Thermoluminescence and thermally stimulated exoelectron emission from CaF2/CaO dual phases doped with lanthanide oxides for UV-ray irradiation

Abstract

A systematic study on thermoluminescence (TL) and thermally stimulated exoelectron emission (TSEE) has been performed for CaF2/CaO dual phases doped individually with all the fourteen available lanthanide oxides, to investigate their TL and TSEE emissivities for the UV and X-ray irradiations. A newly developed apparatus has allowed both the TL and the TSEE to be measured simultaneously, leading to finding a different aspect between the TL and TSEE emissivities. The result clearly indicates that Tb4O7 and Yb2O3 are the most promising lanthanide oxides to be doped in CaF2/CaO. The Tb4O7 leads a double peaked TL glow spectrum below 500 K for UV-light irradiation and the Yb2O3 leads a very intensive single peak of TL glow spectrum around 630 K for X-rays revealing its excellent characteristics of practical use for TL dosimetry. For TSEE dosimetry, La2O3, Tm2O3 and Yb2O3 are also promising for X-rays, and Gd2O3 and Lu2O3 for UV rays as well. The intensities of TL glow and TSEE emission from CaF2/CaO:Tb4O7 depend strongly on quenching rate of the sample during the cooling process of sintering. The TL glow shows the superlinear behavior against the dose of UV rays.