Measurement of high momentum transfer reactions by recoil detection at a cooler ring

A system for the measurement of medium-energy, high-momentum transfer reactions via detection of the heavier ion products has been developed. The system consists of a parallel grid avalanche counter, a proportional counter, and a large-area microstrip silicon detector array, all attached to a large-gap dipole magnet that bends the primary beam through 6° and sweeps the recoil ions into the detection system. The detector stack measures the energy, time-of-flight, nuclear charge, mass, and angle of recoil-ion emission products. Ray tracing gives the emission angle of the recoil ions at the target. The system was installed at the Indiana Cooler Ring and its advantages and use in a storage ring environment are discussed. Preliminary results of differential cross section measurements for the reaction 12C(p, π+)13C at Tp = 166 and 294 MeV are presented.