Journal: Radiocarbon

Abbreviation

Radiocarbon

Publisher

Cambridge University Press

Journal Volumes

ISSN

0033-8222

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Publications 1 - 10 of 86
  • Gas Ion Source Performance of the EnvironMICADAS at HEKAL Laboratory, Debrecen, Hungary
    Item type: Journal Article
    Molnár, Mihály; Mészáros, Marianna; Janovics, Róbert; et al. (2021)
    Radiocarbon
    A coupled accelerator mass spectrometer–gas interface system has been successfully operating at the Hertelendi Laboratory of Environmental Studies, Debrecen, Hungary, since 2013. Over the last 6 years more than 500 gas targets were measured below 100 µg carbon content for carbon isotopic composition. The system was tested with blanks, OxII, IAEA-C1, IAEA-C2, and IAEA-C7 standards. The performance of our instrumentation shows good agreement with other published gas-interface system data and also shows a quite good agreement with the nominal value of international standard samples. There is a measurable but quite small memory effect after modern samples, but this does not significantly affect the final results. Typical ion currents at the low energy side were between 10–15 µA with a 5% CO2 in He mixing ratio. The relative errors average ±6% for samples greater than or equal to 10 µgC sample with mean count rates of 300 counts per microgram C for OxII. The blank is comparable with other systems, which is 0.0050 ± 0.0018 F14C or 34,000–47,000 yr BP, which allows for the routine measurement of both of small environmental and archeological samples.
  • The radiocarbon world according to Wally
    Item type: Other Journal Item
    Hajdas, Irka (2022)
    Radiocarbon
  • Preparation and Handling of Methane for Radiocarbon Analysis at Cologneams
    Item type: Conference Paper
    Melchert, Jan Olaf; Gwozdz, Martina; Gierga, Merle; et al. (2024)
    Radiocarbon ~ 24th Radiocarbon and 10th ¹⁴C & Archaeology, Zurich, Sept. 11–16, 2022 Proceedings Part 1 of 2
    CH₄ is the second most important anthropogenic greenhouse gas and originates from different sources. The use of radiocarbon (¹⁴C) analysis of CH₄ opens up the possibility to differentiate geological and agricultural origin. At the CologneAMS facility, the demand for ¹⁴C analysis of CH₄ required the development of a sample handling routine and a vacuum system that converts CH₄ to CO₂ for direct injection of CO₂ into the AMS. We evaluated the processing of CH₄ using several series of gas mixtures of ¹⁴C-free and modern standards as well as biogas with sample sizes ranging from 10 to 50 µg C. The results revealed a CH₄ to CO₂ conversion efficiency of 94–97% and blank values comparable to blank values achieved with our routinely used vacuum system for processing CO₂ samples. The tests with a near modern CH₄:CO₂ biogas mixture gave reproducible results with a near modern ¹⁴C content of 0.967–1.000 F¹⁴C, after applying the background correction.
  • Radiocarbon Protocols and First Intercomparison Results from the Chronos 14Carbon-Cycle Facility,University of New South Wales, Sydney, Australia
    Item type: Journal Article
    Turney, Chris; Becerra-Valdivia, Lorena; Sookdeo, Adam; et al. (2021)
    Radiocarbon
    The Chronos 14Carbon-Cycle Facility is a new radiocarbon laboratory at the University of New South Wales, Australia. Built around an Ionplus 200 kV MIni-CArbon DAting System (MICADAS) Accelerator Mass Spectrometer (AMS) installed in October 2019, the facility was established to address major challenges in the Earth, Environmental and Archaeological sciences. Here we report an overview of the Chronos facility, the pretreatment methods currently employed (bones, carbonates, peat, pollen, charcoal, and wood) and results of radiocarbon and stable isotope measurements undertaken on a wide range of sample types. Measurements on international standards, known-age and blank samples demonstrate the facility is capable of measuring 14C samples from the Anthropocene back to nearly 50,000 years ago. Future work will focus on improving our understanding of the Earth system and managing resources in a future warmer world.
  • Development of 14C Dating of Mortars at ETH Zurich
    Item type: Conference Paper
    Hajdas, Irka; Maurer, Mantana; Röttig, Maria B. (2020)
    Radiocarbon
    The ages of mortars and plaster can help reveal the history of monuments, their construction, or restoration times. However, these anthropogenic carbonates pose a challenge when it comes to separation of the atmospheric radiocarbon (14C) signal of the CO2 fixed in the mortar at the time of consolidation, i.e., the time of binder formation. The variety and heterogeneity of mortars require individual assessments of each sample and 14C results. Here we present our current preparation method and summarize experience based on results collected during the last 20 years of mortar dating at the ETH laboratory. © 2020 by the Arizona Board of Regents on behalf of the University of Arizona.
  • Intercomparison Exercise On Fuel Samples For Determination Of Biocontent Ratio By 14c Accelerator Mass Spectrometry
    Item type: Journal Article
    Varga, Tamás; Hajdas, Irka; Calcagnile, Lucio; et al. (2023)
    Radiocarbon
    The method of determining the biobased carbon content in liquid fuel samples is standardized, but different laboratories use different protocols during sample preparation and perform the measurements using different machines. The accelerator mass spectrometry (AMS) laboratories use different combustion, preparation, and graphitization methods for the graphite production for the spectrometric measurements. As a result, the intercomparison between the laboratories is inevitable to prove precision and accuracy and to demonstrate that the results are comparable. In this study, we present the results of an intercomparison campaign involving three C-14 accelerator mass spectrometry laboratories. Five samples were used in the measurement campaign, including two biocomponents (fatty acid methyl ester, hydrotreated vegetable oil), one fossil component (fossil diesel), and two blends (mixtures of fossil and biocomponent with 90-10% mixing ratio) in the laboratories of CEDAD (Italy), ETH (Switzerland), and INTERACT (Hungary). The results presented by the laboratories are comparable, and all three laboratories could determine the biobased carbon content of the samples within 1% relative uncertainty, which is acceptable in the scientific, economic, and industrial fields for biocomponent determination.
  • An Atypical Medieval Burial at the Monte Dei Cappuccini Monastery in Torino (Italy): A Case Study with High-Precision Radiocarbon Dating
    Item type: Journal Article
    Rubinetti, Sara; Hajdas, Irka; Taricco, Carla; et al. (2020)
    Radiocarbon
  • Illuminating Intcal During the Younger Dryas
    Item type: Journal Article
    Reinig, Frederick; Sookdeo, Adam; Esper, Jan; et al. (2020)
    Radiocarbon ~ IntCal20: Calibration Issue
    As the worldwide standard for radiocarbon (14C) dating over the past ca. 50,000 years, the International Calibration Curve (IntCal) is continuously improving towards higher resolution and replication. Tree-ring-based 14C measurements provide absolute dating throughout most of the Holocene, although high-precision data are limited for the Younger Dryas interval and farther back in time. Here, we describe the dendrochronological characteristics of 1448 new 14C dates, between ~11,950 and 13,160 cal BP, from 13 pines that were growing in Switzerland. Significantly enhancing the ongoing IntCal update (IntCal20), this Late Glacial (LG) compilation contains more annually precise 14C dates than any other contribution during any other period of time. Thus, our results now provide unique geochronological dating into the Younger Dryas, a pivotal period of climate and environmental change at the transition from LG into Early Holocene conditions.
  • Findings from an in-Depth Annual Tree-Ring Radiocarbon Intercomparison
    Item type: Journal Article
    Wacker, Lukas; Scott, Marian; Bayliss, Alex; et al. (2020)
    Radiocarbon
    The radiocarbon (14C) calibration curve so far contains annually resolved data only for a short period of time. With accelerator mass spectrometry (AMS) matching the precision of decay counting, it is now possible to efficiently produce large datasets of annual resolution for calibration purposes using small amounts of wood. The radiocarbon intercomparison on single-year tree-ring samples presented here is the first to investigate specifically possible offsets between AMS laboratories at high precision. The results show that AMS laboratories are capable of measuring samples of Holocene age with an accuracy and precision that is comparable or even goes beyond what is possible with decay counting, even though they require a thousand times less wood. It also shows that not all AMS laboratories always produce results that are consistent with their stated uncertainties. The long-term benefits of studies of this kind are more accurate radiocarbon measurements with, in the future, better quantified uncertainties.
  • The Marine Reservoir Effect on the Coast of Rio de Janeiro: Deriving Delta R Values from Fish Otoliths and Mollusk Shells
    Item type: Conference Paper
    Macario, Kita D.; Alves, Eduardo Q.; Belem, Andre Luiz; et al. (2018)
    Radiocarbon
Publications 1 - 10 of 86