Scintillation properties of Ce3+-doped, Pr3+-doped calcium orthoborate

To develop new scintillators for thermal neutron detection, we investigated optical and scintillation properties of Ce³⁺-doped, Pr³⁺-doped Ca₃(BO₃)₂ single crystals grown by the micro-pulling down (μ-PD) method. In optical transmission spectra, the absorption was observed around 275 and 345 nm correspond to the transition from the 4f ground state levels ²F_5/2, ²F_7/2 to 5d excited state of Ce³⁺ and Pr³⁺ transition from the ground state ³H to 5d state around 210-245 nm, respectively. The radioluminescence spectra showed intense peak around 400 nm (Ce³⁺:CBO) and 260-310 nm (Pr³⁺: CBO) under ²⁴¹Am 5.5 MeV α-ray excitation due to the 5d-4f transition. The relative scintillation light yield of 0.5 % Ce³⁺: CBO crystal showed about 30 %, while that of 0.5 % Pr³⁺: CBO crystal showed about 10 % compared with that of reference Li-glass (GS20) scintillator under ²⁵²Cf neutron irradiation.