Characterization of natural CaF2 crystals for radiation detection purposes

In this study, co-located natural fluorite crystals of varying colours were comprehensively investigated to elucidate their defect structures using spectroscopic techniques. Detailed analyses revealed oxygen ion-vacancy defect complexes in yellow fluorites and F-centers alongside self-irradiation-induced metallic calcium in purple fluorites. The thermoluminescence (TL) glow curve of natural CaF 2 becomes saturated due to the high natural dose. Therefore, all TL studies were conducted after resetting the signal at an optimized annealing temperature of 400 °C. Raman spectroscopy identified 400 °C as the optimal annealing temperature, aligning the defect structures of natural CaF 2 with those of synthetic fluorites. TL measurements demonstrated a linear beta dose response of the net TL output ranging from 3 to 7000 mSv (Adj. R 2 = 0.99), meeting a key criterion for dosimetry. The findings underscore the significant potential of natural CaF 2 crystals as reliable dosimetric materials for radiation monitoring.