Thermoluminescence response in gamma and UV irradiated CaF₂:Ce,Li phosphor

In this work, the CaF₂ system doped with different Ce and Li concentrations has been synthesized by combustion technique. X-ray diffraction (XRD) and luminescence characterization by thermoluminescence (Tl) have been carried out to observe the effect of the concentration of the dopants on the Tl properties of the prepared phosphor. The XRD pattern reveals the formation of the CaF₂ crystal structure. The maximum Tl intensity is obtained for the concentration of 0.2% Ce and 0.6% Li. Cylindrical shaped pellets of mass ≈(50 ± 1) mg, thickness ≈1.0 mm and diameter of ≈ 6 mm sintered at different temperatures (450, 500, 525, 550 and 575 °C) have been fabricated. The pellets sintered at 525 °C are more sensitive in their Tl response. To analyze the behavior of their Tl response, the samples were irradiated with a Co-60 gamma ray source with doses between 1 and 25 Gy, and with a UV radiation source for different time intervals between 5 and 40 s. The samples irradiated with gamma radiation show two intense Tl peaks, one at approximately 173 °C and the other at 275.3 °C. On the other hand, samples irradiated with UV radiation show two Tl peaks at 192 and 277 °C. The Tl peaks grow with gamma radiation dose, and UV irradiation time. Our preliminary results suggest that, the CaF₂ Ce:0.2% Li 0.6% crystal is suitable for applications in gamma and UV radiation dosimetry. (author)