Carbonate and silicate intercomparison materials for cosmogenic 36Cl measurements

S. Mechernich*, Tibor J. Dunai, Steven A. Binnie, Tomasz Goral, Stefan Heinze, Alfred Dewald, I. Schimmelpfennig, K. Keddadouche, Georges Aumaître, Didier Bourlès, Shasta Marrero, K. Wilcken, Krista Simon, D. Fink, Fred M. Phillips, Marc W. Caffee, Laura C. Gregory, Richard Phillips, Stewart P.H.T. Freeman, Richard ShanksM. Akif Sarıkaya, Stefan Pavetich, G. Rugel, S. Merchel, Naki Akçar, Serdar Yesilyurt, S. Ivy-Ochs, Christof Vockenhuber

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

12 Citations (Scopus)

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.

Original languageEnglish
Pages (from-to)250-259
Number of pages10
JournalNuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms
Volume455
DOIs
Publication statusPublished - 15 Sept 2019

Bibliographical note

Publisher Copyright:
© 2019

Funding

We thank Valéry Guillou (CEREGE, Aix en Provence, France), Bradley Sion (New Mexico Tech, USA), Veronica Prush (University of California, Davis, USA) for the sample preparation and data reductions, and Lucilla Benedetti (CEREGE, Aix en Provence, France) for discussions. Tibor Dunai thanks Finlay Stuart for good company and help during the collection of the materials. The ASTER AMS national facility (CEREGE, Aix en Provence) is supported by the INSU/CNRS, the ANR through the “Projets thématiques d'excellence” program for the “Equipements d'excellence” ASTER-CEREGE action and IRD. The grateful support of the University of Cologne in the framework of the emerging group “Uldetis” and the financial support of the German research foundation (DFG, ME 4212/3-1) made this laboratory comparison possible. Finally we appreciate the editorial handling of the manuscript by Ian Clark and Liam Kieser and the helpful comments of two anonymous reviewers. We thank Valéry Guillou ( CEREGE , Aix en Provence, France), Bradley Sion ( New Mexico Tech , USA), Veronica Prush ( University of California , Davis, USA) for the sample preparation and data reductions, and Lucilla Benedetti (CEREGE, Aix en Provence, France) for discussions. Tibor Dunai thanks Finlay Stuart for good company and help during the collection of the materials. The ASTER AMS national facility (CEREGE, Aix en Provence) is supported by the INSU/CNRS, the ANR through the “Projets thématiques d’excellence” program for the “Equipements d’excellence” ASTER-CEREGE action and IRD. The grateful support of the University of Cologne in the framework of the emerging group “Uldetis” and the financial support of the German research foundation (DFG, ME 4212/3-1) made this laboratory comparison possible. Finally we appreciate the editorial handling of the manuscript by Ian Clark and Liam Kieser and the helpful comments of two anonymous reviewers.

FundersFunder number
CEREGE, Aix en Provence
INSU
Lucilla Benedetti
Valéry Guillou
University of California
University of California, Davis
Natural Environment Research CouncilNE/M019020/1, NE/T009462/1, NE/I02318X/1, come30001
Deutsche ForschungsgemeinschaftME 4212/3-1
Agence Nationale de la Recherche
Centre National de la Recherche Scientifique
Universität zu Köln

    Keywords

    • Accelerator mass spectrometry
    • Consensus values
    • Intercomparison material (ICM)
    • Round robin
    • Terrestrial cosmogenic nuclides (TCN)

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