Is there a common alpha-efficiency in polymineral samples measured by various infrared stimulated luminescence protocols?

Abstract

Dating of polymineral silt-sized samples by use of post-infrared infrared stimulated luminescence (pIRIR) protocols at elevated temperature has recently gained attraction due to assumed lower rates of anomalous fading. The α-efficiency (or a-value) associated with the pIRIR signals as an integral part of age calculation has, however, not yet been sufficiently constrained. Here we present a set of 65 a-values determined for 47 samples collected across Europe with two different IRSL protocols in two laboratories. By testing the basic preconditions for application of the single-aliquot regeneration (SAR) procedure to constrain a-values and by comparing SAR results to a-values obtained by multiple-aliquot protocols, we demonstrate that SAR-derived a-values are reliable for the majority of samples. While aliquot size and signal resetting mode prior to α-regeneration do not appear to affect the resulting a-value, we detected significant differences in mean a-values measured in the two laboratories. For the pIRIR290 signal, a-values average to 0.085 ± 0.010 (Bayreuth) and 0.101 ± 0.014 (Cologne), while a modified SAR protocol yields 0.081 ± 0.008 (Bayreuth). Whereas provenance-specific differences in a-values might be masked by overall scatter, systematic offsets between laboratories are attributed to technical issues such as heater and source calibration. Based on the present data set, use of the same routine dating equipment is strongly advised for both dose and a-value measurements.

Luminescence properties and dating of glacial to periglacial sediments from northern Switzerland

“…For example, for Risø calibration quartz (batch 118) TL counts peak at 87 ± 3 • C during preheat. This is in agreement with observations made by Schmidt et al (2018b), who compared the preheat behaviour of various OSL readers and discovered the appearance of the 110 • C TL peak within a range of 60 • C. This has to be considered when assessing appropriate measurement protocols (see Sect. 4).…”

Luminescence properties and dating of proglacial sediments from northern Switzerland

“…For the polymineral fractions, a-values of up to 0.10 ± 0.01 and 0.11 ± 0.01 (e.g. Rees-Jones, 1995;Lang et al, 2003, Schmidt et al, 2018a are present in the literature while a-values of between 0.05 ± 0.01 and 0.07 ± 0.02 (Preusser, 1999;Preusser et al, 2001;Gaar and Preusser, 2012;Gaar et al, 2013;Lowick et al, 2015) are commonly used for polymineral and coarse-grained feldspar in the studied region. Here, an a-value of 0.05 ± 0.01 is used.…”

Comments on Müller et al.

“…By contrast, the majority of the other articles would favour higher values. Besides, Schmidt et al (2018) presented an extended dataset of a-values (IRSL and pIRIR 290 ), though the focus was pIRIR 290 , which was not measured here.…”