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Bartz M, Arnold LJ, Spooner NA, Demuro M, Campaña I, Rixhon G, Brückner H, Duval M. First experimental evaluation of the alpha efficiency in coarse-grained quartz for ESR dating purposes: implications for dose rate evaluation. Sci Rep 2019; 9:19769. [PMID: 31874956 PMCID: PMC6930274 DOI: 10.1038/s41598-019-54688-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Accepted: 11/09/2019] [Indexed: 11/14/2022] Open
Abstract
We present the first experimental evaluation of the alpha efficiency value for electron spin resonance (ESR) dating of coarse quartz grains, which is used for the evaluation of the internal and external alpha dose rate components. Based on our results, we recommend the use of an a-value of 0.07 ± 0.01 (1σ) for both the Al and Ti centres. Although we acknowledge that quartz ESR alpha efficiency may be sample dependent, and could also be impacted by other sources of uncertainty, this potential variability is presently impossible to evaluate given the absence of other experimental a-values available in the ESR dating literature. Measured radioactivity of quartz grains from the Moulouya catchment (NE Morocco) provides an internal dose rate in the range of 50–70 µGy/a when using an a-value of 0.07. The use of this empirically derived a-value for the evaluation of the internal and external alpha dose rate has a limited overall impact on the final ESR age results: they change by <2% and <3%, respectively, in comparison with those obtained with an assumed a-value. However, the large variability observed among the broader sample dataset for quartz internal radioactivity and hydrofluoric acid (HF) etching rates underscores the potential importance of undertaking experimental evaluations of alpha dose rate parameters for each dated sample.
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Affiliation(s)
- Melanie Bartz
- Institute of Geography, University of Cologne, Albertus-Magnus-Platz, 50923, Cologne, Germany.
| | - Lee J Arnold
- School of Physical Sciences, Environment Institute, and Institute for Photonics and Advanced Sensing (IPAS), University of Adelaide, North Terrace Campus, Adelaide, SA, 5005, Australia
| | - Nigel A Spooner
- School of Physical Sciences, Environment Institute, and Institute for Photonics and Advanced Sensing (IPAS), University of Adelaide, North Terrace Campus, Adelaide, SA, 5005, Australia.,Defence Science and Technology Group, Third Avenue, Edinburgh, SA, 5111, Australia
| | - Martina Demuro
- School of Physical Sciences, Environment Institute, and Institute for Photonics and Advanced Sensing (IPAS), University of Adelaide, North Terrace Campus, Adelaide, SA, 5005, Australia
| | - Isidoro Campaña
- Centro Nacional de Investigación sobre la Evolución Humana (CENIEH), Paseo Sierra de Atapuerca, 3, 09002, Burgos, Spain
| | - Gilles Rixhon
- ENGEES/Laboratoire Image Ville Environnement (LIVE), UMR 7362 - CNRS (University of Strasbourg), Quai Koch 1, 67000, Strasbourg, France
| | - Helmut Brückner
- Institute of Geography, University of Cologne, Albertus-Magnus-Platz, 50923, Cologne, Germany
| | - Mathieu Duval
- Centro Nacional de Investigación sobre la Evolución Humana (CENIEH), Paseo Sierra de Atapuerca, 3, 09002, Burgos, Spain.,Australian Research Centre for Human Evolution (ARCHE), Environmental Futures Research Institute (EFRI), Griffith University, 170 Kessels Road, Nathan, QLD 4111, Australia
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