Characterization of a Cs 2 LiYCl 6 : Ce 3 + scintillator coupled with two silicon photomultiplier arrays of different sizes

Neutrons produced by cosmic rays comprise the main factor in radiation hazards for astronauts and spacecraft during space exploration. A silicon-photomultiplier- (SiPM-) array-coupled Cs₂LiYCl₆: Ce${}^{3+}$ (CLYC) detector was proposed to measure neutrons onboard spacecraft. Since both light-collection efficiency and thermal noise rate are proportional to a SiPM's size, it is necessary to compare CLYC's characterization when coupled with SiPM arrays of different sizes. In this paper, a 4$\times$4 array and an 8$\times$8 array, both of which are composed of 3$\times$3-mm² SiPM elements, were coupled to a $\Phi$38 mm$\times$38 mm cylindrical CLYC detector. The energy resolution, pulse-shape-discrimination (PSD) performance, and temperature dependence were tested with two gamma-ray sources and a neutron source. Results indicate that both energy resolution and PSD performance mainly benefit from the higher light-collection efficiency of the large array. The peak centroids of ¹³⁷Cs varied by $\sim$20% in the testing temperature region from -35 °C to +55 °C.