OSL dosimetric properties of synthetic topaz

Abstract

The optically stimulated luminescence (OSL) properties under beta radiation of synthetic topazes produced from three different reactants are reported for the first time. Topazes were synthesized by chemical vapor deposition using sodium hexafluorosilicate (Na2SiF6) compacts as solid precursor and either aluminum oxide, aluminum hydroxide or kaolinite compacts as reactants. The OSL dosimetric characteristics of the most promising composition, namely, topaz synthesized using aluminum oxide, were determined and analyzed. The alumina-derived topaz exhibited a linear response in the dose range from 0.2 up to 20 Gy, a satisfactory repeatability and a fading of approximately 30% in the first hours, after which the OSL response remained constant. These characteristics, together with a minimum detectable dose (MDD) of 0.01 Gy – corresponding to a 3σ background signal – suggest the potential of synthesized topaz as an OSL dosimeter. The OSL mechanism might be explained by at least two trap types, possibly related to topaz shallow traps. A decreasing behavior – featuring a single exponential decrease –, similar to that of OSL signal was observed in ultraviolet and visible light bleaching measurements.