10Be Measurements Research Articles

Ice-sheet burial and erosion inferred from cosmogenic nuclide bedrock depth profiles: Implications for the glaciation history of northeastern Fennoscandia

In this study, we evaluate the application of shallow (<2.5 m) cosmogenic depth profiles in bedrock to constrain long-term ice-burial and erosion histories. Using Markov Chain Monte Carlo inversion modelling on a series of synthetic scenarios, we demonstrate that cosmogenic 10Be and 26Al profiles provide more robust constraints on ice-burial duration and erosion histories than surface samples alone, particularly when erosion rates are low (<5–10 m Myr−1) and/or non-steady. We apply this method to new depth profiles of 10Be and 26Al measurements from two tors in the Parkajoki region in northeastern Sweden. Our results indicate erosion depths of ∼2–10 m and ice burial for ∼20–35% of the time since 500 ka. These estimates imply more erosion and less ice burial than previously inferred from the same tors. However, by re-assessing the extent of ice cover during the Weichselian from existing records, we show that some cosmogenic nuclide inheritance predates the penultimate glacial maximum (Late Saalian), implying limited glacial erosion in the Parkajoki region during the last glacial cycle.

Characterization of meteoric 10Be in certified reference materials for use in internal control standards

In recent decades, interest in the measurement of 10Be has increased due to its relevance in various fields of science. Trace amounts of 10Be produced from meteoric sources require sensitive accelerator mass spectrometry (AMS) measurements and robust sample preparation. The extraction, separation, and preparation of the appropriate oxide form for AMS require extensive and careful laboratory processing and certified reference materials to validate the chemical performance of the protocols used and the calibration of the AMS system in the measurement. In this work, the meteoric 10Be concentrations in two certified reference materials are characterized to establish their suitability as internal control standards for laboratory chemical preparation and AMS measurements of this radioisotope in our laboratory and the whole AMS community.

Assessing soil erosion in a semiarid ecosystem in Central Argentina using 137Cs and 7Be measurements

ABSTRACT Argentina is a Latin American country which encounters soil degradation problems. The most productive regions have implemented conservative land practices (no-till). However, agricultural frontier has been displaced to marginal lands with arid and semiarid climates, with the consequent disappearance in many areas of native forest and land degradation. In this work, the fallout of gamma-emitting radionuclides, 137Cs and 7Be, was jointly used to assess changes in soil erosion in a recently converted semiarid ecosystem into agricultural land. 137Cs was utilized to estimate the erosion over the past 60 years, whereas 7Be was employed to estimate the erosion after the conversion of the area to cultivated land and soil tillage. For 137Cs the Proportional Model (PM), the Mass Balance Model II (MBMII) and the MODERN model were used, for 7Be the Profile Distribution Model (PDM) and the MODERN model were used. 137Cs indicates mean erosional rates of 8.2, 10.5 and 6.5 Mg ha−1 a−1, using MBMII, PM and MODERN, respectively, and that a soil layer between 0.5 and 0.8 mm was annually lost by erosion. By applying a 7Be tracer, we measured erosion rates of 2.4 and 3.3 Mg ha−1 (with PDM and Modern, respectively), indicating the loss of the upper 0.2 mm of soil. This erosion can be attributed to a few heavy rainfalls that occurred within the past 90 days. The results suggest that current land management practices have led to an increase in soil erosion. This could be attributed to the fact that the soil remains bare after crop harvest, which may compromise its conservation and future productivity.

Atmospheric Δ14C in the northern and southern hemispheres over the past two millennia: Role of production rate, southern hemisphere westerly winds and ocean circulation changes

The variations of atmospheric Δ14C over the past two millennia are classically attributed to changes in its production rate in the upper atmosphere, which in turn is related to changes in solar activity and the Earth's magnetic field. However, the potential contribution of atmospheric and oceanic circulation changes during this period has not been precisely quantified. This has been achieved here using a coupled climate model simulating explicitly the evolution of the different carbon isotopes, driven by a new estimate of 14C production derived from 10Be measurements, and using different production rates for each hemisphere. Our results confirm that changes in global and hemispheric atmospheric Δ14C are primarily driven by changes in production rate. The very good agreement between our results and observed atmospheric Δ14C also highlights the strong consistency of current interpretations of 10Be and 14C measurements. By contrast, the interhemispheric difference in atmospheric Δ14C is controlled by changes in the intensity of southern hemisphere westerly winds (SHWW) that impact atmosphere-ocean exchange and the upwelling of 14C depleted water masses in the Southern Ocean. Changes in deep water formation in both hemispheres or open ocean polynyas in the Southern Ocean only have a small impact on atmospheric Δ14C over that period. When driven by changes in the SHWW proportional to three existing reconstructions of the Southern Annular Mode (SAM) index, the model reproduces some key characteristics of the observed interhemispheric Δ14C gradient. These include the low values in the 15th century and the peak in the 16th century, but there are also clear differences between the experiments and Δ14C observations. This suggests that while SAM reconstructions capture some robust features in the centennial variability, large uncertainties remain.

Development and applications of accelerator mass spectrometry methods for measurement of 14C, 10Be and 26Al in the CENTA laboratory

Terrestrial and extraterrestrial radioisotope research has been strongly dependent on the development of analytical methods which would enable to trace radioisotopes at low concentrations in subgram samples (e.g., in tree rings, ice cores, meteorites, etc.). Accelerator mass spectrometry (AMS) has become the most sensitive technique for ultralow-level analysis of long-lived radioisotopes, such as 14C, 10Be and 26Al. We review developments and applications carried out in the CENTA laboratory, and describe a recently installed fully equipped AMS line, designed for analysis of long-lived radioisotopes from tritium to curium.

Simulations of 7Be and 10Be with the GEOS-Chem global model v14.0.2 using state-of-the-art production rates

Abstract. The cosmogenic radionuclides 7Be and 10Be are useful tracers for atmospheric transport studies. Combining 7Be and 10Be measurements with an atmospheric transport model can not only improve our understanding of the radionuclide transport and deposition processes but also provide an evaluation of the transport process in the model. To simulate these aerosol tracers, it is critical to evaluate the influence of radionuclide production uncertainties on simulations. Here we use the GEOS-Chem chemical transport model driven by the Modern-Era Retrospective analysis for Research and Applications, Version 2 (MERRA-2) reanalysis to simulate 7Be and 10Be with the state-of-the-art production rate from the CRAC:Be (Cosmic Ray Atmospheric Cascade: Beryllium) model considering realistic spatial geomagnetic cutoff rigidities (denoted as P16spa). We also perform two sensitivity simulations: one with the default production rate in GEOS-Chem based on an empirical approach (denoted as LP67) and the other with the production rate from the CRAC:Be but considering only geomagnetic cutoff rigidities for a geocentric axial dipole (denoted as P16). The model results are comprehensively evaluated with a large number of measurements including surface air concentrations and deposition fluxes. The simulation with the P16spa production can reproduce the absolute values and temporal variability of 7Be and 10Be surface concentrations and deposition fluxes on annual and sub-annual scales, as well as the vertical profiles of air concentrations. The simulation with the LP67 production tends to overestimate the absolute values of 7Be and 10Be concentrations. The P16 simulation suggests less than 10 % differences compared to P16spa but a significant positive bias (∼18 %) in the 7Be deposition fluxes over East Asia. We find that the deposition fluxes are more sensitive to the production in the troposphere and downward transport from the stratosphere. Independent of the production models, surface air concentrations and deposition fluxes from all simulations show similar seasonal variations, suggesting a dominant meteorological influence. The model can also reasonably simulate the stratosphere–troposphere exchange process of 7Be and 10Be by producing stratospheric contribution and 10Be/7Be ratio values that agree with measurements. Finally, we illustrate the importance of including the time-varying solar modulations in the production calculation, which significantly improve the agreement between model results and measurements, especially at mid-latitudes and high latitudes. Reduced uncertainties in the production rates, as demonstrated in this study, improve the utility of 7Be and 10Be as aerosol tracers for evaluating and testing transport and scavenging processes in global models. For future GEOS-Chem simulations of 7Be and 10Be, we recommend using the P16spa (versus default LP67) production rate.

Erosion rates and morphogenesis of the El Peñol de Guatapé inselberg, northern Andes (Colombia), inferred from geomorphic analyses and cosmogenic 10Be measurements

Inselbergs are isolated rock bodies that develop as a result of differential weathering and erosion advances during topographic etchplain formation. The timing and rate of inselberg growth are key for constraining external controls on landscape evolution, particularly in etching terrains associated with elevated plateaus carved on granitic lithologies, and in tectonically active provinces in tropical climate zones (e.g., Antioqueño Plateau, AP). We applied new morphostratigraphic and geomorphometric analyses, along with 10Be terrestrial cosmogenic nuclide (TCN) measurements, to in situ rock samples from the Peñol de Guatapé Inselberg (PGI), in the AP of the Colombian Andes to address the chronological framework of bornhardt formation in this tropical setting. The PGI is located in a rejuvenated landscape between middle Miocene to late Mio-Pliocene erosion surfaces. Erosion rates inferred from 10Be analyses ranged between ∼0.0024 ± 0.0001 and 0.24 ± 0.0283 mm/yr. This broad range is consistent with the long-term erosion rate of ∼0.04 mm/yr and mid-term erosion rates of 0.01–0.08 mm/yr previously documented for the region using low-temperature thermochronology. Our findings indicate that the PGI emerged as an important landscape feature over a period of ∼0.5–2.0 Myr and has protruded high above the average AP surface since the Pliocene. The new TCN-derived erosion-rate estimates for the AP Inselberg enable us to better understand the role of weathering and erosional processes that controlled the evolution of landscape surfaces during Andean orogenic cycles documented in the region.

Deglaciation of the north American ice sheet complex in calendar years based on a comprehensive database of chronological data: NADI-1

The most recent deglaciation of the North American Ice Sheet Complex (NAISC: comprising the Innuitian, Cordilleran, and Laurentide ice sheets) offers a broad perspective from which to analyze the timing and rate of ice retreat, deglacial sea-level rise, and abrupt climate change events. Previous efforts to portray the retreat of the NAISC have been focused largely on minimum-limiting radiocarbon ages and ice margin location(s) tied to deglacial landforms that were not, for the most part, chronologically constrained. Here, we present the first version of North American Deglaciation Isochrones (NADI-1) spanning 25 to 1 ka in calendar years before present. Key new features of this work are (i) the incorporation of cosmogenic nuclide data, which offer a direct constraint on the timing of ice recession; (ii) presentation of all data and time-steps in calendar years; (iii) optimal, minimum, and maximum ice extents for each time-step that are designed to capture uncertainties in the ice margin position, and; (iv) extensive documentation and justification for the placement of each ice margin. Our data compilation includes 2229 measurements of 10Be, 459 measurements of 26Al and 35 measurements of 36Cl from a variety of settings, including boulders, bedrock surfaces, cobbles, pebbles, and sediments. We also updated a previous radiocarbon dataset (n = 4947), assembled luminescence ages (n = 397) and gathered uranium-series data (n = 2). After scrutiny of the geochronological dataset, we consider >90% of data to be reliable or likely reliable. Key findings include (i) a highly asynchronous maximum glacial extent in North America, occurring as early as 27 ka to as late as 17 ka, within and between ice sheets. In most marine realms, extension of the ice margin to the continental shelf break at 25 ka is somewhat speculative because it is based on undated and spatially scattered ice stream and geomorphic evidence; (ii) detachment of the Laurentide and Cordilleran ice sheets took place gradually via southerly and northerly ‘unzipping’ of the ice masses, starting at 17.5 ka and ending around 14 ka; (iii) the final deglaciation of Hudson Bay began at 8.5 ka, with the collapse completed by 8 ka. The maximum extent of ice during the last glaciation occurred at 22 ka and covered 15,470,000 km2. All North American ice sheets merged at 22 ka for the first time in the Quaternary. The highly asynchronous Last Glacial Maximum in North America means that our isochrones (starting at 25 ka) capture ice advance across some areas, which is based on limited evidence and is therefore somewhat speculative. In the Supplementary Data, the complete NADI-1 chronology is available in PDF, GIF and shapefile format, together with additional visualizations and spreadsheets of geochronological data. The NADI-1 shapefiles are also available at https://doi.org/10.5281/zenodo.8161764.

In situ 10Be modeling and terrain analysis constrain subglacial quarrying and abrasion rates at Sermeq Kujalleq (Jakobshavn Isbræ), Greenland

Abstract. Glacial erosion creates diagnostic landscapes and vast amounts of sediment. However, knowledge about the rate at which glaciers erode and sculpt bedrock and the proportion of quarried (plucked) versus abraded material is limited. To address this, we quantify subglacial erosion rates and constrain the ratio of quarrying to abrasion during a recent, ∼ 200-year long overriding of a bedrock surface fronting, Sermeq Kujalleq (Jakobshavn Isbræ), Greenland, by combining 10Be analyses, a digital terrain model, and field observations. Cosmogenic 10Be measurements along a 1.2 m tall quarried bedrock step reveal a triangular wedge of quarried rock. Using individual 10Be measurements from abraded surfaces across the study area, we derive an average abrasion rate of 0.13 ± 0.08 mm yr−1. By applying this analysis across a ∼ 1.33 km2 study area, we estimate that the Greenland Ice Sheet quarried 378 ± 45 m3 and abraded 322 ± 204 m3 of material at this site. These values result in an average total erosion rate of 0.26 ± 0.16 mm yr−1, with abrasion and quarrying contributing in roughly equal proportions within uncertainty. Additional cosmogenic 10Be analysis and surface texture mapping indicate that many lee steps are relicts from the prior glaciation and were not re-quarried during the recent overriding event. These new observations of glacier erosion in a recently exposed landscape provide one of the first direct measurements of quarrying rates and indicate that quarrying accounts for roughly half of the total glacial erosion in representative continental shield lithologies.

Optimization of BeO formation parameters for the measurement of 10Be by AMS.

10Be has been widely studied over the last few years. The sensitivity offered by the Accelerator Mass Spectrometry technique (AMS) expands the efficient detection of 10Be by 4-5 orders of magnitude. The chemical species most used in the measurement of 10Be by AMS is beryllium oxide (BeO), which has been shown to offer the best conditions for measurements. In this work, several parameters in the BeO formation have been analyzed. The results show the efficiency of the protocol used but suggest that using Ag instead of Nb as a conductor could improve the measurement conditions.

Cosmogenic 10Be in pyroxene: laboratory progress, production rate systematics, and application of the 10Be–3He nuclide pair in the Antarctic Dry Valleys

Abstract. Here, we present cosmogenic-10Be and cosmogenic-3He data from Ferrar dolerite pyroxenes in surficial rock samples and a bedrock core from the McMurdo Dry Valleys, Antarctica, with the goal of refining the laboratory methods for extracting beryllium from pyroxene, further estimating the 10Be production rate in pyroxene and demonstrating the applicability of 10Be–3He in mafic rock. The ability to routinely measure cosmogenic 10Be in pyroxene will open new opportunities for quantifying exposure durations and Earth surface processes in mafic rocks. We describe scalable laboratory methods for isolating beryllium from pyroxene, which include a simple hydrofluoric acid leaching procedure for removing meteoric 10Be and the addition of a pH 8 precipitation step to reduce the cation load prior to ion exchange chromatography. 10Be measurements in pyroxene from the surface samples have apparent 3He exposure ages of 1–6 Myr. We estimate a spallation production rate for 10Be in pyroxene, referenced to 3He, of 3.6 ± 0.2 atoms g−1 yr−1. 10Be and 3He measurements in the bedrock core yield initial estimates for parameters associated with 10Be and 3He production by negative-muon capture (f10∗=0.00183 and f3∗fCfD=0.00337). Next, we demonstrate that the 10Be–3He pair in pyroxene can be used to simultaneously resolve erosion rates and exposure ages, finding that the measured cosmogenic-nuclide concentrations in our surface samples are best explained by 2–8 Myr of exposure at erosion rates of 0–35 cm Myr−1. Finally, given the low 10Be in our laboratory blanks (average of 5.7 × 103 atoms), the reported measurement precision, and our estimated production rate, it should be possible to measure 2 g samples with 10Be concentrations of 6 × 104 and 1.5 × 104 atoms g−1 with 5 % and 15 % uncertainty, respectively. With this level of precision, Last Glacial Maximum to Late Holocene surfaces can now be dated with 10Be in pyroxene. Application of 10Be in pyroxene, alone or in combination with 3He, will expand possibilities for investigating glacial histories and landscape change in mafic rock.

The slow downwearing of Madagascar: Inferring patterns and controls on long‐term basin‐averaged erosion rates from in situ10Be at the catchment and regional level

AbstractCosmogenic nuclide analysis of river sediment provides insight into catchment‐wide erosion rates and dynamics. Here, we investigate spatial patterns and controls on 10Be‐inferred erosion rates in Madagascar, a moderately seismically active microcontinent surrounded by passive margins with locally steep topography and a climate that varies from humid tropical to semiarid. We use a compiled dataset of 99 detrital 10Be measurements, 63 of which are new, covering more than 30% of the country and a wide range of topographic, bioclimatic and geologic characteristics. Overall, 10Be erosion rates are low (2.4–51.1 mm kyr−1), with clear differences between regions. The lowest rates are measured on the central highlands ( 8 mm kyr−1), in the Alaotra–Ankay graben ( 11 mm kyr−1) and in the large north‐central catchments ( 11 mm kyr−1). Higher rates are found on the steep eastern escarpment ( 20 mm kyr−1), in the northwest ( 31 mm kyr−1) and in the southwest ( 29 mm kyr−1). A stepwise linear regression model identified elevation as the main factor associated with variations in 10Be erosion rates (lower rates for higher catchments). Random within‐between statistical models (REWB), on the other hand, indicated that the differences between different regions can be explained by differences in river concavity, seismic events and gully (lavaka) densities, whereas additional variation within regions is only linked to seismicity. We find no correlation between catchment or river steepness and 10Be‐inferred erosion rates. Our results indicate that in Madagascar, long‐term erosion rates are overall low and that simple topography‐based models do not explain variations in rates of landscape change inferred from 10Be concentrations in river sediment. We demonstrate that identifying different regions aids in interpreting spatial patterns of erosion rates and that REWB models can be a powerful tool in deciphering environmental controls on 10Be erosion rates.

Coulomb explosion of BeO− molecular ions – Revisited

Accelerator mass spectrometry (AMS) measurements of 10Be almost invariably utilize the BeO- molecular negative ion. Molecular ions experience the process of ‘Coulomb explosion’ when dissociated by a stripper in the high-voltage terminal of a tandem accelerator, resulting in energy and angular spread of the subsequently-accelerated positive ions. In this paper, the phenomenon is studied in detail for both foil and gas stripping of BeO, using the 14UD pelletron accelerator at the Australian National University operating at 8.5 MV. In a companion paper by Suter et al. [1], a model is developed to interpret, inter alia, these results.

Performance of low-energy AMS measurement of 10Be at Tianjin University

The AMS system at Tianjin University with a nominal terminal voltage of 500 kV was installed in 2017. After the initial testing and commissioning phase, the facility is now in routine operations. For 10Be, the most challenging nuclide of our repertoire, measurement and analysis have been completed for more than 500 samples from different scientific fields. However, the measurement method of 10Be has to be optimized and developed due to the fact that originally the accelerator had to operate, in each measurement, at 600 kV, the extreme upper limit of its terminal voltage. For this reason, a series of measures have been taken in order to further optimize the 10Be measurement method and to reduce the risk to the equipment during the experiment. In this contribution, the improvements in the setup and the experimental procedures will be briefly introduced.

Seasonal variations in total deposition velocity and washout ratio of fine aerosols revealed from beryllium-7 (7Be) measurements in Sevastopol, the Black Sea region

Washout ratios and deposition velocities are crucial in fine aerosols as they affect their atmospheric concentration, which in turn impacts human health. The only method to estimate the total (dry and wet) aerosol deposition velocity or washout ratio is by using a tracer such as beryllium-7 (7Be). This study collected field data on the temporal variability of monthly total deposition flux of 7Be and monthly mean 7Be activity in Sevastopol station, the Black Sea region from March 2011 to December 2013. From these data, the washout ratio and deposition velocity of fine aerosol particles were derived. The monthly mean values of the washout ratio and deposition velocity ranged from 388 to 3533 (mean 1112 ± 793) and from 0.1 to 1.5 cm s−1 (mean 0.6 ± 0.4 cm s−1), respectively. The dry deposition velocity in the four precipitation-free months varied between 0.10 and 0.15 cm s−1 with an average of 0.13 ± 0.02 cm s−1. The precipitation amount and frequency strongly influenced the seasonal variability of the deposition velocity, whereas the seasonal variability of the washout ratio was controlled only by the precipitation amount. The reduced washout ratio and the increased deposition velocity were associated with the increased precipitation. Thus, the results obtained allowed for parameterizations to estimate the monthly mean values of the washout ratio and deposition velocity from the data of the monthly precipitation amount.

Methodology and Applications of the Determination of Cosmogenic Radionuclides ¹⁰Be and ²⁶Al by Accelerator Mass Spectrometry

The measurement of cosmogenic radionuclides 10Be and 26Al by accelerator mass spectrometry (AMS) has become an invaluable tool for dating events and processes in Quaternary geochronology, and in archaeology and paleoanthropology. Here we present an overview of the current state of research by providing the theoretical and methodological background and describe processes of sample preparation and measurement by AMS. We also summarize the main geochronology calculation models for exposure and burial dating for the above applications and analysis of extra-terrestrial materials.

Principles and Applications of Accelerator Mass Spectrometry

Accelerator mass spectrometry (AMS) represents an ultrasensitive analytical method for measurement of long-lived radionuclides, namely 14C, 10Be, 26Al, 41Ca, 129I, and 236U. It provides information about isotopic ratios up to 10–16 in samples of mass from several miligrams to tens of micrograms. The first AMS laboratory in the Czech Republic was built in Nuclear Physics Institute, Řež, in collaboration with Archaeological Institute, Prague (both Czech Academy of Sciences) and Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, and equipped with AMS MIELA (Ionplus AG, Switzerland). This review summarizes history, principles, and use of this unique analytical method.

TÜBİTAK 1MV Accelerator Mass Spectrometer Designed For 14C, 10Be, 26Al, 41Ca, 129I

A 1 MV Accelerator Mass Spectrometer (AMS) was installed at TÜBİTAK, MRC Turkey in December 2015. The 1MV TÜBİTAK AMS system is based on a Pelletron tandem accelerator, operating up to 1.1MV. Built by National Electrostatics Corporation (NEC), its design was unique during production time. The TÜBİTAK 1MV AMS is based off the design of an XCAMS 0.5MV AMS also produced by NEC, but with a higher energy tandem accelerator. The higher energy accelerator features better precision (1% or less) for 10Be measurements. This new AMS also has larger magnets than the XCAMS. Larger magnets make it possible to measure 41Ca and 129I at the two-anode gas-ionization detector. In this article, the technical features; the parameters of ion source, terminal and other operations, and measurement quality are explained for accomplished performance of the five isotopic ratios, 14C/12C, 10Be/9Be, 26Al/27Al, 41Ca/40Ca, 129I/127I. The five years data for 14C/12C ratio measurement quality control are represented as well.

Cosmogenic 10Be and 26Al sample preparation at the University of Wollongong

The University of Wollongong (UOW) cosmogenic 10Be and 26Al sample preparation laboratory has been in operation since the start of 2017. As primarily a feeder laboratory to ANSTO’s Centre for Accelerator Science, our sample preparation procedures have been optimised with consideration to the setup of ANSTO’s 6MV SIRIUS accelerator, and aim to achieve a balance between sample throughput as well as Be and Al target purity. A comparatively small number of samples (n = 68) have also been prepared for measurement at the Australian National University 14UD accelerator. 10Be/9Be ratios of procedural blanks measured on SIRIUS have fluctuated over time with the median for the year 2017 being 5.16 × 10−16 (IQR = 4.11 × 10−16 to 7.16 × 10−16, n = 18), increasing to 1.62 × 10−15 (IQR = 1.05 × 10−15 to 2.17 × 10−15, n = 31) for 2018 and 2019, a period coinciding with elevated boron levels in our samples, and finally decreasing to 1.15 × 10−15 (IQR = 8.63 × 10−16 to 1.60 × 10−15, n = 34) for 2020 and 2021. In contrast, 26Al/27Al ratios of procedural blanks measured on SIRIUS have shown a slight but continuous improvement over time with the median for 2017 of 1.70 × 10−15 (IQR = 8.19 × 10−16 to 5.25 × 10−15, n = 12) decreasing to 1.07 × 10−15 (IQR = 8.5 × 10−16 to 1.53 × 10−15, n = 13) for 2021. Median 10Be/9Be relative uncertainty of procedural blanks analysed on SIRIUS is 18 % (IQR = 15 % to 22 %; n = 86) whereas the median 26Al/27Al relative uncertainty of procedural blanks is higher at 60 % (IQR = 41 % to 100 %; n = 56), statistic resulting from most blanks yielding low 26Al counts (median = 2; IQR = 1–4.5). Average 9BeO− output relative to standard is between ∼ 70 % – 80 % for samples analysed on SIRIUS (n = 895) and ∼ 130 % for samples analysed at ANU (n = 68). 27Al− output relative to standard is lower for samples pressed into cathodes at UOW (∼60 %, n = 432) and analysed on SIRIUS than for those pressed at ANSTO (∼90 %, n = 119). Average 27Al− output relative to standard for samples analysed at ANU is ∼ 80 % (n = 62). 10Be and 26Al measurements of various laboratory intercomparison materials prepared at UOW between 2017 and 2022 yield results in agreement with consensus values confirming that our chemistry procedures are robust and in line with those elsewhere.

Optimization of 10Be measurements at the 6 MV AMS facility DREAMS

We investigated benefits from raising the ion beam energy during measurements of 10Be with Accelerator Mass Spectrometry (AMS) at the 6MV DREAMS (DREsden AMS) facility. Increasing the terminal voltage to ≥5MV hardly reduces the yield of the Be2+ charge state after the accelerator if one applies only a thin Ar gas stripper and makes use of an overpopulation of the 2+ charge state with respect to the expected equilibrium charge state yield. As a further stripping to the 4+ charge state is conducted in a degrader foil after the analysing magnet, it is desirable to hit the foil with the highest available velocity in order to have optimal stripping of Be2+ to the fully stripped ion. At DREAMS the 10Be yield can be improved by a factor of 1.36. Applying a terminal voltage of 5.8MV the transport efficiency of 10Be from the ion source to the detector is ca. 32.5%.