Crystal Growth and Evaluations of }} Scintillators for Different Nd Concentration

In order to develop novel scintillating materials, we grew 0.5 mol%, 1 mol%, and 3 mol% Nd-doped LuLiF 4 scintillators by the micro-pulling down method, because LuLiF 4 has a very wide band gap and Nd 3+ shows fast and intense 5d-4f emission as a luminescence center. The transmittance and emission peaks were examined in these three samples by using our original spectrometer made by Bunkou-Keiki Company. At wavelengths longer than 180 nm, approximately 60-80% transmittance with three absorption peaks around 140, 160 and 175 nm and emission peak at approximately 180 nm were observed for all the crystals. Light yields and decay time constants of the samples irradiated by 241 Am γ-ray were measured using photomultiplier tubes R8778 (Hamamatsu). The light yield of the 1 mol% doped LuLiF 4 was 700 photons/5.5MeV α that is much greater than that of Nd:LaF 3 scintillator (100 photons/5.5MeV α). As for decay time profiles, the main component of Nd:LuLiF 4 was 12 ns in the case of α-ray irradiation. 137Cs 662 keV γ-ray photoabsorption peak was detected in 1 mol% doped LuLiF 4 only, and the light yield was 300 ph/MeV.