A NEW ATLAS EFFICIENCY AND INTENSITY UPGRADE PROJECT*

The ATLAS facility provides beams of essentially all stable isotopes at energies above the Coulomb barrier for nuclear physics research. We have developed a two-stage ATLAS upgrade plan which includes the replacement of aging split-ring cavities by high-performance quarter-wave resonators (QWR) capable of accelerating ~100 pμA ion beams. The first stage of the upgrade project funded through the American Recovery and Reinvestment Act includes an accelerator efficiency increase by adding a new RFQ injector, development and construction of a new cryomodule containing up to 4 SC solenoids and 7 QWRs. A new 72.75 MHz resonator is designed for an optimum ion velocity β=0.075. To achieve a record high accelerating voltage of ~ 2.5 MV at this very low velocity range, the EM properties of the resonator are highly optimized to reduce peak surface fields. The vast experience gained during the development, commissioning and operation of the ATLAS energy upgrade cryomodule [1,2] will be applied to the design of the new cryomodule