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  • 2010-2014  (5)
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  • 1
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    Update on the Performance of the SUERC In Situ Cosmogenic 14C Extraction Line (2010)
    Cambridge University Press
    Details
    Publication Date: 2010-01-01
    Description: In this paper, we describe improvements to the in situ cosmogenic radiocarbon extraction system at SUERC made since 2004, highlighting the factors that potentially control the reduction of analytical variability. We also present new results on system blanks and of measurements of in situ14C in shielded quartz and a surface quartz sample used at the University of Arizona as an in situ14C standard (PP-4). The SUERC in situ14C extraction system was built in 2001 and is based on a combustion technique following the design of the extraction system at the University of Arizona. Our preliminary results suggest that the continuous running of the extraction system and the monitoring of gas collecting time and of the temperature of the cryogenic traps used in the gas cleaning steps are key to maintaining low and stable system blanks. Our latest average system blank is 2.02 ± 0.23 x 10514C atoms. This is consistent with those recently published by the University of Arizona and ETH in situ14C labs. Measurements of in situ14C concentrations in sample PP-4 yield an average of 3.82 ± 0.23 x 105 atoms g–1 quartz, again consistent with published values.
    Print ISSN: 0033-8222
    Electronic ISSN: 1945-5755
    Topics: Archaeology , Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Published by Cambridge University Press
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  • 2
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    High-Precision Radiocarbon Dating of the Construction Phase of Oakbank Crannog, Loch Tay, Perthshire (2010)
    Cambridge University Press
    Details
    Publication Date: 2010-01-01
    Description: Many of the Loch Tay crannogs were built in the Early Iron Age and so calibration of the radiocarbon ages produces very broad calendar age ranges due to the well-documented Hallstatt plateau in the calibration curve. However, the large oak timbers that were used in the construction of some of the crannogs potentially provide a means of improving the precision of the dating through subdividing them into decadal or subdecadal increments, dating them to high precision and wiggle-matching the resulting data to the master 14C calibration curve. We obtained a sample from 1 oak timber from Oakbank Crannog comprising 70 rings (Sample OB06 WMS 1, T103) including sapwood that was complete to the bark edge. The timber is situated on the northeast edge of the main living area of the crannog and as a large and strong oak pile would have been a useful support in more than 1 phase of occupation and may be related to the earliest construction phase of the site. This was sectioned into 5-yr increments and dated to a precision of approximately ±8–16 14C yr (1 σ). The wiggle-match predicts that the last ring dated was formed around 500 BC (maximum range of 520–465 BC) and should be taken as indicative of the likely time of construction of Oakbank Crannog. This is a considerable improvement on the estimates based on single 14C ages made on oak samples, which typically encompassed the period from around 800–400 BC.
    Print ISSN: 0033-8222
    Electronic ISSN: 1945-5755
    Topics: Archaeology , Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Published by Cambridge University Press
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  • 3
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    Assessment of Infinite-Age Bones from the Upper Thames Valley, UK, as 14C Background Standards (2012)
    Cambridge University Press
    Details
    Publication Date: 2012-01-01
    Description: It is becoming increasingly clear that in order to generate accurate radiocarbon dates for bone collagen samples it is important to determine a sample-specific background correction to account for the greater complexity and higher number of steps in the pretreatment chemistry of this material. To provide suitable samples for the 14C community, 7 bone samples were obtained from contexts within British gravel quarries, which according to other dating techniques or stratigraphic information, should be of infinite age with respect to 14C. The bones were analyzed at the Oxford Radiocarbon Accelerator Unit (ORAU) and the Scottish Universities Environmental Research Centre (SUERC) to determine their suitability. In this paper, we show that 6 of the samples were indistinguishable from background. Both institutions measured finite ages for sample 387 from Oxey Mead that were statistically indistinguishable. Further work is required to establish whether this is because the bone was intrusive and of a younger age than expected or whether it is contaminated either postdepositionally or in the laboratory. We favor the former explanation because (1) the 2 chemistry laboratories use very different pretreatment schemes, (2) collagen yields were high, and (3) the laboratories produced ages that are in good agreement. The 6 “greater than” age samples will be made available to 14C laboratories to be used as background standards.
    Print ISSN: 0033-8222
    Electronic ISSN: 1945-5755
    Topics: Archaeology , Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Published by Cambridge University Press
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  • 4
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    14C AMS at Suerc: Improving QA Data with the 5MV Tandem and 250KV SSAMS (2010)
    Cambridge University Press
    Details
    Publication Date: 2010-01-01
    Description: In 2003, a National Electrostatics Corporation (NEC) 5MV tandem accelerator mass spectrometer was installed at SUERC, providing the radiocarbon laboratory with 14C measurements to 4–5‰ repeatability. In 2007, a 250kV single-stage accelerator mass spectrometer (SSAMS) was added to provide additional 14C capability and is now the preferred system for 14C analysis. Changes to the technology and to our operations are evident in our copious quality assurance data: typically, we now use the 134-position MC-SNICS source, which is filled to capacity. Measurement of standards shows that spectrometer running without the complication of on-line δ13C evaluation is a good operational compromise. Currently, 3‰ 14C/13C measurements are routinely achieved for samples up to nearly 3 half-lives old by consistent sample preparation and an automated data acquisition algorithm with sample random access for measurement repeats. Background and known-age standard data are presented for the period 2003–2008 for the 5MV system and 2007–2008 for the SSAMS, to demonstrate the improvements in data quality.
    Print ISSN: 0033-8222
    Electronic ISSN: 1945-5755
    Topics: Archaeology , Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Published by Cambridge University Press
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  • 5
    facet.materialart.
    Unknown
    Assessment of Infinite-Age Bones from the Upper Thames Valley, UK, as 14C Background Standards (2012)
    Cambridge University Press
    Details
    Publication Date: 2012-01-01
    Description: It is becoming increasingly clear that in order to generate accurate radiocarbon dates for bone collagen samples it is important to determine a sample-specific background correction to account for the greater complexity and higher number of steps in the pretreatment chemistry of this material. To provide suitable samples for the14C community, 7 bone samples were obtained from contexts within British gravel quarries, which according to other dating techniques or stratigraphic information, should be of infinite age with respect to14C. The bones were analyzed at the Oxford Radiocarbon Accelerator Unit (ORAU) and the Scottish Universities Environmental Research Centre (SUERC) to determine their suitability. In this paper, we show that 6 of the samples were indistinguishable from background. Both institutions measured finite ages for sample 387 from Oxey Mead that were statistically indistinguishable. Further work is required to establish whether this is because the bone was intrusive and of a younger age than expected or whether it is contaminated either postdepositionally or in the laboratory. We favor the former explanation because (1) the 2 chemistry laboratories use very different pretreatment schemes, (2) collagen yields were high, and (3) the laboratories produced ages that are in good agreement. The 6 “greater than” age samples will be made available to14C laboratories to be used as background standards.
    Print ISSN: 0033-8222
    Electronic ISSN: 1945-5755
    Topics: Archaeology , Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Published by Cambridge University Press
    Location Call Number Expected Availability
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    PAPER CURRENT
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