CLLBC High Temperature Scintillation Characterization and Detector Integration

Abstract

High temperature detectors are required for nuclear material accounting measurements for some advanced reactor designs including molten salt reactors. The Cs <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> LiLa(Br,Cl) <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> :Ce (CLLBC) scintillator is a dual-mode scintillator that shows excellent gamma detection along with the capability to discriminate gamma-rays from neutrons and is available as a commercial product from RMD. The energy resolution at room temperature (RT) is ~3.0% at 662 keV with a light yield of ~45,000 ph/MeV. The gamma-neutron pulse shape discrimination figure of merit is ~3.5 at RT. We investigated the gamma and neutron detection performance of CLLBC scintillators from 25°C to 200°C. The results showed a good light yield response for gamma events as a function of temperature while the light yield for neutron-capture events monotonically decreased from 100% to 76% at 200°C. When integrated with a high temperature photomultiplier, at 175°C we obtained energy resolutions of 7.8% for 662 keV gammas and 4.2% for neutron-capture events, together with a PSD FOM of 0.74.