Ce Concentration Dependence of Optical and Scintillation Properties for Ce Doped ${\rm LiYF}_{4}$ Single Crystals

We have investigated effects of Ce concentration on optical and scintillation properties for Ce doped LiYF₄ [Ce:LiYF₄] single crystals. Li(Y_1-x,Ce_x)F₄ single crystals with more than 75 % transparency were grown by micro-pulling-down method in the range of 0 ≤ x ≤ 0.03 and the crystals with x = 0.05, 0.1 had milky parts originated from remained starting materials. Photoluminescence spectra of all Ce:LiYF₄ crystals indicated two emission peaks from Ce³⁺ ion which was substituted for Y³⁺ ion site. Light yield and decay time of α-ray irradiation for Ce:LiYF₄ crystals were largely affected by Ce concentration and the largest light yield was observed for the crystal with x = 0.02. In contrast, the decay time systematically became faster with an increase of Ce concentration.