Heavy-ion beam dynamics in the RIA accelerators

Abstract

The Nuclear Science Community in the United States has unanimously concluded that developments in both nuclear science and its supporting technologies make building a Rare-Isotope Accelerator (RIA) facility for production of radioactive beams. The RIA development effort involves several US Laboratories (ANL, JLAB, LANL, LBNL, MSU, ORNL). The RIA project includes a continuous wave 1.4 GV driver linac and a 123 MV post-accelerator, both based on superconducting (SC) cavities operating at frequencies from 48 to 805 MHz. Several new conceptual solutions in physics design of heavy-ion SC linacs have been developed recently. In particular, the concept of multiple charge state beam acceleration in SC linacs was tested and will be used in the driver linac to increase available accelerated beam power. A detailed design has been developed for the focusing–accelerating lattice of the RIA linacs which are configured as an array of short SC cavities, each with independently controllable RF phase. Independent phasing allows the velocity profile to be varied: the linac can be tuned to provide higher energies for the lighter ions. For example, the reference design linac can be tuned to provide a uranium beam at an energy of 403 MeV/ u and can be re-tuned to provide a proton beam at 900 MeV. The linac must provide 100 kW beam power with the possibility to upgrade up to 400 kW.