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 MIni CArbon DAting System (MICADAS) has been recently installed at the Ocean University of China (OUC) mainly for determining the radiocarbon (14C) ages for marine sedimentary organic carbon. In this study, we compared the data from a series of CO2 samples measured independently by the MICADAS at OUC and ETH Zurich to assess whether the data from the OUC MICADAS meet our requirement for carbon cycle research. The measured samples covered a range of 14C ages from 1229 to 12,287 yr, and size from 5 to 162 µg C. The data from the two instruments showed a good linear relationship with only small 14C age offsets, meeting our research demands such as carbon source apportionment. Lastly, we propose that for MICADAS clients, such a cross-lab comparison of the size- and age-dependency of MICADAS using age-known samples is important for 14C data integration.

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.

The transition from the Middle to Late Pre-Pottery Neolithic B (PPNB) happened throughout southwest Asia in the mid-8th millennium cal BC. It entailed the abandonment of a number of sites, rapid growth of others, as well as the wide spread of morphologically domestic caprines. What remains an unknown is how rapid these processes were in real time. Over the period when the transition was taking place, the calibration curve has two shallow sections divided by a sudden drop, which for many of the older dates creates an illusion of a sudden cultural break around 7600–7500 cal BC. Yet a more detailed study presented in this paper suggests that the transition event could have been spread over a more extended period of time. This, however, is still far from certain due to risks of old wood effects and complexities of site formation.

This paper presents first chronological results for a Holocene marshland system from the southern part of the Danube-Tisza Interfluve. Radiocarbon (14C) ages were used to build age-depth models relying of probabilistic tools. Four models have been built: a linear one using dates gained via simple calibration, a P_Sequence model, fitting a polynomial function to calibrated dates; a Gamma_Sequence considering priori given and posterior accumulation rates have been constructed. As there was no significant difference between the mean values of individual models all seem suitable for establishing a reliable chronology despite differences in 95% CI ranges. While P_Sequence models underestimated SR, values calculated from the polynomial model were not significantly different from those of the G_Sequence. Based on multiproxy geochemical, sedimentological, paleoecological data the evolution of the system was reconstructed, covering a timespan of ca. 13,000 years starting from 12,000 BC and lasting until 1300 AD. Highest accumulation rates are dated to the Early Middle Ages from the 11th century. Several climate changes could have been identified which are present in other Hungarian and Western European records too, such as the 5b IRD event at ca. 5800 BC, a humid phase around 1600 BC, and a cool humid phase around the 6th century AD.

El Maye is a community located in the municipality of Ixmiquilpan, Hidalgo, in the central region of Mexico. During the late Postclassic period (1350–1521 AD), the Aztecs controlled the area through the establishment of a dual-headed system, one part belonging to the Aztec government and the other to the local government. El Maye was the local government center for the Ixmiquilpan territory under the Aztec domain. The residential units of El Maye archaeological site were constructed in 6 different occupational phases, with the presence of large rooms, stucco floors and walls, offerings, and a variety of ceramics belonging to the late Aztec III ceramic period (1400–1520 AD). The Axis Project of the Mezquital Valley (PEVM-ENAH) and the Accelerator Mass Spectrometry Laboratory (LEMA-UNAM) have undertaken a collaborative study of the El Maye site by performing absolute radiocarbon accelerator mass spectrometry (14C AMS) dating. For a better understanding of the emergence and development of El Maye, a series of AMS 14C dates of charcoal and bone samples recovered from different stratigraphic levels, was performed. This allowed us to locate the occupation of the site between 1320 and 1625 cal AD.

The CO2 absorption and liquid scintillation counting (LSC) are methods used in radioactivity monitoring programs of nuclear facilities for 14C measurements due to high number of samples and relatively high expected level of 14C concentration. The paper describes the chemical sample preparation applied to a quality control material (IAEA-C3 Cellulose), in order to evaluate the reproducibility of CO2 absorption method for this type of material. Consequently, in the experiments we used two home-made scintillation cocktails, containing two amines, 2-methoxyethylamine (MEA) and 3-methoxypropyl amine (MPA), which detained CO2 as carbamates. Due to the fact that the material used in the dedicated experiments is cellulose (contained in all vegetable materials), the method can be considered as appropriate for 14C determination from biological and vegetable materials.

Use of coral skeletons to determine growth histories of reefs situated in warm, clear tropical waters is well established. Recently, however, there has been increasing awareness of the significance of reefs occurring in environments that are considered as marginal for coral growth, such as turbid inshore settings characterized by episodes of elevated turbidity, low light penetration, and periodic sediment burial. While these conditions are generally considered as limiting for coral growth, coral reefs in these settings can exhibit high live coral cover and species diversity, and thus can be both ecologically and geologically significant. Turbid-zone reefs are also commonly concentrated along eroding shorelines with many analogues to erosional shorelines developed during the Holocene transgression. A growing number of studies of these previously undocumented reefs reveal that the reef deposits are detrital in nature, comprising a framework dominated by reef rubble and coral clasts and set within a fine-grained terrigenous sediment matrix. In addition to the recognized effects of diagenesis or algal encrustations on the radiocarbon signature of coral samples, episodic high-energy events may rework sediments and can result in age reversals in the same stratigraphic unit. As in other reef settings, the possibility of such reworking can complicate the reconstruction of turbid-zone reef growth chronologies. In order to test the accuracy of dating coral clasts for developing growth histories of these reef deposits, 5 replicate samples from 5 separate coral clasts were taken from 2 sedimentary units in a core collected from Paluma Shoals, an inshore turbid-zone reef located in Halifax Bay, central Great Barrier Reef, Australia. Results show that where care is taken to screen the clasts for skeletal preservation, primary mineralogical structures, and δ13C values indicative of marine carbonate, then reliable 14C dates can be recovered from individual turbid reef coral samples. In addition, the results show that these individual clasts were deposited coevally.

For several decades, many efforts have been dedicated to enhancing the accuracy of mortar radiocarbon dating and evaluating the reliability of the results concerning the typology of the examined specimens. Several assumptions that are fundamental for the application of the method may be in many cases not fulfilled, such as (a) complete primary limestone dissociation during calcination, (b) efficient separation of geogenic carbon contained in calcareous aggregates, (c) short carbonation time, and (d) absence of secondary calcite. Many laboratories all over the world have proposed different methods to select suitable fractions of mortar.

The first intercomparison attempt, involving eight international laboratories, was organized in 2016 aiming at comparing and statistically treating the results obtained on the same materials by different laboratories with their own characterization and pre-treatment methods (Hajdas et al. 2017; Hayen et al. 2017). Following this first step, a new intercomparison experiment was proposed and set up in 2018 during the Mortar Dating International Meeting (Bordeaux, FR). A new set of three mortar samples was chosen, taking care of the selection of standardized materials (homogeneity, known mineralogical composition, absence of exogenous inclusions, known expected age).

This work describes the results of two research teams involved in the intercomparison. The samples were characterized, selected, and dated depending on each laboratory strategy. The results stress the importance of the characterization of the raw material is to better understand the mineralogical and petrographical composition of the samples. Such information can support the choice of the most appropriate strategy for the extraction of CO2 and then for data interpretation.

Oxbow lake deposits of the Neris River at the Valakupiai site in Vilnius (Lithuania) have been studied by different methods including radiocarbon dating. A timescale was attained for the development of the oxbow lake and climatic events recorded in the sediments. 14C dates obtained for 24 samples cover the range 990–6500 BP (AD 580 to 5600 BC). Medieval human activity was found in the upper part of the sediments. Mollusk fauna found in the basal part of the terrace indicate contact between people living in the Baltic and the Black Sea basins. Mean rates were calculated for erosion of the river and for accumulation during the formation of the first terrace.

Low-level radiocarbon measurements were made using two liquid scintillation (LS) counters, both with passive lead shields of approximately the same dimensions. The first one had a conventional background reduction with low-activity lead and “high-low” coincidence bias selection, and the second one had a spectrum analysis background reduction based on the different three-dimensional pulse-height signal of background and beta pulses.

The performance of commercial teflon-copper and glass vials were compared with both LS counters. Optimum counting conditions for the two detectors studied were also established. From results obtained, quality parameters and characteristics of quench curves were studied. Performances of each counter in the working conditions established were also compared.

The present list contains 14G dates from archaeologic samples attributed to the European Mesolithic period from the typology of associated finds, especially microliths. Of these samples, 14 are from Germany and 6 from France.

The Fragmenta membranea manuscript fragment collection at the National Library of Finland has proved challenging to date using only traditional paleography. Therefore, radiocarbon dates can contribute to the understanding of these fragments by offering a parallel natural scientific timeline for the parchment the manuscripts are written on. In this study, we apply our previously developed method for radiocarbon dating medieval manuscripts made of parchment. In total 35 datings were made from 14 separate assemblages of manuscripts, being the first systematic wide-scale application of radiocarbon dating to a collection of medieval manuscripts in order to improve their chronological proxy. Additionally, due to the fragmentary and sometimes poor condition of the manuscript fragments of Fragmenta membranea analyzed in this study, we used Fourier-transform infrared spectroscopy (FTIR) to evaluate the quality of the collagen and the presence of contaminants in the fragments affecting the radiocarbon dates. We report out radiocarbon dating results and FTIR screenings for each sample and for each manuscript assemblage, and discuss the applicability of our method in further studies of applying radiocarbon dating on objects of cultural historical interest and value. The results indicate an essential role of high-quality samples and multiple measurements to interpret the radiocarbon dating results.

The concentration of radiocarbon in the earth's atmosphere is used to analyze the complex of problems associated with the study of various astrophysical, geophysical, and geochemical phenomena within the framework of the All-Union problem of Astrophysical Phenomena and Radiocarbon. Effects of the supernovae explosions, solar activity, geomagnetic field and climatic changes in the 14C level in tree-rings are considered.

B. P. Konstantinov and G. E. Kocharov (1965, 1967) addressed the complex problem of astrophysical phenomena and radiocarbon. Currently available data show that the determination of cosmogenic 14C in accurately dated samples of terrestrial and atmospheric origin is one of the most reliable and promising methods for studying cosmic-ray variations in the past. 14C dating samples of terrestrial origin has helped solve the problem of long-term (100 yr or more) 14C variations and, accordingly, of cosmic-ray variations in the past. Short-term (ca. 11 yr or less) variations are still under investigation (Alexeyev et al. 1971; Damon, Long and Wallick 1973).

We describe applications of radiocarbon dating used for establishing a chronology of archaeological sites of the Novgorod region at the end of the first millennium ad. We have 14C-dated known-age tree rings from sites in Latvia and ancient Novgorod, northwest Russia, as well as charcoal and wood from Novgorod. Calendar ages of 14C-dated tree rings span the interval, ad 765–999. We used the Groningen calibration program, CAL15 (van der Plicht 1993) to calibrate 14C ages to calendar years. Comparisons between 14C results and archaeological data show good agreement, and enable us to narrow the calendar interval of calibrated 14C determinations.

The dating equipment and operating procedures in the Physical laboratory remained as described previously (R, 1974, v 16, no. 1, p 6-9).

Dates were calculated using the 5568-year half-life with 1950 as the reference year, the modern standard being 0.95 of the activity of the NBS oxalic acid standard. When done, δ13C was measured on CO2 produced in the combustion of samples, and results are given relative to the PDB standard. All samples were from Ireland.

We present the first Bayesian 14C modeling based on AMS ages from stratified sediments representing continuous occupation across the Early Bronze III/IV interface in the Southern Levant. This new high-precision modeling incorporates 12 calibrated AMS ages from Khirbat Iskandar Area C using OxCal 4.4.4 and the IntCal 20 calibration curve to specify the EB III/IV transition at or slightly before 2500 cal BCE. Our results contribute to the continuing emergence of a high chronology for the Levantine Early Bronze Age, which shifts the end of EB III 200–300 years earlier than the traditional time frame and increases the length of EB IV to about 500 years. Data from Khirbat Iskandar also help direct greater attention to the importance of sedentary communities through EB IV, in contrast to the traditional emphasis on non-sedentary pastoral encampments and cemeteries. Modeling of AMS data from Khirbat Iskandar bolsters the ongoing revision of Early Bronze Age Levantine chronology and its growing interpretive independence from Egyptian history and contributes particularly to re-examination of the EB III/IV nexus in the Southern Levant.

Stable isotopes have been used historically to track food webs. Our approach used a combination of δ13C and radiocarbon (14C) dating to identify carbon sources in cave shrimp within caves of the Karstic Yucatan Peninsula, Mexico. Three sister species of stygobitic Typhlatya shrimps were collected from the cenote pool (cenote hereafter), cavern and cave hydro regions. New and previously reported 14C and δ13C values of whole tissues from the organisms were determined at the AMS laboratory (LEMA) of the Institute of Physics of the Universidad Nacional Autónoma de México. This new set of isotopic values of biomass and potential sources were incorporated into the Bayesian Mixing Modeling Software SIAR. In two hypothetical scenarios, the contribution from each feeding source among three species of the Typhlatya genus was determined. Slight differences were also observed between isotopic values of two groups of the same species collected in two distant cenote pools, suggesting this species may feed on a wider array of sources than previously found, and that the oligotrophic environment may have a strong influence on cave shrimp diet.