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Journal Articles

Atmospheric modeling of $$^{137}$$Cs plumes from the Fukushima Daiichi Nuclear Power Plant; Evaluation of the model intercomparison data of the Science Council of Japan

Kitayama, Kyo*; Morino, Yu*; Takigawa, Masayuki*; Nakajima, Teruyuki*; Hayami, Hiroshi*; Nagai, Haruyasu; Terada, Hiroaki; Saito, Kazuo*; Shimbori, Toshiki*; Kajino, Mizuo*; et al.

Journal of Geophysical Research; Atmospheres, 123(14), p.7754 - 7770, 2018/07

 Times Cited Count:17 Percentile:76.82(Meteorology & Atmospheric Sciences)

We compared seven atmospheric transport model results for $$^{137}$$Cs released during the Fukushima Daiichi Nuclear Power Plant accident. All the results had been submitted for a model intercomparison project of the Science Council of Japan in 2014. We assessed model performance by comparing model results with observed hourly atmospheric concentrations of $$^{137}$$Cs, focusing on nine plumes over the Tohoku and Kanto regions. The results showed that model performance for $$^{137}$$Cs concentrations was highly variable among models and plumes. We also assessed model performance for accumulated $$^{137}$$Cs deposition. Simulated areas of high deposition were consistent with the plume pathways, though the models that best simulated $$^{137}$$Cs concentrations were different from those that best simulated deposition. The ensemble mean of all models consistently reproduced $$^{137}$$Cs concentrations and deposition well, suggesting that use of a multimodel ensemble results in more effective and consistent model performance.

Journal Articles

Development of a correction method for the time-of-flight prompt $$gamma$$-ray analysis

Huang, M.; Toh, Yosuke; Ebihara, Mitsuru*; Kimura, Atsushi; Nakamura, Shoji

Journal of Applied Physics, 121(10), p.104901_1 - 104901_7, 2017/03

 Times Cited Count:2 Percentile:14.14(Physics, Applied)

Journal Articles

Development of Prompt Gamma-ray Analysis at J-PARC/ANNRI

Toh, Yosuke; Ebihara, Mitsuru*; Huang, M.; Kimura, Atsushi; Nakamura, Shoji; Harada, Hideo

Hosha Kagaku, (33), p.1 - 9, 2016/03

Prompt Gamma-ray Analysis (PGA) uses capture $$gamma$$ rays, which are characteristic of each particular nucleus emitted from a sample while it is being irradiated with neutrons. It has been used as a rapid, nondestructive method for performing both qualitative and quantitative multielemental analysis. Therefore, cosmochemical, environmental, archeological samples and samples from materials science and engineering are analyzed. Although, researchers have endeavored to improve the accuracy and the detection sensitivity in PGA with the coincidence and anti-coincidence methods, further improvements are possible. We developed a new analytical technique (TOF-PGA) that combines Prompt Gamma-ray Analysis (PGA) and time-of-flight elemental analysis (TOF) by using an intense pulsed neutron beam at the Japan Proton Accelerator Research Complex (J-PARC). It allows us to obtain the results from both methods at the same time. Moreover, it can be used to quantify elemental concentrations in the sample, to which neither of these methods can be applied independently, if TOF-PGA is used. TOF-PGA showed high merits, although the capability may differ in terms of the target element and coexisting elements.

Journal Articles

Development of elemental analytical methods in BL04 ANNRI

Toh, Yosuke; Huang, M.; Kimura, Atsushi; Nakamura, Shoji; Harada, Hideo; Ebihara, Mitsuru*

Shiki, 28, P. 4, 2015/09

no abstracts in English

Journal Articles

Development of new non-destructive analysis by using an intense pulsed neutron beam

Toh, Yosuke; Ebihara, Mitsuru*; Huang, M.; Kimura, Atsushi; Nakamura, Shoji; Harada, Hideo

Isotope News, (736), p.22 - 26, 2015/08

no abstracts in English

Journal Articles

Synergistic effect of combining two nondestructive analytical methods for multielemental analysis

Toh, Yosuke; Ebihara, Mitsuru*; Kimura, Atsushi; Nakamura, Shoji; Harada, Hideo; Hara, Kaoru*; Koizumi, Mitsuo; Kitatani, Fumito; Furutaka, Kazuyoshi

Analytical Chemistry, 86(24), p.12030 - 12036, 2014/12

 Times Cited Count:13 Percentile:50.54(Chemistry, Analytical)

Non-destructive elemental analyses have been an indispensable tool for many fields of scientific research. Prompt $$gamma$$-ray analysis and time of flight elemental analysis uses the energy of the $$gamma$$ rays and the energy of neutron resonances, respectively. In both analyses, a sample is irradiated with neutrons and $$gamma$$ rays are detected. Thus, these methods are similar and could be replaced by a single measurement. However, these methods have never been applied simultaneously before. We have first developed a novel technique which combines these methods by using an intense pulsed neutron beam. It allows us to obtain the results from both methods at the same time. Moreover, significant synergy has been achieved. Specifically, it will be used to quantify elemental concentrations in the sample that neither of these methods can be applied. Here, we demonstrate how it can be used to extract reliable information from unresolved peaks in the spectra.

Journal Articles

A New X-ray fluorescence spectroscopy for extraterrestrial materials using muon beam

Terada, Kentaro*; Ninomiya, Kazuhiko*; Osawa, Takahito; Tachibana, Shogo*; Miyake, Yasuhiro*; Kubo, Kenya*; Kawamura, Naritoshi*; Higemoto, Wataru; Tsuchiyama, Akira*; Ebihara, Mitsuru*; et al.

Scientific Reports (Internet), 4, p.5072_1 - 5072_6, 2014/05

 Times Cited Count:28 Percentile:79.02(Multidisciplinary Sciences)

After the discovery of X-ray by Rontgen, mankind got a new eye to see through things. This fluoroscopy, so-called X-ray radiography that gives the density distribution of the inside of an object, has been applied to the vast research field such as natural/material/medical sciences, industry and technology. The recent development on the intense pulsed muon source at J-PARC MUSE (rate of 106 cps for 60 MeV/c) enabled us to pioneer a new frontier of analytical sciences. Here we report on a non-destructive elemental analysis by using muon capture. Controlling muon's momentum from 32.5 to 57.5 MeV/c. we successfully demonstrated a depth-profile analysis of light elements from several mm-thick layered materials, and non-destructive bulk analyses of meteorites containing organics. Now it is a beginning to utilize a new eye, muon radiography.

Journal Articles

Development of prompt $$gamma$$-ray analysis using spallation neutrons at J-PARC

Toh, Yosuke; Ebihara, Mitsuru*; Harada, Hideo

Transactions of the American Nuclear Society, 109(1), p.116 - 117, 2013/11

no abstracts in English

Journal Articles

Deep-sea record of impact apparently unrelated to mass extinction in the Late Triassic

Onoue, Tetsuji*; Sato, Honami*; Nakamura, Tomoki*; Noguchi, Takaaki*; Hidaka, Yoshihiro*; Shirai, Naoki*; Ebihara, Mitsuru*; Osawa, Takahito; Hatsukawa, Yuichi; Toh, Yosuke; et al.

Proceedings of the National Academy of Sciences of the United States of America, 109(47), p.19134 - 19139, 2012/11

 Times Cited Count:32 Percentile:72.77(Multidisciplinary Sciences)

The 34 million year (My) interval of the Late Triassic is marked by the formation of several large impact structures on Earth. As with the Chicxulub impact event at the Cretaceous/Paleogene boudary, the Late Triassic impact events have been considered a factor in biotic extinction events in the Late Triassic (e.g., the Triassic/Jurassic boundary). However, the causal link between these impact events and a mass extinction event in the Late Triassic remains controversial because of a lack of stratigraphic records of their ejecta deposits. Here we report evidence for an impact event (platinum group elements anomaly, nickel-rich magnetite and microspherules) deposited within a Paleo-Pacific basin in the middle Norian (Upper Triassic) deep-sea sediment in Japan. This includes anomalously high abundances of iridium, up to 41.5 parts per billion (ppb), in the ejecta deposit, which suggests that the iridium anomaly may be found on a global scale. The middle Norian age of the ejecta deposit suggests that the impact event that produced the 100-km-wide Manicouagan crater in Canada8 is most likely related to its deposition. Our analysis of siliceous microfossils shows no evidence of a mass extinction event across the impact event horizon, and no contemporaneous faunal turnover is seen in other marine fossils. However, such an event has been reported among terrestrial tetrapods and floras in North America. We therefore hypothesize that the Manicouagan impact caused the catastrophic collapse of terrestrial ecosystems near the impact site, but not within the marine realm.

Journal Articles

Characterization of Multiple Prompt Gamma-ray Analysis (MPGA) system at JAEA for elemental analysis of geological and cosmochemical samples

Islam, M. A.*; Ebihara, Mitsuru*; Toh, Yosuke; Murakami, Yukihiro*; Harada, Hideo

Applied Radiation and Isotopes, 70(8), p.1531 - 1535, 2012/08

 Times Cited Count:1 Percentile:11.68(Chemistry, Inorganic & Nuclear)

In this study, the MPGA system was characterized for nondestructive multi-element analysis of geological and cosmochemical samples. Among the three offline sorting modes of coincidence data in MPGA, the add-back mode resulted in relatively high analytical sensitivity and the lowest detection limit. The system is highly sensitive to Sm, Gd and Cd. When MPGA detection limits of the studied elements were compared with other cold neutron facilities, MPGA detection limits for Mg, K, S and Cl were improved around one order of magnitude than other facilities under the present experimental conditions, which consists of 8 Clover and BGO detectors. Analysis of the meteorite Orgueil by both MPGA and PGA imply that MPGA can be used for elemental analysis with sufficient accuracy. For some elements (such as Sm, K and Mg) which can Gnot be determined by conventional PGA, due to the spectral interference or lower sensitivity, it was observed that they could be determined accurately (3%) by MPGA.

Journal Articles

Application of multiple prompt $$gamma$$-ray analysis (MPGA) to geochemical and cosmochemical samples

Oura, Yasuji*; Watanabe, Ryo*; Ebihara, Mitsuru*; Murakami, Yukihiro*; Toh, Yosuke; Kimura, Atsushi; Koizumi, Mitsuo; Furutaka, Kazuyoshi; Oshima, Masumi; Hara, Kaoru; et al.

Journal of Radioanalytical and Nuclear Chemistry, 291(2), p.335 - 339, 2012/02

 Times Cited Count:4 Percentile:36.4(Chemistry, Analytical)

We applied multiple prompt $$gamma$$-ray analysis (MPGA) method to geochemical and cosmochemical samples to evaluate its analytical performance on signal to noise (S/N) ratio, sensitivity, and detection limit. The S/N ratio measured by MPGA system was larger than that by normal prompt $$gamma$$ ray activation analysis (PGAA) at JRR3. For some elements, the S/N ratio was improved more than ten times. Several elements that are not detected by PGAA were detected by MPGA. In the present experiment, concentrations of major elements and trace elements with high neutron capture cross section in geochemical and cosmochemical samples were determined accurately by the MPGA system. It is expected that it will determine a lot of trace elements after appropriate adjustments and modifications.

Journal Articles

Comparison of multiple prompt $$gamma$$-ray analysis and prompt $$gamma$$-ray analysis for the elemental analysis of geochemical and cosmochemical samples

Islam, M. A.*; Ebihara, Mitsuru*; Toh, Yosuke; Harada, Hideo

Analytical Chemistry, 83(19), p.7486 - 7491, 2011/10

 Times Cited Count:9 Percentile:33.14(Chemistry, Analytical)

Multiple prompt $$gamma$$-ray analysis (MPGA) and prompt $$gamma$$-ray analysis (PGA) are non destructive analytical methods for bulk chemical compositions and their analytical capabilities were compared for elemental analyses of geological and cosmochemical samples. MPGA can substantially reduce the background level, especially for hydrogenous samples relative to PGA, which opens up a possibility to use lower energy $$gamma$$-ray of some trace elements. Although it is one of major constituent elements of rock samples, Mg is hard to be determined by PGA. With MPGA, Mg contents could be determined with reasonable consistency with their corresponding recommended values in the samples by carefully selecting suitable $$gamma$$-ray pairs without interference correction. MPGA was applied to a hydrogenous meteorite, Ivuna. MPGA detection limits for most of the elements studied can be reduced up to one order of magnitude when compared with PGA detection limits under the present experimental conditions.

Journal Articles

Irradiation history of Itokawa regolith material deduced from noble gases in the Hayabusa samples

Nagao, Keisuke*; Okazaki, Ryuji*; Nakamura, Tomoki*; Miura, Yayoi*; Osawa, Takahito; Bajo, Kenichi*; Matsuda, Shintaro*; Ebihara, Mitsuru*; Ireland, T.*; Kitajima, Fumio*; et al.

Science, 333(6046), p.1128 - 1131, 2011/08

 Times Cited Count:104 Percentile:95.41(Multidisciplinary Sciences)

A steroid surface materials record regolith processes and a history of cosmic-ray irradiation. Noble gas isotopes in three rocky grains from Itokawa have been determined. High concentrations of solar He, Ne, and Ar, as high as those in lunar soils, are released at variable temperatures from each sample. The isotopic compositions are essentially identical to those of solar wind but distinguishable in He relative abundance. These noble gas characteristics can be explained by repeated implantation and preferential loss of solar He by removal of weathered He-rich rim on the grain surface through friction among regolith grains on Itokawa. Residence time of regolith materials on Itokawa is alculated to be shorter than 10 Myr, suggesting that regolith materials of small asteroids would escape easily to space.

JAEA Reports

Proceedings of the Workshop on Multiple Prompt gamma-ray Analysis; Tokai, February 19, 2008

Ebihara, Mitsuru*; Hatsukawa, Yuichi; Oshima, Masumi

JAEA-Review 2008-056, 65 Pages, 2009/01

JAEA-Review-2008-056.pdf:15.01MB

The workshop on "Multiple Prompt Gamma-ray Analysis" was held on February 19, 2008 at Tokai. It is based on a project, "Development of real time, non destructive ultra sensitive elemental analysis using multiple gamma-ray detections and prompt gamma-ray analysis and its application to real samples", one of the High Priority Cooperative Research Programs performed by Japan Atomic Energy Agency and the University of Tokyo. This report presents the papers and the materials of 9 presentations in the workshop.

Journal Articles

Multiple $$gamma$$-ray detection method and its application to nuclear chemistry

Oshima, Masumi; Toh, Yosuke; Hatsukawa, Yuichi; Koizumi, Mitsuo; Kimura, Atsushi; Haraga, Tomoko; Ebihara, Mitsuru*; Sushida, Kazuyoshi*

Journal of Radioanalytical and Nuclear Chemistry, 278(2), p.257 - 262, 2008/11

 Times Cited Count:22 Percentile:82.38(Chemistry, Analytical)

It is well known that most radioactive nuclides emit coincident multiple $$gamma$$-rays. The multiple $$gamma$$-ray detection method takes advantage of this feature and the $$gamma$$-rays are detected in coincidence with a $$gamma$$-ray detector array. From the correlated data we can create a $$gamma$$-$$gamma$$ two-dimensional matrix or $$gamma$$-$$gamma$$-$$gamma$$ three-dimensional cube. On this matrix or cube an energy resolution much better than the ordinary one-dimensional spectrum can be achieved. Furthermore signal-to-noise ratio is considerably improved. Hence this method can be applied widely to radioactive nuclide analysis. In the talk I will present its typical application to the analysis of nuclear waste, neutron activation analysis (NAAMG), and prompt $$gamma$$-ray analysis (MPGA).

Journal Articles

An Attempt for determining $$^{235}$$U/$$^{238}$$U ratio for a trace amount of uranium: Search for an extinct radionuclide $$^{247}$$Cm in the early solar system

Chai, J.; Miyamoto, Yutaka; Kokubu, Yoko; Magara, Masaaki; Sakurai, Satoshi; Usuda, Shigekazu; Oura, Yasuji*; Ebihara, Mitsuru*

Journal of Radioanalytical and Nuclear Chemistry, 272(2), p.397 - 401, 2007/05

 Times Cited Count:2 Percentile:19.85(Chemistry, Analytical)

$$^{247}$$Cm is an important nuclide because it has the next-shortest half-life (1.6$$cdot$$10$$^{7}$$ yr) from $$^{244}$$Pu among the transuranic nuclides. The disintegration of $$^{247}$$Cm to $$^{235}$$U by three $$alpha$$ decays and two $$beta$$ decays and the chemical fractionation between Cm and U during the formation of solid materials in early solar system lead to changes in the ratios of $$^{235}$$U to $$^{238}$$U. This variation may provide strict constraints on the time interval between the last r-process nucleosynthetic event and the formation of the solar system. It is important to develop a practical analysis protocol to determine the isotope ratio of trace uranium in geochemical and environment samples. As uranium is the least abundant element in our solar system, analytical techniques with high sensitivity and precision are required. In this study, a double focusing inductively coupled plasma mass spectory was applied to measure isotopic ratio of uranium. By one set data obtained from the EDTA phase of the Jilin meteorite sample, the upper limit of $$^{247}$$Cm in the early solar system was calculated and $$^{247}$$Cm/$$^{235}$$U $$<$$ 0.003 was obtained.

Journal Articles

Multiple prompt $$gamma$$-ray analysis and construction of its beam line

Oshima, Masumi; Toh, Yosuke; Kimura, Atsushi; Ebihara, Mitsuru*; Oura, Yasuji*; Ito, Yasuo*; Sawahata, Hiroyuki*; Matsuo, Motoyuki*

Journal of Radioanalytical and Nuclear Chemistry, 271(2), p.317 - 321, 2007/02

 Times Cited Count:11 Percentile:63.76(Chemistry, Analytical)

By combining neutron activation analysis with multiple $$gamma$$-ray detection, we have proved better sensitivity and resolution for the trace element analysis than the ordinary single $$gamma$$-ray detection method. We now try to apply the multiple $$gamma$$-ray detection method to the prompt $$gamma$$-ray analysis (PGA). We have established a new cold neutron beam line for PGA in Japan Research Reactor, JRR-3M, at Tokai establishment of Japan Atomic Energy Research Institute(JAERI). It consists of a beam shutter, a beam attenuator, a $$gamma$$-ray detector array, a sample changer, and a beam stopper. We construct a high-efficiency $$gamma$$-ray detector array specially designed for this purpose. Its performance has been evaluated with the Monte Carlo simulation code, GEANT 4.5.0.

JAEA Reports

Proceedings of the Workshop on Multiple Prompt Gamma-ray Analysis; Tokai, March 8, 2006

Ebihara, Mitsuru*; Hatsukawa, Yuichi; Oshima, Masumi

JAEA-Review 2006-028, 97 Pages, 2006/10

JAEA-Review-2006-028.pdf:29.98MB

The workshop on "Multiple Prompt Gamma-ray Analysis" was held on March 8, 2006 at Tokai. It is based on a project, "Developments of real time, non-destructive ultra sensitive elemental analysis using multiple gamma-ray detections and prompt gamma ray analysis and its application to real samples", one of the High priority Cooperative Research Programs performed by Japan Atomic Energy Agency and the University of Tokyo. In this workshop, the latest results of the Multiple Prompt Gamma ray Analysis (MPGA) study were presented, together with those of Neutron Activation Analysis with Multiple Gamma-ray Detection (NAAMG). This report records the papers and the materials of 9 presentations in the workshop.

Journal Articles

Nuclear data for multiple prompt $$gamma$$-ray analysis

Toh, Yosuke; Oshima, Masumi; Koizumi, Mitsuo; Osa, Akihiko; Kimura, Atsushi; Goto, Jun; Ebihara, Mitsuru*

AIP Conference Proceedings 769, p.1666 - 1669, 2005/05

no abstracts in English

Journal Articles

$$alpha$$-decays of neutron-deficient americium isotopes

Sakama, Minoru*; Asai, Masato; Tsukada, Kazuaki; Ichikawa, Shinichi; Nishinaka, Ichiro; Nagame, Yuichiro; Haba, Hiromitsu*; Goto, Shinichi*; Shibata, Michihiro*; Kawade, Kiyoshi*; et al.

Physical Review C, 69(1), p.014308_1 - 014308_11, 2004/01

 Times Cited Count:19 Percentile:72.76(Physics, Nuclear)

no abstracts in English

45 (Records 1-20 displayed on this page)