A study of two kinds of thermoluminescent dosimeters; CaF2:Tm and CaSO4:Dy in LiF.

We studied two kinds of thermoluminescent dosimeters using 60Co gamma rays. In CaF2:Tm, the intensity of the glow curve integral as a function of dose increased linearly; the dose response curve of the main peak (at 165 degrees C) was sublinear and that of the high temperature peak (at 220 degrees C) was supralinear. In CaSO4:DY in LiF, the main peak (at 215 degrees C) and the glow curve integral as a function of dose were linear; the low temperature peak (at 170 degrees C) was sublinear. The relative responses of CaF2:Tm and CaSO4:Dy in LiF were greater than that of LiF (TLD-100) by a factor of about 11 and 4, respectively. In CaF2:Tm, the high temperature peak was very stable, but the main peak faded away with post-irradiation storage time. For CaSO4:Dy in LiF, the main peak was very stable and the low temperature peak was relatively stable. Based on the glow curve integral, we determined that the fading of CaF2:Tm and CaSO4:DY in LiF was 36 and 38%, respectively, for a month.