Mechernich, S, Dunai, TJ, Binnie, SA et al. (25 more authors) (2019) Carbonate and silicate intercomparison materials for cosmogenic ³⁶Cl measurements. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 455. pp. 250-259. ISSN 0168-583X
Abstract
Two natural mineral separates, labeled CoCal-N and CoFsp-N, have been prepared to serve as intercomparison material (ICM) for in situ-produced cosmogenic ³⁶Cl and natural chlorine (Clnat) analysis. The sample CoCal-N is derived from calcite crystals in a Namibian lag deposit, while the sample CoFsp-N is derived from a single crystal of alkali-feldspar from a Namibian pegmatite. The sample preparation took place at the University of Cologne and a rotating splitter was used to obtain homogeneous splits of both ICMs. Forty-five measurements of CoCal-N (between 1 and 16 per facility) and forty-four measurements of CoFsp-N (between 2 and 20 per facility) have been undertaken by ten target preparation laboratories measured by seven different AMS facilities. The internal laboratory scatter of the ³⁶Cl concentrations indicates no overdispersion for half of the laboratories and 3.9 to 7.3% (1σ) overdispersion for the others. We show that the CoCal-N and CoFsp-N splits are homogeneous regarding their ³⁶Cl and Clnat concentrations. The grand average (average calculated from the average of each laboratory) yields initial consensus ³⁶Cl concentrations of (3.74 ± 0.10) × 10⁶ at ³⁶Cl/g (CoCal-N) and (2.93 ± 0.07) × 10⁶ at ³⁶Cl/g (CoFsp-N) at 95% confidence intervals. The coefficient of variation is 5.1% and 4.2% for CoCal-N and CoFsp-N, respectively. The Clnat concentration corresponds to the lower and intermediate range of typical rock samples with (0.73 ± 0.18) µg/g in CoCal-N and (73.9 ± 6.8) µg/g in CoFsp-N. We discuss the most relevant points of the sample preparation and measurement and the chlorine concentration calculation to further approach inter-laboratory comparability. We propose to use continuous measurements of the ICMs to provide a valuable quality control for future determination of ³⁶Cl and Clnat concentrations.
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Copyright, Publisher and Additional Information: | © 2019 Published by Elsevier B.V. This is an author produced version of a paper published in Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms. Uploaded in accordance with the publisher's self-archiving policy. | ||||||
Keywords: | Accelerator mass spectrometry; Terrestrial cosmogenic nuclides (TCN); Round robin; Intercomparison material (ICM); Consensus values | ||||||
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Institution: | The University of Leeds | ||||||
Academic Units: | The University of Leeds > Faculty of Environment (Leeds) > School of Earth and Environment (Leeds) > Inst of Geophysics and Tectonics (IGT) (Leeds) | ||||||
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Depositing User: | Symplectic Publications | ||||||
Date Deposited: | 12 Feb 2019 16:20 | ||||||
Last Modified: | 30 Jan 2020 01:39 | ||||||
Status: | Published | ||||||
Publisher: | Elsevier | ||||||
Identification Number: | https://doi.org/10.1016/j.nimb.2019.01.024 |
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Filename: NIMB_36Cl-ICM_CoCal+CoFsp_revised_changes-accepted.pdf
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