TL and OSL dosimetric properties of Opal gemstone for gamma radiation dosimetry

• The XRD, SEM and EDX techniques were used to investigate powdered Opal.
• Pellets of three different concentrations of Opal and Teflon were studied.
• The dosimetric properties of the Opal + Teflon pellets were verified.
• TL and OSL techniques were used to analyze the characteristics of the pellets.
• Pellets of concentration of 2:1 (Opal:Teflon) presented the most adequate results.

In this work, the response of the natural material Opal was studied in relation to its thermoluminescence (TL) and optically stimulated luminescence (OSL), after exposure to the gamma radiation of a 60Co source. The structure of the powdered Opal was verified using the X-ray diffraction, scanning electronic microscopy and energy-dispersive X-ray spectroscopy techniques. The material, in its stone form, was turned into powder and mixed to Teflon (also in powder) in three different concentrations, and then pellets were manufactured. The aim of this work was to evaluate the response of these pellets in high-doses of gamma radiation beams, and to observe their possible application as dosimeters, using the TL and OSL techniques. The dosimetric properties of the samples were analyzed by means of different tests, as: TL emission curves and OSL signal decay curves, reproducibility of TL and OSL response, minimum detectable dose, TL and OSL dose–response curves (5 Gy–10 kGy), and fading. The results obtained in this work, for the TL and OSL phenomena, demonstrated that the pellets of Opal + Teflon present an adequate performance e possibility of use as dosimeters in beams of high-dose gamma radiation.