Effects of high ambient temperature on the accuracy of thermoluminescent dosimeters for environmental monitoring

Thermoluminescence dosimeters (TLDs) are widely used for both personal and environmental dosimetry. TLDs should have high accuracy under different conditions. The TL signal can drop over time because of fading (loss of signal due to thermally induced recombination of trapped charriers), thus leading to underestimation of the irradiation dose. The Saudi climate is extremely hot for most of the year, which could significantly affect TLD measurements. Therefore, the effect of ambient temperature, storage time and irradiation dose were investigated both in laboratory controlled-temperature conditions and field experiments, for two commercial dosimeters: Harshaw (TLD-100H™) and RADCARD (MCP-N™), which are used for environmental monitoring. The irradiated TLDs were exposed to a range of ambient temperatures (25 °C–65 °C) then stored for 30, 60, and 90 days. A signal fading due to increasing ambient temperature and storage time was generally observed. MCP-N shows good stability and is less responsive to increasing ambient temperature compared to TLD-100H. TLD-100H is less affected by storage time compared to MCP-N. Irradiation doses play a role in TL signal fading, and TLDs irradiated with 5 mSv have a higher rate of loss compared to those irradiated with 2 mSv in all TLD types. The obtained results permitted to conclude that all TLD types used in this study suffer from TL signal fading, and its degree varies between TLD types.