Characterization of a Boron-Loaded Liquid Scintillator EJ-309:B5 for Neutron Energies Between 0.5 and 10 MeV

摘要

Various neutron and gamma-ray detector types have been investigated for applications in fieldssuch as nuclear nonproliferation, nuclear safeguards, reactor instrumentation, and dosimetry.Recently, various capture-gated organic scintillation detectors have been studied with a focus ontheir neutron-spectroscopy capabilities. When compared to standard organic scintillators, thecapture-gated detectors contain an additional material with a high absorption cross section forthermal neutrons (B-10, Li-6, etc.). Therefore, fast neutrons can be thermalized and capturedwithin the detector, generating two separate pulses (scatter pulse followed by capture pulse) witha characteristic time delay. The data analysis is then used to ‘confirm’ the detection of a neutronand infer the incident neutron spectrum. One example of the capture-gated detector is EJ-309:B5(also known as EJ-339), which is a boron-loaded liquid scintillator manufactured by EljenTechnology, containing ～ 5wt% of natural boron. This detector was used in conjunction with aCf-252 source (neutron energies up to 10 MeV) to acquire its response. An optimized digitalpulse-shape discrimination method was used to separate captured neutrons from scatter neutronsand gamma rays, and to obtain the resulting pulse-height and time-to-capture distributions. Theknowledge of the detector response is especially important if the original neutron spectrum of thematerial under investigation needs to be acquired to identify/characterize the investigatedmaterial. The average pulse height of captured neutrons was estimated to be 98 keVee which isin a good agreement with the expected value. Approximately 0.25% of the measured pulses wereidentified as capture pulses and the ratio of capture and scatter neutron pulses was approximately0.62%.