Thermoluminescence and optically stimulated luminescence dosimetry with NaCl detectors made at different sintering temperatures

Salt (NaCl) is well known as a thermoluminescence (TL) and optically stimulated luminescence (OSL) phosphor that has potential for emergency dosimetry. Using grains of Alpine salt with iodine (Saline Reichenhall, Germany) purchased in a local grocery, detectors in the form of pellets were made. Some of them were sintered at temperatures of 400, 500 and 600 °C. TL and OSL dosimetry characteristics as sensitivity, sensitization, minimum detectable dose (MDD), dose response, energy response and fading were investigated for both the sintered and unsintered detectors. While sintering improved the potential of the detectors for TL dosimetry, the opposite was true for OSL dosimetry. For the sintered detectors, a distinct high-temperature stable TL peak was observed. However, due to its strong sensitization and dose response, the use of the Single-Aliquot Regenerative-dose (SAR) protocol is required for dose reconstruction. The dose response of the OSL signal of sintered detectors already showed saturation for doses in the order of tens of mGy, which excluded them from use for emergency dosimetry. In contrast, the OSL signal of unsintered detectors was distinguished by moderate sensitization and dose response allowing for the use of a simple analytical protocol. MDD values obtained for all the groups of detectors were less than 0.1 mGy. Both the TL and OSL signals monitored within 3 months after irradiation exhibited inverse fading. The energy response suggests that the detectors are suitable for applications in high-energy gamma radiation environment (>200 keV), especially if they are not part of a complex dosemeter with an appropriate filtration and algorithm. The comparison of the obtained characteristics of the investigated groups of salt detectors shows that the needs and requirements of emergency dosimetry are best met by the unsintered OSL detectors.