A practical method to check the heating temperature calibration of automated TL/OSL readers

The objective of this work is to demonstrate a practical method to check the temperature calibration of automated thermoluminescence (TL)/optically stimulated luminescence (OSL) readers. The method is based on the temperature dependence of the luminescence lifetime of TL/OSL materials and requires only the capability to perform pulsed OSL measurements with a time resolution of the order of milliseconds, a capability that is becoming more common in such automated systems. The method is here demonstrated using the lifetime of F-centers in Al2O3:C, which decreases in a predictable manner from its intrinsic value of 35 ms in the range from 80 °C to 220 °C. This temperature dependence was measured in various TL/OSL readers (one Risø TL/OSL reader and two lexsyg smart readers). The dependence was also tested for various heating rates, various holding durations at a fixed temperature before the lifetime measurement, various types of sample holders, and with or without N2 flow during heating. The results demonstrate that the temperature calibration can vary significantly among the various readers, with differences of up to ≈35 °C observed between readers.