Behaviour of LiF:Mg,Cu,P and LiF:Mg,Ti thermoluminescent detectors for electron doses up to 1 MGy

The behaviour of LiF:Mg,Cu,P and LiF:Mg,Ti detectors at ultra-high doses up to 1 MGy, has been investigated. The presence of the ultra-high-temperature peak (450 oC) of reproducible properties was observed in various batches of LiF:Mg,Cu,P, confirming earlier findings. The results indicate that this peak is not an effect of random impurities nor intrinsic effects of LiF, but it is rather connected with the doping. A parameter called ultra-high temperature ratio (UHTR) was defined in order to quantify the observed changes of LiF:Mg,Cu,P glow-curve shape at very high doses and very high temperatures. The use of this parameter allows to determine an absorbed dose in the range from 1 kGy to 1 MGy. This new method of high-dose dosimetry makes LiF:Mg,Cu,P a unique dosimeter, which is capable to cover at least 12 orders of magnitude of dose range: from a microgray to a megagray.