Luminescence properties and thermal neutron response of 6Li-loaded fluoride eutectics

Abstract

Luminescence and scintillation properties of Eu-doped 756LiF-12.5AlF3-12.5CaF2 eutectics suitable for thermal neutron detection are reported. The 0.5 and 1.0% Eu-doped eutectics were grown by micro-pulling down (μ-PD) technique. These materials demonstrated two emission bands with maximums at 375 and 430 nm wavelengths under excitation with 250–400 nm wavelength radiation. The emission band at 375 nm was associated with 4f65d-4f7(8S7/2) transition of Eu2+ in the CaF2 phase, and the 430 nm band could be result of incorporation of Eu2+ into Li3AlF6 and other phases. When alpha-ray excited the eutectics, both Eu2+ 4f65d-4f7(8S7/2) and Eu3+ 4f6-4f6 (5D0-7F1, 2) emission band were detected at 430 nm and 590 nm. The scintillation decay time of the eutectics were determined to be about 540 ns for Eu 0.5% and 380 ns for Eu 1.0%, respectively. According to pulse height spectra registered under 252Cf irradiation, the relative scintillation light yield of the eutectics was observed to be 6000 ph/n (Eu 0.5%) and 2000 ph/n (Eu 1.0%) when compared to 6Li-loaded glass commercial scintillator.