Evaluation of Gamma-Ray Response of Tm: ${\rm BaF} _{2}$ Single Crystals

Tm³⁺ doped BaF₂ single crystal scintillator has been investigated. Undoped, 0.1, 0.5, and 1% Tm -doped BaF₂ are compared in terms of their decay time, light yield, non-proportionality and energy resolution. The fast component of Tm doped BaF₂ is characterized by a 5 ~ 6 ns decay time and it can be related to the Tm³⁺ 5d - 4f VUV emission from 4f^n-1 5d low-spin state (parity allowed and spin allowed transition). The light yield of Tm doped BaF₂ is lower with respect to the undoped BaF₂ and systematically decreases with increasing Tm concentration. However, 0.1%Tm:BaF₂ showed a better non-proportionality and energy resolution than the undoped sample.