Thermal behaviour of a LiF crystal mounted in a TLD card and heated by jet impingement

A numerical model is developed to predict the actual temperature profile evolution in a crystal contained in a TLD card that is used in advanced gas heating TLD reader systems. The flow field above the detector and the resulting heat transfer to and within the crystal are obtained directly, and no empirical constants or adjustment parameters are used. It is found that the typical time lag between the crystal temperature and the jet temperature is about 5 s, for the heating rate of 25 K/s. The calculated temperature profile is substituted into a first-order kinetic model equation (Randall–Wilkins) to obtain the glow curve, and the results are compared to experimental findings. It is shown that the location of the peaks resulting from the calculated temperature profile overlaps those of the experimental results. Thus, calibration is conducted only to match the intensity of the TL peaks.