On the sensitivity normalization for blue stimulated luminescence of quartz

Abstract

In the single aliquot regeneration (SAR) dating method for quartz, the maximum dating limit depends on the saturation dose of sensitivity-corrected luminescence signal (L/T) and is generally found to be around ∼250 Gy. Since saturation is the restraining aspect in luminescence dating, it is important to understand the factors that influence it. This paper, investigates the blue stimulated luminescence (BSL) signals of quartz of different provenance using the multiple aliquot additive dose (MAAD) methodology. Results show that the BSL signal increases beyond the saturation limits of SAR. The early saturation in the SAR is observed primarily due to a disproportional increase in the test dose signal (T) at higher doses resulting from its dependence on the prior regeneration dose. The work further searches for normalization methods, which are independent of regeneration doses at high doses. Results show that zero glow thermo-luminescence (TL), BSL (after annealing, UV emission) and TL (after annealing, blue emission) normalization carry negligible previous dose information. These normalization signals are tested for constructing dose-response curve (DRC) using MAAD and multiple aliquot regeneration (MAR) methods. Laboratory generated DRCs are found to be best fitted with double saturating exponential with a second exponential saturation dose of 5800 ± 800 Gy. However, the scatter in the BSL, multiple aliquot data at higher doses (∼kGy) is significant and needs future investigation. The proposed methodology yields higher equivalent doses for the natural samples than SAR but still found to be lower than expected doses.