Study of optical and dosimetric properties of doped fluoride crystals

Abstract Optical properties and radiation effects of various fluoride crystals and their possible application to solid state dosimetry were studied. In particular optical absorption, PL, OSL, TL and OSTL of LiKYF 5 and LiKYF 5 :Pr 3+ crystals were measured and compared to those of pure and Eu 3+ -doped LiF. After X- or β-irradiation of LiKYF 5 :Pr 3+ a strong TL was recorded. In samples irradiated at RT also an OSTL could be stimulated at LNT; the stimulation maximum for the OSTL was at 442 nm. The traps responsible for the TL were stable to about 600 K. In LiF: Eu 3+ the TL could also be excited by VUV radiation. The VUV excited TL had excitation maxima near 125 and 190 nm. An OSTL emission was recorded in pure irradiated LiF crystals; and had an excitation maximum at 190 nm, indicating that the TL in the doped samples and the OSTL in the pure crystals are due to the same trapping states. Prolonged illumination into the F-band caused in LiF a decrease of the M-luminescence and an increase of the R + -emission, which is apparently due to an M to R conversion. The dose dependence of the TL in LiKYF 5 :Pr 3+ was found to be linear for β doses to above 2 kGy. The TL sensitivity of the powdered LiF:Eu 3+ samples was an order of magnitude greater than that of pure LiF crystals, but by an order of magnitude lower than that of the known efficient LiF:Mg Ti (TLD-100) phosphor. The sensitivity of LiKYF 5 :Pr 3+ crystals were of the order of the TLD-100 phosphor.