Thermal quenching and two peak method - Influences of heating rates in TLDs

The two peak method remains a fascinating tool for simultaneous estimation of doses of low and high LET radiations in mixed field dosimetry. In order to improve the dosimetnic capability of the two peak method, the influence of heating rate on the response of thermoluminescence (TL) glow peaks occurring at different temperatures in a material was evaluated. The ratio of the responses of the 200 degrees C peak and a combined peak at 260-315 degrees C in LiF TLD-700 was found to change by more than 50% with the change in heating rate from 1 degrees C.s(-1) to 50 degrees C.s(-1). The ratio of responses of the glow peak at 150 degrees C and a combined peak at 240-260 degrees C in CaF2:Tm TLD-300 did not show significant change. This adds to the superiority of CaF2:Tm for use in the two peak method. A glow peak at 300 degrees C in Al2O3:C did not exhibit more reduction in response than that of its peak at 180 degrees C. The insensitivity of the 240-260 degrees C glow peak in CaF2:Tm to the heating rate (in contrast to the known behaviour of the 250 degrees C glow peak in CaF2:Mn), the similarity in behaviour of the response of the 200 degrees C peak in LIF TLD-700 and LiF:Mg,Cu,P TLDs to varying heating rates, and the reduction in responses of the 180 degrees C and 300 degrees C peaks in Al2O3:C emphasise the importance of studying the influence of heating rate and thermal quenching in TLDs.