Growth and optical properties of LiF/LaF3 eutectic crystals

Neutron imaging devices employing a scintillator can be used in various fields, and eutectic crystals can be suitable for the imaging with a fine position resolution of a few hundred micrometers. Since LiF and LaF3 have different refractive indexes of 1.41 and 1.64 at 300 nm, respectively, the eutectic crystal is expected to behave as a scintillator with light guiding properties. Thus, the optical properties of Ce-doped LiF/LaF3 eutectic crystal grown by micro-pulling down method were investigated. The light output of LiF/Ce:LaF3 eutectic crystal was relatively small. The emission peaks at 300 nm originating from Ce3+ of 5d–4f transition were observed under excitation by UV photons and 5.5 MeV alpha rays. Moreover, the photo-luminescence decay time of Ce-doped LiF/LaF3 eutectic crystal was estimated to be 17 ± 1 ns.