Usability of VTL from natural quartz grains for retrospective dosimetry

Fujita, Hiroki; Hashimoto, Tetsuo*

To develop retrospective dosimetry of unexpected radiation accident, the basic studies on violet thermoluminescence (VTL) phenomena were conducted using natural quartz grains. All VTL glowcurves of as-received samples exhibited no peaks below 250 C, although there remained VTL peaks in the temperature region below 250 C for artificially irradiated quartz samples. Therefore, accident doses could be estimated without interference of naturally accumulated doses by VTL measurement from natural quartz. The mean lives of VTL were evaluated by the various heating rates method and then the range of values was between some days and ten thousands of years depending on each peak. Especially, the mean life of VTL peak at 200 C was years order. Furthermore, the lower detection limit was calculated to be tens of mGy from the response curve. This value was lower than that of other methods such as ESR dosimetry. From these results, VTL dosimetry would be preferable for accidental evaluation.