Development of rare earth doped CaS phosphors for radiation detection

抄録

CaS-based materials are known as highly efficient phosphors. CaS has excellent properties as host materials of phosphors under ultraviolet irradiation and is expected to have also for radiation detection. In this study, we fabricated CaS ceramic phosphors and measured their photoluminescence (PL), scintillation, and dosimetry characteristics to investigate the applicability of CaS ceramics as scintillators and dosimeters. The scintillation emission spectrum of CaS:Eu ceramics showed an emission peak at 656 nm, originating from the 5d–4f transitions od Eu²⁺ ions. The scintillation emission spectrum of CaS:Ce ceramics showed emission peaks at 510 and 570 nm that originate from the 5d–4f transitions of Ce³⁺ ions. The PL emission peaks of CaS:Ce and CaS:Eu were similar to those of the X-ray-induced radioluminescence emission peaks and were also assigned to the emission of Ce³⁺ and Eu²⁺ ions. The light yield of CaS:Ce and CaS:Eu were estimated to be approximately 1,700 and 4,400 photons/MeV, respectively. As for CaS:Eu, significant afterglow and strong thermoluminescence were observed, which indicates the sample contained trap sites at high concentration. Considering their PL, thermoluminescence, and scintillation properties, CaS:Ce and CaS:Eu have potentials for application as scintillators and dosimeters, respectively.