Scintillation Non-Proportionality of Lutetium- and Yttrium-Based Silicates and Aluminates

This study compares the light yield as a function of gamma-ray energy for several Lu- and Y-based silicate and aluminate scintillators. These comparisons illustrate the effects of crystal matrix, growth atmosphere, activator concentration, and co-doping on proportionality. The radioisotopic sources used in this study produce gamma-rays and X-rays from 22 keV to 1.3 MeV. The samples investigated are 10 times 10 times 10 mm in size and have the following single-phase compositions: LSO:Ce; LSO:Ce, Ca; LPS:Ce; LuAG:Pr; YSO:Ce; and YSO:Ce, Ca. The light yield vs. gamma-ray energy response is similar for scintillators with similar crystal structures, despite significant variations in growth atmosphere and activator concentration. Additionally, sample-to-sample variation is significantly reduced in the Ce-doped oxyorthosilicates when calcium is added as a co-dopant. Overall, the silicates measured in this study exhibit similar non-proportional responses, and in general are less proportional in the lower energy range compared to LuAG and other aluminates.