Temperature dependence of gamma-ray excited scintillation time profile and light yield of GSO, YSO, YAP and BGO

We have measured the temperature dependence of the gamma-ray excited scintillation decay time profile and light yield of four inorganic scintillators GSO (Gd-2(SiO4)O; Ce), YSO (Y-2(SiO4)O; Ce), YAP(YAlO3; Ce) and BGO(Bi4Ge3O12) by the delayed coincidence method between -20 and +20 degrees C. Two to three decay components are found in all crystals, and their light yields and decay time constants are highly dependent on temperature. The total light yield (t = 0 - infinity) and the effective decay time constant are found to increase with decrease in the temperature for all four crystals, When integrated with 500 ns time constant, the light yield increases significantly for EGO and GSO but decreases appreciably for YSO and YAP, as the temperature drops below -10 degrees C. The rising part of the scintillation pulse shows the prompt build-up for GSO in all temperatures measured and for YSO above 10 degrees C, suggesting the energy transfer mechanism from gamma-ray excited Gd3+/Y3+ sites to the Ce3+ luminescent centers noted by Suzuki et al.