Lithium-Loaded Scintillators Coupled to a Custom-Designed Silicon Photomultiplier Array for Neutron and Gamma-Ray Detection

Scintillators capable of detecting both neutrons and gamma rays have generated considerable interest. In particular, the use of such scintillators with silicon photomultipliers (SiPMs) enables low-power and compact-geometry applications. Three types of Li-loaded scintillators, CLYC, CLLB, and NaIL, have been tested with a custom-designed SiPM array for temperatures between -20 degrees C and 50 degrees C. The array consists of four 6x6 mm(2) SiPMs arranged in a 2x2 configuration. Pulse-shape discrimination is used for neutron and gamma-ray identification. Because the pulse shape changes with temperature, the quality of neutron and gamma-ray discrimination varies with temperature. Furthermore, the thermal noise in SiPMs at high-temperatures results in poorer neutron and gamma-ray discrimination. Comparison of the energy resolution and the neutron and gamma-ray discrimination for the three scintillators coupled to the custom SiPM array is discussed.