Lithium-loaded scintillators coupled to a custom-designed silicon photomultiplier array for neutron and gamma-ray detection

Abstract

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 and 50$^{\circ}$C. The array consists of four 6x6~mm$^2$ SiPMs arranged in a 2x2 configuration. Pulse shape discrimination is used for neutron and gamma identification. Because the pulse shape changes with temperature, the quality of neutron and gamma discrimination varies with temperature. Furthermore, the larger dark current in SiPMs at high temperatures results in poorer energy resolution and neutron-gamma discrimination. Comparison of the energy resolution and the neutron-gamma discrimination for the three scintillators coupled to the custom SiPM array will be discussed.