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Accelerator mass spectrometry analyses of environmental radionuclides: sensitivity, precision and standardisation
(Elsevier, 2000-10-01) Hotchkis, MAC; Fink, D; Tuniz, C; Vogt, S
Accelerator Mass Spectrometry (AMS) is the analytical technique of choice for the detection of long-lived radionuclides which cannot be practically analysed with decay counting or conventional mass spectrometry. AMS allows an isotopic sensitivity as low as one part in 1015 for 14C (5.73 ka), 10Be (1.6 Ma), 26Al (720 ka), 36Cl (301 ka), 41Ca (104 ka), 129I (16 Ma) and other long-lived radionuclides occurring in nature at ultra-trace levels. These radionuclides can be used as tracers and chronometers in many disciplines: geology, archaeology, astrophysics, biomedicine and materials science. Low-level decay counting techniques have been developed in the last 40–50 years to detect the concentration of cosmogenic, radiogenic and anthropogenic radionuclides in a variety of specimens. Radioactivity measurements for long-lived radionuclides are made difficult by low counting rates and in some cases the need for complicated radiochemistry procedures and efficient detectors of soft β-particles and low energy x-rays. The sensitivity of AMS is unaffected by the half-life of the isotope being measured, since the atoms not the radiations that result from their decay, are counted directly. Hence, the efficiency of AMS in the detection of long-lived radionuclides is 106–109 times higher than decay counting and the size of the sample required for analysis is reduced accordingly. For example, 14C is being analysed in samples containing as little as 20 μg carbon. There is also a world-wide effort to use AMS for the analysis of rare nuclides of heavy mass, such as actinides, with important applications in safeguards and nuclear waste disposal. Finally, AMS microprobes are being developed for the in-situ analysis of stable isotopes in geological samples, semiconductors and other materials. Unfortunately, the use of AMS is limited by the expensive accelerator technology required, but there are several attempts to develop compact AMS spectrometers at low (⩽0.5 MV) terminal voltages. Recent advances in AMS will be reviewed with highlights from the scientific programs at Lucas Heights and other AMS centres. © 2000 Elsevier Science Ltd.
AMS support for Australian prehistory research
(Australian Institute of Physics, 1998-04-01) Lawson, EM
The major use of ANTARES is Accelerator Mass Spectrometry (AMS) with 14C being the most commonly analysed radioisotope - presently about 35% of the available beam time on ANTARES is used for 14C measurements. The accelerator measurements are supported by, and dependent on, a strong sample preparation section. The ANTARES AMS facility supports a wide range of investigations into fields such as global climate change, ice cores, oceanography, dendrochronology, anthropology, and classical and Australian archaeologgy. Described here are some examples of the ways in which AMS has been applied to support the research into the archaeology, prehistory and culture of this continent's indigenous Aboriginal peoples.
The ANSTO isotope cycling system
(Cambridge University Press, 2016-02-09) Watt, GC; Boronkay, S; Smith, AM; Hotchkis, MAC
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. © 2013 Arizona Board of Regents on behalf of the University of Arizona
The ANTARES AMS Centre : a status report
(Cambridge University Press, 2016-07-18) Tuniz, C; Fink, D; Hotchkis, MAC; Jacobsen, GE; Lawson, EM; Smith, AM; Hua, Q; Drewer, P; Lee, P; Levchenko, VA; Bird, R; Boldeman, JW; Barbetti, M; Taylor, G; Head, J
The ANTARES accelerator mass spectrometry facility at Lucas Heights Research Laboratory is operational and AMS measurements of 14C, 26Al and 36Cl are being carried out routinely. Measurement of 129I recently commenced and capabilities for other long-lived radioisotopes such as 10Be are being established. The overall aim of the facility is to develop advanced programs in Quaternary science, global climate change, biomedicine and nuclear safeguards. © the Department of Geosciences, The University of Arizona
The application of pollen radiocarbon dating and bayesian age-depth modeling for developing robust geochronological frameworks of wetland archives
(Cambridge University Press for the Arizona Board of Regents on behalf of the University of Arizona, 2022-04-27) Cadd, H; Sherborne-Higgins, B; Becerra-Valdivia, L; Tibby, J; Barr, C; Forbes, MS; Cohen, TJ; Tyler, JJ; Vandergoes, MJ; Francke, A; Lewis, RJ; Jacobsen, GE; Marjo, CE; Turney, CSM; Arnold, LJ
Wetland sediments are valuable archives of environmental change but can be challenging to date. Terrestrial macrofossils are often sparse, resulting in radiocarbon (14C) dating of less desirable organic fractions. An alternative approach for capturing changes in atmospheric 14C is the use of terrestrial microfossils. We 14C date pollen microfossils from two Australian wetland sediment sequences and compare these to ages from other sediment fractions (n = 56). For the Holocene Lake Werri Berri record, pollen 14C ages are consistent with 14C ages on bulk sediment and humic acids (n = 14), whilst Stable Polycyclic Aromatic Carbon (SPAC) 14C ages (n = 4) are significantly younger. For Welsby Lagoon, pollen concentrate 14C ages (n = 21) provide a stratigraphically coherent sequence back to 50 ka BP. 14C ages from humic acid and >100 µm fractions (n = 13) are inconsistent, and often substantially younger than pollen ages. Our comparison of Bayesian age-depth models, developed in Oxcal, Bacon and Undatable, highlight the strengths and weaknesses of the different programs for straightforward and more complex chrono-stratigraphic records. All models display broad similarities but differences in modeled age-uncertainty, particularly when age constraints are sparse. Intensive dating of wetland sequences improves the identification of outliers and generation of robust age models, regardless of program used. © The Author(s), 2022. Published by Cambridge University Press for the Arizona Board of Regents on behalf of the University of Arizona
Applications of accelerator physics and ANSTO
(Australian Institute of Physics, 1998-04) Tuniz, C
The Australian Nuclear Science and Technology Organisation (ANSTO) is involved in advanced research programs based on the use of nuclear science and technology for materials microanalysis. This paper is a review of accelerator-based probes to characterise environmental, biological, and industrial materials. Most examples are inspired by the ANSTO research program.
Compatibility of atmospheric 14CO2 measurements: comparing the heidelberg low-level counting facility to international accelerator mass spectrometry (AMS) laboratories
(Cambridge University Press, 2016-09-19) Hammer, S; Friedrich, R; Kromer, B; Cherkinsky, A; Lehman, SJ; Meijer, HAJ; Nakamura, T; Palonen, V; Reimer, RW; Smith, AM; Southen, JR; Szidat, S; Turnbull, J; Uchida, M
Combining atmospheric Δ14CO2 data sets from different networks or laboratories requires secure knowledge on their compatibility. In the present study, we compare Δ14CO2 results from the Heidelberg low-level counting (LLC) laboratory to 12 international accelerator mass spectrometry (AMS) laboratories using distributed aliquots of five pure CO2 samples. The averaged result of the LLC laboratory has a measurement bias of –0.3±0.5‰ with respect to the consensus value of the AMS laboratories for the investigated atmospheric Δ14C range of 9.6 to 40.4‰. Thus, the LLC measurements on average are not significantly different from the AMS laboratories, and the most likely measurement bias is smaller than the World Meteorological Organization (WMO) interlaboratory compatibility goal for Δ14CO2 of 0.5‰. The number of intercomparison samples was, however, too small to determine whether the measurement biases of the individual AMS laboratories fulfilled the WMO goal. © 2016 by the Arizona Board of Regents on behalf of the University of Arizona
Cosmic-ray exposure history of the Norton County enstatite achondrite
(Wiley, 2011-01-28) Herzog, GF; Albrecht, A; Ma, P; Fink, D; Klein, J; Middleton, R; Bogard, DD; Nyquist, LE; Shih, CY; Garrison, DH; Reese, Y; Masarik, J; Reedy, RC; Rugel, G; Faestermann, T; Korschinek, G
We report measurements of cosmogenic nuclides in up to 11 bulk samples from various depths in Norton County. The activities of 36Cl, 41Ca, 26Al, and 10Be were measured by accelerator mass spectrometry; the concentrations of the stable isotopes of He, Ne, Ar, and Sm were measured by electron and thermal ionization mass spectrometry, respectively. Production rates for the nuclides were modeled using the LAHET and the Monte Carlo N-Particle codes. Assuming a one-stage irradiation of a meteoroid with a pre-atmospheric radius of approximately 50 cm, the model satisfactorily reproduces the depth profiles of 10Be, 26Al, and 53Mn (<6%) but overestimates the 41Ca concentrations by about 20%. 3He, 21Ne, and 26Al data give a one-stage cosmic-ray exposure (CRE) age of 115 Ma. Argon-36 released at intermediate temperatures, 36Arn, is attributed to production by thermal neutrons. From the values of 36Arn, an assumed average Cl concentration of 4 ppm, and a CRE age of 115 Ma, we estimate thermal neutron fluences of 1–4 × 1016 neutrons cm−2. We infer comparable values from ε149Sm and ε150Sm. Values calculated from 41Ca and a CRE age of 115 Ma, 0.2–1.4 × 1016 neutrons cm−2, are lower by a factor of approximately 2.5, indicating that nearly half of the 149Sm captures occurred earlier. One possible irradiation history places the center of proto-Norton County at a depth of 88 cm in a large body for 140 Ma prior to its liberation as a meteoroid with a radius of 50 cm and further CRE for 100 Ma. © The Meteoritical Society, 2011
Equipment and methodology for high precision, high throughput 14C AMS analyses at ANTARES
(Elsevier, 1994-06-03) Smith, AM; Fink, D; Hotchkis, MAC; Jacobsen, GE; Lawson, EM; Shying, ME; Tuniz, C; Watt, GC; Fallon, J; Ellis, PJ
The original Rutgers FN tandem accelerator has been modified for high-precision high-throughput AMS analyses at the ANTARES AMS Center. The status of this work and future plans are discussed, with emphasis on 14C. Isotopic ratios are measured at ANTARES by sequentially injecting stable isotopes and the radioisotope, and the systems developed for this purpose are described. Progress with a new injection platform and high intensity, multi-sample ion source is also given. © 1994 Elsevier B.V.
High sensitivity analysis of plutonium isotopes in environmental samples using accelerator mass spectrometry (AMS)
(Royal Society of Chemistry, 2008-02-28) Child, DP; Hotchkis, MAC; Williams, ML
This article presents a methodology for the determination of the concentration and isotopic ratio of plutonium occurring at femtogram levels in environmental matrices such as soils and sediments by accelerator mass spectrometry (AMS). Results on analyses of a number of reference materials ( IAEA-375, IAEA-135, IAEA-300, IAEA-327, NIST 4350, NIST 4353b) are presented as validation of the method in reproducibly measuring the plutonium isotopic ratio Pu-240 : Pu-239 in a variety of environmental sample matrices. © 2008, Royal Society of Chemistry
The instrument suite of the European Spallation Source
(Elsevier B. V., 2020-01-10) Andersen, KH; Argyriou, DN; Jackson, AJ; Houston, J; Henry, PF; Deen, PP; Toft-Petersen, R; Beran, P; Strobl, M; Arnold, T; Wacklin-Knecht, H; Vivanco, R; Parker, SF; Gussen, A; Kanaki, K; Scionti, G; Olsen, MA; Arai, M; Schmakat, Ph; Lechner, RE; Niedermayer, Ch; Schneider, H; Zanetti, M; Petrillo, C; Moreira, FY; Stepanyan, S; Luna, P; Calzada, E; Stahn, J; Voigt, J; Dupont, T; Hanslik, R; Siemers, DJ; Udby, L; Chowdhury, MAH; Klauser, Ch; Rouijaa, M; Lehmann, E; Heynen, A; Bustinduy, I; Schwaab, A; Raspino, D; Scatigno, C; del Moral, OG; Kiehn, R; Aprigliano, G; Zanatta, M; Huerta, M; Bellissima, S; Lerche, M; Holm-Dahlin, S; Huerta, M; Christensen, NB; Lohstroh, W; Gorini, G; Fenske, J; Hansen, UB; Klauser, C; Rodrigues, S; Müller, M; Gorini, G; Bovo, C; Hall-Wilton, R; Fabrèges, X; Siemers, DJ; Khaplanov, A; Tsapatsaris, N; Taylor, J; Christensen, M; Schefer, J; Woracek, R; Tozzi, P; Müller, M; Carlsen, H; Olsen, MA; Orecchini, A; Di Fresco, L; Paciaroni, A; Bovo, C; Magán, M; Hauback, BC; Elmer, J; Heenan, RK; Piscitelli, F; Masi, F; Bakedano, G; Klimko, S; De Bonis, A; Fedrigo, A; Lukáš, P; Frielinghaus, H; Stahn, J; Schweika, W; Markó, M; Pfeiffer, D; Kirstein, O; Di Fresco, L; Schreyer, A; Orszulik, A; Nowak, G; Butterweck, S; Šaroun, J; Paciaroni, A; Kolevatov, R; Lehmann, EH; Filges, U; Schreyer, A; Koenen, M; Bustinduy, I; Magán, M; Feygenson, M; Cooper, JFK; Abad, E; Senesi, R; Longeville, S; Llamas-Jansa, I; Schulz, M; Birk, JO; Sharp, M; Galsworthy, P; Šaroun, J; Martínez, J; Hiess, A; Holm-Dahlin, S; Filges, U; Pullen, SA; Guyon Le Bouffy, J; Schefer, J; Lukáš, P; Udby, L; Kozielewski, T; Niedermayer, C; Sacchetti, F; Hartl, M; Jaksch, S; Salhi, Z; Brückel, T; Aguilar, J; Aguilar, J; Seifert, M; Bordallo, HN; Robillard, T; Villacorta, FJ; Herranz, I; del Rosso, L; Hauback, BC; Orecchini, A; Fabrèges, G; Fenske, J; Neuhaus, J; Schillinger, B; Abad, E; Kittelmann, T; Lefmann, K; Seifert, M; Neuhaus, J; Herranz, I; Kolevatov, R; Annighöfer, B; Oksanen, E; Morgano, M; Laszlo, G; Freeman, PG; Kennedy, SJ; Bertelsen, M; Bellissima, S; Alba-Simionesco, C; Markó, M; Mezei, F; Chowdhury, M; Halcrow, W; Jestin, J; Lieutenant, K; Babcock, E; Rønnow, HM; Engels, R; del Moral, OG; Vickery, A; Rouijaa, M; Lavie, P; Petersson Årsköld, S; Glavic, A; Désert, S; Mannix, D; Scatigno, C; Petry, W; Christensen, NB; Violini, N; Villacorta, FJ; Porcher, F; Glavic, A; Scionti, G; Zanetti, M; Fernandez-Alonso, F; Rønnow, HM; Mosconi, M; Olsson, M; Stepanyan, S; Petrillo, C; del Rosso, L; Harbott, P; Sacchetti, F; Bertelsen, M; Kämmerling, H; Andreani, C; Schulz, M; Colognesi, D; Luna, P; Loaiza, L; Turner, D; Martínez, JL; Tartaglione, A; Sordo, F; Llamas-Jansa, I; Schmakat, P; Lechner, RE; Poqué, A; Fernandez-Alonso, F; Colognesi, D; Tartaglione, A; Morgano, M; Webb, N; Loaiza, L; Whitelegg, L; Petry, W; Iversen, K; Vivanco, R; Tozzi, P; Goukassov, A; Schillinger, B; Carlsen, H; Masi, F; Christensen, M; Nowak, G; Nightingale, J; Schütz, S; Lopez, CI; Langridge, S; Schütz, S; Nagy, G; Zanatta, M; Andreani, C; Lefmann, K; Lohstroh, W; Mosconi, M; Senesi, R; Stefanescu, I; Bakedano, G; Hagen, ME; Wischnewski, A; Bourges, P; Hansen, UB; De Bonis, A; Kiehn, R; Parker, SF; Iversen, K; Sordo, F; Freeman, PG; Birk, JO; Rodríguez, DM; Ansell, S
An overview is provided of the 15 neutron beam instruments making up the initial instrument suite of the European Spallation Source (ESS), and being made available to the neutron user community. The ESS neutron source consists of a high-power accelerator and target station, providing a unique long-pulse time structure of slow neutrons. The design considerations behind the time structure, moderator geometry and instrument layout are presented. The 15-instrument suite consists of two small-angle instruments, two reflectometers, an imaging beamline, two single-crystal diffractometers; one for macromolecular crystallography and one for magnetism, two powder diffractometers, and an engineering diffractometer, as well as an array of five inelastic instruments comprising two chopper spectrometers, an inverse-geometry single-crystal excitations spectrometer, an instrument for vibrational spectroscopy and a high-resolution backscattering spectrometer. The conceptual design, performance and scientific drivers of each of these instruments are described. All of the instruments are designed to provide breakthrough new scientific capability, not currently available at existing facilities, building on the inherent strengths of the ESS long-pulse neutron source of high flux, flexible resolution and large bandwidth. Each of them is predicted to provide world-leading performance at an accelerator power of 2 MW. This technical capability translates into a very broad range of scientific capabilities. The composition of the instrument suite has been chosen to maximise the breadth and depth of the scientific impact of the early years of the ESS, and provide a solid base for completion and further expansion of the facility. © 2020 The Authors. Published by Elsevier B.V. Open access article under the CC BY-NC-ND license.
MOSkin dosimetry for an ultra-high dose-rate, very high-energy electron irradiation environment at PEER
(Frontiers, 2024-07-30) Cayley, J; Tan, YRE; Petasecca, M; Cutajar, DL; Breslin, T; Rosenfeld, AB; Lerch, MLF
FLASH radiotherapy, which refers to the delivery of radiation at ultra-high dose-rates (UHDRs), has been demonstrated with various forms of radiation and is the subject of intense research and development recently, including the use of very high-energy electrons (VHEEs) to treat deep-seated tumors. Delivering FLASH radiotherapy in a clinical setting is expected to place high demands on real-time quality assurance and dosimetry systems. Furthermore, very high-energy electron research currently requires the transformation of existing non-medical accelerators into radiotherapy research environments. Accurate dosimetry is crucial for any such transformation. In this article, we assess the response of the MOSkin, developed by the Center for Medical Radiation Physics, which is designed for on-patient, real-time skin dose measurements during radiotherapy, and whether it exhibits dose-rate independence when exposed to 100 MeV electron beams at the Pulsed Energetic Electrons for Research (PEER) end-station. PEER utilizes the electron beam from a 100 MeV linear accelerator when it is not used as the injector for the ANSTO Australian Synchrotron. With the estimated pulse dose-rates ranging from (7.84±0.21)×105 Gy/s to (1.28±0.03)×107 Gy/s and an estimated peak bunch dose-rate of (2.55±0.06)×108 Gy/s, MOSkin measurements were verified against a scintillating screen to confirm that the MOSkin responds proportionally to the charge delivered and, therefore, exhibits dose-rate independence in this irradiation environment. © 2024 Cayley, Tan, Petasecca, Cutajar, Breslin, Rosenfeld and Lerch. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
A new method to combine IBA of fine aerosols with Radon-222 to determine source characteristic
(Elsevier, 2011-10-01) Crawford, J; Cohen, DD; Zahorowski, W; Chambers, SD; Stelcer, E
Accelerator based ion beam analysis (IBA) techniques were used to determine the elemental composition of aerosol samples from four sites near Sydney, Australia. Hourly measurements of atmospheric Radon-222 (radon) concentration were made at the same sites. We evaluate a new method for quantifying the degree of distribution of aerosol sources based on the correlation analysis of two consecutive years (2007-2008) of IBA and radon data. Seasonal cycles and trends in concentrations of key elemental constituents of the sampled aerosols are characterised, and explained in terms of the regional Sydney climatology and proximity of measurement sites to the coast. Site-to-site correlation analysis was then undertaken between elements to quantify the extent to which a source had a regional impact or was only local to a site (site-specific). This was followed by correlation analysis of elements and radon at each site to identify the degree of spatial and temporal uniformity of the source at each site. Silicon concentrations (usually associated with soil sources), were overall well correlated between three of the four sites, indicative of a regional source for three sites and a local source for the fourth site. Conversely, the highest sulfur correlations were observed between sites that were closest together. On a site-by-site basis, radon was well correlated with black carbon and potassium and particularly during winter when domestic heating constitutes a distributed source. However, in summer the correlation of radon with BC and K was poor indicating that the distribution of these sources varies over the summer fetch region. Radon was also positively correlated with silicon and titanium, but the correlation coefficient for the entire data set was smaller than for black carbon. In summer and winter, when fetch regions were constrained by the prevailing meteorology, silicon and titanium showed a better correlation with radon. A small negative correlation was seen between sodium (a marker for sea salt) and radon. Crown Copyright (C) 2011 Published by Elsevier B.V.
Physics at the Australian Nuclear Science and Technology Organisation
(Association of Asia Pacific Societies, 2015-06-01) Robinson, RA; Ionescu, M; Reinhard, MI
The Australian Nuclear Science and Technology Organisation is Australia’s nuclear national laboratory and is the prime repository of nuclear expertise in the country. It plays a key role in research, operation of major facilities,isotope production and advice to Government. It was founded in 1987, as the successor to the Australian Atomic Energy Commission, which had existed from 1952. For almost 50 years, from 1958 until 2006, the AAEC and ANSTO operated the HIFAR heavy-water reactor, the second research reactor to be established in Asia, the first after India. Initially the AAEC’s focus was on nuclear power and nuclear fuel cycle issues, but in the ANSTO era, the focus has shifted towards the technological use of nuclear methods in medicine, the environment and science more generally. © 2015, Association of Asia Pacific Physical Societies.
Prospects for the new frontiers of earth and environmental sciences
(Elsevier, 2008-08) Yokoyama, Y; Matsuzaki, H; Esat, TM
One of the major advances in environmental geochemistry, over the past two decades, has been the introduction of Accelerator-based Mass Spectrometry (AMS) for radiocarbon dating and for investigating terrestrial surface processes through trace quantities of cosmic-ray produced nuclides. During October 2006, a symposium at the University of Tokyo celebrated 50,000 hours of AMS operations at the Tokyo “Micro Analysis Laboratory, Tandem Accelerator (MALT)”. MALT is one of 10 current AMS facilities in Japan but the only one capable of analyzing multiple nuclides. More than 20 talks and over 30 posters were presented covering a diverse range of AMS studies, including, radiocarbon dating, measurements in ice cores, progress in instrumentation, and analyses of in-situ-produced nuclides. © 2008, Elsevier Ltd.
Radiocarbon production events and their potential relationship with the Schwabe cycle
(Springer Nature, 2019-11-19) Scifo, A; Kuitems, M; Neocleous, A; Pope, BJS; Miles, D; Jansma, E; Doeve, P; Smith, AM; Miyake, F; Dee, MW
Extreme cosmic radiation events occurred in the years 774/5 and 993/4 CE, as revealed by anomalies in the concentration of radiocarbon in known-age tree-rings. Most hypotheses point towards intense solar storms as the cause for these events, although little direct experimental support for this claim has thus far come to light. In this study, we perform very high-precision accelerator mass spectrometry (AMS) measurements on dendrochronological tree-rings spanning the years of the events of interest, as well as the Carrington Event of 1859 CE, which is recognized as an extreme solar storm even though it did not generate an anomalous radiocarbon signature. Our data, comprising 169 new and previously published measurements, appear to delineate the modulation of radiocarbon production due to the Schwabe (11-year) solar cycle. Moreover, they suggest that all three events occurred around the maximum of the solar cycle, adding experimental support for a common solar origin. © The Authors CC BY
Source identification of PM2.5 during the COVID-19 lockdown in Bangkok and the metropolitan region by ion beam analysis (IBA) and positive matrix factorization (PMF) techniques
(Elsevier B. V., 2023-07) Amphalop, S; Chienthavorn, O; Meesat, R; Tangpong, P; Chutichaisakda, M; Manohar, M; Wilkins, F; Sudprasert, W
PM2.5 pollution has significant impacts on human health and has been a persistent problem in Bangkok and its metropolitan area for many decades. To effectively address the issue, source identification is crucial. This study was aimed at determining the sources of PM2.5 in three regions; Pathumwan district in Bangkok, Mueang district in Samut Sakhon province, and Mueang district in Samut Prakan province. PM2.5 sampling was performed according to the Federal Reference Method (FRM). A combined total of 135 samples were collected across all three locations, over a 24-h period from December 2021 to February 2022 with 46.2 mm polytetrafluoroethylene (PTFE) membranes. The filters were analyzed using particle accelerator-based ion beam analysis techniques; Proton-induced X-ray emission, proton-induced gamma-ray emission, and proton elastic scattering analysis. Positive matrix factorization was used for source apportionment for the three locations. The results indicated that the main contributors to PM2.5 in Bangkok, Samut Prakan, and Samut Sakhon were biomass/solid waste burning (45.6%), traffic (43.7%), and construction (36.0%), respectively. These preliminary findings further supported the need for expanding these types of studies to implement specific strategies for a reduction of PM2.5 level in high activity cities and which could then be applied to other urban areas around the world. © 2023 Turkish National Committee for Air Pollution Research and Control. Production and hosting by Elsevier B.V.
Sulphur hexafluoride as a stripper gas for tandem accelerators
(Elsevier Science BV., 2013-05-01) Hotchkis, MAC; Child, DP; Fink, D; Garton, D; Levchenko, VA; Wilcken, KM
We have investigated sulphur hexafluoride as a stripper gas in tandem accelerators by using the ANTARES accelerator system at ANSTO to measure charge state distributions for this gas. Results are reported at 4 MV terminal voltage for injected negative ions ranging from carbon to uranium oxide. For iodine and thorium the distributions are extended across a range of energies of practical use for accelerator mass spectrometry, ion beam analysis and other accelerator applications. Charge state distributions using sulphur hexafluoride are found to have mean charge states up to I charge unit higher than, and to be broader than, corresponding distributions for argon gas, except in the case of carbon beams. As a result, SF6 is shown to provide significantly higher yields for charge states of heavy ions above the mean charge state. We now perform actinide AMS measurements with 9% yield to the 5+ charge state, compared to 4-5% achieved previously with argon gas. © 2013, Elsevier Ltd.

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