Nakane, Tomohiro*; Yoneyama, Shota*; Kodama, Takeshi*; Kikuchi, Koichi*; Nakao, Akiko*; Ohara, Takashi; Higashinaka, Ryuji*; Matsuda, Tatsuma*; Aoki, Yuji*; Fujita, Wataru*
Dalton Transactions (Internet), 48(1), p.333 - 338, 2019/01
Tateiwa, Naoyuki; Pospil, J.*; Haga, Yoshinori; Sakai, Hironori; Matsuda, Tatsuma*; Yamamoto, Etsuji
Physical Review B, 96(3), p.035125_1 - 035125_15, 2017/07
We have carried out an analysis of magnetic data in 69 uranium, 7 neptunium and 4 plutonium ferromagnets with the spin fluctuation theory developed by Takahashi (Y. Takahashi, J. Phys. Soc. Jpn. , 3553 (1986)). The basic and spin fluctuation parameters of the actinide ferromagnets are determined and the applicability of the spin fluctuation theory to actinide system has been discussed. Itinerant ferromagnets of the transition metals and their intermetallics follow a generalized Rhodes-Wohlfarth relation . Here, , , , and are the spontaneous and effective magnetic moments, the Curie temperature and the width of spin fluctuation spectrum in energy space, respectively. The same relation is satisfied for in the most of the actinide ferromagnets.
Masuda, Toshiyuki*; Arase, Junko*; Inagaki, Yusuke*; Kawahara, Masatoshi*; Yamaguchi, Kentaro*; Ohara, Takashi; Nakao, Akiko*; Momma, Hiroyuki*; Kwon, E.*; Setaka, Wataru*
Crystal Growth & Design, 16(8), p.4392 - 4401, 2016/08
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 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.
Toh, Yosuke; Huang, M.; Kimura, Atsushi; Nakamura, Shoji; Harada, Hideo; Ebihara, Mitsuru*
Shiki, 28, P. 4, 2015/09
no abstracts in English
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
Non-destructive elemental analyses have been an indispensable tool for many fields of scientific research. Prompt -ray analysis and time of flight elemental analysis uses the energy of the rays and the energy of neutron resonances, respectively. In both analyses, a sample is irradiated with neutrons and 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.
Tateiwa, Naoyuki; Haga, Yoshinori; Matsuda, Tatsuma*; Yamamoto, Etsuji; Fisk, Z.
Physical Review B, 89(6), p.064420_1 - 064420_8, 2014/02
We report a dc magnetization study of the critical phenomenon around the ferromagnetic transition temperature in high-quality single crystals of uranium ferromagnetic superconductors UGe and URhGe. Although the values of the critical exponent and for the magnetization in UGe and URhGe are close to those in the 3D magnets, the values of the critical exponent for the magnetic susceptibility are close to unity, that expected from the mean field theory. The unconventional critical scaling of magnetization in UGe, and URhGe cannot be explained via previous approaches to critical phenomena.
Toh, Yosuke; Ebihara, Mitsuru*; Harada, Hideo
Transactions of the American Nuclear Society, 109(1), p.116 - 117, 2013/11
no abstracts in English
Islam, M. A.*; Ebihara, Mitsuru*; Toh, Yosuke; Murakami, Yukihiro*; Harada, Hideo
Applied Radiation and Isotopes, 70(8), p.1531 - 1535, 2012/08
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.
Kikuchi, Shin; Kurihara, Akikazu; Ohshima, Hiroyuki; Hashimoto, Kenro*
Journal of Power and Energy Systems (Internet), 6(2), p.76 - 86, 2012/06
In a sodium-cooled fast reactor (SFR), liquid sodium is used as heat transfer fluid to carry the energy from the reactor core to the steam generation (SG) system for power generation. If the heat transfer tube in the SG is failed, high pressurized water vapor blows into the liquid sodium and the sodium-water reaction (SWR) takes place. The extremely high-temperature reaction jet formed by the SWR, causes damage to the surface of the neighboring heat transfer tubes by thermal and chemical effects. Therefore, it is important to clearly understand the SWR for safety assessment of SG. In this study, we investigated the surface reaction mechanism in the SWR by ab initio method. The potential energy profiles of the dissociations of HO and OH were obtained. The estimated rate constant of the former was much larger than the latter.
Kikuchi, Shin; Kurihara, Akikazu; Ohshima, Hiroyuki; Hashimoto, Kenro*
Nippon Genshiryoku Gakkai Wabun Rombunshi, 11(2), p.147 - 157, 2012/06
A breach of the heat transfer tube in a steam generator (SG) of a sodium-cooled fast reactor results in sodium-water reaction (SWR) by direct contact between liquid sodium and water vapor, which generates high temperature reaction jet. This reaction jet causes damage to the surface of neighboring heat transfer tubes by thermal and chemical effects. Therefore, it is important to clearly understand the SWR for safety assessment of SG. Regarding chemical effect, the surface and gas-phase reaction model are considered. As for the surface reaction, the water vapor encounters the liquid sodium, and the reaction occurs at their interface. Subsequently, the chemical reaction heating vaporizes the liquid sodium, causing the gas-phase reaction. However, there is limited knowledge on surface reaction because of extremely rapid-reaction. Therefore, in this study, ab-initio calculation was performed to evaluate the reaction path on surface reaction in SWR. The reaction path on dissociation of a water molecule at the liquid sodium surface was obtained. In addition, we also confirmed the generation mechanism of hydrogen in the liquid sodium.
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
We applied multiple prompt -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 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.
Islam, M. A.*; Ebihara, Mitsuru*; Toh, Yosuke; Harada, Hideo
Analytical Chemistry, 83(19), p.7486 - 7491, 2011/10
Multiple prompt -ray analysis (MPGA) and prompt -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 -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 -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.
Kikuchi, Shin; Ohshima, Hiroyuki; Hashimoto, Kenro*
Proceedings of 19th International Conference on Nuclear Engineering (ICONE-19) (CD-ROM), 8 Pages, 2011/10
In a sodium-cooled fast reactor (SFR), liquid sodium is used as heat transfer fluid to carry the energy from the reactor core to the steam generation (SG) system for power generation. If the heat transfer tube in the SG is failed, high pressurized water vapor blows into the liquid sodium and the sodium-water reaction (SWR) takes place. The extremely high temperature reaction jet formed by the SWR causes damage to the surface of the neighboring heat transfer tubes by thermal and chemical effects. Therefore, it is important to clearly understand the SWR for safety assessment of SG. In this work, we studied the surface reaction in the SWR by using ab initio calculations. The successive OH cleavages of a water molecule at the liquid sodium surface were focused. The possible reaction path and the related energies including the barrier heights were reported. The relative rates of the OH cleavages were also discussed.
Ishii, Yasuo; Toyoshima, Atsushi; Tsukada, Kazuaki; Asai, Masato; Li, Z.*; Nagame, Yuichiro; Miyashita, Sunao*; Mori, Tomotaka*; Suganuma, Hideo*; Haba, Hiromitsu*; et al.
Bulletin of the Chemical Society of Japan, 84(9), p.903 - 911, 2011/09
The cation-exchange behavior of element 104, rutherfordium (Rf), was investigated together with its lighter group-4 homologues Zr and Hf, and the tetravalent pseudo-homologue Th in HF/HNO mixed solution. The results demonstrate that distribution coefficients () of Rf in HF/0.10 M HNO decrease with increasing concentration of the fluoride ion [F], indicating the consecutive formation of fluorido complexes of Rf. We also measured the values of Rf and the homologues as a function of the hydrogen ion concentration [H]. The log values decrease linearly with an increase of log [H] with slopes between -2.1 and -2.5. This indicates that these elements are likely to form the same chemical compounds: mixture of [MF] and [MF] (M = Rf, Zr, Hf and Th) in the studied solution. It is also ascertained that sequence in the fluoride complex formation is Zr Hf Rf Th.
Nishinaka, Ichiro; Tanikawa, Masashi*; Nagame, Yuichiro; Nakahara, Hiromichi*
European Physical Journal A, 47(1), p.1 - 8, 2011/01
The most probable charges of secondary fragments in the 11.5 MeV proton-induced fission of U were determined from the mass yields measured by the double time-of-flight method and the fractional cumulative and independent yields measured radiochemically and reported in literature. The nuclear-charge polarization of primary fragments at scission was obtained by correcting the secondary fragment mass for neutron evaporation. The results show that the nuclear-charge polarization is determined by the minimum potential energy of nuclei at scission and that it is nearly independent not only of mass and excitation energy but also of the neutron-to-proton ratio of the fissioning nucleus.
Toyoshima, Atsushi; Kasamatsu, Yoshitaka*; Tsukada, Kazuaki; Asai, Masato; Kitatsuji, Yoshihiro; Ishii, Yasuo; Tome, Hayato; Nishinaka, Ichiro; Haba, Hiromitsu*; Oe, Kazuhiro*; et al.
Journal of the American Chemical Society, 131(26), p.9180 - 9181, 2009/07
We report here on the successful oxidation of element 102, nobelium (No), on an atom-at-a-time scale in 0.1 M -hydroxyisobutyric acid (-HIB) solution using newly developed flow electrolytic column chromatography. It is found that the most stable No is oxidized to No within 3 min and that the oxidized No complex with -HIB holds the trivalent state in the column above the applied potential of 1.0 V.
Ebihara, Mitsuru*; Hatsukawa, Yuichi; Oshima, Masumi
JAEA-Review 2008-056, 65 Pages, 2009/01
The workshop on "Multiple Prompt -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 -ray detections and prompt -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.
Toh, Yosuke; Oshima, Masumi; Koizumi, Mitsuo; Kimura, Atsushi; Hatsukawa, Yuichi
Journal of Radioanalytical and Nuclear Chemistry, 276(1), p.217 - 220, 2008/04
no abstracts in English
Toh, Yosuke; Koizumi, Mitsuo; Oshima, Masumi; Kimura, Atsushi; Hatsukawa, Yuichi; Osa, Akihiko; Goto, Jun*
Journal of Radioanalytical and Nuclear Chemistry, 272(2), p.303 - 305, 2007/05
no abstracts in English