Blue light stimulated luminescence in calcium fluoride, its characteristics and implications in radiation dosimetry

Strong optically stimulated luminescence (OSL), stimulated by blue light, has been observed, for the first time, in natural calcium fluoride (CaF(2)) phosphor, used as thermoluminescence dosemeters. Traps responsible for all three thermoluminescence (TL) peaks appearing upto 300 degrees C, i.e. 126, 196 and 264 degrees C, were observed to contribute to the blue light stimulated luminescence (BLSL) in CaF(2). When the areas under the respective curves (BLSL and TL) were measured, the BLSL measured at room temperature was found to be approximately 1.8 times the TL output of the dosimetry peak that appeared at approximately 264 degrees C. However, when measured after thermally annealing the first two TL peaks, the BLSL signal was found to be 0.26 times the TL output of the dosimetry peak at 264 degrees C. This paper describes the characteristics of the BLSL signal using linearly modulated OSL after subjecting the phosphor to different annealing treatments. Feasibility studies to assess the usefulness of BLSL in CaF(2) for environmental radiation monitoring are also discussed.