CaF2 :Dy and CaF2 crystal-based UV dosimeters

Monitoring of ultraviolet (UV) exposure in humans is important, since UV has been implicated in the pathogenesis of skin cancer, skin ageing and immunosuppression. Biological and physical dosimeters are being developed to measure occupational and environmental UV radiation exposure. We studied the UV-dependent thermoluminescence in CaF2 :Dy and CaF2 crystals and report on the development of a small personal UV dosimeter based on the thermoluminescent phenomenon.

CaF2 :Dy or CaF2 was sensitized to UV by heating for 1-3 h to 750-950(o) C on different supports (porcelain, steel, preheated steel, silicon, chromium, manganese, iron, cobalt, nickel, copper, Fe2 O3 , Fe3 O4 ). Sensitized crystals were irradiated with UV of different energies and wavelengths. Thermoluminescence of irradiated crystals was measured at different temperatures.

Maximal sensitivity of the crystals to UV was obtained after preheating to 900(o) C on steel and manganese supports. Sensitivity could be improved further by prolonging heating time. CaF2 :Dy and CaF2 were most sensitive to short-wave UVC and UVB radiation. Based on these findings we have constructed personal UVB and UVC dosimeters.

Development of personal UVC and UVB dosimeters based on UV-induced thermoluminescence in CaF2 :Dy and CaF2 crystals is feasible. CaF2 :Dy and CaF2 crystals are not sensitive enough to long-wave UV radiation to be used for construction of UVA dosimeters.