E. V. D. van Loef, P. Dorenbos, C. W. E. van Eijk, K. W. Krämer and H. U. Güdel
Properties and mechanism of scintillation in LuCl₃:Ce³⁺ and LuBr₃:Ce³⁺ crystals
Nucl. Instr. and Methods Phys. Res. A 496, 138-145 (2003)                 

Abstract: 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 g-ray excitation. The highest light yield of 29,000±3000 photons per MeV (ph/MeV) of absorbed g-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, V_K diffusion is probably more important in the case of LuBr₃:Ce³⁺.