Design of a new integral benchmark experiment for large angle scattering using shadow bar and DT neutron source

Abstract

A new integral benchmark experiment was designed for validating large angle scattering cross section. In conventional integral benchmark experiments, events due to small angle scattering was dominant and the information on large angles ones were very little. Therefore, we designed a new experiment using a shadow-bar to suppress the contribution of small angle scatterings and direct incidents from the neutron source. The geometry of the experiment consists of a DT (Deuteron-Triton fusion) neutron source, a shadow-bar, a neutron detector and a target plate. To search the optimum configuration in which large angle scatterings were counted more frequently, the neutron transport was simulated with altering the target plate angle and the position of the neutron detector. It turned out that in the case where the target plate was set at a slant against the shadow-bar, the average scattering angles of the tallied neutrons became smaller. If the activation foil was set on the edge of the target plate, the contribution of large angle scatterings and the reaction rate of the activation foil decreased. By choosing these parameters properly, this new designed experiment may enable large angle scattering cross sections to be validated.