Summary of Recent Target Studies

This report describes recent measurements that have been performed with the new target stack (Fig. 1). Highlights of these measurements are: (1) Pbar yields of nickel and powdered rhenium are comparable to that of copper. (2) Enhancement of pbar yield at the interface between copper and aluminum disks in the target stack has been observed. This effect occurs only when the lens is focused near the upstream edge of the target. (3) The target density depletion study in powdered rhenium showed an apparent yield reduction on the time scale of a single proton pulse, accompanied by release of airborne radioactive material.