Light-ion production for medium-energy heavy-ion interactions

The unique radiation present in space is hard to completely reproduce for applications such as those needed for testing new shielding materials. Instead, the testing procedures involve transport model calculations that can simulate this radiation environment. Because these codes rely on experimental cross section data for validation and verification, it becomes necessary to expand or improve the cross section libraries in order to improve the accuracy of the models´ predictions. There is a critical need for light-ion production cross section measurements, including neutron, proton, deuteron, triton, ³He and alpha particles. To help answer that need, we have analyzed data from a series of previously conducted, medium-energy heavy-ion experiments. The experiments of interest were run at the Heavy-Ion Medical Accelerator in Chiba (HIMAC) facility involving various, medium-energy particle beams and target materials. The experiments were designed to observe neutrons that fragmented from the beam particles to provide measurements for energy and angular dependent cross sections. Although the experiments were originally designed for neutrons, clever manipulation of the data allowed for the same information to be measured for charged light-ion fragments. The advantage of this information is the ability to compare neutron and proton fragmentation cross sections using identical experimental conditions without the need for setting up another experiment. This paper details the analysis of several runs of data collected from the HIMAC experiments. The detectors used in the experiments were arranged in various angles ranging from 10 to 80 degrees off of the beam axis. Analysis includes using pulse height measurements in conjunction with time-of-flight measurements to discriminate between particle type and energy. The final results of the data analysis provided energy and angular dependent cross sections for protons, deuterons, and tritons for various beam types and ta- get materials.