237Np (≃2.14 × 106 yr half-life) is potentially applicable in studies on nuclear safeguards and radioactive waste migration. The atomic ratio of 237Np/U in nature is 10−12 or even lower, depending strongly on the integral neutron flux received by the material. As an ultra-sensitive technique, accelerator mass spectrometry (AMS) is the best for measuring ultratrace 237Np. By extracting negative molecular ions NpO– from the oxide sample using 238UO– and 208Pb16O2– pilot beams for the simulation of 237Np ion transport, identifying the interference isotopes by high-resolution dedicated injector, electrostatic analyzer, and time of flight (TOF) detector, a method for AMS measurement of 237Np was set up on the HI-13 accelerator at the China Institute of Atomic Energy (CIAE). A sensitivity of <10–11 has been achieved for the isotopic ratio 237Np/238U.

To improve the chronology of sediments containing information about Holocene ice shelf and oceanic dynamics in the vicinity of the Antarctic Peninsula, we compare bulk acid-insoluble radiocarbon dating to ramped pyrolysis 14C dating in a sediment core containing ample organic material. This core spans the last 12,000 yr of open-shelf sedimentation in the Bellingshausen Sea, western Antarctic Peninsula. By estimating the spectrum of 14C ages within a given core horizon, the ramped pyrolysis 14C method separates organic carbon relative to thermal stability, isolating younger parts of the mixture from older ones and providing an estimate of the geological uncertainty inherent in a bulk 14C age. Employing the ramped pyrolysis 14C method to this core demonstrates variable bulk 14C age bias and increasing age spectrum downcore, neither of which can be associated with major changes in lithology of the core. The chronology of the sediment core using the youngest ages from the ramped pyrolysis technique allows for correlation between nearby Palmer Deep sediments and these sediments from the Hugo Island Trough.

The question of when the first humans arrived in the New World has been a bone of contention for several decades. Similarly, the age of rock paintings has been heatedly debated. Settlements in the Serra da Capivara National Park have been dated to between 5 kyr and >50 kyr, which is far older than the Clovis barrier. Moreover, calcite formation on a rock-wall painting in a rockshelter yielded thermoluminescence (TL) and electron paramagnetic resonance (EPR) ages older than 35 kyr BP (Watanabe et al. 2003). In an attempt to contribute to this ongoing debate, we have studied calcite deposits covering prehistoric paintings from several rockshelters (Toca da Bastiana, Toca do Serrote de Moendas, and Toca da Gameleirinha [Pedra pintada]). Coupled AMS (accelerator mass spectrometry) 14C and MC-ICPMS (multi-collector inductively coupled plasma mass spectrometry) 230Th/U dating was performed in Toca da Gameleirinha. The ages obtained for these cal-cites are younger than 12 kyr and suggest that the paintings could be more recent than proposed by previous studies.

Center for Accelerator Mass Spectrometry (CAMS) Tasmanian Huon pine (Lagarostrobos franklinii) decadal measurements for the interval AD 745–855 suggest a mean interhemispheric radiocarbon offset (20 ± 5 yr), which is considerably lower than the previously reported mean interhemispheric offset for the last 2 millennia (44 ± 17 yr). However, comparable University of Waikato (Wk) New Zealand kauri (Agathis australis) measurements show significantly higher values (56 ± 6 yr), suggesting the possibility of a temporary geographic (intrahemispheric) offset between Tasmania, Australia, and Northland, New Zealand, during at least 1 common time interval. Here, we report 9 new Wk Tasmanian Huon pine measurements from the decades showing the largest Huon/kauri difference. We show statistically indistinguishable Wk Huon and Wk kauri 14C ages, thus dispelling the suggestion of a 14C geographic offset between Tasmania and Northland.

Based on archaeological and radiometric constraints, previous studies have divided pre-Columbian times of Ecuador into a succession of cultural periods. The Paleoindian and Preceramic periods encompass the time from the first Amerindian occupation to about 4000 BC. The Formative period extends from ∼4000 to ∼300 BC, while the Regional Development (∼300 BC to ∼AD 700) and Integration periods predate the Columbian period, which starts in AD 1533 in Ecuador. The Formative cultural period is poorly known from earlier studies. Here, we bring the first documentation of Formative age occupation around Tungurahua Volcano, 120 km SW of Quito, and show that local settlements were devastated by a violent eruption around 1100 cal BC. Recent volcanological works combining lithostratigraphic, petrologic, and geochronologic analyses reveal that the steep-sloped Tungurahua edifice suffered a major Late Holocene flank failure. We show that the failure event resulted from a major explosive eruption triggered by massive magma intrusion inside the volcano. Decompression of the magma due to a flank collapse resulted in a violent, high-velocity directed blast explosion, which deposited charcoaland sherd-rich ash layers upon and near the volcano. Our 14C results range from 2225 ± 30 to 5195 ± 45 BP, but most cluster between 2640 ± 45 and 3195 ± 45 BP. A calibration analysis indicates that the event took place at ∼1100 cal BC, in the Formative period. We gathered 38 pottery sherds from 3 localities. The sherds show a diversity of size, shape, color, and ornamentation. Examination of pastes, surface finish, and firing indicates that our material shares many common features from site to site. The material from Tungurahua shares affinities with the Cotocollao tradition, which developed in the Quito region between 1500 and 500 BC, and with the Machalilla tradition (coastal region of Ecuador), with the occurrence of carinated bowls with punctuate decorations at 1500–1000 BC. Our study reveals that the ∼1100 cal BC Plinian eruption of Tungurahua Volcano is among the oldest known volcanic disasters in the Andes.

Radiocarbon is a useful tool for studying carbon dynamics in soil aggregates. The objective of the current study was to determine the mean residence time (MRT) of soil organic carbon (SOC) in macroaggregates and microaggregates under contrasting land uses. Contrasting land uses investigated at Alfisol (equivalent to Dermosol in Australian Soil Classification) sites were native pasture (NP), crop-pasture rotation (CP), and Eucalypt woodland (WL), whereas in Oxisol (Ferrosol in Australian Soil Classification) sites, land uses comprised improved pasture (IP), cropping (CR), and forest (FR). Soil aggregates were separated into macroaggregates (250–2000 μm) and microaggregates (53–250 μm) by wet-sieving, and their 14C signatures were determined by accelerator mass spectrometry (AMS). The 14C activity in both macro- and microaggregates was >100 pMC, indicating the presence of post-bomb carbon in the soil. The mean residence time (MRT) of SOC in macro- and microaggregates (MRTagg) was on average 68 yr longer in the Oxisol compared with that in the Alfisol. The MRTagg in microaggregates was 10 yr longer than that of macroaggregates in the Alfisol. However, the MRTagg in microaggregates was 50 yr shorter compared to macroaggregates in the Oxisol.

The MRT of macro- and microaggregates can be separated into active, slow, and stable SOC pools. Among the 3 SOC pools, the MRT of the stable pool is of higher significance in terms of SOC stabilization in soil aggregates because of its longer MRT. However, isolation and direct MRT estimation of the stable SOC pool is difficult. The MRT of active and slow SOC pools associated with macro- and microaggregates was measured using a SOC mineralization experiment to estimate the MRT of the stable SOC pool under contrasting land uses by applying a mass balance criterion. The MRT of active (MRTA) and slow (MRTS) SOC pools in macro- and microaggregates varied between 1–50 days and 13–38 yr, respectively. The estimated MRT of the stable pool carbon (MRTP) in microaggregates was 897 yr longer compared to that of macroaggregates in the Alfisol. However, in the Oxisol, MRTP in microaggregates was 568 yr shorter than that of macroaggregates. Among the land uses, WL in Alfisol and CR in Oxisol had longer MRTagg and MRTP compared to other land uses.

The long-lived radioisotope 59Ni is of interest in various research fields including neutron dosimetry, radioactive waste management, and astrophysics. In order to achieve the sensitivity required for such applications, the technique of accelerator mass spectrometry (AMS) 59Ni measurement has been developed at the AMS facility at China Institute of Atomic Energy (CIAE). Based on the AE-Q3D detection system in the CIAE AMS facility, the interference in 59Ni counting from the isobar 59Co has been reduced by a factor of 8 × 106. A series of laboratory reference samples and a blank sample were measured to check the performance of 59Ni measurement. A detection sensitivity of about 5 × 10−13 (59Ni/Ni) has been obtained.

Wc describe here the New Zealand kauri (Agathis australis) Younger Dryas (YD) research project, which aims to undertake Δ14C analysis of ∼140 decadal floating wood samples spanning the time interval ∼13.1–11.7 kyr cal BP. We report 14C intercomparison measurements being undertaken by the carbon dating laboratories at University of Waikato (Wk), University of California at Irvine (UCI), and University of Oxford (OxA). The Wk, UCI, and OxA laboratories show very good agreement with an interlaboratory comparison of 12 successive decadal kauri samples (average offsets from consensus values of –7 to +4 14C yr). A University of Waikato/University of Heidelberg (HD) intercomparison involving measurement of the YD-age Swiss larch tree Ollon505, shows a HD/Wk offset of ∼10–20 14C yr (HD younger), and strong evidence that the positioning of the Ollon505 series is incorrect, with a recommendation that the 14C analyses be removed from the IntCal calibration database.

Sambaquis, famous Brazilian coastal shellmounds, represent a successful and long archaeological cultural tradition, with hundreds of sites spread over 2000 km of the Brazilian south-southeast coastline. These sites have many burials within a sequence of layers comprising a mix of faunal remains, charcoal, ashes, and sand, thus resulting in very complex stratigraphic structures. Several radiocarbon samples exhibit ages between 8000 and 1000 cal yr BP. In the Brazilian southeastern coastal hinterland, at the Ribeira de Iguape basin, 36 small mounds similar to the sambaquis were found, composed mostly of landsnail shells, bone remains of terrestrial fauna, lithic and osteodontological artifacts, and quite a few burials. Through the last decade an archaeological research project has accomplished extensive surveys and systematic 14C sampling, together with excavations in selected sites. A sequence of ages has been obtained from different samples (16 on shell, 10 on human bone, and 6 on charcoal) representing 19 sites. These dates range from 10,000 to 1000 cal yr BP, highlighting around 9000 yr of cultural continuity, contemporary to both the Paleoindian record over the hinterland plateau, and older than their coastal counterparts, the sambaquis. By presenting the 14C distribution and an overview of the archaeological features of these sites, we discuss briefly the dispersion and settlement processes of early peopling in this area of Brazil.

This article presents the results of 4 excavation seasons in which botanical and animal remains were collected at the Harappan site of Kanmer in the Kachchh District of Gujarat, India. The findings revealed a subsistence economy consisting of food production with domesticated plants and animals, hunting, fishing, and wild plant gathering. Cultural relics and radiocarbon dating support our identification of different cultural periods at the site. This study provides new insights into the subsistence strategies during different phases of occupation and offers the potential for new subsistence models to be applied at nearby sites, particularly in this peripheral zone of the Indus civilization.

The varved sediment profile of Lake Suigetsu, central Japan, offers an ideal opportunity from which to derive a terrestrial record of atmospheric radiocarbon across the entire range of the 14C dating method. Previous work by Kitagawa and van der Plicht (1998a,b, 2000) provided such a data set; however, problems with the varve-based age scale of their SG93 sediment core precluded the use of this data set for 14C calibration purposes. Lake Suigetsu was re-cored in summer 2006, with the retrieval of overlapping sediment cores from 4 parallel boreholes enabling complete recovery of the sediment profile for the present “Suigetsu Varves 2006” project (Nakagawa et al. 2012). Over 550 14C determinations have been obtained from terrestrial plant macrofossils picked from the latter SG06 composite sediment core, which, coupled with the core's independent varve chronology, provides the only non-reservoir-corrected 14C calibration data set across the 14C dating range.

Here, physical matching of archive U-channel sediment from SG93 to the continuous SG06 sediment profile is presented. We show the excellent agreement between the respective projects' 14C data sets, allowing the integration of 243 14C determinations from the original SG93 project into a composite Lake Suigetsu 14C calibration data set comprising 808 individual 14C determinations, spanning the last 52,800 cal yr.

A number of electronic systems are used on the ANTARES accelerator at ANSTO to implement its fast cycling accelerator mass spectrometry (AMS) capability. The fast cycling system was originally installed and commissioned in 1993 and has recently been updated. This paper describes the more significant of the electronic systems, such as the controller (“sequencer”), the high-voltage power supply (“bouncer”), the fast electrostatic beam chopper, and those used for measurement of the pulsed ion beam current. The sequencer, a programmable 15-bit digital pulse generator, generates the timing and sequencing of the control signals for bouncing voltage selection, beam chopping, Faraday cup current measurement, and rare isotope event measurement. The new sequencer is implemented using a National Instruments FPGA (field programmable gate array) card, programmed using LabVIEW 2010. This device has the benefits of host CPU-independent operation, simple interfacing (PCI), a small footprint, off-the-shelf availability at modest cost, and ease of functionality upgrade. The sequencer provides 15 synchronous digital signals, whose “on” and “off” transitions can be independently specified, in both number and time, with a time resolution of between 0.5 and 128 μs, and with the total duration between repetitions adjustable between 65.5 ms and 8.4 s per cycle. It is hosted by a generic PC because of the low-cost and ubiquity of these. The stand-alone FPGA-based approach ensures that the sequencer determinism is unaffected by processes executing in the host CPU.

A new 250kV single stage AMS accelerator (SSAMS) was installed at the Center for Applied Isotope Studies, University of Georgia. The accelerator is intended to be used primarily for radiocarbon measurements of natural and biobased samples, while all other samples such as marine, geological, atmospheric and archaeological samples are measured on the decade-old 500kV compact tandem accelerator (CAMS). The new AMS system is equipped with a 134-cathode MC-SNICS ion source. In this article, we show the results of the tests carried out on standards and blanks and compare the performance of the new machine with that of the CAMS unit. We have also compared the stable isotope data from AMS measurements to the conventional isotope ratio mass spectrometers (IRMS) data.

The archaeological site of Zaballa is a Medieval rural site located in the province of álava (Basque Country, northern Iberia). The site has been excavated during a rescue archaeology project, over an area of about 4.5 ha, where human occupation has been documented ranging from the 6th to 15th century. The archaeological operations have shown the transformation of the village, in diachronic terms, by unearthing the structure of production areas (agricultural lands, storage areas, and craft activities), the shape of domestic spaces, and the Saint Tirso monastery, with its adjacent cemetery. Much of the evidence and features related to a peasant community are small and disturbed by recent agricultural activities, and are therefore difficult to be interpreted in social terms. Studying dietary patterns has helped to fill this gap by providing a protein-rich diet of the elitist population and by highlighting the existence of hierarchies separating the inhabitants of Zaballa. In this paper, we discuss the reconstruction of the chronological sequence of the site inhabitation, with a multidisciplinary approach. The archaeological evidences and the critical use of radiocarbon dating have been integrated with stable isotope analysis on human remains found in the cemetery of the church of San Tirso, resulting in a first attempt to find evidence of the social structure of the rural community of Zaballa.

We present a compilation of tropospheric 14CO2 for the period 1950–2010, based on published radiocarbon data from selected records of atmospheric CO2 sampling and tree-ring series. This compilation is a new version of the compilation by Hua and Barbetti (2004) and consists of yearly summer data sets for zonal, hemispheric, and global levels of atmospheric 14C. In addition, compiled (and extended) monthly data sets for 5 atmospheric zones (3 in the Northern Hemisphere and 2 in the Southern Hemisphere) are reported. The annual data sets are for use in regional and global carbon model calculations, while the extended monthly data sets serve as calibration curves for 14C dating of recent, short-lived terrestrial organic materials.

Age offsets of accelerator mass spectrometry (AMS) assays on food residue taken from pottery vessels are well-documented in Europe and Asia in cultural contexts were freshwater aquatic products are attested, but are less well studied in North America. The present study examines a series of residue dates from the late prehistoric Central Plains of North America, comparing them with context dates run on annual plant remains. At least 13 of 23 assays are either incongruent with ages on annual plant remains, inconsistent among themselves within a site, or not credible for their cultural context. The conclusion is that food residue from ceramics does not produce consistently accurate dates. Some possible factors that may serve to introduce old carbon to residue samples are discussed. It also is noted that one's conclusions about the reliability of residue may be conditioned by the precision of the age determinations and by the goals of a specific chronology-building effort.

If ancient carbon is incorporated into lakes and rivers, it can be transferred along the foodchain where it can cause radiocarbon dates to appear erroneously old. This effect is known as the 14C freshwater reservoir effect (FRE), and causes particular problems when dating human remains. Several studies have attempted to use carbon and/or nitrogen stable isotopes to predict the size of the FRE, with mixed success. We have examined whether the FRE at the Mesolithic-Neolithic burial ground of Minino, northwest Russia, is correlated with these stable isotope systems. To assess the size of the FRE, 9 pairs of human bone and burial goods were dated, such as spears and pendants made of herbivore bone. In addition, further human and faunal bones were analyzed for carbon and nitrogen stable isotopes. Although these stable isotopes suggest that freshwater resources dominated the protein intake of those buried at Minino, no relationship between stable isotopes and the FRE was found. Instead, we found that the FRE was relatively consistent at 490 ± 80 14C yr. With caution, this can be subtracted from burials at Minino to provide a low-resolution chronology for the burial ground. We demonstrate that it is not possible to assume that a relationship exists between stable isotopes and 14C, and each population thought to be affected by a FRE must be examined individually.

A Brandgrubengrab entails a specific way of depositing human remains whereby the cremated remains of the deceased and other remnants of the funeral pyre, such as charcoal and burnt objects, are jointly deposited onto the bottom of a pit. This type of burial became increasingly popular during the Late Iron Age and the Roman period, when it was the main basic funerary structure used in western Flanders. In recent years, more attention has been paid to establishing a more precise chronology for these funerary structures by applying radiocarbon dating. A set of 40 14C dates obtained from samples originating from small cemeteries and isolated cremations now offers new insights in the development of this specific cremation burial ritual.

After 22 yr of the low-level liquid scintillation counting 14C laboratory at the Center for Nuclear Energy in Agriculture (CENA) at São Paulo University (USP), Piracicaba, Brazil, and several collaborative projects with Brazilian and international researchers from distinct scientific areas, the first 14C accelerator mass spectrometry (AMS) laboratory in Latin America was installed at the Physics Institute of the Universidade Federal Fluminense (UFF), Niterói, Brazil. A 250kV single stage accelerator produced by National Electrostatics Corporation began its operation in 2012. In this work, we compare measurements performed at the AMS Radiocarbon Laboratory at UFF (LAC-UFF) with those performed at CENA and the University of Georgia (UGAMS), Georgia, USA. All the results obtained from distinct inorganic and organic samples were in very good agreement.