Rare-isotope production optics of ARIS preseparator

The Advance Rare Isotope Separator (ARIS) at FRIB provides in-flight purification of rare-isotope beams (RIB) generated by projectile fragmentation or fission on a target. Beams of stable ions from a driver linac impinge on a graphite target thin enough such that products main-tain velocities close to that of the incident beam. The incident primary beam impinges on-target at about 200 MeV/u (for uranium and higher for lighter species). The energy may be lower than the maximum allowed, de-pending on the requirements of the experiment. Using multi-charge state acceleration, the linac has most recently provided up to 20 kW on-target with a long-term goal of reaching 400 kW. Specialized magnets, collimators and other components have been integrated into the separator to withstand harsh conditions and facil-itate maintenance. The optics properties at the beam dump are important since the power density must be kept low enough to avoid failure of the material. We describe the various optics modes that have been developed for safe operations and maximizing the beam power allowed for RIB production.