This award will support collaborative research between Dr. Stephen Wender and his research group at Los Alamos National Laboratory and Dr. Jean-Alain Pinston and colleagues at the Institute for Nuclear Science, Grenoble, France. The investigators propose to measure the neutron-proton bremsstrahlung (NPB) cross section, using the continuous, high energy neutron source at the Los Alamos Meson Physics Facility. Data for this reaction are very sparse and some of the existing data may be in error. This experiment is important for several areas of nuclear physics. A major goal is to map out the NBP cross section up to 400 MeV incident neutron energy to investigate meson exchange current. This experiment will also shed light on the origin of high-energy gamma rays seen in heavy-ion reactions. The first year will involve measurements of gamma rays using a multi-element detector. In the second year, the investigators will detect gamma rays in coincidence with recoil proteins. The final configuration may be a triple coincidence, with the scattered neutron detected as well. The collaboration with the Grenoble group is essential because of their knowledge and experience with multi-element gamma-ray detector arrays. Such detectors are vital because of their insensitivity to backgrounds.
