FRIB, East Lansing, Michigan, USA
MSU, East Lansing, Michigan, USA
ANL, Lemont, Illinois, USA
The Facility for Rare Isotope Beams (FRIB) at Michi-gan State University is a 400 kW heavy ion linear accel-erator. Heavy ion accelerators normally include a charge stripper to remove electrons from the beams to increase the charge state of the beams thus to increase the energy gain. Thin carbon foils have been the traditional charge stripper but are limited in power density by the damage they suffer (sublimation and radiation damage) and con-sequently short lifetimes. Because of the high beam pow-er, FRIB had decided to use a liquid lithium charge strip-per (LLCS), a self-replenishing medium that is free from radiation damage. FRIB recently commissioned a LLCS with heavy ion beams (36Ar, 48Ca, 124Xe and 238U beams at energies of 17-20 MeV/u). Since there had been no exper-imental data available of charge stripping characteristics of liquid lithium, this was the first demonstration of charge stripping by a LLCS. The beams were successfully stripped by the LLCS with slightly lower charge states than the carbon foils of the same mass thickness. The LLCS started serving the charge stripper for FRIB user operations with a backup rotating carbon foil charge stripper. FRIB has become the world’s first accelerator that utilizes a LLCS.
TH1I1
ANL, Lemont, Illinois, USA
The CARIBU facility at Argonne National Laboratory has been providing to users low-energy and reaccelerated beams of neutron-rich fission fragments for about a decade. These were obtained from a gas catcher system thermalizing fission fragments from a roughly 1 Ci 252Cf source that were then extracted as a low-energy beam that is purified by successive mass separation in a high-resolution separator and an MR-TOF system. While the system provided world unique beams, obtaining the required thin 252Cf source turned out to be an unreliable process that has hampered sustained operation. To remedy this situation, CARIBU is now being upgraded to nuCARIBU that will use a neutron-generator system to induce neutron-induced fission on a thin foil of 235U located inside the gas catcher. This will provide a more controllable source of fission products and a roughly order of magnitude improvement in total yield. The neutron generator is based on the (p,7Li) reaction with the beam from a compact high-intensity 6 MeV cyclotron hitting a high-power solid lithium target surrounded by a moderator. The nuCARIBU system, its expected performance, connection to ATLAS and current status will be presented.