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

Annual report scientific activities, 1990 TRIUMF Mar 31, 1991

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TRIUMF: ' : "ANNUAL REPORT SCIENTIFIC ACTIVITIES 1990CANADA’S NATIONAL MESON FACILITY OPERATED AS A JOINT VENTURE BY:UNIVERSITY OF ALBERTA SIMON FRASER UNIVERSITY UNIVERSITY OF VICTORIA UNIVERSITY OF BRITISH COLUMBIAUNDER A CONTRIBUTION FROM THE NATIONAL RESEARCH COUNCIL OF CANADA MARCH 1991TRIUMFANNUAL REPORT SCIENTIFIC ACTIVITIES 1990TRIUMF4004 WESBROOK MALL VANCOUVER, B.C. CANADA V6T 2A3EXISTING  PROPOSEDPROTON HALL EXTENSIONANNEXEXTENSIONREMOIHANDLFACILI1SERVICEBRIDGEH ION 5 POLATR 30 ISOTOPE PRODUCTION CYCLOTRONEINGYL 2 C ( P )  L 1 A  ( P )OURCEIZEDOURCEvM15(ju)BAT HOBIOMEDICALLABORATORYTHERMALNEUTRONFACILITYMESON HALLSERVICEANNEXPrinted on recycled paperF O R E W O R DIn the year 1990 T R IU M F  waited with great and increasing hope for a positive decision on K A O N  while it remained strongly active in science and responsive to the major forces shaping the future o f the project.The K A O N  Impact Study was released on May 24, 1990 and set the stage for the funding campaign which followed. The findings o f the Impact Study strongly reinforced the technical feasibility o f the project. The fed­eral/provincial Steering Committee for the Study was “o f the unanimous and strong opinion that the Canadian and international community is ready and waiting for the K A O N  Factory to proceed” . Further, the international consultations carried out under the Study pointed toward a foreign contribution to construction costs equal to one-third o f the total ($708 M over a six year construction period).A  review o f K A O N  by the National Advisory Board on Science and Technology (N A B S T ) followed. NABST, apparently, reinforced the strong science judgment for K A O N  but was concerned about K A O N ’s cost to Canada. Subsequently, the government o f the province o f British Columbia dramatically addressed the cost issue. In a major public rally o f several thousand people gathered to manifest wide community support for K A O N , the Premier ofB.C. announced, on September 24, 1990, that B.C. would provide a full third o f K A O N ’s construction funds. In doing so, it offered to match the anticipated contribution from Ottawa.The funding campaign which then followed was not fully concluded by year end. The Honourable Stanley Hagen -  B.C. Minister o f Economic Development and, later, B.C. Minister o f Education -  has been a remarkably visionary proponent o f K A O N .The future evolution o f T R IU M F , K A O N  or not, will be strongly influenced by the Long Range Plan for Subatomic Physics in Canada which was prepared, in early 1990, by a committee under the very able chairmanship o f Robin Armstrong, commissioned by NR C  and NSERC. This plan ranked K A O N  as the highest future priority for the Canadian program. In the absence o f K A O N  it described, in various funding scenarios, the duration and extent o f the scientific program based on the present T R IU M F  cyclotron. In any non-KAON scenario it recommended a strong future for T R IU M F  as an infrastructure laboratory for Canadian nuclear and particle physicists planning to work at facilities abroad. Evidence o f the influence o f the Armstrong Report can be looked for in T R IU M F ’s future Five-Year Plans.In direct response to the federal Ministry o f Industry, Science and Technology, T R IU M F  prepared alternative non-KAON develoment plans for TR IU M F . These alternative plans were presented to the Honourable W illiam Winegard in early October.The process o f waiting for K A O N  delayed a number o f decisions on T R IU M F ’s future, particularly those pertaining to corrections in the federal (N R C ) contribution for salary increases in recent years. T R IU M F  struggled through the year with some budget uncertainties, but with fine cyclotron performance and much new science, as chronicled in this Report.Also, while waiting for K A O N , T R IU M F  extended its work on the Project Definition Study for K A O N  and remained strongly involved in technology transfer activities. The completion o f the Ebco TR30 cyclotron, in mid-1990, as the world’s best isotope producing cyclotron, is a source o f great satisfaction.In 1990 Bruce daym an  retired as a Board member. He established a world record for longevity on the T R IU M F  Board and has been intensely involved in much o f T R IU M F ’s management problems for more than a decade. He served a very distinguished two-year term as Board Chairman (1988-89). daym an  was replaced on the T R IU M F  Board by W illiam  Leiss, Vice-President (Research) o f SFU. Also Robin Armstrong left the Board, in late 1990, when he became President o f the University o f New Brunswick. He had represented the University o f Toronto very well for a number o f years.(y X  ^A .T . MathesonChairman, Board o f ManagementT R IU M F  was established in 1968 as a laboratory operated and to be used jointly by the University o f Alberta, Simon Fraser University, the University o f Victoria and the University o f British Columbia. The initial consortium has been expanded to include the University o f Manitoba, Universite de Montreal, the University o f Toronto and the University o f Regina as associate members. The facility is also open to other Canadian as well as foreign users.The experimental program is based on a cyclotron capable o f producing three simultaneous beams o f protons, two o f which are individually variable in energy, from 180-520 MeV, and the third fixed at 70 M eV. The potential for high beam currents -  100 p A  at 500 M eV to 300 pA  at 400 M eV -  qualified this machine as a ‘meson factory’ .Fields o f research include basic science, such as medium-energy nuclear physics and chemistry, as well as applied research, such as isotope research and production and nuclear fuel research. There is also a biomedical research facility which uses mesons in cancer research and treatment.The ground for the main facility, located on the UBC campus, was broken in 1970. Assembly o f the cyclotron started in 1971. The machine produced its first full-energy beam in 1974 and its full current in 1977.The laboratory employs approximately 354 staff at the main site in Vancouver and 18 based at the four universities. The number o f university scientists, graduate students and support staff associated with the present scientific program is about 625.C O N T E N T SIN T R O D U C T IO N ............................................................................................................................................  jSCIENCE D IV IS IO N  ....................................................................................................................................... 2In troduction ......................................................................................................... 2Particle Physics ...................................................................................................................  5Radiative muon capture on hydrogen ........................................................................ 5Measurement o f the flavour-conserving hadronic weak interaction ..................................................... 6Measurement o f the lifetimes o f isomeric states during atomic cascade o fnegative pions in liquid He and Ne ....................................................................................  gFast outgoing protons and deuterons from muon capture on 3He nuclei ..........................................  8Study o f rare K  d ecays .........................................................................................  gMeasurement o f A  —+ n j  ...........................................................................................  22Search for a strangeness —2 d iba ryon ................................................................. 23Spin structure functions o f the nucleon .......................................................... 24Polarization and weak decay o f hypernuclei ................................................................... 27Measurements o f angular distributions o f absolute cross sections and analyzingpowers o f the reaction pp —*■ dir+ between 1.3 and 2.4 GeV 29M ECL .......................................................................................................  19M E T R  ...................................................................................................................   2qe+ e~ annihilation at LE P using the O PAL d e tec to r.............................................................. 20Nuclear Physics and Chemistry ..................................................................  22Resonant structure in Cu(p, 7r± )X :  A  possible dibaryon signal ............................................................22Measurement o f 5 + (G T )  for 26M g ....................................................................  23Single pion production in np scattering ................................................................................  23Measurement o f n± d elastic scattering cross sections and charge asymmetriesat 30, 50 and 65 M eV .........................................................................  23Research and development studies with T ISO L .......................................................................... 24Differential cross sections for 7T*p  elastic scattering at 87 to 143 M eV ...............................................28Spin transfer coefficients in pd elastic scattering ........................................................................  28Gamow-Teller and spin dipole strength in (sd)-shell nuclei .................................................................29Measurement o f analyzing powers in low energy wd elastic scattering ............................................... 30Analyzing powers for tt± 13C scattering at T t =  100 M eV ..................................................................... 31Low energy pion absorption analyzing powers  ....................................................................  32Radiative decay o f the A  resonance................................................................................  32Spin response o f magnetic dipole transitions in 158Gd ...........................................................................32Experiment 540/596 development ................................................................................................... 34Spin-momentum correlations o f nucleons in polarized 3IIe ................................................................... 35Quasi-free 160 ( 7r+, 7p ) 150  ...................................................................................................... 37The 4H e(7r + ,7r+7r - )A r reaction at T t+ =  280 M eV  . . . ..38Elastic scattering o f 100 M eV 7r+ from a polarized 3IIe target.............................................................. 40Measurement o f the I I ( 7r , ir+TT' '^)n and I I (7r~, 7r+7r~ )n  cross sections very nearthreshold and chiral symmetry ............................................................................................. 42Differential cross sections and analyzing powers for the 4IIe(/f,7r4" )3IIe reactionin the region o f the A 1232 resonance ........................................................................................................ 43Elastic proton scattering from polarized 3IIe .......................................................................................... 43Distribution o f 6“  strength in the mass-32 nuclides via the 32S (n ,p )  reaction .................................. 46Momentum distributions o f backward-production protons in proton-nucleus interactions ...............46Investigation o f the d(p, p ' )d * reaction ...........................................................................................  4gGiant spin excitation in deformed nuclei .......................................................................................... 4gIntegral cross sections for 7r + p interaction in the 3,3 resonance region ............................................... 50Low energy pion double charge exchange in calcium isotopes ...............................................................51Parity conservation and time reversal invariance tested with low energy neutrons at L A N L  .......... 53Research in Chemistry and Solid-State Physics ............................................................................................ 54Muonic hydrogen in vacuum ...................................................................................................................... 54/.tSR studies o f dioxygen and ethylene physisorbed on pure silica powder ..........................................54The electronic structure o f muonium in the cuprous halides ................................................................ 55Studies o f oxide superconductors using negative muons ........................................................................56fiSR  studies o f (LaSr)Cu0 4 , Ba(PbBi)C>3 and (B aK )B i03  ...................................................................57Muonium reactivity enhancements............................................................................................................59Copolymerization in micelles by /iLCR ....................................................................................................60Muonium reactions with 0 2, CO and NO in high pressure moderators ..............................................60Kinetic isotope effects in the muonium +  hydrogen halides (H X ) gas reactions ............................... 62H+ SR in exotic single-crystal superconductors ....................................................................................... 63/z+ SR in single-crystal organic superconductors ..................................................................................... 65Ultra-slow fi~ production via muon catalyzed fusion .............................................................................67fiSR  study o f Bi-Sr-Ca-Cu-O, Y B a 2Cu40s and magnetic oxides ......................................................... 68Muonium studies o f the silicon suboxides ................................................................................................ 69Muonium-substituted organic free radicals on surfaces ......................................................................... 69Positive muons and muonium in condensed hydrogens ......................................................................... 70/zSR in high-Tc superconductors ................................................................................................................73Atom ic Physics .................................................................................................................................................. 76Light transmission through Rb vapour at different 3IIe pressures ........................................................76Theoretical P ro g ra m ......................................................................................................................................... 80Introduction .....................................................................................................................  80Electroweak physics .................................................................................................................................... 80Hadron physics ............................................................................................................................................ 81Field th e o ry ....................................................................................................   88Condensed matter theory .......................................................................................................................... 88Experimental Facilities .....................................................................................................................................90The laser-pumped polarized 3lie  target ................................................................................................... 90Polarized targets ..........................................................................................................................................90Cryogenic targets ........................................................................................................................................ 90T IS O L  ........................................................................................................................................................... 91CHAOS ......................................................................................................................................................... 92Detector fa c i l i t y ........................................................................................................................................... 94DASS/SASP .................................................................................................................................................94E LE C TR O N IC S  A N D  C O M PU T IN G  D IV IS IO N  ....................................................................................... 98In troduction ........................................................................................................................................................98Data Acquisition and Analysis ........................................................................................................................ 98Data acquisition .......................................................................................................................................... 98Standard acquisition systems .....................................................................................................................98NO VA ........................................................................................................................................................... 99The future -  standard systems ..................................................................................................................99The future -  non-standard systems .......................................................................................................... 99Computing Services .......................................................................................................................................... 99Hardware ...................................................................................................................................................... 99Software ...................................................................................................................................................... 101Data Analysis Centre (D A C ) .........................................................................................................................101Software .......................................................................................................................................................101Hardware .....................................................................................   101Electronic Services ...........................................................................................................  102Electronics shop .......................................................................................................................................102Site communications ............................................................................................................................... 102Nucleonics Pool/Repair Shop ................................................................................................................. 102PC  service/Ataris .....................................................................................................................................103Local L A N .................................................................................................................................................. 103Systems Support ............................................................................................................................................. 103Project Team A  ...............................................................................................................................................104TR30 r f controls ........................................................................................................................................104Experimental support ..............................................................................    104Controls group support ............................................................................................................................ 104ISIS support and others ........................................................................................................................... 105Project Team B ............................................................................................................................................... 105TR30 ........................................................................................................................................................... 105K A O N  kicker con tro ls ............................................................................................................................... 105System upgrades and hardware developm ent......................................................................................   106A P P L IE D  PR O G R AM S  A N D  T E C H N O LO G Y  D IV ISIO N  .................................................................... 107Applied Programs ........................................................................................................................................... 107Biomedical p rog ram .................................................................................................................................107Isotope production group .......................................................................................................................108Radioisotope processing (Nordion) ....................................................................................................... 110Positron emission tomography (P E T ) ..................................................................................................I l lTomograph design ................................................................................................................................... I l lT R IM  and beam line 2C ........................................................................................................................ 112Microstructures and electron ics..............................................................................................................112Technology and Site Services .........................................................................................................................113Safety program ........................................................................................................................................ 113Building program .....................................................................................................................................115Design office ............................................................... .............................................................................. 115Machine shop ............................................................................................................................................116Planning group ........................................................................................................................................ 116C Y C L O T R O N  D IV IS IO N  ............................................................................................................................. 118Introduction .....................................................................................................................................................118Beam Production .....................................................................................  120Beam D evelopm ent......................................................................................................................................... 123Acceleration enhancement cavity ...........................................................................................................124Beam quality development ..................................................................................................................... 126Extraction probe for beam line 2C ....................................................................................................... 126Beam diagnostics .....................................................................................................................................127Data acquisition and analysis ................................................................................................................127Radio-frequency Systems ............................................................................................................................... 128R esonator...................................................................................................................................................128Amplifiers, combiners, transmission line .............................................................................................. 128Parasitics, transients, crowbar ................................................................................................................129Main amplifier control system ................................................................................................................129RF separator ............................................................................................................................................129RF controls ............................................................................................................................................... 129Mechanical Engineering ................................................................................................................................. 130Cyclotron ...................................................................................................................................................130Other systems ..........................................................................................................................................131Remote han d lin g ...................................................................................................................................... 131Ion Sources and Injection Systems ..............................................................................................................131IXThe optically pumped polarized ion source .......................................................................................... 131H~ ion source developm ent...................................................................................................................... 132Injection system ........................................................................................................................................ 132Beam Lines ...................................................................................................................................................... 133Developments .............................................................................................................................................133Maintenance, operations and im provem ents.......................................................................................... 134Collaborations ............................................................................................................................................134Central Control System ................................................................................................................................. 135NO VA system ............................................................................................................................................135Central control system maintenance and developm ent........................................................................135Cyclotron development serial highway ..................................................................................................136Database .....................................................................................................................................................136Beam line 2C ............................................................................................................................................. 136Control system upgrade ............................................................................................................................136Operational Serv ices........................................................................................................................................137Power supplies ........................................................................................................................................... 137Plant -  cooling and ventilation ..................................................    137Plant -  electrical ........................................................................................................................................137Vacuum and cryogenics ............................................................................................................................ 138New Projects ......................................................................................................................................   13930 M eV cyclotron -  TR30 ........................................................................................................................ 139ISAC ........................................................................................................................................................... HOK A O N  FA C T O R Y  PR O JE C T  D E F IN IT IO N  S TU D Y  .............................................................................141Introduction .....................................................................................................................................................H IScience Workshops .......................................................................................................................................... H 2Accelerator Design .......................................................................................................................................... 142Tracking studies ........................................................................................................................................ 142Single-particle e ffe c ts .................................................................................................................................144Collective effects ........................................................................................................................................ 145Magnet waveforms .....................................................................................................................................146I I -  injection/accumulation ...................................................................................................................... 146Transfer beam lines ................................................................................................................................... 147Instrumentation ......................................................................................................................................... 147Magnet Development ...................................................................................................................................... 148Magnet Power Supplies ...................................................................................................................................150Kicker Magnets ................................................................................................................................................151Prototype kicker magnet .........................................................................   •     151Prototype 1 M IIz chopper ..........................................................................................................   151Computer modelling stu d ies .................................................................................................   152Radio-frequency Systems ............................................................................................................................... 153Eddy current losses.....................................................................................................................................153Cavity tuning ............................................................................................................................................. 154Tuner bias power supply .......................................................................................................................... 154Anode power supply ................................................................................................................................. 154Amplifier and cavity ................................................................................................................................. 154RF controls .................................................................................................................................................154TR IU M F/Los Alamos/SSC collaboration ..............................................................................................155Beam Pipe and Vacuum .................................................................................................................................155I I -  Extraction from the T R IU M F  Cyclotron ..............................................................................................156Controls ............................................................................................................................................................158Experimental Areas ........................................................................................................................................ 161Remote handling ..............................................................................  161xBeam line design ........................................................................................................................................161Targets ............................................................................................................................................................. 162Neutron Sources...............................................................................................................................................163Technical Design and Systems Integration .................................................................................................. 164CO NFERENCES, W O R K SH O PS  A N D  M EETING S ...............................................................................166O R G A N IZ A T IO N  ........................................................................................................................................... 170A PPE N D IC E SA. Publications ..........................................................................................................................................174B. Users Group ..........................................................................................................................................189C. Experiment Proposals ..........................................................................................................................193XII N T R O D U C T I O NChallenge is the lifeblood o f good science. 1990 has been a year o f considerable challenge for TR IU M F. These pages describe briefly the response to that chal­lenge both by the T R IU M F  scientific users and by the overworked, overestimulated, underpaid and under- officed T R IU M F  staff.There is, first, the scientific challenge arising from the standard model o f quarks, leptons and unified forces. For a decade now the driving force o f the whole world community o f particle and nuclear physicists has been the new ideas about nature’s basic building blocks and fundamental forces. The important questions for the all-encompassing standard model are: how does one go beyond it? how does one improve it? how does one achieve a better understanding o f its detailed proper­ties? On all fronts there is much to win.One response to the urgent new questions is the con­struction o f a world network o f about half a dozen very large new accelerator facilities -  a network to which T R IU M F ’s proposed unique new K A O N  facility will belong. K A O N  is complementary to the super colliders, such as the SSC under construction in Texas. A  prime goal o f the SSC is to find the predicted Higgs particle through which the basic building blocks acquire mass. K A O N  will provide large quantities o f one o f the mas­sive quarks, the strange quark. The rare decays o f the kaon -  the carrier o f the strange quark -  address the same physics o f the SSC. K A O N  experiments promise to provide some o f the best tests delineating the limits o f the standard model.In 1990, large steps were made toward the completed design o f K A O N  and toward its funding. The KAO N  Impact Study, released on May 24, 1990, gave a very strong endorsement to the results o f the 18 month study and to the technical readiness o f the project. The report also found the world ready and waiting to provide one third o f the construction funds for K AO N .Waiting for a decision on K A O N  was on the minds o f everyone at T R IU M F  in the last half o f 1990. The province o f British Columbia increased its offer for K A O N , in late September. It promised to provide fully one third o f K A O N ’s construction funds. The remain­ing one third was then sought from Ottawa.T R IU M F ’s staff waited and continued, as overload from its normal cyclotron duties, to extend the study of K A O N  components with extra funds provided for this purpose by the province o f British Columbia. The in­ternational user community waited and planned initial K A O N  experiments. The province o f British Columbia waited expectantly and strongly continued its advo­cacy o f K A O N . Thousands o f T R IU M F ’s friends from across British Columbia, Canada and the world waitedand wrote letters to Ottawa about their hopes for K A O N ’s science and about its importance for high technology in western Canada. In this Annual Report some o f the achievements o f the extended K A O N  stud­ies are recorded.The new science o f the normal T R IU M F  science pro­gram continues to respond to the challenge o f the stan­dard model. The response is on a wide front and occu­pies almost half o f this report.Much o f the drama o f the standard model has per­tained to the unification o f the weak force with elec­tromagnetism. To  better understand the weak force, a key 1990 experiment at T R IU M F  (radiative muon capture in hydrogen) for the first time ever accurately determined one o f the components o f the weak force (the induced pseudoscalar piece).T R IU M F  has a major involvement in a current ex­periment at Brookhaven National Laboratory which seeks to go beyond the standard model. This experi­ment involves a rare decay mode o f the kaon. Mean­while, muon rare decay experiments which dominated T R IU M F ’s early life are having a renaissance. A  next generation o f such experiments is being planned with collaborators from the USSR. These new T R IU M F  ex­periments also provide opportunities for going beyond the standard model.However, the central standard model challenge at T R IU M F  remains the effort to understand how the strong interaction works in composite systems of quarks. The strong force between quarks involves gluon exchange. Here, nature really challenges our under­standing. This force is so strong that is is not tractable within the methods physicists now use to cope with the quantum world. This makes it hard and important to describe simple strongly-interacting systems o f quarks -  such as pions and protons -  in terms o f the standard model. Much experiment and theoretical ingenuity will be required. A  large amount o f T R IU M F  theory and experiment, as described in this Annual Report, per­tains to the fascinating physics o f strongly interacting systems o f quarks.One o f T R IU M F ’s greatest challenges in 1990 was to make a success o f technolog