Fabrication and characterization of rectangular strontium iodide scintillator coupled to TSV-MPPC array

Abstract

Europium-doped strontium iodide (SrI2(Eu)) is a promising material for the scintillation crystals in a Compton imaging system, which requires an excellent energy resolution, as an alternative to NaI(Tl) crystals. Rectangular SrI2(Eu) crystals with dimensions of 10×10×10mm3 are fabricated, aiming for coupling with semiconductor-based photodetectors, especially silicon photomultipliers (SiPMs) in array detectors. The fabricated crystals are evaluated by coupling with a through silicon via (TSV)-type multipixel photon counter (MPPC) with dimensions of 12.6×12.6mm2. The saturation response of the SiPMs is corrected by using several photopeaks of isotopes with a fitting function. The measured energy resolution is approximately 4.4% at 662keV compared with an energy resolution of 3.4% with a PMT, and the crystals exhibit the best energy resolution with a shaping time of 6μs. All of the five prepared samples exhibit very stable performance and are promising for our future Compton imaging system for environmental radiation monitoring.