Ce-doped LiF-SrF₂ eutectic scintillators for thermal neutron detection produced at different solidification rates

Ce 0.1% doped LiF-SrF₂ eutectic scintillators were produced by vertical Bridgman method at various solidification rates of 1, 5, 20, 80, 320, and 1280 mm/hr. The LiF contained 95% of ⁶Li. The SEM images of the samples solidified at 1-80 mm/hr demonstrated clear lamellar structures. The α-ray induced radioluminescence spectra of the scintillators had intense emission peak at 310 and 330 nm due to the emission from Ce³⁺ 5d-4f transition of Ce:SrF₂ layers. When the samples were irradiated with ²⁵²Cf neutrons, they exhibited almost the same light yields of 4500-5500 ph/n and typical decay times of 120-160 ns. The optimal layer thickness of LiF-SrF₂ was determined to be 0.9 μm.