Characterization of the CLYC detector for neutron and photon detection

Cs2LiYCl6 (CLYC) is a new scintillator that is suitable for dual gamma-neutron detectors due to its gamma spectroscopic capabilities while producing monoenergetic pulses from neutron captures with 6Li. We present new characterization results for a 2×2 cm2 CLYC crystal. The detector resolution was characterized using weak check photon sources including 137Cs, and the detector's neutron capture capabilities were characterized with several measurements of 252Cf with varying thicknesses of polyethylene moderator. It was found that the 6Li neutron capture rate was maximized when using approximately 7.6 cm of polyethylene moderator. A 5% resolution for the 662-keV line of 137Cs and a 3.4% resolution of the 6Li neutron capture peak were measured with our experimental set-up. MCNPX-PoliMi was used to model the measurements performed with the CLYC detector, and MPPost was used to determine the light output distribution, convert 6Li neutron captures into light, and apply energy resolution. It was found that the modeling technique was capable of predicting 137Cs photon light output distributions for all light output greater than 200 keVee, and also to predict the same optimal polyethylene thickness as the measurement. Intrinsic neutron capture efficiency was estimated to be about 10%, which is a factor-of-5 improvement over an equivalent volume of 3He at a pressure of 10 atm.