The systematics of thermoluminescence in rare earth activated sulfate lattices

A systematic survey of the thermoluminescence (TL) of rare earth activated sulfates of Be, Mg, Ca, Sr, Ba, Zn, Cd, and Pb was made. The sulfates of Sr, Ba, and Cd (as well as Ca) were found to exhibit an extremely bright TL following gamma irradiation, many of the phosphors being comparable in efficiency to CaSO4:Dy (Harshaw). The temperature of the glow peak induced by a rare earth ion in a given lattice was found to be determined only by the valence state of the rare earth. A decrease in trap depth with increasing lattice spacing was also observed. The most sensitive of these new phosphors are SrSO4:Tb3+ and BaSO4:Eu2+. Due to their relatively high-Z and large efficiency, these phosphors could prove useful as quality indicators for personnel dosimetry or for detecting very small exposures of low-energy x-rays (of a known quality). The TL properties of interest in dosimetry were determined for these phosphors. (author)