Evaluation of the modified single-aliquot regenerative-dose procedure for equivalent dose determination

Abstract

A common optically stimulated luminescence (OSL) method for dating sediments is the single-aliquot regenerative-dose (SAR) protocol, which is widely applied to measure the equivalent dose (De) in various sedimentary samples. The modified SAR protocol is distinguished from the conventional SAR protocol by the application of additional high-temperature (e.g. 280 °C) optical stimulation at the end of the procedure. In this study, we performed a dose recovery test using fine-grained (4–11 μm) quartz sample derived from coastal sediments and found that the De values recovered using the modified SAR protocol were significantly overestimated by ∼30% compared with the given dose, except for a preheating temperature of 160 °C. In contrast, De values recovered using the conventional SAR protocol showed good agreement with the given dose (within ±10%) over a large preheating temperature range (160–260 °C). Differences in the dose-response curves between the conventional and modified SAR protocols may have led to the overestimation of De values recovered using the latter approach. The lack of proportionality between Lx and Tx in the modified SAR protocol complicated the construction of the SAR dose-response curve and dose recovery. To avoid these phenomena, which may be highly sample dependent, modified SAR for OSL dating should be applied only to samples dominated by the slow OSL component and with high recuperation levels.