Development of a modular mixed-radiation directional rotating scatter mask detection system

摘要

The ability to simultaneously identify the direction of both fast neutrons, above 1 MeV, and gamma rays using a light-weight system consisting of a single 1" EJ-309 organic liquid scintillator and a plastic Spartan rotating scatter mask (RSM) is demonstrated computationally through Monte Carlo simulations and validated with experimental measurements. Two sets of directional measurements were performed with an americium-beryllium source, emitting both neutrons and gamma rays. The RSM identified the direction of the source within one 10° rotational increment in the azimuthal and polar directions based on both the neutron and gamma-ray induced signals discriminated by charge integration pulse-shape discrimination. These results indicate the RSM system is a compact, light-weight, and modular directional detection system useful for rapid identification of the type and direction of radioactive sources, a desirable feature for many nuclear security and safety applications.