Progress in Radiocarbon Target Preparation at the Antares AMS Centre

Hua, Quan; Jacobsen, Geraldine; Zoppi, Ugo; Lawson, Ewan; Williams, Alan; Smith, A. M.; McGann, M J

doi:10.1017/s003382220003811x

Cited by 264 publications

(189 citation statements)

References 15 publications

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“…The graphite was then rear-pressed in an aluminium cathode for AMS measurement. For a more detailed description of these methods refer to Hua et al (2001). It should be noted that radiocarbon ages of carbonate powders may be affected by surface contamination with modern atmospheric CO 2 .…”

Section: C Measurementsmentioning

confidence: 99%

Hydrological control of the dead carbon fraction in a Holocene tropical speleothem

Griffiths

Fohlmeister

Drysdale

et al. 2012

Quaternary Geochronology

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a b s t r a c tOver the past decade, a number of speleothem studies have used radiocarbon ( 14 C) to address a range of palaeoclimate problems. These have included the use of the bomb pulse 14 C to anchor chronologies over the last 60 years, the combination of U-Th and 14 C measurements to improve the radiocarbon agecalibration curve, and linking atmospheric 14 C variations with climate change. An issue with a number of these studies is how to constrain, or interpret, variations in the amount of radioactively dead carbon (i.e. the dead carbon fraction, or DCF) that reduces radiocarbon concentrations in speleothems. In this study, we use 14 C, stable-isotopes, and trace-elements in a U-Th dated speleothem from Flores, Indonesia, to examine DCF variations and their relationship with above-cave climate over the late Holocene and modern era. A strong association between the DCF and hydrologically-controlled proxy data suggests that more dead carbon was being delivered to the speleothem during periods of higher cave recharge (i.e. lower d 18 O, d 13 C and Mg/Ca values), and hence stronger summer monsoon. To explore this relationship, we used a geochemical soil-karst model coupled with 14 C measurements through the bomb pulse to disentangle the dominant components governing DCF variability in the speleothem. We find that the DCF is primarily controlled by limestone dissolution associated with changes in open-versus closed-system conditions, rather than kinetic fractionation and/or variations in the age spectrum of soil organic matter above the cave. Therefore, we infer that periods of higher rainfall resulted in a higher DCF because the system was in a more closed state, which inhibited carbon isotope exchange between the karst water dissolved inorganic carbon and soil-gas CO 2 , and ultimately led to a greater contribution of dead carbon from the bedrock.Published by Elsevier B.V.

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Section: C Measurementsmentioning

confidence: 99%

Hydrological control of the dead carbon fraction in a Holocene tropical speleothem

Griffiths

Fohlmeister

Drysdale

et al. 2012

Quaternary Geochronology

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“…Finally, the graphite was loaded into an aluminium sample holder ready for the AMS measurement. The technical details of these methods are described in Hua et al (2001).…”

Section: Technical Data: Preparation and Processingmentioning

confidence: 99%

The End of the Chalcolithic Period in the South Jordan Valley: New ¹⁴C Determinations from Teleilat Ghassul, Jordan

et al. 2004

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This article reports on 12 new accelerator mass spectrometry (AMS) dates from the latest phases of the Chalcolithic period occupation (late 5th millennium cal BC) at Teleilat Ghassul, type site for the south Levantine Ghassulian Chalcolithic culture. The new AMS dates from Teleilat Ghassul favor an amendment to a previous suggestion (Bourke et al. 2001), that all significant occupation at the site had ceased by 4000/3900 cal BC. This end-date should now be amended to 3900/3800 cal BC. Follow-up statistical modelling sourced to published 14C data drawn from a wide selection of south Levantine Chalcolithic period sites (Bourke 2001; Burton and Levy 2001) raises the possibility that Chalcolithic period occupation had ceased at virtually all major centers by 3800/3700 cal BC. This, in turn, suggests that the new data bearing on the end-date for occupation at Teleilat Ghassul may reflect a more widespread horizon of abandonment in the southern Levant.

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“…Reaction tubes undergo an entire cycle of combustion at 920 °C for 6.5 hr in open air. This procedure (Vandeputte et al 1996) decreases the 14 C background, burning out a fraction of carbon potentially present on the quartz and copper oxide original materials (Hua et al 2001). An amount of sample able to ensure about 2 mg of carbon (depending on its C concentration) is weighed directly into the pretreated reaction tubes with clean iron spatulas.…”

Section: Sample Combustionmentioning

confidence: 99%

“…The timer-controlled muffle furnace can hold 2 bricks of 32 samples, allowing the combustion of 64 samples a day. After combustion overnight and after the temperature of the samples decreases (about 4 hr after the end of combustion; Hua et al 2001), samples are iden tified via a grid engraved on the upper face of each brick. …”

Section: Sample Combustionmentioning

confidence: 99%

“…High degrees of reproducibility for the graphite production ensure the feasibility of high-precision AMS (σ = 0.3%) (Steier et al 2004) while stabilizing current yields and isotopic fractionation of the targets. A systematic study of contamination sources and iso topic fractionation phenomena and their relationships with the imposed treatment conditions can lead to an improvement of the AMS technique precision and sensitivity (Hua et al 2001). Usually, most of the contamination during sample treatment is due to the C0 2 gas production, handling (Step 2), and reduction (Step 3) (Aerts-Bijma et al 1997).…”

Section: Introductionmentioning

confidence: 99%

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Zinc Reduction as an Alternative Method for AMS Radiocarbon Dating: Process Optimization at Circe

Marzaioli¹,

Borriello²,

Passariello³

et al. 2008

Radiocarbon

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ABSTRACT. The pretreatment of samples for radiocarbon measurements, transforming a variety of materials into graphite solid targets, represents a critical point in the accelerator mass spectrometry (AMS) procedure. We describe the new, state-ofthe-art CIRCE AMS preparation laboratory, particularly the setup and optimization of an alternative method, the zinc reduc tion method, for graphite target production, compared to the more common hydrogen reduction method. Measured ,4 C values on standard and blank samples reduced via zinc reaction revealed mean background levels, accuracy, and sensitivity compa rable to those obtained by our conventional hydrogen reaction lines. Zinc line reduction at the CIRCE laboratory represents an effective and powerful alternative to the conventional hydrogen reduction, ensuring higher sample throughput with lower costs at a comparable performance level.

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Progress in Radiocarbon Target Preparation at the Antares AMS Centre

Cited by 264 publications

References 15 publications

Hydrological control of the dead carbon fraction in a Holocene tropical speleothem

Hydrological control of the dead carbon fraction in a Holocene tropical speleothem

The End of the Chalcolithic Period in the South Jordan Valley: New ¹⁴C Determinations from Teleilat Ghassul, Jordan

Zinc Reduction as an Alternative Method for AMS Radiocarbon Dating: Process Optimization at Circe

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Progress in Radiocarbon Target Preparation at the Antares AMS Centre

Cited by 264 publications

References 15 publications

Hydrological control of the dead carbon fraction in a Holocene tropical speleothem

Hydrological control of the dead carbon fraction in a Holocene tropical speleothem

The End of the Chalcolithic Period in the South Jordan Valley: New 14C Determinations from Teleilat Ghassul, Jordan

Zinc Reduction as an Alternative Method for AMS Radiocarbon Dating: Process Optimization at Circe

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The End of the Chalcolithic Period in the South Jordan Valley: New ¹⁴C Determinations from Teleilat Ghassul, Jordan