Publication

(K,Rb)₂CuBr₃ crystals were fabricated by the slow cooling method, and their photoluminescence (PL) and scintillation properties were examined. Emission bands were observed at 350–550 nm under UV and X-ray irradiation. PL quantum yields of K₂CuBr₃, (K_0.25,Rb_0.75)₂CuBr₃, (K_0.5,Rb_0.5)₂CuBr₃, (K_0.75,Rb_0.25)₂CuBr₃, and Rb₂CuBr₃ were respectively 75.8, 71.0, 82.3, 96.9, and 96.3%. The scintillation decay curves were approximated by a sum of three exponential functions, and the decay time constants due to recombination of self-trapped excitons were 58–63 μs. The afterglow levels of the K and Rb-mixed samples at 20 ms passed after X-ray irradiation decreased to 10–40 ppm, compared with those of K₂CuBr₃ and Rb₂CuBr₃. Among these samples, (K_0.75, Rb_0.25)₂CuBr₃ showed the highest light yield of 7400 ph/MeV among the samples calculated from the pulse height spectra of ¹³⁷Cs γ-rays (662 keV).