Thermoluminescence in calcium fluoride doped with terbium and gadolinium ions

Thermoluminescence (TL) in sintered CaF2 co-doped with Tb4O7 and Gd2O3 has been investigated for UV and X-ray irradiation. Three TL glow peaks for the CaF2:Tb, Gd sample are observed at about 353, 435 K (437 K: for X-ray) and 523 K by heating the sample at a rate of 20Kmin-1 after UV or X-ray irradiation at room temperature. It was found that the second peak (435 K) intensity became stronger than that of the sample singly doped with only terbium or gadolinium ions. From the TL emission spectrum and the excitation and emission spectra of photo luminescence for the CaF2 doped activators, it is concluded that the TL of Tb3+Tb3+ ions is sensitized by the existence of Gd3+Gd3+ ions. The 435 K TL peak may be also suitable for using it as a dosimeter.