 60 shields— 22,000 lb of Pb) has been com­pleted in slightly less than three shifts with three operators per shift. The general reduction of radiation levels in the tank with the shadow shields in was a factor of about A. A lower resonator, after unbolting, was72removed 'hands off1 with three people (one was only watching) in about 30 min.Beam linesThe hot cell (actually 'warm' cell) was fully commissioned and successfully used to exchange several 12 targets, exchange 1M9 monitors, repair an M9 blocker H2O leak, remove temporary Cu blocker in beam line 1, add collimator 'A' to beam line 1, repair M8-Q.1 bellow actuator; also, an ad hoc set-up allowed good handling and view­ing of the TNF target with master/slave manipulators during its first inspection. The exercise proved the versatility of the remote handling equipment at TRIUMF for tackling 'emergency' situations, but the procedure should not again be consid­ered for TNF.Hot cellsThe 'warm' cell was fully commissioned, and a medium-sized lathe was added to the 'hot' shop.Remote handling is entering the third year of a three-year capital expansion program and is scheduled to complete construction of those basic facilities and equipment that are necessary for adequate remote handling capability at TRIUMF after some considerable time of full power operation. All these items should be commissioned by the end of fiscal 78/79•Cyclotron servicingService bridge. Descrete locating. Commissioned 1976.Service bridge trolleys.Manned vehicle: Commissioned 1976.Lift and positioning trolley: Prototype commissioned 1976. This trolley will have to be rebuilt and replaced in 1979- Lower resonator trolley: Semi-commissioned 1977- Complete 1978.Upper resonator trolley: Constructed 1977, commissioning in 1978.Outrigger trolleys: #1 prototype tried 1977; ft2, 3 and k to be commissioned 1978. These are to be used for viewing leak testing, lifting and general master/slave operat ion.Nutrunner trolley: Now in design. Com­pletion 1978.All TRIUMF radiation-hard or semiradia- tion-hard beam line sections (except TNF) are now set up for remote or rapid handling. This includes quick disconnects for power, water, beam line connections, and methods to support beam line sections and to collapse bellows. Future designs for Mil, beam line IB and the 70 MeV line have also been completed. The TI/T2/LD2 flask is complete except for changing the manual steering controls for power, to be added in 1978.Beam line servicingRF SYSTEMResonator heating prob 1ems are sti11 being fought but this year great strides have been made towards correcting and under­standing the heating phenomenon.Because of the somewhat circular shape of the vacuum tank and the physical layout of the components inside the tank, the RF impedance of the beam gap along the dee varies from an inductive impedance at the centre to a capacitive impedance at the outer radii crossing through a zero impedance at resonator #8. A history of the RF performance and recent measure­ments of the tuning effect of the reso­nators at the outer radii on RF leakage and temperatures inside the tank would indicate that most of the problems with RF pick-up on diagnostic probes and melt­ing of resonator tips, tulips, 1M ' foils and lead dampers have been caused by the low RF impedance of the beam gap at resonator ft8, in conjunction with up-down resonator voltage asymmetry.The fact that the RF impedance of the beam gap at resonator §8 is a short cir­cuit is significant o n ly if a voltage is developed across the short circuit imped­ance. If the resonators are properly aligned electrically, there will be no voltage developed from upper to lower hot arms; however, since we have no means of electrically aligning the resonators there will obviously be some electrical misalignment in the RF system since we depend entirely on optical alignment of the resonators. It has been known for73some time that most of the RF leakage in the beam gap is due to voltage asymmetry at the dees, but only after analysis of the results from newly installed thermocouple and RF pick-up loops, along with the cal­culations of the RF impedance of the beam gap, was it realized how sensitive the RF leakage to the adjustment of the reso­nators in the outer region, especially #8 resonators. It was estimated for each resonator segment that approximately 200 W of RF power radiating into the beam gap was sufficient to raise lead to its melting point and introduce enough thermal expansion of the strong-backs to cause the resonator tips to sag (even with the tip supports installed). A voltage asymmetry of 1 kV across a short circuit impedance at the dees would be sufficient to produce the necessary 200 W of RF- radiated power into the beam gap.Thermocouples were installed on the strong-backs of resonators #3, #6 and #9 and on the lower probe housing. Tests indicated that these temperatures were very sensitive to the adjustment of #8 and §3 resonator ground-arm tips.RF pick-up on the high-energy probes appear as a dc offset on the current sig­nal. This dc offset was eliminated by critically adjusting §8 resonator ground- arm tips.At various times during the year there were 'glow discharges' above the cryo- panels, 'M ' foils between resonators #7 a n d  #8 b u r n i n g  red hot, a n d  s p a r k i n g  at the levelling arms. These problems were eliminated by, again, critically adjust­ing §8 resonator ground-arm tips.Another observation was that the adjust­ment of resonators #7, #8 and #3 ground- arm tips had a much greater effect on frequency than the other resonator ground-arm tips. This again correlates to the sensitivity of the #8 resonator because of the low RF impedance of the beam gap at that point.During the two major shutdowns this year, in addition to investigating the heating problems the following major modifica­tions were undertaken to improve the reliability of the RF system:1) Root-to-root contacts and M foils (panel-to-panel contacts) between reso­nators were modified in order to make the replacement of some easier and facilitate remote handling of the resonators.2) Remote control motorized ground-arm tip adjusters were installed on #8 reso­nators as a coarse frequency tuning control.3) The 1 ead vibration dampers were re­placed with copper dampers.b) Adjusting screws were added to the extreme end of the levelling arms to re­duce the amount of time spent in the tank for a shimming program on the resonator hot arms.5) The d ee gap probe housing was replaced with a water-cooled probe hous- i ng.6) Adjusting screws were added to the resonator ground-arm panels to improve the electrical contact of the ground-arm fingerstock to the probe housing. This modification also makes it easier to install the probe housing.Third harmonic R F  systemSuccessful signal level (20 W) third harmonic tests were carried out with full fundamental RF power of 1000 kW ap­plied to the resonators. A third harmonic to-fundamenta1 ratio of 3:1 was obtained but at a f r e q u e n c y  of a p p r o x i m a t e l y  30 kHz lower than the desired operating fundamental frequency. No measurements were made with regards to the stability of the 3:1 ratio as to whether it can be successfully maintained with the tuning adjustments available. Since these measurements were taken an extensive pro­gram of resonator alignment was carried out to minimize RF leakage into the beam gap. This will definitely affect the frequency at which we would be able to obtain a 3:1 ratio if it is at all possible to obtain it without further major modification.lbCyclotron chamber vacuum systemNo significant changes were made in the cyclotron chamber vacuum system during 1977- The normal running pressure during the year varied between 6 x ]0~8 Torr and1.5 x 10~7 Torr, depending on condition­ing and the RF running conditions. The lowest base pressure achieved with the RF off was 9-2 x 10-9 Torr, and was commonly1.5 x 10“8 Torr. During the early part of the year tests were carried out on a liquid helium cooled hydrogen cryopump. These tests were suspended before comple­tion to allow for work on a major rebuild­ing of the beam line vacuum system.Beam line vacuum system Beam line AAThe vacuum system for beam line AA was up­graded by installation of a Sargent Welch turbomolecu 1ar pump (speed 1500 £/sec) and by the addition of pumping lines around the in-line experimental facilities. As a result of these modifications the sec­tions of beam tube connecting the experi­mental sites can be kept under good vacuum at all times, greatly simplifying the operating procedure for the beam lines.A beam-stopping carbon block was put into the hole in the AA beam dump, to reduce the level of backstreaming radiation. This block is isolated from the AA vacuum sys­tem by a 0.005 in. thick stainless steel window, coated with 0.002 in. of copper for heat dissipation. The space around the block is rough pumped by a small mechanical pump.Beam line 1As a result of the installation of the T1 vessel and the TNF, the beam line 1 vacuum system in the meson hall has been completely redesigned and rebuilt. In the new system there are no windows in the beam line upstream of the TNF, where there are two thick (0.005 in.) windows with a helium-cooled interspace. The pumping system is based on one Sargent Welch turbomolecular pump (speed 1500 i /  sec), located near the cyclotron, and a Rootes blower roughing system which roughVACUUM SYSTEM pumps the secondary channels as well as the primary beam line. This system is designed to accommodate future secondary lines at T1 and a future beam line IB.When it was commissioned in late December, the system had a base pressure of 3 x 10-5 Torr at the turbopump. This was a factor six higher than expected, based on measured outgassing and leak rates for the individual components along the beam line. The source of this gas­load has not yet been discovered. In the event of a serious irreparable leak at some future time, provisions have been left for installation of thin windows (0.00035 in. aluminum) immediately up­stream of either T1 or T2.EXPERIMENTAL FACILITIESIn 1977 the New Facilities Group was in­corporated into a group titled Experimental Fac i1i t i es .M9CHANNELThe low momentum pion/muon beams from the M9 channel have been in high demand from meson hall experimenters during the year. Many of these experiments are described elsewhere in this report. The channel has performed well with only minor problems with some of the power supplies and magnets.During the fall shutdown starting in September the channel underwent a sub­stantial mechanical upgrading in prepara­tion for 100 pA beams on T2. At the same time a long-term improvement in the shielding was put in place with specially cast, close-packed shielding in the chan­nel and new steel shielding in the main beam line T2 wall between M20 and M9 replacing concrete.Among the improvements to the channel it­self were the following:The front end consisting of the first two quadrupoles was modified to include an indium vacuum seal at T2 and a quick dis­connect flange downstream. All service75connections and the quadrupole stand were modified to facilitate removal and in­stallation and to allow some remote hand 1i ng.As part of the front end changes the 12 in. gate valve was moved from between Q2 and B1 to downstream of B2 in a low radiation area. This change resulted in a large part of the channel becoming an integral part of the T2 vacuum system. Several changes were made to the vacuum system to reduce the number of leaks, in­cluding a new box for the midplane slit mechan i sm.Other changes included a new vacuum roughing system, a larger view port and better mount for the TV and Cerenkov monitors, and a new vacuum box for B2 which has a port for visual access to the midsection for alignment, diagnostics and a possible future new beam extraction.The power supplies for M9 were moved off the floor to the mezzanine and are now controlled remotely from a rack near the exclusion area entrance.Several additional improvements to the channel are being planned. The most im­portant is the design of an extension to include a velocity-fi1 ter muon separator being obtained from LBL. Plans are also under way to install a large volume mag­net and time projection chamber system to provide high solid angle ray tracing spectroscopy for a series of experiments to further study 'forbidden' decay modes of the muon.The installation of the muon separator will give TRIUMF its first high intensity clean muon beam.Activity in 1977 was directed primarily at supporting those cyclotron activities leading to routine operation at 100 yA.A major effort was made during the spring shutdown to support the upgrading of ISIS for reliable intensity operation, and during the fall shutdown to support the installation of the beam line 1 extension, including the thermal neutron facility.InterlocksReliable and safe high intensity opera­tion required the rationalization of both hardware and software interlock systems. The hardware has been configured using interlock status fan-out and isolation units (0L64's) and interlock summary units (0465's) for the generation of permissives which incorporate simple logic operations, manual over-ride capability, and the possibility of software-generated permis­sives. All status information in these un i ts— i nc 1 ud i ng the status of manual over-ride switches— is monitored and dis­played, via CAMAC, by the central control system.These modules have been installed for the beam line vacuum interlock systems, where 336 conditions are monitored; the thermal neutron facility, where 171 conditions are monitored; and ISIS, where 500 conditions are monitored. By the end of 1977, approximately one-half of these conditions could be displayed on the control room CRT.The software machine protection scans which supplement these hardware interlocks have been increased in number during 1977- The status of all software inter­locks may now be seen on the control room CRT, and they may be over-ridden by operator command.In addition to the monitoring of specific devices, checking of the CAMAC system it­self has increased, and the program has been taught not to address crates which have gone off line.Operational improvementsISIS. Because diagnostic equipment for high-current operation must also be usedCONTROL SYSTEM76for low-current polarized beam operation, a multiple input range amplifier with set point indicator (MIRASPl) has been developed which permits the monitoring of beams in 6 ranges from 10 nA f.s. to 1 mA f.s. in the injection line. Gain ranging is under software control via CAMAC.To facilitate tuning of the ISIS beam line a new system for beam stop control and monitoring, which uses these ampli­fiers, has been installed. All stops are actuated under REMCON control from sepa­rate buttons on a single panel. Currents are amplified, digitized in the control system, and selected signals may then be displayed on one of four moving coil meters located near the ISIS control sta­tion. Amplifier gain is determined by operator selection. The ISIS beam stop control panel is duplicated in the control room, and control of all ISIS beam line parameters has been made available on the main control console. When the polarized ion source is running, the polarization of the extracted beam is now calculated and displayed on the main console.Logging. The primary logging device for cyclotron parameters continues to be a slow DECwriter terminal. The procedure has been simplified, however, so that a single command results in a complete hard­copy log. Many parameters have been added to this log— most notably time- integrated extracted beam and filament currents. Hardcopy logs are still operator initiated; however, site radia­tion levels are now logged automatically on disc for later transfer to magnetic tape.Automatic Procedures. In 1977 a 30 min automatic procedure for turning on the main magnet was implemented, forcing the same hysterisis curve to be followed each time, and imposing a delay for stability to be reached before manual control is possible. It is felt that this has resulted in improved reproducibility of the magnetic field.In addition, a facility was provided to permit any sequence of simple operations, including time delays and loops, to be defined and started from the console.This has been used to run the acceleratorin a macroscopic pulsed mode with vari­able beam on and off times.ProblemsTwo major problems preoccupied the Controls group in 1977- The large number of spurious error messages which have been an annoyance for some time were traced to an executive crate noise problem related to mu 11isourcing. The cause has not been fully understood; however, a con­figuration has been found which reduces these messages to a minimum.Secondly, the continued growth of the control system programs, illustrated in Fig. 71, resulted in the need to add one 8K memory module to the 'console' com­puter, and to remove the symbol table in the 'REMCON' computer which had reached its 32K word limit. All three programs can be expected to reach that limit with­in the next year, and a long-range pro­gram has been proposed to solve this problem.ReliabilitySeveral steps were taken in 1977 to im­prove the overall reliability of the con­trol system. The phasing out of unreliable KSR 37 teletypes and their replacement by LA 36 DECwriters was completed. Three fixed head disc drives, two of them seven years old, were retired and replaced with 10 Mbyte moving head drives. This hasF ig . 71. Core use in  three con tro l system  eomputers.11resulted in increased reliability, as well as permitting the upgrading of the operating system. As a byproduct, in­creased disc capacity permitted the radiation log to be placed on disc, obvi­ating the need to keep a magnetic tape drive in continuous operation. This, in turn, has improved reliability of the magnetic tape system, which had been the cause of considerable control system downtime. The improved record of the control system, which was responsible for less than 3% of cyclotron downtime in 1977, may be attributable to these im­provements .INSTRUMENTATIONAgain in 1977 the Instrumentation Advis­ory Committee rented electronic equipment to the experimental groups from the TRIUMF Pool. This year 80% of the requests were satisfied. Several new devices were added to the list of items available for rent; the complete list as of December 1977 is shown in Table XIV.The committee has also completed a list (see Table XIV) of recommended data acqui sition equipment because there are experi enced people on site who can repair and maintain these items. This equipment is not available for rental.Table XIV. TRIUMF Pool Standard Instrumentation*1. RACKS NIM MODULES (cont'd)Premier Metal Housings (Montreal) Type 00003070 Spark chamber TDC (routing unit)Clock generator (up to 200 MHz) and2. POWER SUPPLIES, BINS AND CRATES scaler required. Dual unit TRIUMF B0 0100NIM bins SLOW NIMBin and power supply: Bin NB1002 gated biased amplifier 0RTEC 444research amplifier 450CAMAC crate timing filter amplifier 454Crate: NE 9503—10—30 delay line amplifier 460Power supply: delay amplifier 427APhotomultiplier high voltage Power Designs 1570 linear gate 426linear gate and stretcher 442High voltage distribution TRIUMF THV100 fast coincidence 414Auniversal coincidence 4l8A3. PHOTOMULTIPLIERS AND HOUSINGS time-to-pu1se height converter 467 Npw bases gate and delay generator 416A2 in. 12-stage, bi-alkali precision pulse generator 1)19photomultipliers RCA 8575R 5 kV power supply 59housings N.P.W. England Ltd. constant fraction timing SCA 9555 in. 19-stage, 118 spectral response digital current integrator 939photomultipliers RCA 9522 biased ampl ifier 908Ahousings Under development5- CAMAC MODULES4. NIM MODULES Precision 12-bit ADC NE 9060Fast NIM Coincidence buffer (pattern unit)Discriminators, quad updating dual 12-fold EGG C212(bridged input) LRS 621 BLZ Multi-ADCQuad zero-cross EGG T190/NL octal 8-bit units NE 9090 AND (coincidence) gates 10-bit units LRS 3001Triple 9-fold logic LRS 965 12-fold unit LRS 2299A(Dual 4-fold majority logic LBS 364 and 365 accepted but Multi-TDCnot recommended for new purchases) octal 10-bit LRS 2228Quad 2-fold overlap ~ TRIUMF B092 Scalers: Hex 29-bit, 100 MHz Kinetics 3615 Quad 2-fold and/or (updating) LRS 622 Crate A controller Kinetics 3900(LRS 322A accepted but not recommended) (G.E.C. Elliott accepted but not recommended for new purchases)OR gates and logic fan-out Dedicated crate controller (NOVA) EGG NC 023C Logic 8-fold fan-out TRIUMF 19X295 recommended for new appUcatmons)OR gate: Dual 9-fold LRS 929 TTY output NE 7061-1Linear fan-in/fan-out LRS 928F 16-bit (relay-type) output register GEC 0D 1606{LRS 127 and 128 accepted but not recommended for 24-bit (TTL) output register SEC PR 612new purchases) 24-bit in/out (TTL) register NE 9017Linear gate TR B033 24-bit input gate SEC SEC PG 604Linear gate and stretcher (integrator) EGG LG 105/N 16-fold fast NIM out SENLevel converter (NIM Fast NIM Positive) EGG L1380/WL 256-bit input gate (for MWPC) GEC{LRS 638 AL accepted but not recommended) 2550 quad units accepted but not recommended forGate pulse and delay generator LRS 222 (EGG GG 202) new purchases)Scaler (visual display): 100 MHz, 6 digitDual unit Joerger VS 6. RECOMMENDED EQUIPMENT {not yet available for rental){accepted for maintenance only - no new units) 0RTEC 772 Minicomputer DEC PDP11 or Data GeneralVariable delay units (cable-switched) Nova seriesPassive '64 nsec' TRIUMF B007 Visual display unit Tektronix 4010 (or 4023)Variable attenuators (50ft) LRS A101 L Hardcopy Versatec PrinterFast pulse generator (Berkeley) BNC 8010 Console interface DECwriterRegenerators (Quad) TRIUMF B009 Discs Diablo QVT digitizer LRS 3001 Tapes WangcoCAMAC adapter 2301 (UBC will soon have very few 800 bpi tape mounts: present standard Data cable DC 44/4 is ]600 bpi)’'Equipment in headings 2-5 are available for rental from the TRIUMF Equipment Pool.PROGRESS TOWARDS ULTIMATE PERFORMANCE1 0 0  (jA T A S K  F O R C EThe task force was set up in June 1975 to plan, oversee and effectuate the timely achievement of the l00 yA 500 MeV design goal down beam line 1 to the thermal neutron facility. At the time of funding (February 1976) it seemed that Christmas 1977 would be the desirable date to look forward for a 100 yA demonstration. As a matter of fact, 114 yA were demonstrated on July 29 for about 45 min, although the beam dump and the beam line 1 configura­tion used for this demonstration were not yet the final 'thermal neutron facility' and the final '100 yA beam line 1 configu­ration'. The final systems were installed during the fall shutdown and by the end of 1977 were essentially ready to accept a beam. It is fair to state that the task force objectives for 1977 had been reached very close to schedule.With the demonstration of 100 yA extracted at 500 MeV it was shown that the design criteria of the machine were correct. The space charge effects at injection were within the capabilities of the injection optics. The system's stability was ade­quate and the ion source current and beam emittance adequate. The vacuum in the main cyclotron tank had been brought well below 10~7 Torr to values around 5-6 x 10-8 Torr, and the RF voltage on the reso­nators to 85-90 kV. The overall beam transmission between ion source and ex­traction radius was 25% despite the 1 arger initial emittance and the space charge dependent tuning. The beam loading of the RF voltage, which could have caused instability and as a result a loss in beam transmission through the cyclotron, turned out to be, as expected, very ac­ceptable. The transmissions at higher currents were,as a matter of fact, as good as at low currents, and the fraction­al beam spilled along the external line was the same as at lower currents. The diagnostic devices and controls installed in order to avoid thermal damage seemed adequate, and the shielding which was very much upgraded during 1977 was such as to make the meson hall and the outside of vault and beam line tunnels well ac­cessible to experimenters. A 1 mil thickpyrolitic graphite foil proved to be us­able to extract the beam without any ob­servable damage after the test. Almost every system had to be brought to its highest possible level of reliability and best performance to make the 100 yA goal poss i b 1e .Progress was also made towards the longer term program of '100 yA continuous opera­tion', which means 100 yA beam production available on request and operable contin­uously without concern for increasing residual activities. This program will be completed when all systems can be maintained, with remote handling where necessary, in spite of the residual activ­ity acquired during extended 100 yA running.High residual activity areas are the areas of the targets along beam line 1, the collimators and beam lines downstream from these targets and the thermal neutron facility. Practically all beam line 1 was rebuilt during the four-month fall shutdown with great emphasis on radiation hardening of components and their remote handleabi1i ty.An extensive planning effort has assisted the various phases of progress during the year. The three PERT diagrams for cyclotron, proton hall and meson hall, which had been drawn up at the end of 1976 with more than 1000 activities, were followed closely. Progress was continu­ously monitored and PERTs updated during the year. By mid July a detailed shut­down installation schedule had been pre­pared in the form of a bar chart and was revised weekly throughout the shutdown. Critical paths, items to be expedited, late deliveries and shortages of manpower were continuously printed out as soon as realized so that corrective action could be taken.In the proton area the raising of the current along beam line 4A, which was one of the task force jobs, was also under­taken. By the end of 1977 the 4A beam dump, with a special carbon dump inserted,80was ready to accept a beam of 10 yA, the final design current for this line.Concluding, 1977 has been for the 100 yA task force a great year!SEPARATED TURNS TASK FORCEWith all priorities directed towards run­ning a 100 yA beam to TNF, work towards separated turns was at a virtual stand­still for most of the year. Nevertheless a few forward steps have been taken in the areas of RF third harmonic, dee volt­age stabilization, probes and beam deve1opment.In the case of the RF the components of the water-cooled stubs needed to upgrade the third harmonic transmission line to full power have been completed; the draw­ings for the power amplifier are virtual­ly complete; and the pre-driver for the 2 kW driver amplifier has been repaired and returned by the makers.The most prominent fluctuations in dee voltage occur at about b Hz and are at­tributed to sma 1 1 mechanical vibrations in the resonators excited by the flow of cooling water. Not only are these fluc­tuations unacceptably large for separated turn operation but they limit beam performance in other ways as well (split ratio, improved energy resolution with slits, etc.). They also give rise to fluctuations in the time of flight of the beam in the cyclotron, measured either on one of the HE probes, or in beam line 1. Regulating out the voltage fluctuations is complicated by the fact that the dees consist of 80 separate resonators only weakly coupled together mechanically. Ideally the voltage would be sensed in each of these resonators and an averaged signal fed back to the main amplifiers. The number of voltage probes and current loops available is much more limited. Nevertheless, by combining the signals from just one probe and one loop to regu­late the dee voltage it has been possible to reduce the time-of-f1ight fluctuations in some preliminary tests from 1.0 to0.6 ysec FWHM. It is also planned to try regulating the dee voltage directly from the time-of-f1ight signal.The successful operation of the centring probes and beam selection slits has been described in the Beam Development section of this report (pp.11,12). These will be essential tools in improving the beam quality and selecting the emittance for separated turn operation.81FACILITIES UNDER DESIGN AND CONSTRUCTIONM11 CHANNELAs the year 1977 progressed it became ap­parent that there were not the resources at TRIUMF to install a complete Mil by the end of the year. Instead it was planned to install the front end only, up to llBl. This amended plan was cut back further when two events occurred. One, the brazing of the septum magnet (llSl) coil was unsuccessful as there were too many leaks in the septum-return coil junction. Two, the dipole llBl was not completed as there was not enough copper to finish the coils. The minimum instal­lation plan then became the completion of beam line lA in the Tl region. This meant the installation of the Tl shield, 1Q9, the Tl collimator shield, IQ.10 and lQll. This was completed in December during the fall shutdown.It should be pointed out that the three quadrupoles installed by the Mil group were designed to be remotely handleable. The features of this design are:1) All service connections are complete­ly radiation hard.2) All service connections and vacuum connections can be quickly discon­nected and reconnected with the use of remote tools.3) The crane alone can pick up a magnet and replace it without the need of a rigger beside the magnet to rig it or guide it. Furthermore when the magnet is set back into the beam line it is automatically aligned.Magnets 1Q9, l Q.10 and lQll all have the above features.Computer calculations on the M 11 septum magnetThe leakage field to be seen by the pro­ton beam passing by the Mil septum magnet will be completely dominated by end effects.The program GFUN3D [Armstrong e t a t . ,Proc. 5th Int. Conf. on Magnet Technology, l68 (1975)] has been used to calculatethe three-dimensional fields expected from the Mil septum magnet. For the mag­net as designed the coil field will dominate the iron field due to a peak in the coil field strength produced by the cross-connection between the septum sheet and the current return. The iron contri­bution can be increased by placing iron shims of 5 to 10 cm longitudinal extent below the current cross-connections.These shims will saturate badly,_so an exact match of (/B• dJl) ; ron and )mB ­dT) Co i 1> as seen by the proton beam, will be pos­sible only at one current setting. This current setting will be chosen to corre­spond to the most probable operating mode of the Mil channel. Away from this operating point, steering coils will be needed for correction of the proton beam d i rect i o n .MEDIUM RESOLUTION SPECTROMETER (MRS)The MRS is a large acceptance (±5% Ap/p) medium resolution (0.05% Ap/p) magnetic spectrometer for detecting protons, deuterons, tritons, etc. It is designed as a general user facility. The facili­ty includes the spectrometer, target chamber, electronics, general purpose data acquisition system, and dedicated counting room.The dipole magnet, quadrupole magnet, de­tectors, and electronics have been in­stalled and tested. Apart from minor bugs they are working satisfactorily.The initial tests are summarized in the following excerpt from a recent report (TRIUMF design note TRI-DN-77“ 15):'The combined energy resolution of the dispersed beam, kinematic broadening and MRS resolution was measured to be1.^ MeV FWHM at an energy of ^90 MeV. As the kinematic broadening (from dE/d0) was expected to be 0.9 MeV, the spectrometer may already be approaching its design goal of 0.6 MeV. The displacement and tilt of the focal plane (caused by the wedge dipole edges) are as predicted by82the design calculations [Kitching and Stinson, TRI-DNA~75~5]■ The most impor­tant second-order aberrations have been measured and found to be software correctable (as expected).'The electronics system was shown to be capable of cleanly separating protons from deuterons by time of flight (in the case in which a thin plastic is used at the entrance to the MRS). The presence of a thin scintillator at the entrance to the MRS was shown to have no appreciable effect on the resolution at A90 MeV, again as predicted by the design study.1For scattering angles greater than 22° the MRS has a solid angle acceptance of 3 msr. At angles less than 22° the solid angle acceptance will be smaller (0.7 - 3 msr) because the quadrupole must be moved back to avoid a clash with the downstream beam pipe.The MRS is expected to reach its full capability in the summer of 1978. The major areas which should be completed by then are:1) The shielding in the proton hall will be improved to allow a full range of angles to be covered. At present the MRS can operate only at the fixed angle of 22.5°, and there is only limited space for a coincidence detector on the opposite side of the target.2) The data acquisition system will be completed. Presently there is no soft­ware for the acquisition computer and the cables from the experimental area to the MRS counting room are not yet installed. Preliminary experiments have been pos­sible with the co-operation of the Uni­versity of Alberta groups, who have used their own cables and computer system to allow the early experiments to proceed.BEAM LINE 1BDuring the fall shutdown partof the front end of beam line IB ('Peanuts' line) was installed, namely the first bending mag­net at the lA-IB junction and a front-end quadrupole.In the spring and summer of 1978 the group expects to acquire the kB beam dump and to install the rest of the beam line components. Financial considerations . will limit construction at this time to one target station.THERMAL NEUTRON FACILITYThe design of this facility, as presented in the previous annual report, has essen­tially not changed during the year, and was publsihed in full detail in August [TRI -77~1]- Site construction, started in December 1976, continued through the year resulting in a facility, ready to receive a 100 yA beam, by the middle of December. An overall view of the facility, as described in the 1976 annual report, is shown in Fig. 72.Some milestones worth remembering are:January: All reject steel plates cut anddelivered. (The meson hall looked like a scrap yard.)March: The vacuum tank arrived on site,(it took four weeks to get it in an ac­ceptable shape.)May: The 230-ton iron shield was erectedand the first concrete was poured.August: All 60 concrete blocks poured inplace (end of the mess!).November: Reflector, moderator, targetand cooling package installed.December: All vacuum and water systemsoperat iona1.At the beginning of the year the chosen neutron target concept still had to be worked out in detail and the heat trans­fer principles had to be proven. The lead target/beam stop is contained in a #316 stainless steel can, 15 cm in diam­eter and 25 cm long. This material was tested for its compatibility with molten lead and boiling water. The thickness of the wall is chosen such that with molten lead on the inside at somewhat above 325°C and boiling water on the outside at approx I08°C the heat transfer density is838^Fig. 73. Inside view of the thermal neutron tcurget, moderator and reflector. 1) Shadow shield, 2) plug, 3) D20 moderator access, 4) iron-concrete shield, 5) reflector H20, 6) proton beam access, 7) water window, 8) protons, 9) neutron channels, 10) moderator D20, 11) target, 12) moderator H20, 13) steel shield, 14) water window and target front cooling.85limited to approx 125 W/cm2 . This is a safe limit for heat transfer from the outside surface by nucleated boiling.This feature then essentially prevents burn-out, as long as the total effective heat transfer area is large enough to transfer the beam power at this heat transfer density. At 100 yA at 500 MeV most of the lead will be molten and heat will be transferred effectively by natural convection from the core where the beam is stopped to the inside of the target wall. Heat transfer from the outside of the target wall to a heat exchanger near the upper end of the moderator tank is also by natural convection. The assembly is illustrated in Fig. 73-From the beam line vacuum the beam first passes through a 0.12 mm thick helium cooled double vacuum window into the TNF tank vacuum. Subseuqently it passes through a 3 mm thick aluminum water window, through a 5 mm thick layer of water into the target container. The water in this layer is circulated to pro­vide effective cooling of both the water window and the target front wall (see Fig. 73 insert).In parallel with construction lead tar­get heat transfer tests were conducted, up to a heat load of 50 kW (equivalent to 100 yA at 500 MeV). This limit was set by the concentrated heating elements and not by heat transfer failure. It leaves a reasonable safety margin, since only 75% of the beam power will end up in the target and, with a target at T2, normally only 60% of the beam will reach the TNF. Heat transfer in the water layer between target can and water window was tested sepa rately.However, there are still some unanswered questions about the behaviour of the can under actual operating conditions, so thorough inspections after the first few hours of full beam current are planned, and it will probably be necessary to change the target after every 600 yA months, as a measure of preventive ma i n tenance.F ig . 74. The thermal neutron ta rge t, moderator and re f le c to r assembly.TARGETSThe main effort through the year has been expended on the thermal neutron facility. The group has been responsible for the engineering design, drafting, contract bidding and inspection during manufacture of the entire central part (from the vacuum vessel inward) of the facility.The lead target assembly, shown in Fig. 74, was manufactured 'in house'.All components of this facility have been manufactured and delivered to TRIUMF main site and are currently being installed and commissioned for operation in early January.A proposal to build a EEX production tar­get using liquid methane and capable of functioning at 100 yA beam current (l kW dissipation in the target) has been made and accepted.1,1.? 'NCHES I 0_________'9........ jp CM86SHIELDING AND ACTIVATION DATA INTERFACE TASK FORCEThe reconstruction of beam line 1 from the vault to T2 and its extension to TNF necessitated the removal and reinstalla­tion of virtually all of the movable shielding in the meson hall. Most of the large concrete blocks (Vx6'x]2' and k 1x61x]8 1) were removed from the main ac­celerator building during the beam line (re-) construction period to provide ade­quate working space. Approximately 300 tons of additional iron shielding was fabricated and installed around the exist­ing T2 target assembly and the quadrupole focusing elements in the beam line 1 ex­tension. This shielding was provided to reduce the high-energy neutron background in the M9 secondary channel experimental area and to provide protection for the M8 channel area from the radiation source caused by proton beam spill in the beam line 1 quadrupole triplet immediately behind T2. To relieve the shielding re­quired for the rest of beam line 1 exten­sion to the TNF three proton beam scrapers were installed, one immediately following the quadrupole triplet and two others about equally spaced in the remaining 12 m drift length to the TNF target shield. These scrapers were 3 ft wide by A ft high by 5 or 6 ft long iron shielding assem­blies with beam tubes of reduced diameter imbedded along the longitudinal centre line of the assemblies. Beam transport estimates indicate that most of the pro­tons scattered by thick targets at T2 will be scraped off at these constrictions, thus reducing the beam line shielding re­quired and burying the residual activity produced by these spills.Approximately 50 special concrete shield­ing blocks were fabricated and installed to give a close packing around the M9 and M20 secondary channels at T2 and to ac­commodate the service connections to beam line monitors along beam line 1 and other components to be installed later at target Tl .With one programmer spending approximate­ly 80% of his time on the data interface, considerable progress was made in 1977. Consistent with the stated objectives of the data interface, this progress can be discussed under the headings communica­tions within TRIUMF, communications with the UBC Computing Centre, and background app1i cat i ons.Communications within TRIUMFDue to a lack of available manpower development of the module required for CAMAC-CAMAC communications between the data interface and experimental CAMAC systems has not proceeded as quickly as hoped, and the module was not available in 1977- In order to test some applica­tions of experimenter-data interface com­munications, two experiments were connected to the data interface using available asynchronous channels of its communications multiplexer.The experimental data acquisition systems used CAMAC teletype drivers to send and receive data. Both experiments used BASIC for their data acquisition language, and a subroutine call was added to BASIC allowing the user to initiate a conversa­tion with the data interface, send or re­ceive data blocks of varying lengths, and request that programs be executed in the data interface.This facility was first tested on the system analyzing samples from radioiso­tope production runs. When a spectrum had been accumulated in the data acquisi­tion computer it was sent to the data interface to be typed out and plotted on the printer/plotter in the control room. This complete operation took only about 2 min, whereas the data acquisition sys­tem itself had no plotting facility and took nearly 10 min to type out the spect rum.The second application was for the proton radiography experiment. In this case the data acquisition computer moves the beam from point to point on the sample. As the data is acquired the co-ordinates and 5 scaler values for each point are sent to the data interface for filing on disc.87A FORTRAN program on the data interface then does preliminary data reduction and plotting. The raw data had previously been sent directly to the UBC Computing Centre, and the low data transmission rates available were limiting the speed for a scan. Use of the data interface increased the speed of data acquisition s i gn i f icant 1y .Communications with UBC Computing CentreBecause of an inadequate number of tele­phone wires linking TRIUMF with the UBC Computing Centre, enough lines for ayn- chronous communication links— used pri­marily for conversational applications with CRT termina1s— have never been available. In 1977 two TRIUMF designed and built asynchronous line multiplexers were installed, each allowing 7 lines to use one wire. Use of these multiplexers should satisfy TRIUMF's line requirements for the next one or two years— or until new cable can be laid.The principal means of communication between the UBC Computing Centre and the data interface was to have been a medium speed (9600 bd) synchronous link using the SDLC protocol. By the end of 1977 this facility had not yet been provided by UBC, and once again an alternative method had to be found. In this case achannel of the asynchronous multiplexerdescribed above was used.Using this channel, reduced data from the proton radiography experiment has been sent to the UBC Computing Centre for further analysis there; and data on fileat the Computing Centre has been returnedto TRIUMF for plotting.It should be pointed out that these ac­complishments have been achieved as tests only, and that there is not yet a commun­ications task running routinely and reliably in the data interface foregroundBackground useWhen not in use for development of the communications tasks described above, the data interface has been used by ex­perimenters and others for a variety of tasks. Probably the most useful feature of the data interface for experimental users has been the availability of two dual density magnetic tape drives. This feature has been used to place on one tape events of interest skimmed from another, and to copy data from 800 bpi to 1600 bpi. This latter use will be of increasing importance as the UBC Comput­ing Centre reduces its support for 800 bp d r i ves.Major experimental users have been the ppy experiment, which did much of its data analysis using the data interface; the University of Victoria Experiment 52 which has used the data interface for lengthy Monte Carlo calculations; the TINA group; and others. In addition, the TRIUMF Safety group radiation logs are analyzed and printed using the data inter face.By the end of 1977 it had become neces­sary to provide a reservation system for data interface use. As anticipated, con­siderably more than 50% of available time is used by experimental or cyclotron groups for 'off-line' activities, and this use is expected to increase consider ably. When the communications tasks are running reliably in the foreground, more time should be available for these back­ground jobs.ORGANIZATIONBoard o f ManagementThe Board of Management of TR IU MF manages the business of the project and has equal representation from each of the four universities. At the end of 1977 the Board compr i s e d :University of Alberta President H.E. GunningDean Kenneth B. Newbound SecretaryMr. W.A.B. SaundersSimon Fraser University Mr. W. DeVries Dean J.M. Webster D r . B .G . W i 1 sonUniversity of Victoria Dean J.M. Dewey Dr. R.M. Pearce President H.E. PetchUniversity of British Columbia Dr. M. Shaw Mr. D. Sinclai r Dr. E.W. Vogt ChairmanNon-voting members: Dr. R.A. Foxall, National Research CouncilDr. J.T. Sample, Director, TRIUMFThere we re no changes in Board membership in 1977- The Board met three times during the year.Operating CommitteeThe Operating Committee of TRIUMF is responsible for the operation of the project.It reports to the Board of Management through its chairman, Dr. J.T. Sample. It has four voting members, one from each of the four universities. The Asso ci at e Directors, one of wh o m  serves as secretary', are non-voting members. The members of the committee (alternate members in parentheses) at the end of 1977 were:Dr. J.T. Sample ChairmanDr.Dr.Dr.Dr.Dr.Dr.K.L. B.D. W.C. R.G. G. R. J.B.Erdman Pate 01 sen K o r t e 1 i ng Mason WarrenSecretaryD i rectorAsso ci at e Director, Facilities Asso ci at e Director, Applied Programs Un iversity of Alberta (Dr.Simon Fraser University (Dr.Un iversity of Victoria (Dr.University of British Columbia (Dr.P . Ki tch i ng) J.M. D 1Auria) L.P. Robertson) G. Jones)Changes in university representation in 1977 were: J.M. D'Auria succeeded A.S. Arrottas the al ternate member for Simon Fraser University in August; L.P. Robertson and G.R. Mason exchanged places in April as University of Victoria member and alternate; and in March G. Jones took the place of D.A. Axen as Un iversity of British Columbia al ternate member.The Committee met thirteen times during the year.89TRIUMF Safety Advisory CommitteeOr. B.D. Pate ChairmanOr. E.W. BlackmoreMr. J.J. BurgerjonMr. J.W. CareyDr. L.P. RobertsonM r . 1.M . ThorsonDr. G.D. Wait Se c re ta ryDr. M.W. Greene, B.C. Dept, of Health Services and Hospital Insurance Mr. W. Rachuk, Radiation Protection and Pollution Control Officer, UBCNon-voting members:Dr. D.R. Gill Mr. L .E . Mor i tz Mr. P. TaylorMr. M.K. McGee, Workers' Compensation BoardExperiments Evaluation CommitteeDr. A.E. Litherland Chairman University of TorontoDr. A. Astbury Rutherford LaboratoryDr. J.M. Cameron (until Dec 31) University of AlbertaDr. R. Engfer Un i vers i tat ZUr ichDr. G.T. Ewan Queen's UniversityDr. M.D. Hasinoff University of British ColumbiaDr. E .M . Hen 1ey University of WashingtonDr. J-M Poutissou (Jan 1978) Universite de MontrealDr. J.T. Sample TRIUMFDr. L.D. Skarsgard B.C. Cancer FoundationDr. A.W. Thomas Se c re ta ry TRIUMFDr. E.W. Vogt University of British ColumbiaDr. L. Yaffe McG ill Uni vers i tyBiomedical Experiments Evaluation CommitteeDr. L.D. Skarsgard Chairman B.C. Cancer FoundationDr. M. J. Ashwood-Smi th University of VictoriaDr. H.C. Johns Ontario Cancer InstituteDr. R.R. Johnson University of British ColumbiaDr. A.E. L i ther1 and University of TorontoDr. T.R. Overton University of AlbertaDr. J.T. Samp 1e TRIUMFDr. A.W. Thomas TRIUMFDr. D.C. W a 1ker University of British ColumbiaDr. G.F. Wh i tmore University of Toronto90Appendix APUBLICATIONSConference proceedings:M.K. Craddock, E.W. Blackmore, G. Dutto,C.J. Kost, G.H. Mackenzie and P. Schmor,Improvements to the beam properties of the TRIUMF cyclotron, IEEE Trans. NS-24(3), 1615 (1977). [TRI-PP-77-1]G. Dutto, J.L. Beveridge, E.W. Blackmore, M.K. Craddock, K.L. Erdman, D.P. Gurd,C.J. Kost, G.H. Mackenzie, P.A. Reeve,J.R. Richardson, J.T. Sample, P. Schmor and M. Zach, Developments at TRIUMF, ib id . , 1653. [TRI-PP-77-2]D.P. Gurd, D.R. Heywood and C.J. Kost,The TRIUMF data interface, i b id . ,  1801.[TRI —PP —77 —3]G.H. Mackenzie, TRIUMF: Status and devel­opment plans, Proc. X Int. Conf. on High- Energy Accelerators, Protvino (IHEP, Serpukhov, 1977), p.184.A.W. Thomas, Pion reactions with few nuc­leon systems, Proc. 7th Int. Conf. on High-Energy Physics and Nuclear Structure, Zurich, (Birkhauser, Basel, 1977), p.109-[TRI-PP-77-7]D.F. Measday, The nucleon-nuc1 eon inter­act i o n , ib id . , 61.C. Amsler, D.A. Axen, J. Beveridge, R.C. Brown, D .V . Bugg, A.S. Clough, J.A. Edgington, L. Felawka, S. Jaccard,G. Ludgate, C.J. Oram, J.R. Richardson, L.P. Robertson, N.M. Stewart, J. Va'vra, Neutron-proton scattering experiments at TRIUMF, Proc. 7th Int. Conf. on High- Energy Physics and Nuclear Structure, Abstract Volume, p.232.E.G. Auld, A. Haynes, R.R. Johnson,G. Jones, T. Masterson, E. Mathie,D. Ottewell and P. Walden, Positive pion production from nuclei by polarized pro­tons, ib id ., 21.E.G. Auld e t a l . , The p+p-»d+Tr+ reaction using polarized protons, ib id . ,  26.M.D. Hasinoff, F. Corriveau, D.F. Measday, J-M Poutissou and M. Salomon, The Panofsky ratio in 3He, ib id . , 48.A.W. Thomas, A.S. Rinat, Y. Starkand andE. Hammel, A relativistic three-body calculation of ttD scattering in the resonance region, ib id . , 68.F. Corriveau, M.D. Hasinoff, D.F. Measday, M. Salomon, J.E. Spu11er and J-M Poutissou, Charge exchange of stopped tt- in nuclei, ib id .  , 87.E.G. Auld, H. Averdung, J. Bailey, G.A. Beer, B. Dreher, K.L. Erdman, U. Gastaldi,E. Klempt, K. Merle, K. Neubecker,H. Schwenk, V.H. Walther, R.D. Wendling,B.L. V/hite, The search for X-rays of pro­ton i urn (pp-atom) in hydrogen gas, ib id . , 304.K.L. Erdman, R.R. Johnson, T.G. Masterson, R. Feenstra, D.R. Gill, A.W. Thomas and R.H. Landau, tt- elastic scattering on 12C at 30 MeV, ib id .  , 112.R.H. Landau and A.W. Thomas, The theory of low energy pion-nucleus elastic scattering, ib id . ,  122.L.G. Greeniaus, J.M. Cameron, D.A. Hutcheon, R.H. McCamis, C.A. Miller, G.A. Moss, G. Roy, J.G. Rogers, B.T. Murdoch, M.S. de Jong, W.T.H. van Oers, A.W. Stetz, A study of the reaction p+ltHe->3He at back­ward angles, ib id . ,  190.J.M. Cameron, L.G. Greeniaus, D.A. Hutcheon, R.H. McCamis, C.A. Miller, G.A. Moss, G. Roy, J.G. Rogers, B.T. Murdoch,M. de Jong, W.T.H. van Oers, A.W. Stetz, Backward angle elastic p-^He scattering at intermediate energies, ib id . ,  194.A.N. Anderson, J.L. Beveridge, C.A. Gouiding, D.P. Gurd, J.G. Rogers, H.W. Fearing, J.M. Cameron, L.G. Greeniaus,J .V. Jovanovich, C.A. Smith, A.W. Stetz, J.R. Richardson, Proton-proton bremsstrah- lung at small angles, ib id . , 255.G.A. Beer, G.R. Mason, A. Olin, R.M. Pearce, P. Poffenberger, D.A. Bryman, M.S. Dixit and J.A. Macdonald, Pionic 2p-ls transition in 19F and 23Na, ib id . ,  284.S.K. Kim, G.A. Beer, G.R. Mason, A. Olin, R.M. Pearce, D.A. Bryman, M.S. Dixit, J.A. Macdonald and J.S. Vincent, X rays from pionic helium-three, ib id . ,  286.P. Depommier, J-P Martin, J-M Poutissou,R. Poutissou, D. Berghofer, M.D. Hasinoff, D.F. Measday, M. Salomon, D. Bryman, M.S. Dixit, J.A. Macdonald and G. Opat, A search for the y-^ey decay mode of the muon, ib id .  , 319-D.A. Bryman, M.S. Dixit, J.A. Macdonald,D. Berghofer, J-M Poutissou, G.A. Beer, G.R. Mason and A. 01 in, Measurement of the Tr^ -ev branching ratio, ib id . , 322.G.M. Marshall, J.B. Warren, J.H. Brewer,G. Clark, D.G. Fleming, D.M. Garner, Muonium diffusion into a vacuum,ib id . , 323•R.S. Sloboda and H.W. Fearing, On radia­tive muon capture rates and the maximum photon energy, ib id . , 345-J . FI. Brewer, D.G. Fleming, D.M. Garner,G.M. Marshall, J.B. V/arren, The kinetics of gas phase muonium reactions: Mu+X2 and Mu+HX, X=F,C 1,Br,I , ib id . 364.A.W. Thomas, The deuteron, Proc. 2nd Int. Conf. on the Nuc1eon-Nuc1 eon Interaction, Vancouver, AIPCP #41 (AIP, New York,1978), p.373- [TR1-PP-77-10]H.W. Fearing, Some comments on the soft- photon approach to proton-proton brems­strahiung, ib id . ,  506. [TR I-PP-77- 11]J.L. Beveridge, D.P. Gurd, J.G. Rogers,H.W. Fearing, A.N. Anderson, J.M. Cameron, L.G. Greeniaus, C.A. Goulding, J.V. Jovanovich, C.A. Smith, A.W. Stetz, J.R. Richardson and R. Frascaria, Proton- proton bremsstrahiung at small angles,ib id .  , 446. [TRI-PP-77-12]G. Jones, pp->d7r+ near threshold,ib id .  , 787. [TRI-PP-77-13]J.H. Brewer, p+SR studies at TRIUMF,Proc. Symp. on Chemical and Physical Ap­plications of Positron and Muon Spectros­copy, New Orleans, March.D.M. Garner, J.H. Brewer, D.G. Fleming, G.M. Marshall, J.B. Warren and G. Clark, Muonium chemistry in the gas phase, ib id .D.M. Garner, J.H. Brewer, D.G. Fleming,G.M. Marshall, J.B. Warren and G. Clark, The effect of moderations on the spin re­laxation of muonium in the gas phase, ib id .D.G. Fleming, J.H. Brewer, G.M. Marshall, Muonium chemistry - A review, Proc. Joint Conference and Exhibition of ACS and CIC, Montrea1, June.D.M. Garner, D.G. Fleming, J.H. Brewer,G.M. Marshall and J.B. Warren, Muonium chemistry in the gas phase, ib id .L. Vaz, J.H. Brewer, D.G. Fleming and D.C. Walker, Epithermal muonium reactions in liquids, ib id .J.H. Brewer, Muon spin rotation: Recent developments of application in chemistry and material science, Proc. Int. Symp. on Muon Chemistry and Mesomolecular Pro­cesses in Matter, Dubna, June (to be pub 1i shed).P.A. Reeve, Magnetic separation in quad­rupole fields, Proc. 6th Int. Conf. on Magnet Technology, Bratislava (ALFA, Bratislava, 1978), p. 319-Journal publications:C. Amsler, R.C. Brown, D.V. Bugg, J.A. Edgington, C. Oram, D. Axen, R. Dubois,L. Felawka, S. Jaccard, R. Keeler,J. Va'vra, A. Clough, D. Gibson, G.A. Ludgate, N.M. Stewart, L.P. Robertson and J.R. Richardson, A monoenergetic polar­ized neutron beam from 200 to 500 MeV, Nucl. Instr. £ Meth. 144, 401 (1977).C. Amsler, D. Axen, J. Beveridge, D.V. Bugg, A.S. Clough, J.A. Edgington,S. Jaccard, G. Ludgate, C. Oram, J.R. Richardson, L. Robertson, N. Stewart and J. Va'vra, Neutron-proton elastic scatter i ng at 325 MeV, Phys. Lett. 6913, 419 (1977)D. Axen, L. Felawka, S. Jaccard,J. Va'vra, G.A. Ludgate, N.M. Stewart,C. Amsler, R.C. Brown, D.V. Bugg, J.A. Edgington, C.J. Oram, K. Shakarchi and A.S. Clough, D, R, R' and P in pp elastic scattering from 209 to 515 MeV, Lett, al Nuovo Cimento 20, 151 (1977).P. Depommier, J-P Martin, J-M Poutissou, R. Poutissou, D. Berghofer, M.D.Hasinoff, D.F. Measday, M. Salamon, D.A. Bryman, M.S. Dixit, J.A. Macdonald andG. I . Opat, A new limit on the p+-*e+y decay, Phys. Rev. Lett. 39., 1113 (1977)[TRI -PP-77-8]M.K. Craddock, K.L. Erdman and J.T. Sample, Basic and applied research at the TRIUMF meson factory, Nature 270, 671(1977) [TRI-PP-77-5]C.A. Goulding, B.T. Murdoch, M.S. de Jong R.H. McCamis and W.T.H. van Oers, A liquid helium-4 target for intermediate- energy nuclear physics, Nucl. Instr. £ Meth. 148, 11 (1978) [TRI-PP-77-9]A.W. Stetz, J.M. Cameron, D.A. Hutcheon,R. McCamis, C.A. Miller, G.A. Miller,G.A. Moss, G. Roy, J.G. Rogers, C.A. Goulding and W.T.H. van Oers, Elastic92proton scattering from 4He in the forward direction at 200, 350 and 500 MeV, Nucl. Phys. A290, 285 (1977).H. Lang, R.W. Harrison, R.R. Johnson and R.M. Henkelman, CAMAC control of the bio­medical EEb  beam line at TRIUMF, Nucl. Instr. & Meth. 144, 589 (1977)-A.G. Seamster, R.E.L. Green and R.G. Korteling, Silicon detector AE,E particle identification: A theoretically based analysis algorithm and remarks on the fundamental limits to the resolution of particle type by AE,E measurements, Nucl. Instr. & Meth. 145, 583 (1977)-D.G. Fleming, D.M. Garner, J.H. Brewer, J.B. Warren, G.M. Marshall, G. Clark,A.E. Pifer and T. Bowen, The chemical reaction of muonium with CZ2 in the gas phase, Chem. Phys. Lett. 4!3, 393 (1977) -D.G. Fleming, J.H. Brewer and D.M. Garner, Muonium chemistry in the gas phase, Ber. Bunsenges. Physik. Chem. 8_1_, 159 (1977).D.A. Bryman, J. Cresswell and R. Skegg, Delay line readout of the anode wires in a multiwire proportional chamber, Nucl. Instr. S Meth. ]4J_, 573 (1977).[TRI-PP—76—111H.W. Fearing, DWIA (p,ir) calculations: Effects of realistic wave functions and factors determining resonance position, Phys. Rev. C _[6_, 313 (1977).[TRI-PP-76-12]Prepr i nts:R.H. Landau and A.W. Thomas, A theory of low energy pion-nucleon scattering (to be published, Nucl. Phys. A). [TRI-PP-77-4]R.R. Johnson, T.G. Masterson, K.L.Erdman, A.W. Thomas, R.H. Landau, Elastic scattering of positive pions from 12C at 30, 40 and 50 MeV (to be published,Nucl. Phys. A). [TRI-PP—77-6]R.M. Woloshyn, Neutral pion photoproduc­tion in a phenomenological isobar doorway model (to be published, Phys. Rev. C).[TRI-PP-77- 14]R.S. Sloboda and H.W. Fearing, On radia­tive muon capture rates and the maximum photon energy (to be published, Phys.Rev. C). [TRI-PP-77-15]J.M. Cameron, L.G. Greeniaus, D.A. Hutcheon, R.H. McCamis, C.A. Miller, G.A. Moss, G. Roy, M.S. de Jong, B.T. Murdoch, W.T.H. van Oers, J.G. Rogers, A.W. Stetz, Large angle measurements of p+'tHe-s-3He+d at intermediate energies (to be published, Phys. Lett. B), [TRI-UAE-5005]A.W. Thomas and R.H. Landau, The connec­tion between elastic and quasi-e1 astic pion-pion scattering from nuclei (to be published, Phys. Rev. Lett.). [LBL-7166]D.V. Bugg, J.A. Edgington, C. Amsler,R.C. Brown, C.J. Oram, K. Shakarchi, N.M. Stewart, G.A. Ludgate, A.S. Clough,D. Axen, S. Jaccard, J. Va'vra, Proton- proton elastic scattering from 150 to 515 MeV (to be published). [RL-77-146/B]D.M. Garner, D.G. Fleming and J.H. Brewer, Muonium chemistry: Kinetics of the gas phase reaction MU+F2 MuF+F from 300 to 400 K (tobe published, Chem. Phys. Lett.).D.G. Fleming, D.M. Garner, L.C. Vaz, D.C. Walker, J.H. Brewer and K.M. Crowe,Muonium chemistry, a review (to be pub­lished in P o s it ro n iu m  and muonium chem is­t r y ,  Advances in Chemistry series of ACS).Reports:A.S. Arrott, T.L. Templeton, 1.M. Thorson, R.E. Blaby, J.J. Burgerjon, T.A. Hodges and R.R. Langstaff, The TRIUMF thermal neutron facility as planned for operation by 1978. [TRI-77-1]T.L. Templeton and A.S. Arrott, Two- dimensional calculation of the optimum reactor design for the TRIUMF thermal neutron facility. [TRI-I-77_1]R.M. Henkelman, K.Y. Lam, R.W. Harrison, K.R. Shortt, M. Poon, H. Lang, B.W. Jaggi,B. Palcic and L.D. Skarsgard, Progress during the first year of operation of the Batho Biomedical Facility at TRIUMF.[TRI-77-2]W.T.H. van Oers, Proton elastic scattering from light nuclei at intermediate energies[TRI-77-3]G.l. Opat, Monte Carlo simulation of ex­periments: An introduction illustrated by the computer programs SI MUL8 and Monte- Pion. [TRI-77-4]93Appendix BSTAFFBREAKDOWN OF TRIUMF STAFF TOTAL AS OF DECEMBER 31, 1977Ma i n S i te UBC UVic SFU UA1 ta Tota 1a b a b a b a b a b a bScientists 22 A 8 lc 1 4 1 c 2C 24 19Faculty at main site 1977/78^ (3) (2) (1)Faculty part-time [12] [6] [3] [12]Engi neers 19 - - lc - - - 1 20 1Operators 15 15Computing staff 5.14 - 0.5 1 - 1 - 6.4 1.5Graduate students 14 3 - 3 3 - 23Techn i ci ans 69 2 3 2 2 - - 3C 71 10Des i gner-draftsmen 15 - 1 - - - 16Machine shop staff 13 - 1 - - 1 14 1PI ant 9 9Admi n i st rat i on 5 5Office staff:Secretarial & clerical Library/1nformation Office1211 0.8 - 1 - 1 15.8 - 1Stores 5 5190. A 6 1 25.5 6.8 6 2 8 2 10 202.2 55-5aFunded personnel ^Supported by research grantscMain site totals include two additional Victoria scientists (grant), three Alberta scientists (one funded, two grant), one Victoria engineer (funded) and two Alberta technicians (grant) who are based at main site.^Faculty spending the 1977/78 academic year at main site have been included in the appropriate category; during such leave faculty members are paid by TRIUMF rather than by the respective un i vers i ty.Appendix CUSERS GROUPUniversity of Alberta: University of Victoria:L. Antonuk G . C . Ne i1 son M.J. Ashwood-Smith J.A. MacdonaldE . B . Ca i rns A.A. Noujaim G.A. Beer G.O. MackieJ.M. Cameron W.C. Olsen G. Bushnel1 G.R. MasonW.K. Dawson T.R. Overton T.W. Dingle A. OlinJ . B . Elliott G . Roy M.S. Dixit R.M. PearceG.R. Freeman R.F. Ruth G.B. Friedmann C .E . PicciottoL.G. Greeniaus M. Schacter J . Haywood P.A. ReeveH . E . Gunn i ng D.M. Sheppard T.A. Hodges L.P. RobertsonJ . Kal 1 ne H . Sher i f A.K. Kirk C.S. WuA.N. Kamal R. Sloboda D.E. LobbP . Ki tch i ng L.G. Stephens-NewshamR. McCamis G .M . St i nsonW.J. McDonald A. SzyjewiczC.A. Miller R.C. UrtasunG.A. Moss J. WeijerUniversity of British Columbia: Simon Fraser UniversityM.D. Hasinoff [Chairman] G. Ludgate A.S. Arrott C.H.W. JonesY. Alexander K.C. Mann J.M. D 1Auria M . Ki elyN. Auersperg T. Marks H. Blok R . G . Korteli ngE.G. Auld G . Marsha 1 1 B .L . Funt 1 . M . Thor sonD.A. Axen P .W. Mart i n R. Green W.J. W i esehahnB . Bassa11eck T. MastersonD.V. Bates E . L . Ma t h i eD.S. Beder C.A. MeDowel 1J.H. Brewer J.M. McM i11 anM. Comyn D.F. Measday TRIUMF:D.H. Copp R . Nodwe11 P. Bennett C.J. KostM.K. Craddock R.L. Nob 1e J.L. Beveridge G.H. MackenzieR. Dubois C. Oram E.W. Blackmore L . E . Mo r i t zA. Duncan B.D. Pate C.W. Bordeaux D . Ottewe11K.L. Erdman J . Phillips W.J. Bryan J.G. RogersD .G . FIemi ng M. Salomon D.A. Bryman J.T. SampleD. Garner J . Sams J. Doornbos A.W. ThomasL.G. Harrison H . St i ch G. Dutto V.K. VermaY .C .J . Jean J. Trotter H.W. Fearing J .S . VincentR.R. Johnson E.W. Vogt D.R. Gil 1 G . D . Wa i tG. Jones D . C . Wa 1 ke r D.P. Gurd P. WaldenR. Keeler 1 . H . Wa r ren D.C. Healey G. WatersR. Kiefl J.B. Warren D.R. Heywood R. WoloshynB. Larkin B .L . Wh i te D.A. Hutcheon M. ZachK.P. JacksonB.C. Cancer Foundation:B. Douglas J . Nord i nC.J. Eaves B . Pa 1c i cJ .M .W. G i bson K.R. ShorttR . W. Ha rr i son L . D . SkarsgardR.M. Henkelman D.M. Wh i te1 awR.O. Kornelsen *M.E.J. YoungK.Y. Lam *B. C. Cancer Control AgencyVisiting experimenta lists:J- M Poutissou [Chairman 1978], R. Poutissou, University de Montr6alC. Amsler, R. Gibson, Queen Mary CollegeD. Gibson, University of SurreyN. Nishida, R. Hayano, J. imazato , Y. Uemura, University of TokyoB. T. Murdoch, University of ManitobaS. Kaplan, Lawrence Berkeley LaboratoryK. Gotow, Virginia Polytechnic Institute and State UniversityW.C. Sperry, Central Washington State CollegeC. Sabev, CERN 35Other institutions:J. Matthews, S. Rowlands, U n iv e rs ity  o f  CalgaryR. Cobb, T. Walton, Cariboo College R.L. Clarke, E.P. Hincks, J. Spuller,J. Va'vra, Carleton U n iv e rs ityG.A. Bartholomew, E.D. Earle, J.S. Fraser,O.F. Hbusser, F.C. Khanna, H.C. Lee,A. McDonald, Chalk R iv e r Nuclear Labora to rie s  W.W. Scrimger, S.R. Usiskin, Dr. W.W. Cross Cancer In s t i t u t e ,  EdmontonB.S. Bhakar, N. Davidson, W. Falk, M. de Jong, J. Jovanovich, A.M. Sourkes, K.G. Standing, W.T.H. van Oers, U n iv e rs ity  o f  ManitobaJ.K.P. Lee, B. Margolis, K. Scott, L. Yaffe, McG ill U n iv e rs ity  J. McAndrew, Memorial U n iv e rs ity  o f  Newfoundland P. Depommier, B. Goulard, J--P Martin,U n iv e rs it y  de M ontria lC. Hargrove, Nationa l Research CouncilG.T. Ewan, H.B. Mak, B. McKee, B.C. Robertson, A.T. Stewart, Queen’s  U n iv e rs ityP. Egelstaff, U n iv e rs ity  o f GuelphH.S. Caplan, U n iv e rs ity  o f  Saskatchewan M. Krell, U n iv e rs ite  de SherbrookeJ.M. Daniels, T.E. Drake, A.E. Litherland, U n iv e rs ity  o f Toronto  A. Cone, Vancouver C ity  College Langara Campus R.T. Morrison, Vancouver General H o sp ita l L.W. Reeves, U n iv e rs ity  o f  Waterloo W.P. Alford, U n iv e rs ity  o f  Western OntarioD.V. Bugg, J.A. Edgington, Queen Mary College N.M. Stewart, Bedford College A.S. Clough, U n iv e rs ity  o f  Su rreyA. Astbury, R. Brown, Ruthe rfo rd  LaboratoryD. Wilkinson, U n iv e rs ity  o f  Su ssexI.M . Blair, AERE Uarwe11A.N. James, U n iv e rs it y  o f L ive rpoo l N. Tanner, Oxford U n iv e rs ity  R. Engfer, U n iv e rs ita t  Zu richS. Jaccard, U n iv e rs it y  de Neuch&tel J.P. Blaser, Schweizerisches In s t i t u t  f u r  Nuklearforschung  R. Frascaria, B. Tatischeff, I n s t i t u t  de Physique Nuc iya ire , Orsay Cl. Perrin, In s t i t u t  des Sciences Nuc lea ire s, U n iv e rs ity  de Grenoble R. Grynszpan, CNRS V it ry  Rr van Dantzig, IKO Amsterdam M. Furic, In s t i t u t e  R. Boskovic, Zagreb K. Nagamine, S. Okada, T. Ono, K. Sakamoto,N. Suzuki, T. Yamazaki, U n iv e rs ity  o f TokyoG.E. Coote, IN S , Dept, o f Science & In d u s t r ia l Research, New Zealandl.R. Afnan, B lin d e rs  U n iv e rs ity  o f  South A u s t ra liaK.W. Jones, Brookhaven Nationa l Laboratory J.R. Richardson, U n iv e rs ity  o f  C a lifo rn ia ,Los Angeles R. Eisberg, U n iv e rs ity  o f  C a lifo rn ia ,Santa BarbaraF.P. Brady, U n iv e rs ity  o f C a lifo rn ia , Davis M.P. Epstein, D.J. Margaziotis, C a lifo rn ia  State  U n iv e rs ity  L. Wolfenstein, Camegie-Mellon U n iv e rs ityH. Anderson, C. Wright, U n iv e rs ity  o f ChicagoC.A. Goulding, F lo r id a  A&M U n iv e rs ityH.S. PI end 1, F lo r id a  State  U n iv e rs ity  M. Rickey, G.T. Emery, Indiana U n iv e rs ity  T.R. Witten, Kent Sta te  U n iv e rs ity  K.M. Crowe, F.S. Goulding, R.H. Pehl ,V. Perez-Mendez, Lawrence Berke ley Laboratory J.W. Blue, Lew is Research Center, NASA L. Agnew, R. Macek, L. Rosen, Los Alamos S c ie n t if ic  Laboratory N.S. VYa 11 , U n iv e rs it y  o f  MarylandC. Schultz, U n iv e rs ity  o f  Massachusetts M. Bardon, Nationa l Science Foundation L.M. Lederman, Nevis Labora to rie sB. Dieterle, U n iv e rs ity  o f  New MexicoJ.K. Chen, State  U n iv e rs it y  o f  N . I .  GeneseoD.K. McDaniels, U n iv e rs ity  o f  OregonK.A. Krane, R. Landau, T.C. Sharma, A.W. Stetz, L.W. Swenson, Oregon Sta te  U n iv e rs ityH. Primakoff, U n iv e rs ity  o f  Pennsylvania  R.F. Carlson, A.J. Cox, U n iv e rs ity  o f  Redlands L. Church, Reed CollegeR. Bryan, R.B. Clark, Texas A&M U n iv e rs ity  VI. Denig, E.N. Hatch, V.G. Lind, R.E. McAdams,O.H. Otteson, Utah Sta te  U n iv e rs ity  K. Ziock, U n iv e rs ity  o f  V irg in ia  M. Blecher, V irg in ia  Polytechnic  In s t it u te  and Sta te  U n iv e rs ityH. Bichsel, J.S. Blair, V. Cook, I Halpern,E.M. Henley, J.E. Rothberg, K. Snover,P. Wooton, U n iv e rs ity  o f  WashingtonH.B. Knowles, Washington Sta te  U n iv e rs ity  R.R. McLeod, Western Washington State  CollegeC.F. Perdrisat, College o f W illiam  and Mary96Appendix DEXPERIMENT PROPOSALSThe following lists experiment proposals received up to the end of 1977 (missing numbers coverproposals that have been withdrawn, replaced by later versions, or combined with another pro­posal). Page numbers are given for those experiments which are included in this annual report.[Spokesman underlined] Page1. Low-energy pi nuclear scattering, K.L. Erdman, R.R. Johnson, T. Masterson {Univ. of 31British Columbia), P. Walden (TRIUMF)2. Investigation of the D(p,2p)n reaction, J.M. Cameron, P. Ki tch i ng, W.J. McDonald,G.A. Moss, W.C. Olsen (Univ. of Alberta)3. The study of fragments emitted in nuclear reactions, R.E.L. Green, R.G. Korteli ng hi(Simon Fraser University) , K.P. Jackson {TRIUMF) , L. Church {Reed College). A study of the reaction p + p - ^p  + p + , D.F. Measday {Univ. of British Columbia) ,J.E. Spuller {Carleton University)6. Studies of the proton- and pion-induced fission of light to medium mass nuclides, hhB.D. Pate {Univ. of British Columbia), H. Blok, D. Dautet {Simon Fraser University),Z. Fraenkel {Weizmann Institute)9- A study of the reaction of t t ~  + p -> y  + n at pion kinetic energies from 20-200 MeV,M.D. Hasinoff, D.F. Measday, M. Salomon {Univ. of British Columbia.), J-M Poutissou,R. Poutissou {Univ. de Montreal)10. Positive pion production in proton-proton and proton-nucleus reactions, E.G. Auld, 27R.R. Johnson, G. Jones, T. Masterson {Univ. of British Columbia), P. Walden {TRIUMF)11. A study of new, high neutron excess nuclides, G. Bischoff, J.M. D 1Au r i a , H. Dautet, hGR.G. Korteling, W. Wiesehahn {Simon Fraser University), B.D. Pate {Univ. of British Columbia), G.E. Coote {INS, Dept, of Science & Industrial Research, New Zealand),J.K.P. Lee {McGill University), K.P. Jackson (TRIUMF)12. An experiment to measure the mass of new elements with isospin Tz=-2 and Tz=-5/2using (p,8He) and (p,9Li), J.M. Cameron, G.C. Neil son, G.M. Stinson {Univ. of Alberta),D.R. Gill, D.A. Hutcheon {TRIUMF)13- Measurement of the electromagnetic size of the nucleus with muonic X-rays, particu­larly the 2s-2p transition, G.A. Beer, G.R. Mason, R.M. Pearce, C.E. Picciotto,C.S. Wu {Univ. of Victoria), D.G. Fleming {Univ. of British Columbia), W.C. Sperry {Central Washington State College)l'f. The interaction of protons with very light nuclei in the energy range 200-500 MeV, 35J.M. Cameron, L.G. Greeniaus, J. Kallne, R. McCamis, C.A. Miller, G.A. Moss, G. Roy {Univ. of Alberta), M. de Jong, B. Koene, B.T. Murdoch, W.T.H . van Oers {Univ. of Manitoba), A.W. Stetz {Oregon State University), D.A. Hutcheon, J.G. Rogers {TRIUMF)15- A proposal to study quasi-free scattering in nuclei, J.M. Cameron, W.K. Dawson, 38P. Kitching, W.J. McDonald, C.A. Miller, G.C. Neilson, W.C. Olsen, J.T. Sample, G.M.Stinson {Univ. of Alberta), D.A. Hutcheon {TRIUMF), A.N. James {Univ. of Liverpool),E.D. Earle {CRNL), A.W. Stetz {Oregon State University)16. Proton-deuteron quasi-e1 astic scattering, P. Ki tch i ng, W.J. McDonald, C.A. Miller,G.A. Moss, W.C. Olsen, D.M. Sheppard {Univ. of Alberta), D.A. Hutcheon, J.G. Rogers{TRIUMF), A.W. Stetz {Oregon State University), A.N. James {Univ. of Liverpool)17- Cross-section measurements for p(p,2p)y, p(p,2p)7r° and D(p,2p)n reactions,J.V. Jovanovich {Univ. of Manitoba)18. Influence of chemical environment on atomic muon capture rates, G.A. Beer, T.W.Dingle, D.E. Lobb, G.R. Mason, R.M. Pearce {Univ. of Victoria), D.G. Fleming {Univ.of British Columbia), W.C. Sperry {Central Washington State College)97Page19- Nuclear decays following muon capture, G.A. Beer, G.R. Mason, R.M. Pearce, C.E.Picciotto, C.S. Wu {Un iv . o f  V ic to r ia ) , G.A. Bartholomew, E.D. Earle, F.C. Khanna{Chalk R iv e r  Nuclear La b o ra to r ie s ), D.G. Fleming {Un iv . o f  B r i t i s h  Columbia),W.C. Sperry {Centra l Washington S ta te  College)20. Isotope effect in y capture, G.A. Beer, G.R. Mason, R.M. Pearce, C.E. Picciotto,C.S. Wu {Un iv . o f  V ic to r ia ) , D.G. Fleming {Un iv . o f  B r i t i s h  Columbia) , W.C. Sperry{Centra l Washington S ta te  College)21. Optical activity induced by polarized elementary particles, L.D. Fiayward,D.C . Wa1ker {U n iv . o f  B r i t i s h  Columbia)22. Fragmentation of light nuclei by low-energy pions, H.B. Knowles et a l.  {WashingtonS ta te  U n iv e r s it y ) . Now known as 'Negative pion capture and absorption on carbon,nitrogen and oxygen1. [Passed to Biomedical Experiments Evaluation Committee]23a. Search for the decay mode EE1 -> 3y, P. Depommier, J-P Martin, J-M Poutissou,R. Poutissou {Un iv . de Montreal)23b. Investigation of the decay mode EEX ->- e+ + ve + y, P . Depommi er, J-P Martin,J-M Poutissou, R. Poutissou {Un iv . de Montreal)23c. A study of the decay tt+ -* it0 + e+ + ve , P. Depommier, J-P Martin, J-M Poutissou R. Poutissou {U n iv . de Montreal)2k. Elastic scattering of polarized protons on 12C, L.G. Greeniaus, C.A. Miller, G.A. 21Moss, G . Roy {U n iv . o f  A lb e rta ), D.A. Hutcheon {TR IUM F), C. Amsler {Queen MaryCo llege ), R. Dubois {U n iv . o f  B r i t i s h  Columbia)26. Measurement of the differential cross-section for free neutron-proton scattering and for the reaction of D(n,p)2n, L.P. Robertson {Un iv . o f  V ic to r ia ) , E.G. Auld,D.A. Axen {U n iv . o f  B r i t i s h  Columbia), J. Va'vra {Carle ton U n iv e r s it y )  , C. Amsler,D.V. Bugg, J.A. Edgington {Queen Mary C o llege ), J.R. Richardson {UCLA),A.S. Clough {U n iv . o f  S u r re y ) , N.M. Stewart (Bedford College)27. Measurement of the polarization in free neutron-proton scattering, E.G. Auld, 17D.A. Axen {Un iv . o f  B r i t i s h  Columbia), J. Va'vra {Carle ton U n iv e r s it y ) , L.P.Robertson {U n iv . o f  V ic to r ia ) , G. Roy {Un iv . o f  A lb e rta ) , J.R. Richardson {UCLA),C. Amsler {U n iv . o f  New Mexico), D.V. Bugg, J.A. Edgington {Queen Mary Co llege ),A.S. Clough {Un iv . o f  S u r re y ) , N.M. Stewart {Bedford College)28. A programme of direct pickup reactions at intermediate energies, D.G. Fleming{U n iv . o f  B r i t i s h  Columbia)29- A study of the reactions Tr + p-^TT + p a t  pion kinetic energies from 10 to 90 MeV,D.A. Axen, R.R. Johnson {Un iv . o f  B r i t i s h  Columbia), E.W. Blackmore {TRIUMF)30. Scattering of pions from isotopes of hydrogen and helium, B.S. Bhakar, N. Davidson,W. Falk, W.T.H. van Oers {Un iv . o f  Manitoba)31. p-n elastic scattering with polarized protons and polarized neutrons, J.M. Dan iels,P. Kirkby, R.S. Timsit {Un iv . o f  To ro n to ) , J. McAndrew {Memorial U n iv e r s it y )33- Basic radiobiological experiments with pions versus 260-280 kV X-rays,M.J. Ashwood-Smith {Un iv . o f  V ic to r ia ) [to Biomedical EEC]3A. Low-energy )EEX vEEb( differential and total cross-section measurements, R.R. Johnson{Un iv . o f  B r i t i s h  Columbia)35. A study of positive muon depolarization phenomena in chemical systems, J.H. Brewer, 52D.G. Fleming, D.C. Walker, J.B. Warren {U n iv . o f  B r i t i s h  Columbia), K.M. Crowe{U n iv . o f  C a lifo rn ia ,  B e rke le y ) , R.M. Pearce {U n iv . o f  V ic to r ia ) , A.E. Pifer {U n iv . o f  A rizona )36. Neutron diffraction, J. Trotter {U n iv . o f  B r i t i s h  Columbia), M.J. Bennett {U n iv . o f  A lb e rta ) , G. Bushnell {U n iv . o f  V ic to r ia )  , F.W. Einstein {Simon F ra se r  U n iv e r s it y )37- Search for y- + Z -* e + Z^, D.A. Bryman {TR IUM F), G.A. Beer, M.S. Dixit,J.A. Macdonald, R.M. Pearce, P.A. Reeve, L.P. Robertson {U n iv . o f  V ic to r ia )  ,M. Blecher, K. Gotow {V irg in ia  Po ly techn ic  In s t .  <$ S ta te  U n iv . ) , C. Hargrove {NRC),9839-40.41a. 41b. 42a.42b.46.47-48.49.50.51.52.53.54.55.56.38.H. Mes, R. McKee, J. Spuller (Carleton University) , etc. [Amended July 19, 1973;Addendum 2, October 1, 1973] Updated August 1977 to include groups from TRIUMF,Univ. of Victoria, NRC, Carleton, Chicago, VPI, Univ. de Montreal, UBC - see Exp 104.Neutron scattering from fluids and amorphous solids, C.A. McDowel1 {Univ. of British Columbia) , P.A. Egelstaff {Univ. of Guelph) , I.M. Thorson {Simon Fraser University)S-wave pion-nuclear interactions, D.A. Axen, G. Jones {Univ. of British Columbia)A proposal for neutron experiments at TRIUMF, D.A. Axen, M.K. Craddock {Univ. of 17British Columbia), J. Va'vra {Carleton Univ.), D.V. Bugg, J.A. Edgington {Queen Mary College), N.M. Stewart {Bedford College), A.S. Clough {Univ. of Surrey) , I.M. Blair {AERE) .Radiative capture of pions in light nuclei, M.K. Craddock, M.D. Hasinoff,M. Salomon {Univ. of British Columbia)Charge exchange of stopped negative pions, D. Berghofer, M.K. Craddock, M.D. Hasinoff, 25 R. MacDonald, M. Salomon {Univ. of British Columbia) , J-M Poutissou {Univ. de Montreal)Tr_-3He: Strong interaction shift, G.A. Beer, M.S. Dixit, S.K. Kim, J.A. Macdonald, 33 G.R. Mason, A. Olin, R.M. Pearce, C.E. Picciotto, L.P. Robertson, C.S. Wu {Univ. of Victoria), M. Krell {Univ. de Sherbrooke), D.A. Bryman, J.S. Vincent {TRIUMF)ir""-3He: Neut ron-neut ron scattering length, G.A. Beer, M.S. Dixit, J.A. Macdonald,G.R. Mason, R.M. Pearce, C.E. Picciotto, L.P. Robertson, C.S. Wu {Univ. of Victoria),M. Krell {Univ. de Sherbrooke), D.A. Bryman, J.S. Vincent {TRIUMF)Hyperfine splitting in polarized muonic 209Bi atoms, G.T. Ewan, H.B. Mak, B.C. 48Robertson {Queen’s University) , G.A. Beer, G.R. Mason, A. Olin, R.M. Pearce {Univ. of Victoria) , K. Nagamine, T. Yamazaki {Univ. of Tokyo) , D.G. Fleming {Univ. ofBritish Columbia)Photon asymmetry in radiative muon capture, J.H. Brewer, M.D. Hasinoff, R. MacDonald{Univ. of British Columbia), K.A. Krane {Oregon State Univ.), J-M Poutissou {Univ. de Montreal)Fertile-to-fissile conversion in electrical breeding (spallation) targets (FERFICON), 60F.M. Kiely, I.M. Thorson {Simon Fraser University), B.D. Pate {Univ. of British Columbia) , J.S. Fraser {Chalk River Nuclear Laboratories)A comparative study of the radiation effects of pions and electrons, D.C■ Wa1ker{Univ. of British Columbia) [Letter of intent]A measurement of the muon neutrino mass, G. Jones, P.W. Martin, M. Salomon {Univ. ofBritish Columbia), D.A. Bryman (TRIUMF )Search for transfer of y- from lithium lattice to heavy impurities, G.A. Beer, A.D.Kirk, G.R. Mason, A. Olin, R.M. Pearce, L.P. Robertson {Univ. of Victoria) ,D.A. Bryman {TRIUMF)A measurement of the SE -> ev branching ratio, D.A. Bryman, J.S. Vincent {TRIUMF),G.A. Beer, M.S. Dixit, J.A. Macdonald, G.R. Mason, A. Olin, R.M. Pearce, C.E.Picciotto, L.P. Robertson {Univ. of Victoria), D. Berghofer {Univ. of British Columbia), J-M Poutissou {Univ. de Montreal)Emission of heavy fragments in pion absorption, G. Jones, P.W. Mart i n , M. Salomon,E.W. Vogt {Univ. of British Columbia), D.R. Gill {TRIUMF), J.M. Cameron {Univ. of Alberta)ir* reaction cross-section measurements on isotopes of calcium, K.L. Erdman, 31R.R. Johnson {Univ. of British Columbia), J.L. Beveridge {TRIUMF)y- capture in deuterium and the two-neutron interaction, J.M. Cameron, W.J. McDonald,G.C. Neilson {Univ. of Alberta) , H. Fearing (TRIUMF ) [Letter of intent]A study of the decay of the muon, D. Berghofer, M.D. Hasinoff, R. MacDonald,D.F. Measday, M. Salomon {Univ. of British Columbia), P. Depommier, J-M Poutissou {Univ. de Montreal), J.E. Spuller {Carleton University)Page9957- Search for the y+ -»■ e+ + y decay mode, P. Depommier, J-P Martin, J-M Poutissou, 22R. Poutissou {Univ. de Montreal)58. Polarization effects of the spin-orbit coupling of nuclear protons, A. Anderson, L.A. 39Antonuk, J.M. Cameron, W.K. Dawson, P■ Ki tch i ng, W. J. McDona1d , C. A . Miller, G.C. Neilson,W.C. Olsen, D.M. Sheppard, G.M. Stinson {Univ. of Alberta), D.A. Hutcheon {TRIUMF),A.W. Stetz {Oregon State Univ.), A.N. James {Univ. of Liverpool) , E.D. Earle (CRNL)59- Investigation of the (p,2p) reactions on 3He, 3H and ^He, B.S. Bhakar, AlW.T.H. van Oers {Univ. of Manitoba) , J.M. Cameron, G.A. Moss {Univ. of Albert a) ,J.G. Rogers {TRIUMF)60. Study of muonium formation in MgO and related insulators and its diffusion into a 52vacuum, J.H. Brewer, D.G. Fleming, G. Jones, J.B. Warren {Univ. of British Columbia)61. Pre-clinical research on the ir" beam at TRIUMF (Biomedical), C.J. Eaves, R.W. 56Harrison, R.M. Henkelman, B. Palcic, K.R. Shortt, L.D. Skarsgard {B.C. CancerFoundation) , R.O. Kornelsen, M.E.J. Young {B.C. Cancer Control Agency)62. Measurement of the ir" atomic cascade time in light elements, G.A. Beer, G.R. Mason,A. 01 in, R.M. Pearce, L.P. Robertson {Univ. of Victoria), D.A. Bryman (TRIUMF )63. Measurement of the SEl mass, G.A. Beer, S.K. Kim, G.R. Mason, A. 01 in, R.M. Pearce,C.E. Picciotto {Univ. of Victoria) , D.A. Bryman {TRIUMF)6A. Total cross-section and total reaction cross-section measurements for the p-3Hesystems and n-3He systems, B.S. Bhakar, C.A. Goulding, M.S. de Jong, W.T.H. van Oers,A.M. Sourkes {Univ. of Manitoba) , J.M. Cameron, G.A. Moss {Univ. of Alberta) ,R.F. Carlson, A.J. Cox {Univ. of Redlands)65. Radiosensitivities of tumours in situ to ir-meson irradiation, S. Okado, T. Ono,K. Sakamoto, N. Suzuki {Univ. of Tokyo)66. Survey of p-p bremsstrahiung far off the energy shell, H.W. Fearing, J.G. Rogers 30{TRIUMF), J.M. Cameron, A.N. Kamal, A. Szyjewicz {Univ. of Alberta) , J.V. Jovanovich{Univ. of Manitoba) , A.W. Stetz {Oregon State Univ.), J.R. Richardson {UCLA)67. Two-nucleon emission following reactions induced by stopped pions, J.M. Cameron,W.J. McDonald, G.C. Neilson {Univ. of Alberta) , P.W. Martin {Univ. of British Columbia), G.A. Beer, G.R. Mason, A. 01 in {Univ. of Victoria)68. Feasibility study of use of high-purity germanium detectors for detection of high- energy charged particles, J.M. Cameron {Univ. of Alberta), D.R. Gill {TRIUMF),F.S. Goulding, R.H. Pehl {Lawrence Berkeley Laboratory), P.W. Martin, M. Salomon {Univ. of British Columbia)69. Pion double charge exchange on very light nuclei, A.W. Stetz {Oregon State Univ.),N.E. Davidson, B.T. Murdoch, W.T.H. van Oers {Univ. of Manitoba) , J.M. Cameron,W.J. McDonald {Univ. of Alberta) , V. Perez-Mendez {Lawrence Berkeley Laboratory)70. Proton total cross-section and total reaction cross-section measurements for light nuclei, B.S. Bhakar, C.A. Goulding, B.T. Murdoch, W.T.H. van Oers, A.M. Sourkes {Univ. of Manitoba) , R.F. Carlson, A.J. Cox {Univ. of Redlands) , J.M. Cameron {Univ.of Alberta) , H. Postma {Univ. of Groningen)71. Muon spin rotation project, R. Hayano, S. Kobayashi, K. Nagamine, S. Nagamiya, 50N. Nishida, T. Yamazaki {Univ. of Tokyo) , J.H. Brewer, A. Duncan, D.G. Fleming{Univ. of British Columbia)72. Solid-state studies by muonic X-ray polarization, R. Hayano, K. Nagamine, N. Nishida,T. Yamazaki {Univ. of Tokyo), R.M. Pearce {Univ. of Victoria)73- Artificial muon polarization, R. Hayano, K. Nagamine, N. Nishida, T. Yamazaki {Univ.of Tokyo) , J.H. Brewer, D.G. Fleming, M.D. Hasinoff {Univ. of British Columbia),H.B. Mak {Queen's University)7h. Proposal to measure D, R and R' in pp scattering, 200 to 520 MeV, D.V. Bugg, J.A.Edgington, K. Shakarchi {Queen Mary College), D.A. Axen, G. Ludgate, C. Oram {Univ.of British Columbia), J. Va'vra {Carleton Univ.), S. Jaccard {Univ. de Neuchatel),N.M. Stewart {Bedford College), A.S. Clough {Univ. of Surrey)100Page75- The d(p,ir+ )t pion production reaction for high momentum transfer, P. Kitching, 29W.C. Olsen {Univ. of Alberta) , D.A. Hutcheon, P. Walden {TRIUMF), C.F. Perdrisat {College of William and Mary), E.G. Auld, R.R. Johnson, G. Jones, E.L. Mathie {Univ. of British Columbia), B. Tatischeff {Orsay)76. A proposal to study elastic scattering on 160 and 40Ca, D.P. Gurd, P. Kitching,W.J. McDonald, C.A. Miller, G.C. Neilson, W.C. Olsen, G. Roy, G.M. Stinson {Univ. ofAlberta), D.A. Hutcheon {TRIUMF)77. Evaporation-cooled metallic cesium target assembly for productionof 123I, J.W. Blue 59(NASA Cleveland), T.A. Hodges {Univ. of Victoria), J.S. Vincent {TRIUMF), R.T.Morrison, D.M. Lyster {Vancouver General Hospital), J.B. Warren {Univ. of British Columbia), W.J. Wiesehahn {Simon Fraser University)78. Importance of defects in y+SR in metals, K. Nagamine, T. Yamazaki {Univ. of Tokyo) , 50A.T. Stewart {Queen's University), B. Bergersen, J.H. Brewer, D.G. Fleming {Univ. of British Columbia)79- Low-energy ir production as a function of energy at 500 MeV and below, G.A. Beer,G.R. Mason, A. Olin, R.M. Pearce, L.P. Robertson {Univ. of Victoria), P.W. James {AECL), D.A. Bryman, J.S. Vincent (TRIUMF), J-M Poutissou (Univ. de Montreal),R.R. Johnson, J.B. Warren (Univ. of British Columbia)80. Measurements of pionic X-ray energies, widths and intensities, G.A. Beer, M.S. Dixit,J.A. Macdonald, G.R. Mason, A. Olin, R.M. Pearce, P.R. Poffenberger (Univ. ofVictoria), D.A. Bryman (TRIUMF), W.C. Sperry (Central Washington State College)81. Interaction of stopped negative pions with complex nuclei, J.K.P. Lee (McGill Univ.),G.R. Mason, A. Olin (Univ. of Victoria), D.A. Bryman (TRIUMF), M.D. Hasinoff,M. Salomon (Univ. of British Columbia), J-M Poutissou (Univ. de Montreal), G.E. Coote (INS, DSIRj New Zealand), W.J. Wiesehahn (Simon Fraser University)82. Mossbauer spectroscopic studies using short-lived sources, C.H.W. Jones (Simon Fraser University), J. Sams (Univ. of British Columbia)83. Bound muon decay in nuclei, J.H. Brewer, F. Corriveau, M.D. Hasinoff, R. MacDonald(Univ. of British Columbia) , J-M Poutissou (Univ. de Montreal), K. Nagamine (Univ. of Tokyo)8A. The (n^jd) reaction on light nuclei, K.L. Erdman, R.R. Johnson, T.G. Masterson (Univ. of British Columbia), J.S. Vincent (TRIUMF), V.G. Lind, R.E. McAdams, O.H. Otteson(Utah State University)85. Single and coincidence studies of prompt gamma-rays in ir-nuclear interactions,W. Denig, E.N. Hatch, V.G. Lind, R.E. McAdams, O.H. Otteson (Utah State University),H. Dollard, K.L. Erdman, R.R. Johnson, T.G. Masterson (Univ. of British Columbia),R.B. Clark (Texas ASM), H.S. Plendl (Florida State University)86. Elastic and inelastic scattering of polarized protons from calcium and lead,J.M. Cameron, J. Kallne, P. Kitching, W.J. McDonald, C.A. Miller, G.C. Neilson,G. Roy, H.S. Sherif, G.M. Stinson (Univ. of Alberta), D.K. McDaniels (Univ. of Oregon), J.S. Blair (Univ. of Washington), W.T.H. van Oers (Univ. of Manitoba),D.A. Hutcheon (TRIUMF)87. Proton radiography studies at TRIUMF, E.W. Blackmore, D.A. Bryman, G.H. Mackenzie 58(TRIUMF)88. Systematic studies of total muon capture rates, R. Hayano, K. Nagamine, N. Nishida,T. Yamazaki (Univ. of Tokyo) , J-M Bangoura, J.H. Brewer, M.D. Hasinoff, D.F. Measday,T. Suzuki (Univ. of British Columbia)89. y fission, S.N. Kaplan (Lawrence Berkeley Laboratory) , G.A. Beer, M.S. Dixit, h7J.A. Macdonald, G.R. Mason, A. Olin, R.M. Pearce (Univ. of Victoria)90. Test of time reversal invariance, B.K.S. Koene, B.T. Murdoch, W.T.H. van Oers (Univ. of Manitoba) , J.M. Cameron, L.G. Greeniaus, C.A. Miller, G.A. Moss, G. Roy Univ. of Alberta), R.G. Beurtey, J.C. Duchazeaubeneix (CEN, Saalay) , M. S i mon i us (ETH Zurich)Page10191. Muonium in semiconductors, J.H. Brewer, D.G. Fleming {U n iv . o f  B r i t i s h  Columbia), 52 K. Nagamine {U n iv . o f  To kyo ), K.M. Crowe, S.S. Rosenblum {Lawrence Be rke ley  Labo ra to ry)92. The effect of nuclear structure on fragmentation processes with 300 MeV protons,L.B. Church {Reed College), R.E.L. Green, R.G. Korteling {Simon F ra se r  U n iv e r s it y )93. Production of radioisotopes at medium energies for pure and applied research,L. Moritz, J.S. Vincent {TR IUM F), B.D. Pate, L. Patrick {U n iv . o f  B r i t i s h  Columbia),C.H.W. Jones {Simon F ra se r  U n iv e r s it y ) , D.M. Lyster, W. Rowe {Vancouver General H o sp ita l)9^ t. The optical transitions of pionium and muonium, A ■L■ Carter, D. Kessler {CarletonU n iv e r s i t y ) , C.K. Hargrove, E.P. Hi neks, R.J. McKee, H. Mes {na tio na l Research Counci I )95- Test of T-invariance in np scattering, C. Amsler, D.V. Bugg, J .A. Edg i ngton {QueenMary C o llege ), D.A. Axen, G. Ludgate {U n iv . o f  B r i t i s h  Columbia), A.S. Clough {Un iv . o f  S u r re y ) , J. Beveridge {TR IUM F), J.R. Richardson {UCLA), L.P. Robertson {Un iv . o fV ic to r ia ) , N.M. Stewart {Bedford. College)96. Spin dependence in pp -*■ pmr+ , D.A. Axen, G. Ludgate, C. Oram {U n iv . o f  B r i t i s hColumbia), C. Amsler, D.V. Bugg, J.A. Edgington {Queen Mary Co llege ), J. Beveridge {TR IUM F), A.S. Clough {U n iv . o f  S u r re y ) , L.P. Robertson {U n iv . o f  V ic to r ia )  , J.R. Richardson {UCLA), N.M. Stewart {Bedford College)97- Rare electromagnetic decays of pionic atoms, M .D. Has i noff, D.F. Measday, M. Salomon{Un iv . o f  B r i t i s h  Columbia), P. Depommier, J-M Poutissou, R. Poutissou {Un iv . deMontreal)98. The detection and characterization of the heavy partner in fragmentation reactions,R.E.L. Green, R.G. Korteli ng, A. Kurn {Simon F ra se r  U n iv e r s i t y ) , L.P. Church {Reed College)99. Studies of (p,d) reactions in nuclei, J ■ Ka11ne, W.J. McDonald et a l.  {U n iv . o fA lb e rta , U n iv . o f  Manitoba, TR IUMF, Un iv . o f  Oregon, Oregon S ta te  Un iv . and Un iv . o f  Colorado)100. Studies of (p,3He) and (p,3H) reactions in ‘♦He, A.N. Anderson, J.M. Cameron,J. Kallne, P. Kitching, W.J. McDonald, C.A. Miller {U n iv . o f  A lb e rta ) , W.T.H. van Oers {U n iv . o f  Manitoba), J. Beveridge {TRIUMF)101. Investigation of (tt,2tt) reaction, E.G. Auld, R.R. Johnson, G. Jones {Un iv . o fB r i t i s h  Columbia), P.L. Walden {TRIUMF)102. Absolute cross-sections of 12C (it* ,ttN) 1 1C reactions at low energy, G.W. Butler, B.J. Dropesky, C.J. Orth, R.A. Wi11 jams {LA S L ) , B.D. Pate {U n iv . o f  B r i t i s h  Columbia),R.G. Korteling {Simon F ra se r  U n iv e r s i t y ) , M. Henkelman (B .C.  Cancer Foundation)103. Search for target spin dependence in proton elastic scattering, D.P. Gurd, G.A. Moss,G. Roy, H. Sherif, G.M. Stinson {Un iv . o f  A lbe rta )10A. The time projection chamber - A new facility for the study of decays of muons andpions, H.L. Anderson, C.S. Wright {Un iv . o f  Chicago), M. Blecher, K. Gotow {V irg in ia  Po ly techn ic  In s t i t u t e ) , G.A. Beer, M.S. Dixit, J.A. Macdonald, R.M. Pearce, P.A.Reeve, L.P. Robertson {U n iv . o f  V ic to r ia ) , W. Dey, M.D. Hasinoff, D.F. Measday {Un iv . o f  B r i t i s h  Columbia), P. Depommier, J.P. Martin, J-M Poutissou, R. Poutissou {Un iv .de M on tre a l) , A.L. Carter, C.K. Hargrove, E.P. Hincks, D, Kessler, H. Mes,J. Spuller {Ca rle ton U n iv e r s it y ) , D.A. Bryman {TRIUMF)105. Backward inclusive scattering, G.A. Moss, G . Roy {Un iv . o f  A lb e rta ) , J. Beveridge,D.A. Hutcheon, R. Woloshyn {TRIUMF)106. New proposal for a yey experiment, J-M Poutissou and collaboration {U n iv . de Montrea l,UBC, vi, Carleton U n iv e r s it y ,  U n iv . o f  Chicago, TRIUMF, U n iv . o f  V ic to r ia )Page102Page107. Study of the (p,dir) reaction, A.N. Anderson, J.M. Cameron, J ■ Ka11ne, P. Kitching, W.J. McDonald, C.A. Miller, W.C. Olsen {Univ. of Alberta), J.L. Beveridge, H.W. Fearing, J.G. Rogers, R.M. Woloshyn {TRIUMF), W.T.H. van Oers {Univ. of Manitoba)108. Meson cascade studies, G.A. Beer, M.S. Dixit, J.A. Macdonald, G.R. Mason, A. Olin, R.M. Pearce {Univ. of Victoria), D.A. Bryman {TRIUMF), W.C. Sperry {Central Washington State College) , S.N. Kaplan, C.R. Wiegand {Laurence Berkeley Laboratory)109. A measurement of pd -> 3He y to test detailed balance, P. Glodis, R. Haddock,B. Nefkens, J.R. Richardson, M. Sadler {UCLA), J.G. Rogers {TRIUMF)103■’. 4 - ;  f c a k  *3-* ^  > :  n ’/ ^ w j  ■' 'V v----,:~:' 'iv ®,-.,‘: ■ .v-y„ '....' v ■...-vy;....-.;/. •' -/■■■■-■: •- ;> - ■ -v j - -'■ : ■ .1 ■ ■ "■ ■.- . ■- . '■■■■■.■:’ - •' t * y . ‘ . • ', v«>« * :  ^. - „* -iV -■ .V . 'v-® ■>'. Ki : . ; ■ ! - yy.y r A *  . - ■■' y  y y.;r T  : i: ;y  :■A y i :- A  ;A'® " " "p ®©S&AA-- ■'-■Vi':: *\rV-:--'v; Ay T T T  T T I T T T vbbI T  v ® ? T I vc.ggxRg0I v T R- a f  g I vIT  =-" :"Vf' "• w .3vx5RT -R--l5 g5I T  IIl- -­-xx- bT b I' : A / a  A A H A A a  \  A '^ -A A ^ 'a A A  A=3 ' 'A A a H ;l'Syi;y y yy;:,-: A^^AA-.AAAW \A' sA ^ A A - :  A y V a A a A.J' ■: :■ A--' T T g  aa.aaA,. " A/ A ’ > -A .V : .A A A,.. A A a .  A ' : A  A .:■ A.v.a.-.AAa, u ... :aaA: : A A.AA'y. .. . .. ,- ; ■ a."VA. ~ . yA.. y A'.-A  r A  A>ggw ' ■; >Va •, 3&t$, Mv:‘ . ’/■ ■ '■•.■.■•■• ' '-• '. V.. : ' 'r '• : .’■ '-'r '■ : .■’■ ■• ,« •. ■•

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