Electronic structure and magnetic properties of the half-metallic ferrimagnet MnVAl probed by soft X-ray spectroscopies

Nagai, Kodai*; Fujiwara, Hidenori*; Aratani, Hidekazu*; Fujioka, Shuhei*; Yomosa, Hiroshi*; Nakatani, Yasuhiro*; Kiss, Takayuki*; Sekiyama, Akira*; Kuroda, Fumiaki*; Fujii, Hitoshi*; et al.

Physical Review B, 97(3), p.035143_1 - 035143_8, 2018/01

AA2017-0644.pdf:1.01MB

https://doi.org/10.1103/PhysRevB.97.035143

We have studied the electronic structure of ferrimagnetic MnVAl single crystals by means of soft X-ray absorption spectroscopy (XAS), X-ray absorption magnetic circular dichroism (XMCD), and resonant soft X-ray inelastic scattering (RIXS). We have successfully observed the XMCD signals for all the constituent elements. The Mn L XAS and XMCD spectra are reproduced by spectral simulations based on density-functional theory, indicating the itinerant character of the Mn 3 states. On the other hand, the V 3 electrons are rather localized since the ionic model can qualitatively explain the V L XAS and XMCD spectra. This picture is consistent with local excitations revealed by the V L RIXS.

Prototype manufacturing of small tritium target inside JAEA

Tanaka, Shigeru; Abe, Yuichi; Kawabe, Masaru; Kutsukake, Chuzo; Oginuma, Yoshikazu; Yamada, Masayuki; Suzuki, Takumi; Yamanishi, Toshihiko; Konno, Chikara

Journal of Plasma and Fusion Research SERIES, Vol.9, p.338 - 341, 2010/08

We have conducted a small tritium target production R&D for FNS inside JAEA. The tritium target is produced by adsorbing tritium in a thin titanium layer. Since titanium is very active to oxygen, glow discharge cleaning was carried out to remove an oxidation film of the titanium surface. Through many tests with deuterium, we found out that it was not an oxidation film but humidity to disturb tritium absorption. The following procedures were necessary; (1) to outgas the inside of an absorption chamber, (2) to keep environmental humidity under 3% in handling the titanium-deposited substrate, (3) to keep the titanium-deposited target substrate in the vacuum. The DT neutron generation performance of the tritium target produced with the above procedures was the same as that with discharge cleaning. The manufacture condition of the small target was established.

Measurement of reaction rate distribution in partial mockups for the ITER TBM with DT neutrons

Sato, Satoshi; Takakura, Kosuke; Ochiai, Kentaro; Kondo, Keitaro; Tatebe, Yosuke; Onishi, Seiki; Wada, Masayuki*; Kutsukake, Chuzo; Tanaka, Shigeru; Abe, Yuichi; et al.

Fusion Science and Technology, 56(1), p.227 - 231, 2009/07

https://doi.org/10.13182/FST09-A8907

Previously DT neutronics experiments were performed by using partial blanket mockups for Japanese ITER test blanket module at JAEA FNS, and tritium production rates (TPR) inside blanket mockups were measured in details. The calculation with the nuclear data library FENDL-2.1 and Monte Carlo code MCNP4C agreed well with most of the measured TPRs within uncertainty of 10%. On the other hand, overestimations were found for the TPR in the experiment with a reflector and the TPR around the boundary between the rear part of the breeder layer and the beryllium layer by more than 10%. In order to confirm this concern, we measured reaction rate distribution in the partial blanket mockups with DT neutrons with two solid breeder blanket partial mockups, (Be/LiTiO/Be, SS316/LiTiO/SS316). Experiments were performed with and without a neutron source reflector. In order to measure reaction rate distributions, the activation foil method was applied using Nb and Au foils in this study. Experimental analyses were performed by MCNP4C with FENDL-2.1. Calculation results to experimental ones (C/Es) on the Au reaction rate with a reflector were larger than those without one. Detailed results are presented in this conference.

D-T neutron streaming experiment simulating narrow gaps in ITER equatorial port

Ochiai, Kentaro; Sato, Satoshi; Wada, Masayuki*; Iida, Hiromasa; Takakura, Kosuke; Kutsukake, Chuzo; Tanaka, Shigeru; Abe, Yuichi; Konno, Chikara

Fusion Engineering and Design, 83(10-12), p.1725 - 1728, 2008/12

https://doi.org/10.1016/j.fusengdes.2008.06.031

Under the ITER/ITA task, we have conducted the neutron streaming experiment simulating narrow and deep gaps at boundaries between ITER vacuum vessel and equatorial port plugs. Micro fission chambers and some activation foils were utilized to measure fission rates and reaction rates to evaluate the relative fast and slow neutron fluences along the gap in the experimental assembly. The MCNP4C, TORT and Attila codes were used for the experimental analysis. From comparing our measurements and calculations, the following facts were found: (1) In case of a such narrow and deep gap structure, the calculation with MCNP, TORT and ATTILA codes and FENDL-2.1 is sufficient to predict fast neutron field inside the gap.: (2) Angular quadrature set of upward biased U315 and last collided source calculation on TORT and Attila were very important technique for accurate estimation of neutron transport.

The Prospective role of JAEA Nuclear Fuel Cycle Engineering Laboratories

Ojima, Hisao; Dojiri, Shigeru; Tanaka, Kazuhiko; Takeda, Seiichiro; Nomura, Shigeo

Proceedings of International Conference on Advanced Nuclear Fuel Cycles and Systems (Global 2007) (CD-ROM), p.273 - 282, 2007/09

The Nuclear Fuel Cycle Engineering Laboratories of Japan Atomic Energy Agency (JAEA) was established to take over activities of the Tokai Works of Japan Nuclear Cycle Development Institute (JNC). From 1959, several kinds of technologies (such as uranium refining, centrifuge for uranium enrichment, LWR spent fuel reprocessing and MOX fuel fabrication) have been accomplished. And also, R&Ds on the treatment and disposal of high level waste and the FBR fuel reprocessing have been carried out. Through such activities, control of environmental release of radioactive material and radiation exposure and management of nuclear materials have been done appropriately. The Laboratories will contribute to establish the closed cycle with R&Ds of the reprocessing technology during the transition period from LWR era to FBR era, improved MOX fuel fabrication technology, advanced FBR fuel reprocessing technology and high level waste disposal technology.

Ion beam breeding of rice variety suitable for low nitrogen input

Katayama, Hisato*; Kitamura, Harushige*; Mori, Mari*; Nakagawa, Junya*; Yoshida, Takahiro*; Kawai, Toshihiko*; Hase, Yoshihiro; Tanaka, Atsushi

JAEA-Review 2006-042, JAEA Takasaki Annual Report 2005, P. 94, 2007/02

https://jopss.jaea.go.jp/pdfdata/JAEA-Review-2006-042.pdf

no abstracts in English

Structural basis for the fast phase change of GeSbTe; Ring statistics analogy between the crystal and amorphous states

Kohara, Shinji*; Kato, Kenichi*; Kimura, Shigeru*; Tanaka, Hitoshi*; Usuki, Takeshi*; Suzuya, Kentaro; Tanaka, Hiroshi*; Moritomo, Yutaka*; Matsunaga, Toshiyuki*; Yamada, Noboru*; et al.

Applied Physics Letters, 89(20), p.201910_1 - 201910_3, 2006/11

https://doi.org/10.1063/1.2387870

The three-dimensional atomic configuration of amorphous GeSbTe were derived by reverse Monte Carlo simulation with synchrotron-radiation X-ray diffraction data. The authors found that amorphous GeSbTe can be regarded as "even-numbered ring structure", because the ring statistics is dominated by four- and six-fold rings analogous to the crystal phase. On the other hand, the formation of Ge-Ge homopolar bonds in amorphous GeTe constructs both odd- and even-numbered rings. They believe that the unusual ring statistics of amorphous GeSbTe is the key for the fast crystallization speed of the material.

Study on Mixing Phenomena in T-Pipe Junction; Temperature Measurement Test in Pipe by Liquid Crystal Sheet

Tanaka, Masaaki; Kawashima, Shigeyo*; Igarashi, Minoru; Hayashi, Kenji; Tobita, Akira; Kamide, Hideki

JNC TN9400 2003-117, 65 Pages, 2004/03

JNC-TN9400-2003-117.pdf:3.49MB

Temperature fluctuation due to mixing of hot and cold fluids gives thermal fatigue to the structure (thermal striping phenomena).Investigation of this phenomenon is significant for the safety of a fast breeder reactor, which uses liquid metal as a coolant. In Japan Nuclear Cycle Development Institute, experiments and numerical analyses have been carried out to understand this phenomenon and also to construct the evaluation rule, which can be applied to the design. A water experiment of fluid mixing in T-pipe with long cycle fluctuation (WATLON),which notices thermal striping phenomena in the T-pipe junction, is performed to investigate the key factor of mixing phenomena by reason of long cycle fluctuation observed in a plant. By the former visualization test, it was showed that the flow pattern of branch pipe jet could be classified into (A) impinging jet, (B) deflecting jet (C) re-attachment jet and (D) wall jet according to the inflow condition. It was confirmed that the each jet pattern could be predicted by the momentum ratio of the each piping fluid. In this study, a thermo-chromic liquid crystal sheet was put on the inner wall in the main pipe, and temperature field on the wall surface was visualized. We established a new method to convert the color image data to temperature data. And measurement uncertainty of this method was evaluated + and - about 2.0 [deg-C], using by the typical picture in the temperature calibration test. From the temperature fluctuation visualization test by liquid crystal sheet, the cold spot was formed in just downstream region from the outlet of the branch pipe in the cases of the wall jet and impinging jet. Since this cold spot moved in time, high value of temperature fluctuation intensity was shown around the cold spot. And the validity of this method was shown from the comparison of the thermocouple data installed in a wall surface with the temperature conversion result.

Measurement of radiation skyshine with D-T neutron source

Yoshida, Shigeo*; Nishitani, Takeo; Ochiai, Kentaro; Kaneko, Junichi*; Hori, Junichi; Sato, Satoshi; Yamauchi, Michinori*; Tanaka, Ryohei*; Nakao, Makoto*; Wada, Masayuki*; et al.

Fusion Engineering and Design, 69(1-4), p.637 - 641, 2003/09

https://doi.org/10.1016/S0920-3796(03)00196-0

no abstracts in English

An Insight into the pathway of the amyloid fibril formation of hen egg white lysozyme obtained from a small-angle X-ray and neutron scattering study

Yonezawa, Yasushige*; Tanaka, Shimpei*; Kubota, Tomomi*; Wakabayashi, Katsuzo*; Yutani, Katsuhide*; Fujiwara, Satoru

Journal of Molecular Biology, 323(2), p.237 - 251, 2002/10

https://doi.org/10.1016/S0022-2836(02)00941-5

It is known that hen egg white lysozyme (HEWL) forms amyloid fibrils in highly concentrated ethanol solutions. In order to gain an insight into the mechanism of the amyloid fibril formation, the structures of HEWL in solutions of various protein and ethanol concentrations were investigated with small-angle X-ray and neutron scattering. It was shown that the structural states of HEWL were distinguished as the monomer state, the state of the dimer formation, the state of the protofilament formation, the protofilament state, and the state towards the formation of the amyloid fibrils. Circular dichroism measurements showed that the large changes in the secondary structures of HEWL occurred during the dimer formation. Structural characterization showed that the dimers had an elongated shape, the protofilaments were formed by stacking of the dimers with their long axis (nearly) perpendicular to the protofilament axis, and the changes of the structural states towards the amyloid fibril formation occurred via lateral association of the protofilaments.