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Towards Achieving Low Background Levels in Routine Dating by Liquid Scintillation Spectrometry

Published online by Cambridge University Press:  18 July 2016

Alan G Hogg
Alan G Hogg*
Affiliation:
Waikato Radiocarbon Dating Laboratory, University of Waikato, Private Bag 3105, Hamilton, New Zealand. Email: alan.hogg@waikato.ac.nz.
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Abstract

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International radiocarbon intercalibration studies have revealed that radiometric laboratories using liquid scintillation (LS) spectrometry of benzene reported, on average, younger ages for near-background standards than either gas proportional counter (GPC) or accelerator mass spectrometry (AMS) laboratories. These studies suggested that the younger LS ages are probably related to the use of spectrophotometric benzene as a background standard. An analysis of successive 110-ka subfossil wood (Airedale Reef Ancient Wood: ARAW) standards shows that vacuum line memory effects occur in LS spectrometry and, consequently, must be corrected to obtain accurate 14C dates. ARAW standards, measured at monthly intervals in the Waikato laboratory, are used to provide blank corrections for both research and routine dating applications. The strong correlation between the ARAW δ14C data and the sample activities that preceded the standards may provide an opportunity to obtain sample-specific blank corrections. Lithium carbide synthesis is likely to prove a source of contamination. This work suggests that reproducible background levels for routine dating of less than 0.1 pMC (55 ka 14C yr) are achievable.

Type
Articles
Information
Radiocarbon , Volume 46 , Issue 1: Proceedings of the 18th International Radiocarbon Conference (Part 1 of 2), Conference Editors: Nancy Beavan Athfield, Rodger J Sparks , 2004 , pp. 123 - 131
Copyright
Copyright © 2004 by the Arizona Board of Regents on behalf of the University of Arizona 

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