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.

Differential cross sections and analyzing powers for the <(p)over right arrow p> --> d pi(+) reaction have been measured to within T-pi(cm) = 85 keV of threshold. The S-wave strength is extracted and found to be similar to 13% larger than that determined from recent measurements of np --> d pi(0). Both the analyzing power and the anisotropy in the angular distribution show the expected energy dependence and these data are used to obtain values for the two contributing P-wave amplitudes.

Analyzing powers and total cross sections for the p(p↘,π+)d reaction near threshold have been measured at the Indiana University Cyclotron Facility Cooler. The analyzing power follows a sin θcm distribution. These preliminary results are consistent with the calculated factor of two enhancement of the s‐wave cross section from heavy meson exchange currents. (AIP)

A readout system for Si microstrip detectors has been developed in which inductors are placed between each strip thus forming an LC delay line with the detector's intrinsic capacitance. Each strip in a 50-strip detector is resolved and a time resolution of 800 ps is obtained with 5.49 MeV alpha particles. Only two fast signals and an energy signal are needed from an entire detector in order to determine a particle's time of arrival, position and energy. The system requires little power and is made of components that are available commercially.

Studies of (p,pi) and (p,2pi) reactions on the Indiana cooler ring using recoil-ion detection

The use of thin fibers as internal targets for nuclear physics experiments in storage rings is discussed. We have measured the lifetime and the energy spread of stored, electron-cooled beams in the presence of an internal carbon fiber target. Measurements have been carried out in the Indiana Cooler with proton beams between 100 MeV and 300 MeV. The effect of the inhomogeneous fiber target on the beam is the same as that of a homogeneous gas target of equivalent thickness within the accuracy of the measurement. The measurements are compared with a Monte Carlo simulation of the stored beam. It is demonstrated that charging of the fiber target can significantly affect the lifetime and energy spread of the stored beam.