Usability of VTL from natural quartz grains for retrospective dosimetry

Abstract

To develop retrospective dosimetry of unexpected radiation accident, basic studies on violet thermoluminescence (VTL) phenomena were conducted using natural quartz grains. All VTL glowcurves of as-received samples did not exhibit peaks <250 degrees C, although for artificially irradiated quartz samples there were VTL peaks in the temperature region <250 degrees C. Therefore, accident doses could be estimated without the interference of naturally accumulated doses by VTL measurements from natural quartz. The mean lives of VTL were evaluated by the various heating rates method and the range of values was found to be between some days and ten thousands of years depending on each peak. Especially, the mean life of VTL peak at 200 degrees 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, we conclude that VTL dosimetry can be preferred for accidental evaluation.

Using soils for accident dosimetry: a preliminary study using optically stimulated luminescence from quartz

“…The dose profile was also estimated by VTL measurement. No natural signals of the VTL peak at 160 • C could be found in any of the VTL measurements as suggested in a previous paper (Fujita and Hashimoto, 2007). The results confirmed that the VTL dosimetry using the peak at 160 • C could evaluate, without background effects, the dose accumulated in a site affected by an accident.…”

Retrospective dosimetry using Japanese brick quartz: A way forward despite an unstable fast decaying OSL signal

“…The MDL value is, for example, similar to that from violet TL dosimetry using quartz (Fujita and Hashimoto, 2007) and to that obtained using electron spin resonance dosimetry of saccharose (Kai et al, 1990).…”

“…The slices were gently crushed and chemically treated with 6 M HCl, 6 M NaOH and then 46% HF to extract quartz in the routine manner (e.g. Fujita and Hashimoto, 2007). From the remaining grains, coloured minerals were removed by hand picking.…”