Optically Stimulated Luminescence in Tm-Doped Calcium Fluoride Phosphor Crystal for Application to a Novel Passive Type Dosimeter

An intense optically stimulated luminescence (OSL) with four emission bands in the wavelength range from 290 to 420 nm is observed for the first time in X-ray-irradiated Tm-doped CaF 2 (CaF 2 :Tm) phosphor crystal. The OSL intensity increases almost linearly with increasing X-ray absorbed dose. Thermally stimulated luminescence (TSL) glow curves with four peaks are also observed in X-ray-irradiated CaF 2 :Tm phosphor crystal. It is confirmed that the shape of the TSL glow curve in X-ray-irradiated CaF 2 :Tm phosphor crystal is the same as that of a commercially available dosimeter (TLD-300). An OSL emission and stimulation mechanism of X-ray-irradiated CaF 2 :Tm phosphor crystal is proposed.