The Stony Brook Superconducting Heavy-Ion Booster Project

A superconducting LINAC to be injected with heavy-ion beams from the Stony Brook FN tandem is described. The basic LINAC elements are lead-plated copper splitloop resonators operated at a frequency of 150 MHz and a temperature of 4.2 K. With the anticipated effective accelerating gradient of 3.0 MV/m, the booster will provide an energy gain of 20 MeV per charge for (Q=19) 58Ni ions, and have a useful mass range of A=16 to about A=100. The linac structure consists of compact independent cryostat modules separated by room temperature quadrupole doublets, each module containing four (ß=0.055) or three (ß=0.10) independently phased resonators. The tandem beam is bunched at the 16th subharmonic (pulse spacing 107 nsec) to facilitate lifetime and flight time measurements. A post-tandem rebuncher system compresses these bunches into less than ±6° around the -20° mean phase of the LINAC. Existing room geometry dictates charge selection after the first as well as the second stripping. A ß=0.055 prototype cavity has already been operated with beam and successfully stabilized to ±0.1° in phase with a computer-controlled RF feedback system. A prototype module of 4 such cavities in a common cryostat is presently under construction.