Modeling and investigation of heavy oxide and alkali-halide scintillators for potential use in neutron and gamma detection systems

Abstract

Heavy inorganic oxide and alkali-halide crystals, which previous experimental research has indicated to have fast neutron detection efficiencies well over 40%, were investigated for potential use as highly efficient gamma-neutron radiation detectors. The Monte Carlo N-Particle radiation transport code (MCNP) was used to characterize the radiation interactions in a candidate set of crystals, including Bismuth Germanate (BGO), Lead Tungstate (PWO), Cadmium Tungstate (CWO), Zinc Tungstate (ZWO), Cerium-doped Lutetium-Gadolinium Orthosilicate (LGSO:Ce), and Cerium doped Lutetium-Aluminum Garnet (LuAG:Ce). Specific detection systems proposed and studied in the laboratory were also modeled and assessed. The candidate crystal set proved to be most susceptible to energy deposition from incident gamma quanta below 0.7 MeV and above 4 MeV, most likely due to photoelectric absorption and pair production, respectively. Inelastic and elastic scattering proved to be about 98% of the total neutron interactions from a Plutonium Beryllium (PuBe) neutron source, about a fourth of which were inelastic scattering. Various components of the detector configuration were evaluated in detail. The crystal dimensions and moderation especially affected detector efficiency, which showed potential for detection efficiencies comparable to experimental data.