Heavy-Ion Beam Dynamics in the RIA Post-Accelerator

The RIA post-accelerator (RIB) includes three main sections: a room temperature injector with design ion charge-to-mass ratio 1/240 and output energy of ∼ 93 keV/u, a superconducting (SC) linac for ions with charge-to-mass ratio 1/66 or higher up to an energy of ∼ 1 MeV/u and a higher energy SC linac including existing ATLAS to produce 10 MeV/u beams up to uranium. Two strippers are installed between the sections. Extensive accelerator design studies and end-to-end beam dynamics simulations have been performed to minimize the cost of the linac while providing high-quality and high-intensity radioactive beams. Specifically, we have found that cost-effective acceleration in the front end can be provided by several hybrid RFQs proposed and developed for acceleration of low-velocity heavy ions. For beam focusing in the second section it is appropriate to use electrostatic lenses and SC quadrupoles inside common cryostats with the resonators.