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Journal Articles

Broken C$$_{4}$$ symmetry in the tetragonal state of uniaxial strained BaCo$$_{0.9}$$Ni$$_{0.1}$$S$$_{1.9}$$

Shamoto, Shinichi; Yamauchi, Hiroki; Ikeuchi, Kazuhiko*; Kajimoto, Ryoichi; Ieda, Junichi

Physical Review Research (Internet), 3(1), p.013169_1 - 013169_9, 2021/02

Journal Articles

The $$f$$-electron state of the heavy fermion superconductor NpPd$$_5$$Al$$_2$$ and the isostructural family

Metoki, Naoto; Aczel, A. A.*; Aoki, Dai*; Chi, S.*; Fernandez-Baca, J. A.*; Griveau, J.-C.*; Hagihara, Masato*; Hong, T.*; Haga, Yoshinori; Ikeuchi, Kazuhiko*; et al.

JPS Conference Proceedings (Internet), 30, p.011123_1 - 011123_6, 2020/03

Rare earths (4$$f$$) and actinides (5$$f$$) provide variety of interesting states realized with competing interactions between the increasing number of $$f$$ electrons. Since crystal field splitting of many-body $$f$$ electron system is smaller than the bandwidth, (1) high resolution experiments are needed, (2) essentially no clear spectrum with well defined peaks is expected in itinerant Ce and U compounds, and (3) Np and Pu is strictly regulated. Therefore, systematic research on magnetic excitations by neutron scattering experiments of localized compounds and rare earth iso-structural reference is useful. We describe the $$f$$ electron states of heavy electron compounds NpPd$$_5$$Al$$_2$$ and actinide and rare earth based iso-structural family.

JAEA Reports

Work and safety managements for on-site installation, commissioning, tests by EU of quench protection circuits for JT-60SA

Yamauchi, Kunihito; Okano, Jun; Shimada, Katsuhiro; Omori, Yoshikazu; Terakado, Tsunehisa; Matsukawa, Makoto; Koide, Yoshihiko; Kobayashi, Kazuhiro; Ikeda, Yoshitaka; Fukumoto, Masahiro; et al.

JAEA-Technology 2015-053, 36 Pages, 2016/03

JAEA-Technology-2015-053.pdf:8.33MB

The superconducting Satellite Tokamak machine "JT-60SA" under construction in Naka Fusion Institute is an international collaborative project between Japan (JA) and Europe (EU). The contributions for this project are based on the supply of components, and thus European manufacturer shall conduct the installation, commissioning and tests on Naka site. This means that Japan Atomic Energy Agency (JAEA) had a quite difficult issue to manage the works by European workers and their safety although there is no direct contract. This report describes the approaches for the work and safety managements, which were agreed with EU after the tough negotiation, and then the completed on-site works for Quench Protection Circuits (QPC) as the first experience for EU in JT-60SA project. With the help of these approaches by JAEA, the EU works for QPC were successfully completed with no accident, and a great achievement was made for both EU and JA.

Journal Articles

Bipartite magnetic parent phases in the iron oxypnictide superconductor

Hiraishi, Masatoshi*; Iimura, Soshi*; Kojima, Kenji*; Yamaura, Junichi*; Hiraka, Haruhiro*; Ikeda, Kazutaka*; Miao, P.*; Ishikawa, Yoshihisa*; Torii, Shuki*; Miyazaki, Masanori*; et al.

Nature Physics, 10(4), p.300 - 303, 2014/04

 Times Cited Count:99 Percentile:96.19(Physics, Multidisciplinary)

Journal Articles

Measurements of electron-induced neutrons as a tool for determination of electron temperature of fast electrons in the task of optimization laser-produced plasma ions acceleration

Sakaki, Hironao; Nishiuchi, Mamiko; Maeda, Shota; Sagisaka, Akito; Pirozhkov, A. S.; Pikuz, T.; Faenov, A.*; Ogura, Koichi; Fukami, Tomoyo; Matsukawa, Kenya*; et al.

Review of Scientific Instruments, 85(2), p.02A705_1 - 02A705_4, 2014/02

 Times Cited Count:2 Percentile:12.4(Instruments & Instrumentation)

High intensity laser-plasma interaction has attracted considerable interest for a number of years. The laser-plasma interaction is accompanied by generation of various charged particle beams. Results of simultaneous novel measurements of electron-induced photonuclear neutrons (photoneutron), which are a diagnostic of the laser-plasma interaction, are proposed to use for optimization of the laser-plasma ion generation. The proposed method is demonstrated by the laser irradiation with the intensity os 1$$times$$10$$^{21}$$ W/cm$$^{2}$$ on the metal foil target. The photoneutrons are measured by using NE213 liquid scintillation detectors. Heavy-ion signal is registered with the CR39 track detector simultaneously. The measured signals of the electron-induced photoneutrons are well reproduced by using the Particle and Heavy Ion Transport code System (PHITS). The results obtained provide useful approach for analyzing the various laser based ion beams.

Journal Articles

Emergent phenomena in perovskite-type manganites

Taguchi, Yasujiro*; Sakai, Hideaki*; Okuyama, Daisuke*; Ishiwata, Shintaro*; Fujioka, Jun*; Fukuda, Tatsuo; Hashizume, Daisuke*; Kagawa, Fumitaka*; Takahashi, Yoichiro*; Shimano, Ryo*; et al.

Physica B; Condensed Matter, 407(11), p.1685 - 1688, 2012/06

 Times Cited Count:4 Percentile:21.05(Physics, Condensed Matter)

Journal Articles

Deuterium concentration of co-deposited carbon layer produced at gap of wall tiles

Nobuta, Yuji*; Yokoyama, Kenji; Kanazawa, Jun*; Yamauchi, Yuji*; Hino, Tomoaki*; Suzuki, Satoshi; Ezato, Koichiro; Enoeda, Mikio; Akiba, Masato

Journal of Nuclear Materials, 417(1-3), p.607 - 611, 2011/10

 Times Cited Count:2 Percentile:19.59(Materials Science, Multidisciplinary)

Journal Articles

X-ray photon correlation spectroscopy study in valence fluctuation compound Eu$$_{3}$$S$$_{4}$$

Nakao, Hironori*; Owada, Kenji; Shimomura, Susumu*; Ochiai, Akira*; Namikawa, Kazumichi*; Mizuki, Junichiro; Mimura, Hidekazu*; Yamauchi, Kazuto*; Murakami, Yoichi*

AIP Conference Proceedings 1234, p.935 - 938, 2010/06

 Times Cited Count:2 Percentile:68.48

Journal Articles

Anisotropic and inhomogeneous magnetic interactions observed in all-organic nitroxide radical liquid crystals

Uchida, Yoshiaki*; Suzuki, Katsuaki*; Tamura, Rui*; Ikuma, Naohiko*; Shimono, Satoshi*; Noda, Yohei; Yamauchi, Jun*

Journal of the American Chemical Society, 132(28), p.9746 - 9752, 2010/06

 Times Cited Count:48 Percentile:75.18(Chemistry, Multidisciplinary)

An anisotropic and inhomogeneous magnetic interaction (the average spin-spin interaction constant, $$bar{rm J}$$ $$>$$ 0) was observed in the various liquid crystalline (LC) phases of racemic and nonracemic all-organic radical LC compounds. We discussed how the LC superstructures induced the magnetic interaction to operate in the LC phases in terms of spin-spin dipole and exchange interactions by means of VT-EPR spectroscopy. The magnitude of the magnetic interaction depended on the type of LC phase, or the superstructure. Furthermore, these radical LC droplets floating on water were commonly attracted to a permanent magnet and moved freely under the influence of this magnet, whereas the crystallized particles of the same compounds never responded to the magnet. The response of the LC droplets to the magnet also varied depending on the type of LC phase, that is, the extent of the magnetic interaction.

Journal Articles

X-ray intensity fluctuation spectroscopy using nanofocused hard X-rays; Its application to study of relaxor ferroelectrics

Owada, Kenji; Namikawa, Kazumichi*; Shimomura, Susumu*; Nakao, Hironori*; Mimura, Hidekazu*; Yamauchi, Kazuto*; Matsushita, Mitsuyoshi*; Mizuki, Junichiro

Japanese Journal of Applied Physics, 49(2), p.020216_1 - 020216_3, 2010/02

 Times Cited Count:3 Percentile:15.81(Physics, Applied)

Journal Articles

Retention and depth profile of hydrogen isotopes in gaps of the first wall in JT-60U

Nobuta, Yuji*; Arai, Takashi; Yagyu, Junichi; Masaki, Kei; Sato, Masayasu; Tanabe, Tetsuo*; Yamauchi, Yuji*; Hino, Tomoaki*

Journal of Nuclear Materials, 390-391, p.643 - 646, 2009/06

 Times Cited Count:5 Percentile:37.69(Materials Science, Multidisciplinary)

The hydrogen and deuterium retention in gap side surfaces of the first wall tiles exposed to DD and HH discharges in JT-60U were investigated. The hydrogen and deuterium retention and boron deposition increased with the gap width. The depth profile of deuterium was very similar to that of boron, indicating that deuterium was incorporated with boron. Thick carbon deposition layer ($$sim$$ 1e$$^{-5}$$m) was observed in the gap of inboard tile and the atomic ratio in (H+D)/C at the carbon layer was estimated to be approximately 0.15. This value is higher than that observed in the divertor region. In this study, the H+D amount in gap side surfaces of the first wall was of the order of 1e23 $$sim$$ 1e24m$$^{-2}$$.

Journal Articles

Multi-scattering time-of-flight neutron spectrometer for deuterium to tritium fuel ratio measurement in fusion experimental reactors

Asai, Keisuke*; Yukawa, Kyohei*; Iguchi, Tetsuo*; Naoi, Norihiro*; Watanabe, Kenichi*; Kawarabayashi, Jun*; Yamauchi, Michinori*; Konno, Chikara

Fusion Engineering and Design, 83(10-12), p.1818 - 1821, 2008/12

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

The fuel ratio in a DT burning plasma can be derived from the intensity ratio of DD/DT neutrons, and detecting a trace of DD neutrons in the DT burning plasma is a key issue. A new type of neutron spectrometer is proposed to monitor the fuel ratio in the core of the ITER plasma. The system based on a conventional time-of-flight method consists of a water cell as a neutron scattering material and tens of scintillator pairs arranged around the first scintillator in a corn shape. We call it a multi-scattering time-of-flight neutron spectrometer (MS-TOF). A trial experiment was conducted for the prototype MS-TOF system with a DT neutron beam (20-mm diameter) at the Fusion Neutronics Source (FNS), Japan Atomic Energy Agency. The experimental results show that the DD and DT neutron peaks are clearly observed, and the experiment has successfully demonstrated the feasibility of the MS-TOF concept for detecting trace-DD neutrons within a DT neutron beam extracted from a DT burn plasma.

Journal Articles

Unusual intermolecular magnetic interaction observed in an all-organic radical liquid crystal

Uchida, Yoshiaki*; Ikuma, Naohiko*; Tamura, Rui*; Shimono, Satoshi*; Noda, Yohei; Yamauchi, Jun*; Aoki, Yoshio*; Nohira, Hiroyuki*

Journal of Materials Chemistry, 18(25), p.2950 - 2952, 2008/07

 Times Cited Count:39 Percentile:75.07(Chemistry, Physical)

We found out an unusual intermolecular magnetic interaction in the liquid-crystalline (LC) state of an all-organic radical compound on surface of water (73 $$^{circ}$$C); the magnetic interaction actually allows the LC droplet on water to be attracted by a weak permanent magnet, whereas the crystalline phase did not respond to the magnet.

Journal Articles

Activation analysis for sequential reactions of a fusion Demo-reactor

Yamauchi, Michinori; Nishitani, Takeo; Nishio, Satoshi; Hori, Junichi*; Kawasaki, Hiromitsu*

Fusion Science and Technology, 52(4), p.781 - 785, 2007/11

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

Low activation material is one of the important factors for constructing high power fusion reactors in future. Unexpected activation, however, may be produced through sequential reactions due to charged particles created by primary neutron reactions. In the present work, the effect of the sequential activation reaction was studied for candidate low activation materials of a fusion demo-reactor. The calculations were conducted by the ACT4 code developed in JAEA for the activation analysis of fusion reactor designs and revised for dealing with the sequential activation reactions. The results say that the real dose rate around vanadium alloy which may be used as structural material becomes larger after the cooling for 3 years by considering the reaction. Although metal hydrate is regarded as an excellent low activation shield material, the reactions due to recoil protons are influential and the dose rate around vanadium hydrate is several orders of magnitude larger than the value calculated without the sequential process after 2 weeks cooling. In case of liquid breeders, the effect of sequential reactions is popularly observed and it affects the shield design of circulation loop.

JAEA Reports

ACT-XN; Revised version of an activation calculation code for fusion reactor analysis; Supplement of the function for the sequential reaction activation by charged particles

Yamauchi, Michinori; Hori, Junichi*; Sato, Satoshi; Nishitani, Takeo; Konno, Chikara; Kawasaki, Hiromitsu*

JAEA-Data/Code 2007-016, 58 Pages, 2007/09

JAEA-Data-Code-2007-016.pdf:7.33MB

The ACT-XN is a revised version of the ACT4 code, which was developed in the Japan Atomic Energy Agency (JAEA) to calculate the transmutation, induced activity, decay heat, delayed $$gamma$$-ray source etc. for fusion devices. The ACT4 code has not dealt with the sequential reactions of charged particles generated by primary neutron reactions. However, the reactions cannot be disregarded in the design employing low activation material, and the code was newly supplemented with the function to calculate the activation for sequential reactions and renamed the ACT-XN. The FISPACT data were adopted for (x,n) reaction cross sections, charged particles emission spectra and stopping powers. An application of the code to the analysis of FNS experiment for LiF activation confirmed that the function is enough reliable, and a notice was presented through the design calculation of the Demo-reactor with FLiBe that the dose rate may be enhanced by sequential reactions.

JAEA Reports

Evaluation of deuteron-induced activation for IFMIF accelerator structural materials

Nakao, Makoto*; Hori, Junichi*; Ochiai, Kentaro; Kubota, Naoyoshi; Sato, Satoshi; Yamauchi, Michinori; Ishioka, Noriko; Suto, Hiroyuki*; Nishitani, Takeo

JAEA-Research 2006-071, 37 Pages, 2006/11

JAEA-Research-2006-071.pdf:6.72MB

In the design of IFMIF, long-term operation with total facility availability of at least 70 % is required. However, activation of structural materials by deuteron beam limits maintenance, which causes lower facility availability. Thus it is essential to prepare deuteron-induced activation cross section database and to select low activation materials based on it. In this work, we measured deuteron-induced activation cross sections of aluminum, vanadium, chromium, manganese, iron, nickel, copper, tantalum, tungsten and gold. The measured cross sections were compared with other experimental data and calculations. Deuteron-induced activities of nuclides produced in SS316 and F82H alloys used as the accelerator structural material were also measured to validate the measured cross sections comprehensively. It demonstrated that the measured activities of almost all the nuclides were in agreement with evaluated ones based on the measured cross sections within error.

Journal Articles

Measurements of deuteron-induced activation cross-sections for IFMIF accelerator structural materials

Nakao, Makoto*; Hori, Junichi*; Ochiai, Kentaro; Kubota, Naoyoshi; Sato, Satoshi; Yamauchi, Michinori*; Ishioka, Noriko; Nishitani, Takeo

Nuclear Instruments and Methods in Physics Research A, 562(2), p.785 - 788, 2006/06

 Times Cited Count:23 Percentile:83.68(Instruments & Instrumentation)

Activation cross sections for deuteron-induced reactions on aluminum, iron, copper, tantalum and tungsten were measured by using stacked-foil method. The stacked-foils were irradiated with deuteron beam at the AVF cyclotron in TIARA facility, JAERI. We obtained the activation cross-sections for $$^{27}$$Al(d,x)$$^{22,24}$$Na, $$^{nat}$$Fe(d,x)$$^{55,56}$$Co, $$^{nat}$$Cu(d,x)$$^{61}$$Cu, $$^{nat}$$Cu(d,x)$$^{62}$$Zn, $$^{nat}$$Ta(d,x)$$^{178,180}$$Ta and $$^{nat}$$W(d,x)$$^{181,183}$$Re in 20-40MeV region. These cross-sections were compared with other experimental ones and the data in the ACSELAM library calculated by the ALICE-F code.

Journal Articles

Measurements of deuteron-induced activation cross sections for IFMIF accelerator structural materials

Nakao, Makoto; Hori, Junichi*; Ochiai, Kentaro; Kubota, Naoyoshi; Sato, Satoshi; Yamauchi, Michinori; Ishioka, Noriko; Nishitani, Takeo

FAPIG, (172), p.3 - 7, 2006/03

The IFMIF (International Fusion Materials Irradiation Facility) is in the design planning stage as neutron source to test fusion reactor materials for high fluence neutron. In the design of it long-term operation that total facility is 70 % at least is required. However, deuteron beam activates the structural materials and these activation limits maintenance and makes long-term operation difficult. Thus the accurate estimation of deuteron-induced activity and the selection of structural materials are important. In this work, measurements of deuteron-induced activation cross sections for aluminum, iron, copper, tantalum, and tungsten were performed.

Journal Articles

Analysis of sequential charged particle reaction experiments for fusion reactors

Yamauchi, Michinori*; Hori, Junichi*; Ochiai, Kentaro; Sato, Satoshi; Nishitani, Takeo; Kawasaki, Hiromitsu*

Fusion Engineering and Design, 81(8-14), p.1577 - 1582, 2006/02

 Times Cited Count:1 Percentile:10.41(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Measurements of deuteron-induced activation cross sections for IFMIF accelerator structural materials in the energy range of 22-40 MeV

Ochiai, Kentaro; Nakao, Makoto*; Hori, Junichi*; Sato, Satoshi; Yamauchi, Michinori*; Ishioka, Noriko; Nishitani, Takeo

Fusion Engineering and Design, 81(8-14), p.1459 - 1464, 2006/02

 Times Cited Count:2 Percentile:17.97(Nuclear Science & Technology)

The IFMIF consists of two 40 MeV deuteron linear accelerators with 125 mA beam current each. The structure materials of the accelerators are activated with high energetic deuteron. To measure the activation cross sections with $$^{27}$$Al, $$^{rm nat}$$Cu, $$^{rm nat}$$W, $$^{rm nat}$$V, $$^{rm nat}$$Ni, $$^{rm nat}$$Fe, and $$^{rm nat}$$Ta samples irradiated with 22-40 MeV deuteron beams, we have carried out the irradiation experiment of the main elements of the IFMIF candidate materials by using the deutron beam of the AVF cyclotron of the TIARA facility in JAERI/Takasaki.

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