Evaluation of TL and OSL responses of recycled crab shell biowaste for radiation dosimetry

Abstract

The aim of this work was to evaluate the applicability of crab shell biowaste composites as thermoluminescent (TL) and optically stimulated luminescent (OSL) detectors, since recent researchers have found it to be a valuable intrinsic luminescent material. The waste of crabs shells (Ucides cordatus) species was taken from a bar located at Atalaia beach in Aracaju city, Sergipe State, Brazil, and calcined at 800 °C for 2 h. The calcined crab shell powder was mixed with Teflon (2:1 mass ratio) and molded in pellets of 6 mm diameter and 1 mm thickness. The pellets were sintered at 400 ºC for 1 h. The luminescent and dosimetric characterization of the crab shell composites were performed using a TL/OSL Risø Reader, model DA-20. The crab shell composites showed TL signals between 100°C and 400°C, with an intense peak around 155°C and a less intense peak around 350°C. The first peak, although at a relative low temperature, can be used as a dosimetric peak, due to its high intensity and acceptable fading (12% after 7 days). The OSL signal of the samples was very intense and with a very fast decay, which means that the luminescent centers are easily optically stimulated by the reader blue LEDs. The emission spectra of the samples showed a broad emission from 300 nm to 400 nm. All samples produced showed variation coefficients for homogeneity and reproducibility below 9.5%, in addition to a linear response in the dose range used (80 mGy to 1 Gy) and minimum detectable doses of the order of miligrays. Evaluating the dosimetric applicability, the crab shell composites presented potential application as TL/OSL detectors in processes that employ ionizing radiation such as beta particles, X and gamma rays.