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Journal Articles

Prompt $$gamma$$-ray analysis for volcanic rocks by JRR-3 reactor

Osawa, Takahito; Fukuoka, Takaaki*

Gekkan Chikyu, 40(5), p.302 - 309, 2018/05

Contents of boron, chlorine, hydrogen, and water in volcanic rocks provide important information of magma origin. Here we describe the measurement for boron in volcanic rocks using the automatic prompt $$gamma$$-ray analysis system installed in Japan research reactor-3 (JRR-3) at Japan atomic Energy Agency.

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

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.

Journal Articles

JENDL-4.0; A New library for nuclear science and engineering

Shibata, Keiichi; Iwamoto, Osamu; Nakagawa, Tsuneo*; Iwamoto, Nobuyuki; Ichihara, Akira; Kunieda, Satoshi; Chiba, Satoshi; Furutaka, Kazuyoshi; Otsuka, Naohiko*; Osawa, Takaaki*; et al.

Journal of Nuclear Science and Technology, 48(1), p.1 - 30, 2011/01

 Times Cited Count:1249 Percentile:100(Nuclear Science & Technology)

The fourth version of Japanese Evaluated Nuclear Data Library has been produced. In the new library, much emphasis is placed on the improvements of fission product and minor actinoid data. Two nuclear model codes were developed to evaluate the cross sections of fission products and minor actinoids. Coupled-channel optical model parameters, which can be applied to wide mass and energy regions, were obtained for nuclear model calculations. Thermal cross sections of actinoids were determined by considering recent experimental data or by the systematics of neighboring nuclei. A simultaneous evaluation was performed for the fission cross sections of important uranium and plutonium isotopes above 10 keV. The data on FP were re-evaluated, and new evaluations were performed for 30 nuclides. The data on light elements and structural materials were partly re-evaluated. The new library was released as JENDL-4.0 in May 2010.

Journal Articles

Interior textures, chemical compositions, and noble gas signatures of Antarctic cosmic spherules; Possible sources of spherules with long exposure ages

Osawa, Takahito; Yamamoto, Yukio*; Noguchi, Takaaki*; Iose, Akari*; Nagao, Keisuke*

Meteoritics & Planetary Science, 45(8), p.1320 - 1339, 2010/08

 Times Cited Count:11 Percentile:37.11(Geochemistry & Geophysics)

The interior texture and chemical and noble gas composition of 99 cosmic spherules collected from the meteorite ice field around the Yamato Mountains in Antarctica were investigated. Their textures were used to classify the spherules into six different types reflecting the degree of heating. An enigmatic spherule, labeled M240410, had an extremely high concentration of cosmogenic nuclides. Assuming 4$$pi$$ exposure to galactic and solar cosmic rays as a micrometeoroid and no exposure on the parent body, the cosmic-ray exposure (CRE) age of 393 Myr could be computed using cosmogenic $$^{21}$$Ne. Under these model assumptions, the inferred age suggests that the particle might have been an Edgeworth-Kuiper Belt object. Alternatively, if exposure near the surface of its parent body was dominant, the CRE age of 382 Myr can be estimated from the cosmogenic $$^{38}$$Ar using the production rate of the 2$$pi$$ exposure geometry, and implies that the particle may have originated in the mature regolith of an asteroid.

Journal Articles

Recent progress in the energy recovery linac project in Japan

Sakanaka, Shogo*; Akemoto, Mitsuo*; Aoto, Tomohiro*; Arakawa, Dai*; Asaoka, Seiji*; Enomoto, Atsushi*; Fukuda, Shigeki*; Furukawa, Kazuro*; Furuya, Takaaki*; Haga, Kaiichi*; et al.

Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.2338 - 2340, 2010/05

Future synchrotron light source using a 5-GeV energy recovery linac (ERL) is under proposal by our Japanese collaboration team, and we are conducting R&D efforts for that. We are developing high-brightness DC photocathode guns, two types of cryomodules for both injector and main superconducting (SC) linacs, and 1.3 GHz high CW-power RF sources. We are also constructing the Compact ERL (cERL) for demonstrating the recirculation of low-emittance, high-current beams using above-mentioned critical technologies.

Journal Articles

JENDL actinoid file 2008

Iwamoto, Osamu; Nakagawa, Tsuneo; Otsuka, Naohiko*; Chiba, Satoshi; Okumura, Keisuke; Chiba, Go; Osawa, Takaaki*; Furutaka, Kazuyoshi

Journal of Nuclear Science and Technology, 46(5), p.510 - 528, 2009/05

JENDL Actinoid File 2008 (JENDL/AC-2008) was released in March 2008. It includes nuclear data for neutron-induced reactions for 79 nuclides from Ac ($$Z=89$$) to Fm ($$Z=100$$). The neutron energy range is $$10^{-5}$$ eV to 20 MeV. Almost all data for 61 actinoids in JENDL-3.3 were revised. New evaluations were performed for 17 nuclides which have half lives longer than 1 day. New comprehensive theoretical model code CCONE was widely used for the evaluation of cross sections and neutron emission spectra. Thermal cross sections for many nuclides were revised based on experimental data. Resonance parameters were readjusted to reproduce them. Simultaneous evaluations of fission cross sections were performed for six important nuclei. The least-squares fitting code GMA was used for evaluation of fission cross sections for minor actinoid. In this paper, we present the evaluation methods and results of the JENDL/AC-2008.

Journal Articles

Progress in R&D efforts on the energy recovery linac in Japan

Sakanaka, Shogo*; Ago, Tomonori*; Enomoto, Atsushi*; Fukuda, Shigeki*; Furukawa, Kazuro*; Furuya, Takaaki*; Haga, Kaiichi*; Harada, Kentaro*; Hiramatsu, Shigenori*; Honda, Toru*; et al.

Proceedings of 11th European Particle Accelerator Conference (EPAC '08) (CD-ROM), p.205 - 207, 2008/06

Future synchrotron light sources based on the energy-recovery linacs (ERLs) are expected to be capable of producing super-brilliant and/or ultra-short pulses of synchrotron radiation. Our Japanese collaboration team is making efforts for realizing an ERL-based hard X-ray source. We report recent progress in our R&D efforts.

Journal Articles

Evidence of complete fusion in the sub-barrier $$^{16}$$O+$$^{238}$$U reaction

Nishio, Katsuhisa; Ikezoe, Hiroshi; Nagame, Yuichiro; Asai, Masato; Tsukada, Kazuaki; Mitsuoka, Shinichi; Tsuruta, Kaoru; Sato, Kenichiro; Lin, C. J.; Osawa, Takaaki*

Physical Review Letters, 93(16), p.162701_1 - 162701_4, 2004/10

 Times Cited Count:77 Percentile:90.47(Physics, Multidisciplinary)

The fission fragment angular distributions for reactions using actinide targets such as $$^{16}$$O+$$^{238}$$U show anomalously large anisotropy than the prediction of the transition state model. To interprete this phenomenon, the orientation dependent quasi-fission model was proposed. As the $$^{238}$$U has prolate deformation, the interaction of $$^{16}$$O with the $$^{238}$$U in the sub-barrier region is restricted to the tip collisions. Hinde et al. interpreted that the anomalously large angular anisotropy is due to the quasi-fission, that is the complete fusion is not achieved in the sub-barrier region. The presence (or absence) of the complete fision is found by measuring the evaporation residue cross sections. We measured the evaporation residue cross sections for $$^{16}$$O+$$^{238}$$U by using the $$^{16}$$O beams supplied by the JAERI-tandem accelerator. As a result, complete fusion was observed in the sub-barrier region and no significant fusion hindrace was observed.

JAEA Reports

Proceedings of the 2003 Symposium on Nuclear Data; November 27-28, 2003, JAERI, Tokai, Japan

Osawa, Takaaki*; Fukahori, Tokio

JAERI-Conf 2004-005, 262 Pages, 2004/04

JAERI-Conf-2004-005.pdf:15.24MB

The 2003 Symposium on Nuclear Data was held at Tokai Research Establishment, Japan Atomic Energy Research Institute (JAERI), on 27th and 28th of November 2003. Japanese Nuclear Data Committee and Nuclear Data Center, JAERI organized this symposium. In the oral sessions, presented were 18 papers on topics of ADS development and nuclear data for transmutation, nuclear data needs for next generation reactors and future JENDL plan, frontier of nuclear physics studies and nuclear data measurements, advanced science study and nuclear data, nuclear data needs and activities in Asian region, future of nuclear data study and other subjects. In the poster session, presented were 26 papers concerning experiments, evaluations, benchmark tests and so on. Those presented papers are compiled in the proceedings.

JAEA Reports

Evaluations of heavy nuclide data for JENDL-3.3

Kawano, Toshihiko*; Matsunobu, Hiroyuki*; Murata, Toru*; Zukeran, Atsushi*; Nakajima, Yutaka*; Kawai, Masayoshi*; Iwamoto, Osamu; Shibata, Keiichi; Nakagawa, Tsuneo; Osawa, Takaaki*; et al.

JAERI-Research 2003-026, 53 Pages, 2003/12

JAERI-Research-2003-026.pdf:2.48MB

New evaluations of neutron nuclear data for Uranium, Plutonium, and Thorium isotopes which are essential for applications to nuclear technology were carried out for the Japanese Evaluated Nuclear Data Library, JENDL-3.3. The objectives of the current release of JENDL were to fix several problems which have been reported for the previous version, to improve the accuracy of the data, and to evaluate covariances for the important nuclides. Quantities in JENDL-3.2 were extensively re-evaluated or replaced by more reliable values. The heavy nuclide data in JENDL-3.3 were validated with several benchmark tests, and it was reported that the current release gave a good prediction of criticalities.

JAEA Reports

Proceedings of the 2002 Symposium on Nuclear Data; November 21-22, 2002, JAERI, Tokai, Japan

Osawa, Takaaki*; Fukahori, Tokio

JAERI-Conf 2003-006, 318 Pages, 2003/06

JAERI-Conf-2003-006.pdf:23.8MB

The 2002 Symposium on Nuclear Data was held at Tokai Research Establishment, Japan Atomic Energy Research Institute (JAERI), on 21st and 22nd of November 2002. Japanese Nuclear Data Committee and Nuclear Data Center, JAERI organized this symposium. In the oral sessions, presented were 18 papers on topics of release of JENDL-3.3, requests from users, status of FP nuclear data, international activities and other subjects. In the poster session, presented were 33 papers concerning experiments, evaluations, benchmark tests and on-line database on nuclear data. Those presented papers are compiled in the proceedings.

Journal Articles

Fragment mass distribution of the $$^{239}$$Pu(${it d,pf}$) reaction via the superdeformed $$beta$$-vibrational resonance

Nishio, Katsuhisa; Ikezoe, Hiroshi; Nagame, Yuichiro; Mitsuoka, Shinichi; Nishinaka, Ichiro; Duan, L.*; Sato, Kenichiro; Goto, Shinichi*; Asai, Masato; Haba, Hiromitsu; et al.

Physical Review C, 67(1), p.014604_1 - 014604_5, 2003/01

 Times Cited Count:9 Percentile:54.08(Physics, Nuclear)

no abstracts in English

Journal Articles

Japanese evaluated nuclear data library version 3 revision-3; JENDL-3.3

Shibata, Keiichi; Kawano, Toshihiko*; Nakagawa, Tsuneo; Iwamoto, Osamu; Katakura, Junichi; Fukahori, Tokio; Chiba, Satoshi; Hasegawa, Akira; Murata, Toru*; Matsunobu, Hiroyuki*; et al.

Journal of Nuclear Science and Technology, 39(11), p.1125 - 1136, 2002/11

 Times Cited Count:642 Percentile:96.97(Nuclear Science & Technology)

Evaluation for JENDL-3.3 has been performed by considering the accumulated feedback information and various benchmark tests of the previous library JENDL-3.2. The major problems of the JENDL-3.2 data were solved by the new library: overestimation of criticality values for thermal fission reactors was improved by the modifications of fission cross sections and fission neutron spectra for $$^{235}$$U; incorrect energy distributions of secondary neutrons from important heavy nuclides were replaced with statistical model calculations; the inconsistency between elemental and isotopic evaluations was removed for medium-heavy nuclides. Moreover, covariance data were provided for 20 nuclides. The reliability of JENDL-3.3 was investigated by the benchmark analyses on reactor and shielding performances. The results of the analyses indicate that JENDL-3.3 predicts various reactor and shielding characteristics better than JENDL-3.2.

Journal Articles

Effect of alkali metals on the accuracy of isotope ratio measurement of uranium by ICP-MS

Magara, Masaaki; Sakakibara, Takaaki; Kurosawa, Setsumi; Takahashi, Masato; Sakurai, Satoshi; Hanzawa, Yukiko; Esaka, Fumitaka; Watanabe, Kazuo; Usuda, Shigekazu

Journal of Analytical Atomic Spectrometry, 17(9), p.1157 - 1160, 2002/09

 Times Cited Count:11 Percentile:45.64(Chemistry, Analytical)

no abstracts in English

Journal Articles

Evaluation of Delayed Neutron Data for JENDL-3.3

Yoshida, Tadashi*; Okajima, Shigeaki; Sakurai, Takeshi; Nakajima, Ken; Yamane, Tsuyoshi; Katakura, Junichi; Tahara, Yoshihisa*; Zukeran, Atsushi*; Oyamatsu, Kazuhiro*; Osawa, Takaaki*; et al.

Journal of Nuclear Science and Technology, 39(Suppl.2), p.136 - 139, 2002/08

no abstracts in English

Journal Articles

Recent status of developments in analytical methods for safeguards environmental samples; Focused on particle analysis

Esaka, Fumitaka; Magara, Masaaki; Hanzawa, Yukiko; Sakurai, Satoshi; Taguchi, Takuji; Takai, Konomi; Sakakibara, Takaaki; Kurosawa, Setsumi; Takahashi, Masato; Yasuda, Kenichiro; et al.

Dai-22-Kai Kaku Busshitsu Kanri Gakkai Nihon Shibu Nenji Taikai Rombunshu, 8 Pages, 2001/11

no abstracts in English

Journal Articles

Development of trace analytical technology for nuclear materials in the clean laboratory for environmental analysis and research

Usuda, Shigekazu; Watanabe, Kazuo; Sakurai, Satoshi; Magara, Masaaki; Hanzawa, Yukiko; Esaka, Fumitaka; Miyamoto, Yutaka; Yasuda, Kenichiro; Saito, Yoko; Gunji, Katsubumi*; et al.

KEK Proceedings 2001-14, p.88 - 92, 2001/06

no abstracts in English

Journal Articles

Current status of JAERI program on development of ultra-trace-analytical technology for safeguards environmental samples

Adachi, Takeo; Usuda, Shigekazu; Watanabe, Kazuo; Sakurai, Satoshi; Magara, Masaaki; Hanzawa, Yukiko; Esaka, Fumitaka; Yasuda, Kenichiro; Saito, Yoko; Takahashi, Masato; et al.

IAEA-SM-367/10/02 (CD-ROM), 8 Pages, 2001/00

no abstracts in English

Journal Articles

Simultaneous evaluation of fission cross sections of uranium and plutonium isotopes for JENDL-3.3

Kawano, Toshihiko*; Matsunobu, Hiroyuki*; Murata, Toru*; Zukeran, Atsushi*; Nakajima, Yutaka*; Kawai, Masayoshi*; Iwamoto, Osamu; Shibata, Keiichi; Nakagawa, Tsuneo; Osawa, Takaaki*; et al.

Journal of Nuclear Science and Technology, 37(4), p.327 - 334, 2000/04

no abstracts in English

24 (Records 1-20 displayed on this page)