Commissioning of the Argonne positron accumulator ring

The Advanced Photon Source (APS) injector consists of a 250-MeV electron linac, a 450-MeV positron linac, a 450-MeV positron accumulator ring (PAR), and a 7-GeV synchrotron. The purpose of the PAR is to accumulate and damp positrons from the 60-Hz linac during each cycle of the 2-Hz synchrotron, thus increasing the fill rate for the main ring. This paper discusses the rapid progress of PAR commissioning. Less than a year was required from first acceptance of beam to transfer of PAR operations to the APS Operations Group. PAR has been well characterized and already meets most of its design specifications. An accurate model has been developed for linear and chromatic properties. Hardware improvements are planned to allow specifications to be fully met