Thermoluminescence and F-center annealing in alkaline-earth fluoride crystals after reactor irradiation at low temperature

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Abstract
Thermoluminescence is related to the F‐center annealing stage in undoped alkaline‐earth fluoride (CaF2, SrF2, and BaF2) single crystals irradiated at 20 K with reactor neutrons. The temperature of glow peak maxima are classified in four groups (P‐1–4); P‐1: 110–130 K, P‐2: 134–152 K, P‐3: 183–200 K and P‐4: 201–245 K with a heating rate of 4 K/min. at temperatures ranging 77–300 K. These temperatures of peak maxima correspond well to decay stages of F‐centers. F‐centers play an important role as recombination centers in the TL process. The main TL emission spectrum of P‐1–4 peaks consists of the intrinsic luminescence as well as the case of the x‐ray emission spectrum at 77 K. It is revealed that these TL emission bands near 300 nm of P‐1, 2, and 3 peaks are due to the radiative recombination of (VK+F) and (H+F) reactions, respectively.