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

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