Thermoluminescence of some Pr3+ doped fluoride crystals

Irradiation effects and dosimetric properties have been studied for CaF2, KYF4 and CsY2F7 crystals doped with Pr3+. In particular, thermoluminescence (TL) excitation spectra have been measured in the 120–200nm region and the CaF2:Pr3+ and KYF4:Pr3+ crystals show excitation maxima at 135 and 140nm, respectively. Some of the main TL peaks appear after vacuum ultraviolet (VUV) irradiation at the same temperatures as after β irradiation, indicating that they are due to the same radiation-induced trapping levels. Optically stimulated luminescence (OSL) and phototransferred TL (PTTL) have also been recorded in pre-irradiated samples and stimulation spectra have been measured. The OSL emission spectra show some of the same bands as in the case of the XL and TL, indicating that they are due to the same luminescence centers. The TL sensitivity of CaF2:Pr3+ is ∼5 times higher than that of TLD-100, and the TL sensitivity of KYF4:Pr3+ is slightly higher than that of TLD-100, whereas the sensitivity of CsY2F7:Pr3+ is much lower. The main TL peaks of KYF4:Pr3+ and CaF2:Pr3+ appear above 480 K and, accordingly, only low TL fading is expected during storage at RT. The dose dependence of the main TL peaks is nearly linear in a dose range up to about 2000Gy.