Crystal Growth and Scintillation Properties of Tm, Nd Codoped LaF $_{3}$ Single Crystals

Because there is an overlap of the 5d-4f emission transition of Tm³⁺ and absorption transition of Nd³⁺, an energy transfer between Nd³⁺ and Tm³⁺ in LaF₃ was supposed to enhance the efficiency of the previously studied Nd:LaF₃ scintillation material. In this study, 0.1% and 1%Tm, Nd, and Tm, Nd codoped LaF₃ single crystals scintillators were developed using micro-pulling down method (μ-PD), and their optical properties in the vacuum ultraviolet (VUV) region were evaluated. Tm³⁺ codopant did not show positive contribution to VUV emission, but energy transfer between Nd³⁺ and Tm³⁺ cannot be excluded, although the photoluminescence spectra point just to a competition for energy between the two ions. Gamma-ray response was also measured using the pulse-height distribution measurement.