Year
2018
Abstract
Normal 0 false false false EN-US JA X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:\"Table Normal\"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:\"\"; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:Calibri;} Advanced safeguards instruments based on organic scintillators are being investigated by many research groups around the world. Such systems are of direct interest to the International Atomic Energy Agency, especially for characterizing fresh nuclear fuel. To effectively design a system, the efficiency of these detectors must be well understood. Organic scintillators directly detect fast neutrons through elastic scatter reactions; therefore, there is a strong energy dependence on the detection efficiency. An experiment was performed to measure the intrinsic neutron detection efficiency of multiple organic scintillation detectors, such as EJ-309 liquid and stilbene. The detectors were placed 2 m from a Cf-252 spontaneous fission source, 1.4 m above the floor, and data were collected with a variety of shielding materials, such as polyethylene and lead. Optimized pulse-shape discrimination was performed on each data set to separate the neutron pulses from the gamma-ray pulses. In the full paper, we will present the measured detection efficiencies as well as Monte Carlo simulations using MCNPX-PoliMi.