Neutron Yields from Stopping- and Near-Stopping-Length Targets for 256-MeV Protons

Absolute neutron yields at angles of 30, 60, 120, and 150 deg for the 256-MeV proton bombardment of elemental carbon, aluminum, and iron and of depleted uranium were measured. We used time-of-flight techniques to identify and discriminate against backgrounds and to determine the neutron energy spectrum. Comparison of the experimental yields with intranuclear cascade evaporation model calculations using the HETC and ISABEL codes showed very good agreement over the entire neutron energy range except at 150 deg.