FRIB, East Lansing, Michigan, USA
The Facility for Rare Isotope Beams (FRIB) will be a new national user facility for nuclear science. This cw, high power, superconducting (SC), heavy ion driver linac consists of a frontend to provide various highly charged ions at 0.5 MeV/u, three SC acceleration segments connected by two 180° bending systems to achieve an output beam energy of ≥200 MeV/u for all varieties of stable ions, and a beam delivery system to transport multi-charge-state beams to a fragmentation target at beam power of up to 400 kW. The linac utilizes four types of low-beta resonators with one frequency transition from 80.5 to 322 MHz after Segment 1, where ion charge state(s) is boosted through a stripper at ≤20 MeV/u. The beam dynamics design challenges include simultaneous acceleration of multi-charge-state beams to meet beam-on-target requirements, efficient acceleration of high intensity, low energy heavy ion beams, limitation of uncontrolled beam loss to <1 W/m, accommodation of multiple charge stripping scenarios, etc. We present the recent optimizations on linac lattice, the results of end-to-end beam simulations with machine errors, and the simulation of beam tuning and fault conditions.
NSCL, East Lansing, Michigan, USA
The National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University (MSU) is currently constructing its new rare isotope reaccelerator facility: ReA3, which will provide unique low-energy rare isotope beams by stopping fast rare isotopes in gas stopping systems, boosting the charge state in an Electron Beam Ion Trap (EBIT) and reaccelerating them in a superconducting linac. The rare isotope beams will be producted intially by Coupled Cyclotron Facility (CCF) at NSCL and later by Facility for Rare Isotope Beams (FRIB), currently being designed and constructed at MSU. The accelerator system consists of a Low Energy Beam Transport (LEBT), a room temperature RFQ and a linac utilizing superconducting QWRs. An achromatic High Energy Beam Transport (HEBT) will deliver the reaccelerated beams to the mutiple target stations. Beams from ReA3 will range from 3 MeV/u for heavy nuclei such as uranium to about 6 MeV/u for ions with A<50. The commissioning of the EBIT, RFQ and two cryomodules of the linac is currently underway. The ReA3 accelerator system design and status of commissioning will be presented.