Optical and scintillation properties of Pr3+-doped Ca3(BO3)2 single crystals

Optical and scintillation properties of Pr3+-activated Ca-3(BO3)(2) (CBO) single crystals for neutron scintillator applications were examined. The crystals were grown by the micro-pulling down (mu-PD) method. In transmittance spectra, two absorption lines at 210 and 245 nm were observed and they were identified as Pr3+ transition from the ground state H-3 to 5d state. The both of photo- and radio-luminescence spectra of Pr3+-doped CBO crystals demonstrated intense peak at 260 and 310 nm which was ascribed to the transition from the lowest 5d excited state to the 4f ground state levels of H-3. The main decay component was about 16-17 ns under 245 nm excitation wavelength. The relative scintillation light yield of 1.0% Pr3+-doped CBO was about 90% when compared with that of reference Li-class scintillator (GS20) under Am-241 5.5 MeV alpha-ray excitation, while that measured under Cf-252 neutron irradiation was about 20%. It was concluded that this difference originated from the difference of energy released from the neutron reactions. (C) 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim