The temperature dependence of gamma-ray responses of YAG:Ce ceramic scintillators

The temperature dependence (from -20 to +20 degrees C) of gamma-ray irradiated light outputs, energy resolutions, and decay time profiles of three YAG:Ce poly-ceramic scintillators is studied. The Ce concentrations are 0.5, 0.05, and 0.005 mol%. The relative light yield of the YAG:Ce with 0.5 mol% was measured as 1:1.08:1.14 at +20, 0, and -20 degrees C, respectively, including the temperature dependence of the phototube (-0.2%/degree). The energy resolution stays almost constant at 7.2% for 662 keV gamma-rays. The ceramic with 0.05 mol% shows the almost same properties, while the light yield of that with 0.005 mol% is 2-4 times lower (hence the energy resolution becomes 14-19%). All the scintillators exhibit good linearities within ∼1% between the light output and the irradiated gamma-ray energy from 59.5 keV to 662 keV. The decay time constants of the dominant decay components are about 80 ns and 300 ns at +20 degrees C. As the temperature increases, the effective decay of all the ceramics becomes faster, because the decay time constants become shorter and the fractions of the faster components increase. This decrease of the slower components is thought to suppress the light yield toward higher temperatures. These results indicate that thermal quenching dominates the temperature dependence of the ceramic YAG:Ce, and that the effect is almost negligible below the room temperature for the ceramics doped with Ce by ≳0.05 mol%. Because of self absorption of Ce emission, the 0.5 mol% scintillator starts to show a slight decrease in its light yield at lower temperatures than the 0.05 mol% one.