ISAC-II : a project for higher energies at ISAC
Creators: name: TRIUMF-ISAC Facility
name: Towner, I.
Publisher: name: TRIUMF
Year: 2015

description: In the field of nuclear physics it is generally acknowledged that a new frontier will be probed when radioactive ion beams of sufficient intensity and quality become available. With the ISAC facility, TRIUMF has positioned itself as offering the best possible source of exotic beams in the world for many years to come. Based upon the ISOL method of production with a 100 μA, 500 MeV proton beams incident on thick targets, the production source has been built and is starting to operate. The intensity of the proton beam will be progressively increased as the commissioning of the remote handling facilities and the production target development proceed. While the source will produce any elements within the constraints of target/ion source efficiencies, the initial facility, ISAC-I, has been optimized for the requirements of the nuclear astrophysics program (A ≤ 30 and E ≤ 1.5 MeV /u) as far as the accelerator systems are concerned. The scientific program has been initiated and is catering to precision tests of the Standard Model, static properties of exotic nuclei, and opportunities in condensed matter research. ISAC-II is a project that will extend the reach of ISAC-I both in energy and mass. The demands of the nuclear-structure community, in Canada and worldwide, would be largely satisfied by raising the final energy for all masses up to A = 150 to 6.5 MeV/u; an energy sufficient to overcome the Coulomb barrier for all possible target nuclei. Current interests focus on nuclear-structure physics from heavy-ion fusion-evaporation reactions with proton- or neutron-rich projectiles, the spectroscopy of exotic nuclei with resonance reactions, studies of shell structures near the limits of stability, the exploitation of the isospin degree of freedom to study heavy-ion reaction dynamics, Coulomb excitation of neutron-rich nuclei relevant to astrophysical processes and reaction-mechanism studies with neutron-rich projectiles leading to the production of heavy elements. While some of the instruments, which were dispersed after the closure of TASCC, would be reconfigured for a new life at ISAC, some more modern spectrometers would also be built. The accelerator complex would be modified by increasing the energy at which the initial stripping occurs (from 150 keV to 400 keV) by the addition of a short DTL linac section after the present RFQ accelerator. It will be followed by a superconducting linac based upon existing technologies (Legnaro or Argonne). A modular cavity configuration will be used to reach 6.5 MeV/u for A = 150 (and higher energies for lower masses) while maintaining very high transport efficiency throughout the accelerator. The extended mass range is obtained by introducing a state-of-the-art charge-state boosting system between the present ion source/separator system and the RFQ. It is anticipated that an initial configuration giving energies in the 5 MeV/u range for masses up to A = 60 would be available in the latter part of the year 2003. The ISAC experimental complex will require additional buildings to provide space for the new accelerator and their ancillary services as well as a new experimental area for the research program. In the planning, further improvements are anticipated to allow for the possibility of servicing several users concurrently by increasing the number of sources of radioactive ions. With its ISAC-II extension, TRIUMF will provide a truly unique radioactive beam facility, which will meet the demands of a large segment of the community worldwide as was recommended by the Working Group in Nuclear Physics of the OECD Megascience Forum.