Energy Resolution of LGSO Scintillators

Several LGSO samples with different Ce doping were studied in comparison to a GSO crystal. The light output, non-proportionality of the light response, energy resolution and intrinsic resolution were measured and compared to the intensity of the afterglow recorded in the second range of time. A high light output of 17000 plusmn 1700 ph/MeV and a good energy resolution of 6.5 plusmn 0.2% for 662 keV gamma rays from a ¹³⁷Cs source were obtained for the best sample, doped with 1 mol% of Ce. The energy resolution and, in particular, the intrinsic resolution varied with the concentration of Ce in the tested crystals and were not correlated with their common non-proportionality characteristics. In contrast, the observed correlation of the intrinsic energy resolution of the LGSO crystals and the intensity of their afterglow suggests that the energy resolution of scintillation detectors may be affected by a strong afterglow of the crystals. A further improvement of the crystals exhibiting a strong afterglow can be expected due to the improvement of its quality.