Characterizations of Ce ³⁺-doped CaB ₂O ₄ crystalline scintillator

Single crystals of undoped and 0.5% Ce ³⁺-doped calcium metaborate CaB ₂O ₄ have been grown successfully by micropulling down (μ-PD) technique. The material can find its application in the neutron detection. After the single-phase of CaB ₂O ₄ was confirmed using X-ray diffraction analysis, optical and scintillation characteristics were investigated. In the transmittance spectra, Ce ³⁺-doped crystals showed absorption bands around 270 and 320 nm which are ascribed to the transition from 4f ground state to 5d excited state of Ce ³⁺. Under the ²⁴¹Am 5.5 MeV α-ray excitation, strong emission peak at 370 nm because of the Ce ³⁺ 5d-4f transition was observed for Ce ³⁺-doped crystal, while the undoped crystal showed broad intrinsic emission band around 300-400 nm which is caused by the lattice defects in the host crystal. The absolute light yield was calculated to be about 2200 photons per neutron under ²⁵²Cf neutron irradiation.