Accelerator Mass Spectrometry Technique Research Articles

The Arpu Kuilpu meteorite: In‐depth characterization of an H5 chondrite delivered from a Jupiter Family Comet orbit

AbstractOver the Nullarbor Plain in South Australia, the Desert Fireball Network detected a fireball on the night of June 1, 2019 (7:30 pm local time), and 6 weeks later recovered a single meteorite (42 g) named Arpu Kuilpu. This meteorite was then distributed to a consortium of collaborating institutions to be measured and analyzed by a number of methodologies including SEM‐EDS, EPMA, ICP‐MS, gamma‐ray spectrometry, ideal gas pycnometry, magnetic susceptibility measurement, μCT, optical microscopy, and accelerator and noble gas mass spectrometry techniques. These analyses revealed that Arpu Kuilpu is an unbrecciated H5 ordinary chondrite, with minimal weathering (W0‐1) and minimal shock (S2). The olivine and pyroxene mineral compositions (in mole%) are Fa: 19.2 ± 0.2 and Fs: 16.8 ± 0.2, further supporting the H5 type and class. The measured oxygen isotopes are also consistent with an H chondrite (δ17O‰ = 2.904 ± 0.177; δ18O‰ = 4.163 ± 0.336; Δ17O‰ = 0.740 ± 0.002). Ideal gas pycnometry measured bulk and grain densities of 3.66 ± 0.02 and 3.77 ± 0.02 g cm−3, respectively, yielding a porosity of 3.0% ± 0.7. The magnetic susceptibility of this meteorite is log χ = 5.16 ± 0.08. The most recent impact‐related heating event experienced by Arpu Kuilpu was measured by 40Ar/39Ar chronology to be 4467 ± 16 Ma, while the cosmic ray exposure age is estimated to be between 6 and 8 Ma. The noble gas isotopes, radionuclides, and fireball observations all indicate that Arpu Kuilpu's meteoroid was quite small (maximum radius of 10 cm, though more likely between 1 and 5 cm). Although this meteorite is a rather ordinary ordinary chondrite, its prior orbit resembled that of a Jupiter Family Comet (JFC) further lending support to the assertion that many cm‐ to m‐sized objects on JFC orbits are asteroidal rather than cometary in origin.

MONITORING OF MODERN CARBON FRACTION IN DISPOSABLE PACKAGING

ABSTRACT Radiocarbon (14C) methodology was used to investigate the presence of biocarbon in different bio-based disposable packaging products. Packaging waste contributes to a municipal solid waste, which is increasing environmental concerns and resulting in the enhancement of EU regulations that aim to reduce packaging waste. The 14C amount in samples reflects how much of the biocarbon has been used. In this study, the concentration of 14C was determined in commonly used types of disposable packaging, such as cups, plates, straws, cutlery, and baking paper. Samples were made of materials such as paper, wheat bran, sugarcane, and wood. The mean concentration of the 14C isotope, measured by the accelerator mass spectrometry (AMS) technique, is greater than 100 pMC in all tested samples, indicating that the samples are modern. The relatively high 14C concentration values in the waterproof layer of the sample indicate that bioplastic, rather than plastic, was used in its production. The highest 14C isotope concentration values were measured for samples that used the oldest biomass (wood and paper), and the lowest for products from current crops (sugarcane and wheat bran), which is consistent with the trend of changes in 14C concentration in the biosphere. The study also addresses the problem of heterogeneity and representativeness of subsamples.

Accelerator mass spectrometry measurements of 233U in groundwater, soil and vegetation at a legacy radioactive waste site

Low-level radioactive wastes were disposed at the Little Forest Legacy Site (LFLS) near Sydney, Australia between 1960 and 1968. According to the disposal records, 233U contributes a significant portion of the inventory of actinide activity buried in the LFLS trenches. Although the presence of 233U in environmental samples from LFLS has been previously inferred from alpha-spectrometry measurements, it has been difficult to quantify because the 233U and 234U α-peaks are superimposed. Therefore, the amounts of 233U in groundwaters, soils and vegetation from the vicinity of the LFLS were measured using accelerator mass spectrometry (AMS). The AMS results show the presence of 233U in numerous environmental samples, particularly those obtained within, and in the immediate vicinity of, the trenched area. There is evidence for dispersion of 233U in groundwater (possibly mobilised by co-disposed organic liquids), and the data also suggest other sources of 233U contamination in addition to the trench wastes. These may include leakages and spills from waste drums as well as waste burnings, which also occurred at the site. The AMS results confirm the historic information regarding disposal of 233U in the LFLS trenches. The AMS technique has been valuable to ascertain the distribution and environmental behaviour of 233U at the LFLS and the results demonstrate the applicability of AMS for evaluating contamination of 233U at other radioactive waste sites.

RETREATMENT OF BONE MATERIAL IN THE GLIWICE RADIOCARBON LABORATORY USING ULTRAFILTRATION

ABSTRACTPreparation of bones for radiocarbon (14C) dating is still quite a challenge for researchers. The methods are being tested and improved, to increase reliability of dating results and to verify the previous ones. In this work, a set of gelatine samples, extracted from Cervus elaphus and Cervus canadensis bones from various sites in Europe and a set of human bones from archaeological sites in Poland were subjected to retreatment using ultrafiltration in Gliwice Radiocarbon Laboratory. The tested samples represent a wide range of ages, from older than 40,000 14C years BP to modern. The prepared material was subjected to the measurement of C/N atomic ratios and 14C dating using the accelerator mass spectrometry (AMS) technique. Also, the stable isotopes (δ13C and δ15N) values were determined. In a few cases ultrafiltration allows to improve gelatine quality for long-stored samples, by increasing the %C and %N as well as decreasing C/Nat ratios. Nevertheless, this effect was not observed for majority of the samples. Remeasurements of long-term stored samples give mostly the same 14C ages for ultrafiltered ones and for those without ultrafiltration.

Improved method for calculating CO2 emission from industrial solid wastes combustion system based on fossil and biogenic carbon fraction

Waste-to-Energy (WtE) technology is the most effective solution for managing non-recyclable wastes through mass burning and energy recovery. Owing to the significant volumes of plastics in China’s industrial solid wastes (ISW), a large amount of greenhouse gases (GHG) is generated during the incineration process. Therefore, monitoring GHG emissions from WtE facilities is essential. Owing to the lack of suitable accounting models and characterized fossil carbon fraction (FCF) data, current studies use default values provided by the Intergovernmental Panel on Climate Change’s (IPCC), which increases calculation inaccuracies. Therefore, this study established an improved method to accurately account for carbon emissions during solid waste incineration by firstly using radiocarbon dating by accelerator mass spectrometry (AMS) technique to determine the FCF of the solid waste components in China. Monte Carlo analysis was employed to perform the sensitivity analysis, and the results indicated that there was a significant deviation between the measured value and IPCC’s default values of FCF, 3.2, 32.48, 93.39, 93.76, 90.49, and 93.8 % for paper, cotton, synthetic textiles, artificial rubber, artificial leather, and plastics, respectively. By replacing coal with ISW in a 2 × 110 t/h circulating fluidized bed boilers, 9.251 × 104 t CO2-eq emissions were reduced, and the carbon emission factor reached 0.56 t CO2-eq/t waste. This study complements the research gap fossil carbon data of wastes in the IPCC guidelines and provides a more accurate and effective way to calculate carbon emissions during ISW incineration treatment.

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.

Comparison of AMS, TIMS, and SIMS techniques for determining uranium isotope ratios in individual particles.

The determination of isotope ratios in individual uranium particles is very important for nuclear safeguards. In this work, accelerator mass spectrometry (AMS), thermal ionization mass spectrometry (TIMS), and secondary ion mass spectrometry (SIMS) were applied to isotope ratio analysis of individual uranium particles and compared in terms of background, measurement accuracy, and efficiency. Several individual uranium particles (1-7μm) from certified reference materials were used as samples. The results show that the average values of blank counting rate of 235 U for AMS, FT-TIMS (FT: fission track), SEM-TIMS (SEM: scanning electron microscope), and SIMS were 7.3, 7.8, 2.7 and 2.2cps, respectively. The relative error of 234 U/235 U and 234 U/236 U isotope ratios of the particles from U200 for AMS were within 10% and 20%, whereas the results of FT-TIMS and SIMS were within 5% and 10%, respectively. The relative error and external precision of 234 U/238 U and 235 U/238 U of the particles from U850 for the method of AMS, SEM-TIMS, and SIMS were within 10% and 5%, respectively. For 236 U/238 U, the average values of the relative error and external precision measured by AMS were within 5%, which measured by SEM-TIMS and SIMS were all within 10%. AMS has advantages in measuring 236 U/238 U. The measurement time of AMS and SEM-TIMS was shorter than that of FT-TIMS and longer than that of SIMS. It is considered that AMS and SEM-TIMS have a certain development prospect, and it is necessary to research deeply.

AMS 14C ages determination of the late Holocene Pilas, Mula and Cabeza de Vaca monogenetic volcanoes, Nicaragua

Here we present six new 14C ages using the accelerator mass spectrometry (AMS) technique for five samples of paleosol and one charcoal collected from the central part of the Maribios volcanic mountain range, located in the northwestern part of Nicaragua. This region is part of the Nicaraguan active volcanic arc characterized by the occurrence of a historic eruption that gave rise to the “birth” of the Cerro Negro volcano in 1850 CE. The young relief and the new 14C ages obtained in this work reveal that three other Holocene eruptions had recently occurred before the growth of the Cerro Negro volcano in this region. These volcanic events were independently established from an emission vent with simultaneous Strombolian explosions to dominantly effusive eruptions, forming extensive lava flows and associated scoria cones of the Cabeza de Vaca, Mula, and Pilas monogenetic volcanoes. AMS radiocarbon dating from charcoal and paleosols underlying these deposits yielded maximum ages of 1050 ± 30 years BP for Cabeza de Vaca volcano, 860 ± 30 yrs BP for Mula volcano, and 520 ± 15 yrs BP for Pilas volcano. These results of AMS 14C analyses provide reliable age ranges of 990–1025 cal yr AD for Cabeza de Vaca volcano, 1166–1220 cal yrs AD for Mula volcano, and 1410–1424 cal yrs AD for Pilas volcano.

The 41Ar(n,y)42Ar reaction

The cross-section of the thermal neutron capture 41Ar(n,γ)42Ar(t1/2=32.9 y) reaction was measured by irradiating a 40Ar sample at the high-flux reactor of Institut Laue-Langevin (ILL) Grenoble, France. The signature of the two-neutron capture has been observed by measuring the growth curve and identifying the 1524.6 keV γ-lines of the shorter-lived 42K(12.4 h) β− daughter of 42Ar. Our preliminary value of the 41Ar(n,γ)42Ar thermal cross section is 240(80) mb at 25.3 meV. For the first time, direct counting of 42Ar was performed using the ultra-high sensitivity technique of noble gas accelerator mass spectrometry (NOGAMS) at Argonne National Laboratory, USA.

STUDY OF BIO-BASED CARBON FRACTIONS IN TIRES AND THEIR PYROLYSIS PRODUCTS

ABSTRACTWasted tires are the great source of fuel and valuable components but could be a cause of environmental and land pollution. This study shows the detailed method for the determination of radiocarbon isotope (14C) concentration in tires and their pyrolysis products. Samples are taken from truck and passenger car tires in the form of shredded rubber, pyrolysis oil and recovered carbon black. Liquid scintillation counting (LSC) and accelerator mass spectrometry (AMS) techniques were used for the investigation at Gliwice Radiocarbon and Mass Spectrometry Laboratory, and National Laboratory for Age Determination, Trondheim, Norway. The results are in good agreement. Radiocarbon concentration of the rubber varies significantly because of its complex structure and composition within the tires. The 14C concentration values were found to be higher in pyrolytic oil compared to rubber, and greater in truck tires rather than car tires.

RUDJER BOŠKOVIĆ INSTITUTE RADIOCARBON MEASUREMENTS XVIII

ABSTRACTIn this paper we present dating of archaeological samples from Croatia only performed since our last reports (Obelić et al. 2011; Horvatinčić et al. 2012). Liquid scintillation radiometric measurement technique with benzene synthesis (LSC-B) and accelerator mass spectrometry (AMS) technique were applied.

Investigation of target materials for low energy accelerator mass spectrometry of 26Al

The Aluminum-26 accelerator mass spectrometry (AMS) technique has been widely applied in many scientific fields. At present, Al2O3 is routinely used as the target material for Al− extractions. However, the lower Al− ion beam current limits the measurement sensitivity. In this study, a series of experiments on Al− ion beam current, conductive agent, and interference background were carried out based on previous research and the low-energy AMS system of Tianjin University. The results showed that AlN as a potential target material to replace Al2O3 is worth further study, while Mg element is still one of the main interference factors for low-energy 26Al-AMS.

A preliminary study of rapid measurements of aqueous 210Po by accelerator mass spectrometry

This study covers the preliminary assessment of a novel accelerator mass spectrometry technique for rapid quantitation of polonium-210 in water samples.

RADIOCARBON IN MEXICO: FROM PROPORTIONAL COUNTERS TO AMS

ABSTRACTAugusto Moreno is credited with establishing the first radiocarbon (14C) laboratory in Mexico in the 1950s, however, 14C measurement with the accelerator mass spectrometry (AMS) technique was not achieved in our country until 2003. Douglas Donahue from the University of Arizona, a pioneer in using AMS for 14C dating, participated in that experiment; then, the idea of establishing a 14C AMS laboratory evolved into a feasible project. This was finally reached in 2013, thanks to the technological developments in AMS and sample preparation with automated equipment, and the backing and support of the National Autonomous University of Mexico and the National Council for Science and Technology. The Mexican AMS Laboratory, LEMA, with a compact 1 MV system from High Voltage Engineering Europa, and its sample preparation laboratories with IonPlus automated graphitization equipment, is now a reality.

236U/238U Analysis of Femtograms of 236U by MC-ICPMS.

A new analytical method has been developed to determine atomic 236U/238U ratios in samples with only femtograms of 236U using a secondary electron multiplier (SEM) on a multicollector high-resolution inductively coupled plasma mass spectrometer (MC-ICPMS). The abundance sensitivity of the 238U tail at 236 atomic mass unit is reduced from 10-6 to 10-10 with the deployment of a retarding potential quadrupole lens. This method features the reduction of polyatomic interferences from hydride, nitride, lead, and plutonium and the evaluation of nonlinear SEM behavior. The instrument sensitivity is 1-2%, and the estimated methodological detection limit of the 236U/238U atomic ratio is as low as 2 × 10-10. Measurements on reference materials with 236U/238U ratios of 10-7-10-9, including the IRMM-075 series and the ETH Zurich in-house standard ZUTRI, demonstrate the accuracy of our MC-ICPMS technique. The analytical precisions (2σ) are ±4% for 5 fg of 236U at a 236U/238U of 1 × 10-8 and ±8% for 2 fg of 236U at a 236U/238U of 4 × 10-9 level. Compared to state-of-the-art accelerator mass spectrometry techniques and triple quadrupole-based ICPMS, our detection limit is not as low, but the required sample size is 3-40 times lower, and the throughput is as high as 3-4 samples per hour. The new MC-ICPMS-SEM technique is sensitive enough for determining 236U/238U in various small natural samples, such as marine carbonates and seawater.

Prehistoric charcoal drawings in the caves in the Slovak Republic, Central Europe: Successful radiocarbon dating by a micro-sample 14C AMS

In Central Europe, only a few caves with ancient drawings on the walls are known. During the past years, simple lines and sketches made of charcoal or smearing traces from torches are found mainly in less accessible locations in some caves of the Slovak Karst. Previous attempts to date these findings were unsuccessful since the painted layers were too thin to allow sampling and enable routine AMS dating. Now the application of the small mass radiocarbon accelerator mass-spectrometry (AMS) technique developed at the Australian Nuclear Science and Technology Organisation (ANSTO) made possible successful 14C determinations for a set of cave drawings and markings from the Slovak Karst. This research confirmed the prehistoric/protohistoric nature of the drawings/sketches in Čikova Diera, Silická Ľadnica, Ardovská and Domica Caves. Moreover, this research widens the scope for prehistoric rock art dating, one of the major constrains in rock art studies.

P165 - Improved on-line accelerator mass spectrometry techniques for the analysis of environmental chemicals at ultra-low exposure levels

P165 - Improved on-line accelerator mass spectrometry techniques for the analysis of environmental chemicals at ultra-low exposure levels

236U identification in the new AMS beamline at the TANDAR accelerator

236U (T1/2 = 23 My) is an excellent monitor for nuclear contamination in the environment. Indeed, spent nuclear fuels present isotopic ratios 236U/238U several orders of magnitude higher than natural samples. 236U also provides a useful fingerprint to identify and trace nuclear material for safeguards purposes. Here we describe a new beamline for the discrimination of 236U using the accelerator mass spectrometry (AMS) technique. This system comprises a Wien velocity filter and a 6.7 m long time-of-flight (ToF) path with a focusing quadrupole. The ToF is determined by a time zero detector and a surface barrier detector, which also provides an energy measurement. The capability of the system to discriminate 236U from the much more abundant isotopes 235U and 238U is shown. While sensitivity values of 236U/238U∼ 10−8 were achieved, ongoing works aim to improve this performance.

Monitoring the biogenic fraction of sugarcane-based plastic bags

For environmental reasons, the production of plastic from renewable sources is gaining importance worldwide. In the case of polyethylene made from sugarcane-based ethanol, Brazil, being the world leader in sugarcane production, plays a fundamental role. Nevertheless, the absence of national regulations for monitoring the manufacturing process or verifying the biogenic fraction of what is already on the market raises concerns in Brazil. The main reason for the lack of such regulations is that the only approach fully capable of distinguishing identical chemical compounds of biogenic or fossil origin is the measurement of radiocarbon concentrations using an expensive and time-consuming method. Nevertheless, the measurement of stable carbon isotopes ratios has proven to be an acceptable approach to distinguish between C4 plant-derived plastics and petroleum-derived plastics. The present study compares the potential of the conventional mass spectrometry and radiocarbon accelerator mass spectrometry techniques as tools to determine the biogenic fraction of green polyethylene in Brazil. For plastics derived from either corn or sugarcane sources, δ13C values less negative than −20‰ indicate biofractions of 51% or higher. Other values would indicate the need to follow up to the radiocarbon accelerator mass spectrometry measurement, since it would not be possible to distinguish between lower biofractions and the presence of wheat or soy. The conventional mass spectrometry method can be employed for the preliminary screening of bio-based materials in manufacturing industries, representing a relatively cheap and accessible way of inspecting these products in developing countries.

Radiocarbon Dating of Historical bricks: Exploring the unprotected archaeological mounds in the environs of excavated site of Nalanda

Nalanda was a renowned Buddhist monastery which is believed to have been active for 800 years from around 4th/5th to 12th centuries AD. We know about the site from the accounts of 7th century Chinese traveler (Xuanzang) and later from 19th century British surveyors (Buchanan, Cunningham and Broadley). There are many studies on this site, recent one among them is a geospatial analysis which has revealed a larger extent (~7.25 sq. km) of the site compared to what is protected at present as World Heritage (WH) inscribed by UNESCO (0.23 sq. km. as core zones and 0.58 sq. km. as buffer zone) and has identified several unprotected archaeological mounds in the vicinity. Since we have a range of period when the site was active, it is possible that the dates of structures in each unexcavated mound are decades or centuries apart. To understand the time sequence in which the site existed one could use absolute dating method. This paper reports result of preliminary dating analysis using the Accelerator Mass Spectrometry (AMS) technique on bricks collected from unprotected mounds in the environs of Nalanda. This paper also reports methods and issues in sample collection, preparation and discusses challenges to overcome in future efforts.