Advantages and Disadvantages in the Utilisation of Thermoluminescence (tl) and Optically Stimulated Luminescence (osl) for Radiation Dosimetry

Thermoluminescence is an established method for radiation dosimetry as well as retrospective dosimetry. In spite of its great success, different difficulties are associated with its application. These include anomalous fading, changes in the properties of the sample due to its heating in the readout phase, including a sensitization due to the combined effect of irradiation and heating and non-linear dose dependence observed in some potential dosimetric materials. Another point is that once the sample is heated during the read-out, the TL signal is erased; this is of help for re-use of the sample, but prevents a repeated reading of the measured quantity. The alternative of using optically stimulated luminescence has become very popular in recent years. Here, the ill effects associated with the heating of the sample are avoided. Also, the possibility of reading out the sample several times exists. This can be done by using short pulses of stimulating light, which deplete only a small part of the trapped charge carriers. The present work points out some difficulties that may take place with OSL. These include a possible superlinearity in the dose dependence as well as dose-rate dependence. Also is discussed the difference between pulsed and integral OSL signals.