Temperature characterization of scintillation detectors using solid-state photomultipliers for radiation monitoring applications

We have characterized two state-of-the-art solid-state photomultipliers, one by SensL, the other by Hamamatsu, coupled to scintillators by Saint-Gobain Crystals in the -25 to +50 oC temperature range. At room temperature, the energy resolution at 661.6 keV measured with both detectors is worse than the resolution obtained when the crystals are coupled to a regular photomultiplier tube. Both the pulse height and pulse height resolution of the 661.6 keV gamma rays in the 137Cs spectrum vary strongly with temperature. The noise threshold determined from the 22Na spectrum increases quadratically as the temperature is increased to well above 100 keV at +50 oC for both detectors.