Hostname: page-component-cd9895bd7-jkksz Total loading time: 0 Render date: 2024-12-26T07:37:01.714Z Has data issue: false hasContentIssue false
  • English
  • Français

Towards High-Precision AMS: Progress and Limitations

Published online by Cambridge University Press:  18 July 2016

Christopher Bronk Ramsey ,
Thomas Higham  and
Philip Leach
Christopher Bronk Ramsey*
Affiliation:
Oxford Radiocarbon Accelerator Unit, University of Oxford, United Kingdom.
Thomas Higham
Affiliation:
Oxford Radiocarbon Accelerator Unit, University of Oxford, United Kingdom.
Philip Leach
Affiliation:
Oxford Radiocarbon Accelerator Unit, University of Oxford, United Kingdom.
*
Corresponding author. Email: christopher.ramsey@archaeology-research.oxford.ac.uk.
Rights & Permissions [Opens in a new window]

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

Precision and accuracy in accelerator mass spectrometry (AMS) dating relies on the systematic reduction of errors at all stages of the dating process, from sampling to AMS measurement. With new AMS systems providing much better precision and accuracy for the final stage of the process, we need to review the process as a whole to test the accuracy of reported results. A new High Voltage Engineering Europa (HVEE) AMS system was accepted at Oxford in September 2002. Since then, the system has been in routine use for AMS dating and here we report on our experiences during the first year. The AMS system itself is known to be capable of making measurements on single targets to a precision of better than 0.2% for the 14C/13C ratio and better than 0.1% for the 13C/12C ratio. In routine operation, we measure known-age wood to a precision of just above 0.3%, including uncertainties in background and pretreatment. At these levels, the scatter in results is no higher than reported errors, suggesting that uncertainties of ±25 to ±30 14C yr can be reliably reported on single target measurements. This provides a test of all parts of the process for a particular material in a particular state of preservation. More generally, sample pretreatment should remove as much contamination as feasible from the sample while adding as little laboratory contamination as possible. For more complex materials, such as bone, there is clearly more work needed to prove good reproducibility and insignificant offsets in all circumstances. Strategies for testing accuracy and precision on unknown material are discussed here, as well as the possibilities of one day reaching precisions equivalent to errors of <±20 14C yr.

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. 17 - 24
Copyright
Copyright © 2004 by the Arizona Board of Regents on behalf of the University of Arizona 

References

Bayliss, A. 2000. On the taphonomy of charcoal samples for radiocarbon dating. In: Acte du colloque “C14 and Archaeology.” Revue d'Archéometrie. 1998. GMCPA. p 51–6.Google Scholar
Bonsall, C, Cook, GT, Hedges, REM, Higham, TFG, Pickard, C, Radovanovic, I. 2004. Radiocarbon and stable isotope evidence of dietary change from the Mesolithic to the Middle Ages in the Iron Gates: new results from Lepenski Vir. Radiocarbon , these proceedings.CrossRefGoogle Scholar
Bronk Ramsey, C, Hedges, REM, Mous, D, Gottdang, A, van den Broek, R. 2002. Status of the new AMS at Oxford. Talk given at the 9th AMS Conference, Nagoya, Japan, September 2002.Google Scholar
Bronk Ramsey, C, Higham, TFG, Bowles, A, Hedges, REM. 2004. Improvements to the pretreatment of bone at Oxford. Radiocarbon , these proceedings.CrossRefGoogle Scholar
Bryant, C, Carmi, I, Cook, GT, Gulliksen, S, Harkness, DD, Heinemeier, J, McGee, E, Naysmith, P, Possnert, G, Scott, EM, van der Plicht, J, van Strydonck, M. 2001. Is comparability of 14C dates an issue?: A status report on the Fourth International Radiocarbon Intercomparison. Radiocarbon 43(2A):321–4.Google Scholar
Cook, GT, Bonsall, C, Hedges, REM, McSweeney, K, Boroneant, V, Pettitt, PB. 2001. A freshwater diet-derived 14C reservoir effect at the Stone Age sites in the Iron Gates gorge. Radiocarbon 43(2A):453–60.CrossRefGoogle Scholar
Galimberti, M, Bronk Ramsey, C, Manning, SW. 2004. Wiggle-match dating of tree-ring sequences. Radiocarbon , these proceedings.Google Scholar
Gottdang, A, Klein, M, Mous, DJW. 2001. Accelerator mass spectrometry at High Voltage Engineering Europa (HVEE). Radiocarbon 43(2A):149–56.CrossRefGoogle Scholar
Hedges, REM, Law, IA, Bronk, CR, Housley, RA. 1989. The Oxford accelerator mass spectrometry facility: technical developments in routine dating. Archaeometry 31:99–113.CrossRefGoogle Scholar
Kalin, RM, McCormac, FG, Damon, PE, Eastoe, CJ, Long, A. 1995. Intercomparison of high-precision 14C measurements at the University of Arizona and the Queen's University of Belfast Radiocarbon Laboratories. Radiocarbon 37(1):33–8.Google Scholar
McCormac, FG. 1992. Liquid scintillation counter characterization, optimization and benzene purity correction. Radiocarbon 34(1):37–45.Google Scholar
Pearson, GW. 1979. Precise 14C measurement by LS counting. Radiocarbon 21(1):1–22.CrossRefGoogle Scholar
Stuiver, M, Reimer, PJ, Bard, E, Beck, JW, Burr, GS, Hughen, KA, Kromer, B, McCormac, FG, van der Plicht, J, Spurk, M. 1998. INTCAL98 radiocarbon age calibration, 24,000–0 cal AD. Radiocarbon 40(3):1041–83.CrossRefGoogle Scholar
van Strydonck, M, Nelson, DE, Crombé, P, Bronk Ramsey, C, Scott, EM, van der Plicht, J, Hedges, REM. 2000. Rapport du groupe de travail: les limites de methode du carbone 14 applicquée a l'archéologie, What's in a 14C date? In: Acte du colloque “C14 and Archaeology.” Revue d'Archéometrie. 1998. GMCPA. p 433–48.Google Scholar