Initial performance of the IUCF cooler injector synchrotron

Construction of a compact 2.4 Tm Cooler Injector synchrotron (CIS) to inject intense polarised proton and deuteron beams into the IUCF 3.6 Tm electron cooled storage ring (Cooler) is complete. Beam commissioning began in 1997 with unpolarized H strip injection and progressed to the extraction of 210 MeV protons from CIS and the injection of 10¹⁰ protons at 200 MeV into the Cooler for experiment. With circumference of 17.36 m, CIS is possibly the smallest and least expensive example of this accelerator type for protons, and may serve as a practical proton source for medical and other applications. This contribution discusses our design choices, the resulting technical and fabrication challenges, and their solutions. Emphasis is given to the CIS ring beam performance from 7 MeV H injection through Cooler 200 MeV proton injection and accumulation