Evaluations of scintillation properties of LiSrAlF6 scintillator for thermal neutron detection

Ce 1%, Eu 1%, and Eu 2%-doped LiSrAlF₆ (LiSAF) single crystals were grown by the micro-pulling-down (μ-PD) method for thermal neutron applications. The crystals were transparent, 2.0 mm in diameter and 20-40 mm in length. Neither visible inclusions nor cracks were observed. Their transmittance spectra were measured. The strong absorption lines were observed at 200, 240, and 300 nm for Ce:LiSAF due to Ce³⁺ 4f-5d transition. In Eu:LiSAF, 200 (4f-5d) and 300 (4f-4f) nm absorption lines appeared. When they were irradiated by ²⁴¹Am α-ray simulating neutron excitation, strong emission peak appeared at 300 nm in Ce:LiSAF and 370 nm in Eu:LiSAFs, respectively. Thermal neutron responses were investigated under ²⁵²Cf irradiation. The absolute light yield of Ce, Eu 1%, and Eu 2% samples were 3400, 18000, and 30000 ph/n, respectively. Main components of the scintillation decay time of Ce, Eu 1%, and Eu 2%-doped LiSAFs were 63, 1293, and 1205 ns.