Properties and mechanism of scintillation in LuCl3:Ce3+ and LuBr3:Ce3+ crystals

The optical and scintillation properties of pure LuCl3, LuCl3:0.45%, 2%, 4%, 10% Ce3+, LuBr3:0.021%, 0.46%, 0.76%, 2.5%, and 8% Ce3+ are studied under X-ray and γ-ray excitation. The highest light yield of 29,000±3000 photons per MeV (ph/MeV) of absorbed γ-ray energy was measured for LuBr3:0.021% Ce3+. Energy resolutions obtained with a Hamamatsu R1791 photomultiplier tube (PMT) range from 6.0±0.5% to 18±2% for LuBr3:8% Ce3+ and LuCl3:0.45% Ce3+, respectively. For both LuCl3:Ce3+ and LuBr3:Ce3+, binary electron–hole diffusion was proposed as the dominant scintillation mechanism. At lower irradiation temperatures, VK diffusion is probably more important in the case of LuBr3:Ce3+.