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

A proposal for an intense radioactive beams facility ISAC


The last decade has seen a growing worldwide interest in the possibility of generating beams of unstable nuclei for use in a variety of applications ranging from nuclear physics and nuclear astrophysics through atomic physics, condensed matter physics, medicine, etc. This interest has been generated by the considerable improvements which have occurred over the past 20 years in the fields of heavy-ion acceleration, ion sources and, more particularly, in on-line production and separation of unstable nuclear isotopes (ISOL), in the development of high-resolution isotope separators, and in advances in experimental techniques, such as ion trapping. Coupling very intense production sources of unstable elements to efficient accelerator structures should lead to the general availability of radioactive beams for a wide range of nuclei far from the line of stability. The high energy (500 MeV) and high intensity (> 100 μA) proton beam from the TRIUMF cyclotron makes TRIUMF the prime choice for a radioactive beams facility in North America. The present proposal is based upon the experience which has been gathered at TRIUMF in the operation of its test facility (TISOL) for the on-line production of isotopes, its expertise in ion sources, its experience in handling high-intensity proton beams, and on the development of RFQ accelerators. The goal is to accept proton beams of up to 10 μA on a production target, separate the relevant species in an appropriate ISOL separator, and to accelerate the accepted ions up to an energy of 1.5 MeV /u. Products from the target/ion source will be available over a very wide mass range due to the high energy of the proton beam. The acceleration of the extracted ions will be accomplished by continuous ( CW) RFQ and two-stage linac structures, will accept ions with q/A ≤ 1/30, and could be expanded to higher energies in the future. The primary focus of the subatomic physics programme for ISAC will be: • Studies of fundamental interactions in particle physics using β-decaying nuclei; • Studies of the Standard Model using parity violation in atomic systems such as selected Cs and Fr isotopes; • Studies of nuclear reactions of interest in astrophysics; • Studies of nuclear reactions below the Coulomb barrier. Other fields of research will include: • Studies of condensed matter structures via radioactive impurities; • Production of selected isotopes for medical imaging. The cost of the ISAC facility has been estimated at $46,000,000, inclusive of salaries and buildings; it could be in full operation by the middle of 1999. By then the ISAC facility would be a unique instrument which would provide Canadian physicists with the best radioactive beams facility in the world. It also paves the way to the ultimate facility ISL (ISospin Laboratory) as defined by the United States nuclear physics community in their long-range planning.

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