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Journal Articles

Challenging studies by accelerator mass spectrometry for the development of environmental radiology; Status report on the analysis of $$^{90}$$Sr and $$^{135}$$Cs by AMS

Honda, Maki; Martschini, M.*; Wieser, A.*; Marchhart, O.*; Lachner, J.*; Priller, A.*; Steier, P.*; Golser, R.*; Sakaguchi, Aya*

JAEA-Conf 2022-001, p.85 - 90, 2022/11

https://doi.org/10.11484/jaea-conf-2022-001

Accelerator mass spectrometry (AMS) is an analytical method that combines mass spectrometry with a tandem accelerator, which has been used mainly in nuclear physics experiments. AMS is used to measure radionuclides with half-lives of 10$$^{3}$$-10$$^{8}$$ years. For radionuclides with half-lives of this order, the method of measuring their mass is 10$$^{3}$$-10$$^{6}$$ times more sensitive than measuring their activity. Because of this advantage, AMS has been widely applied in Earth and planetary sciences, atomic energy research, and other fields. Among the various studies, Wallner et al. (2021, 2016) have achieved excellent work in Earth and planetary sciences. For example, they have attained the ultra-sensitive analysis of $$^{60}$$Fe and $$^{244}$$Pu in environmental samples. These are radionuclides produced by rapid-neutron-capture (r-process) nucleosynthesis. Our recent work shows that a new AMS system (VERA, University of Vienna), which combines laser isobaric separation and a typical AMS system, has been successfully applied to the ultra-sensitive determination of $$^{90}$$Sr and $$^{135}$$Cs in environment. For $$^{90}$$Sr in environmental samples, the $$beta$$-ray measurement by the milking of the daughter nuclide $$^{90}$$Y is still the principal method, which takes 3-6 weeks. The new AMS method has a detection limit of $$<$$ 0.1 mBq, which is comparable to that of $$beta$$-ray measurement, with a more straightforward chemical treatment than $$beta$$-measurement. Our achievement demonstrates that AMS can be a practical new method for determining $$^{90}$$Sr in the environment.

Journal Articles

Novel $$^{90}$$Sr analysis of environmental samples by ion-laser interaction mass spectrometry

Honda, Maki; Martschini, M.*; Marchhart, O.*; Priller, A.*; Steier, P.*; Golser, R.*; Sato, Tetsuya; Tsukada, Kazuaki; Sakaguchi, Aya*

Analytical Methods, 14(28), p.2732 - 2738, 2022/07

https://doi.org/10.1039/D2AY00604A
 Times Cited Count：2 Percentile：60.24(Chemistry, Analytical)

The sensitive $$^{90}$$Sr analysis with accelerator mass spectrometry (AMS) was developed for the advances of environmental radiology. One advantage of AMS is the ability to analyze various environmental samples with $$^{90}$$Sr/$$^{88}$$Sr atomic ratios of 10$$^{-14}$$ in a simple chemical separation. Three different IAEA samples with known $$^{90}$$Sr concentrations (moss-soil, animal bone, Syrian soil: 1 g each) were analyzed to assess the validity of the chemical separation and the AMS measurement. The $$^{90}$$Sr measurements were conducted on the AMS system combined with the Ion Laser InterAction MasSpectrometry (ILIAMS) setup at the University of Vienna, which has excellent isobaric separation performance. The isobaric interference of $$^{90}$$Zr in the $$^{90}$$Sr AMS was first removed by chemical separation. The separation factor of Zr in two-step column chromatography with Sr resin and anion exchange resin was 10$$^{6}$$. The $$^{90}$$Zr remaining in the sample was removed by ILIAMS effectively. This simple chemical separation achieved a limit of detection $$<$$ 0.1 mBq in the $$^{90}$$Sr AMS, which is lower than typical $$beta$$-ray detection. The agreement between AMS measurements and nominal values for the $$^{90}$$Sr concentrations of IAEA samples indicated that the new highly-sensitive $$^{90}$$Sr analysis in the environmental samples with AMS is reliable even for high matrix samples of soil and bone.

Journal Articles

Developing accelerator mass spectrometry capabilities for anthropogenic radionuclide analysis to extend the set of oceanographic tracers

Hain, K.*; Martschini, M.*; G$"u$lce, F.*; Honda, Maki; Lachner, J.*; Kern, M.*; Pitters, J.*; Quinto, F.*; Sakaguchi, Aya*; Steier, P.*; et al.

Frontiers in Marine Science (Internet), 9, p.837515_1 - 837515_17, 2022/03

https://doi.org/10.3389/fmars.2022.837515
 Times Cited Count：9 Percentile：97.43(Environmental Sciences)

Recent major advances in accelerator mass spectrometry (AMS) at the Vienna Environmental Research Accelerator (VERA) regarding detection efficiency and isobar suppression have opened possibilities for the analysis of additional long-lived radionuclides at ultra-low environmental concentrations. These radionuclides, including $$^{233}$$U, $$^{135}$$Cs, $$^{99}$$Tc and $$^{90}$$Sr, will become important for oceanographic tracer application due to their generally conservative behavior in ocean water. In particular, the isotope ratios $$^{233}$$U/$$^{236}$$U and $$^{137}$$Cs/$$^{135}$$Cs have proven to be powerful fingerprints for emission source identification as they are not affected by elemental fractionation. Improved detection efficiencies allowed us to analyze all major long-lived actinides, i.e. $$^{236}$$U, $$^{237}$$Np, $$^{239, 240}$$Pu, $$^{241}$$Am as well as the very rare $$^{233}$$U, in the same 10 L water samples of an exemplary depth profile from the northwest Pacific Ocean. Especially for $$^{90}$$Sr analysis, our new approach has already been validated for selected reference materials (e.g. IAEA-A-12) and is ready for application in oceanographic studies. We estimate that a sample volume of only (1-3) L ocean water is sufficient for $$^{90}$$Sr as well as $$^{135}$$Cs analysis, respectively.

Journal Articles

$$^{60}$$Fe and $$^{244}$$Pu deposited on Earth constrain the r-process yields of recent nearby supernovae

Wallner, A.*; Froehlich, M. B.*; Hotchkis, M. A. C.*; Kinoshita, N.*; Paul, M.*; Martschini, M.*; Pavetich, S.*; Tims, S. G.*; Kivel, N.*; Schumann, D.*; et al.

Science, 372(6543), p.742 - 745, 2021/05

https://doi.org/10.1126/science.aax3972
 Times Cited Count：31 Percentile：96.38(Multidisciplinary Sciences)

Half of the chemical elements heavier than iron are produced by the rapid neutron capture process (r-process). The sites and yields of this process are disputed, with candidates including some types of supernovae (SNe) and mergers of neutron stars. We search for two isotopic signatures in a sample of Pacific Ocean crust-iron-60 ($$^{60}$$Fe) (half-life, 2.6 million years), which is predominantly produced in massive stars and ejected in supernova explosions, and $$^{244}$$Pu (half-life, 80.6 million years), which is produced solely in r-process events. We detect two distinct influxes of $$^{60}$$Fe to Earth in the last 10 million years and accompanying lower quantities of $$^{244}$$Pu. The $$^{244}$$Pu/$$^{60}$$Fe influx ratios are similar for both events. The $$^{244}$$Pu influx is lower than expected if SNe dominate r-process nucleosynthesis, which implies some contribution from other sources.

Oral presentation

Feasibility of $$^{90}$$Sr measurements using accelerator mass spectrometry

Honda, Maki; Martschini, M.*; Marchhart, O.*; Priller, A.*; Steier, P.*; Golser, R.*; Sakaguchi, Aya*; Sueki, Keisuke*

no journal, , 

no abstracts in English

Oral presentation

Pioneering applications in AMS for the development of environmental radiology; Studies towards the implementation of $$^{90}$$Sr and $$^{135}$$Cs AMS

Honda, Maki; Martschini, M.*; Lachner, J.*; Marchhart, O.*; Wieser, A.*; Priller, A.*; Steier, P.*; Golser, R.*; Sakaguchi, Aya*

no journal, , 

We have developed new analytical methods for$$^{90}$$Sr (28.79 yr) and $$^{135}$$Cs (2.3x10$$^{6}$$ yr) by accelerator mass spectrometry (AMS) for the further development of the research on the environmental fate of artificial radionuclides$$^{90}$$Sr and $$^{137}$$Cs (30.1 yr). The AMS method enables the analysis of trace amounts of$$^{90}$$Sr and $$^{135}$$Cs with a simple chemical separation procedure. Having a longer half-life $$^{135}$$Cs applies as a proxy for $$^{137}$$Cs. For $$^{90}$$Sr, SrF$$_{2}$$ targets were prepared from radioactive environmental reference materials with known $$^{90}$$Sr concentrations (IAEA) by a chemical separation procedure that takes about two days to complete. $$^{90}$$Sr measured by AMS at VERA, University of Vienna. As a result, a limit of detection of $$<$$0.1 mBq was obtained, which is comparable to the $$beta$$ ray measurement. The detection of $$^{90}$$Sr in environmental samples was also successful, indicating that the $$^{90}$$Sr AMS can apply to environmental samples. On the other hand, there are still some technical challenges in the $$^{135}$$Cs AMS. Therefore, the experimental measurements are in progress.

Oral presentation

Accelerator mass spectrometry of $$^{90}$$Sr in environmental samples utilizing laser photo-detachment

Honda, Maki; Martschini, M.*; Marchhart, O.*; Steier, P.*; Golser, R.*; Sakaguchi, Aya*

no journal, , 

Accelerator mass spectrometry (AMS) is a relatively new analytical chemistry in applied research utilizing accelerators. In Japan, AMS has been used to measure $$^{14}$$C, which is applied for dating in archaeology, and $$^{36}$$Cl, which is used to assess the environmental effects of the disposal of radioactive waste from nuclear power plants and accelerator facilities. In recent years, conventional AMS systems have been combined with new analytical chemistry techniques to separate isobars, such as laser photo-detachment, leading to improved performance and the possibility of measuring new nuclides in AMS. This presentation will mainly focus on developing a highly sensitive $$^{90}$$Sr analysis technique utilizing the laser photo-detachment method equipped in the 3MV AMS at the University of Vienna. Furthermore, the feasibility of $$^{90}$$Sr AMS at facilities in Japan will be discussed.

Oral presentation

Accelerator mass spectrometry of $$^{90}$$Sr in environmental samples collected in the vicinity of a nuclear power plant

Honda, Maki; Martschini, M.*; Steier, P.*; Golser, R.*; Kanivets, V.*; Rahman, I. M. M.*; Yamasaki, Shinya*; Sakaguchi, Aya*

no journal, , 

A new analytical method for $$^{90}$$Sr utilizing accelerator mass spectrometry (AMS) achieved better detection limits (1/10 of $$<$$0.1 mBq) than conventional $$beta$$-ray detection methods. In order to demonstrate the applicability of the AMS method to environmental samples of various properties, the present study analyzed impurity-rich water samples collected from the cooling water supply ponds of the Chornobyl NPP. The $$^{90}$$Sr/$$^{88}$$Sr atomic ratio of the water samples (evaluated by $$beta$$-ray detection and ICP-MS), the expected detection limit, and the analysis method are reported in this meeting. Furthermore, the adaptability of the AMS method for $$^{90}$$Sr concentration (Bq/L) in water samples will be demonstrated by comparing the AMS method with the $$beta$$-ray detection method.

Oral presentation

Frontiers of challenging studies in geoscience utilizing accelerator mass spectrometry

Honda, Maki; Martschini, M.*; Lachner, J.*; Wieser, A.*; Marchhart, O.*; Steier, P.*; Golser, R.*; Sakaguchi, Aya*

no journal, , 

The effective isobar suppression system based on the interaction between accelerated ions and lasers (photons) has been introduced into conventional AMS systems, allowing an increasing number of nuclides to be measured by AMS. This presentation will give an overview of the analytical technique, the measurement results, and the remaining challenges as examples of world-leading successful AMS of $$^{90}$$Sr and $$^{135}$$Cs in environmental samples obtained from the IAEA and others. Moreover, the applicability of the AMS method in geoscience (e.g., studies of $$^{90}$$Sr distribution in the hydrosphere and the range of applicable environmental samples) will also be discussed.

Oral presentation

Analysis of $$^{90}$$Sr in environmental samples at the attogram-level by accelerator mass spectrometry

Martschini, M.*; Honda, Maki; Merchel, S.*; Winkler, S.*; Golser, R.*

no journal, , 

The quantitative analysis of $$^{90}$$Sr is cumbersome and time-consuming because it is a pure $$beta$$-ray emitter. The detection limit of $$^{90}$$Sr by conventional accelerator mass spectrometry (AMS) methods is comparable to the typical detection limit of 3 mBq for $$beta$$-ray detection methods, mainly due to the interference of the isobaric $$^{90}$$Zr. The worldwide unique Ion Laser Interaction Mass Spectrometry (ILIAMS), performed at the University of Vienna, effectively removes $$^{90}$$Zr with a laser and reaction gases. Therefore, the detection limits of $$^{90}$$Sr is superior ($$<$$0.1 mBq) to conventional AMS systems not equipped with such an ion-laser interaction isobaric removal system. In this study, $$^{90}$$Sr analysis in coral samples etc., an environmental sample under extreme conditions (e.g. low concentrations of $$mu$$Bq/g and limited sample volumes of grams), was tried. To lower the detection limit $$<$$0.1 mBq, Sr was purified (Sr carrier) from old age coral with almost no $$^{90}$$Sr contamination from atmospheric nuclear tests, chemical separation of environmental samples were conducted, and $$^{90}$$Sr was measured by AMS. The results showed that the detection limit of $$^{90}$$Sr achieved in the analysis was $$<$$0.03 mBq ($$^{90}$$Sr/Sr $$<$$5$$times$$10$$^{-16}$$, 1/100 of the $$beta$$-ray detection methods). The detection limit achieved in this study corresponds to 2 ag of $$^{90}$$Sr in 1 mg of Sr target. The latest results of highly sensitive $$^{90}$$Sr analysis in small amounts of general environmental samples (coral, seawater, etc.) are mainly presented.

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