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 s cintillation decay time profile and light yield of four inorganic scin tillators 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 effec tive decay time constant are found to increase with decrease in the te mperature for all four crystals, When integrated with 500 ns time cons tant, the light yield increases significantly for EGO and GSO but decr eases 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 deg rees C, suggesting the energy transfer mechanism from gamma-ray excite d Gd3+/Y3+ sites to the Ce3+ luminescent centers noted by Suzuki et al .