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Journal Articles

Metalloid substitution elevates simultaneously the strength and ductility of face-centered-cubic high-entropy alloys

Wei, D.*; Wang, L.*; Zhang, Y.*; Gong, W.; Tsuru, Tomohito; Lobzenko, I.; Jiang, J.*; Harjo, S.; Kawasaki, Takuro; Bae, J. W.*; et al.

Acta Materialia, 225, p.117571_1 - 117571_16, 2022/02

 Times Cited Count:39 Percentile:99.78(Materials Science, Multidisciplinary)

Journal Articles

Deexcitation dynamics of muonic atoms revealed by high-precision spectroscopy of electronic $$K$$ X rays

Okumura, Takuma*; Azuma, Toshiyuki*; Bennet, D. A.*; Caradonna, P.*; Chiu, I. H.*; Doriese, W. B.*; Durkin, M. S.*; Fowler, J. W.*; Gard, J. D.*; Hashimoto, Tadashi; et al.

Physical Review Letters, 127(5), p.053001_1 - 053001_7, 2021/07

 Times Cited Count:5 Percentile:52.75(Physics, Multidisciplinary)

We observed electronic $$K$$X rays emitted from muonic iron atoms using a superconducting transition-edge-type sensor microcalorimeter. The energy resolution of 5.2 eV in FWHM allowed us to observe the asymmetric broad profile of the electronic characteristic $$K$$$$alpha$$ and $$K$$$$beta$$ X rays together with the hypersatellite $$K$$$$alpha$$ X rays around 6 keV. This signature reflects the time-dependent screening of the nuclear charge by the negative muon and the $$L$$-shell electrons, accompanied by electron side-feeding. Assisted by a simulation, this data clearly reveals the electronic $$K$$- and $$L$$-shell hole production and their temporal evolution during the muon cascade process.

Journal Articles

The Study of the magnetization process of Fe film by magnetic Compton scattering and M$"o$ssbauer spectroscopy

Agui, Akane; Masuda, Ryo*; Kobayashi, Yasuhiro*; Kato, Tadashi*; Emoto, Shun*; Suzuki, Kosuke*; Sakurai, Hiroshi*

Journal of Magnetism and Magnetic Materials, 408, p.41 - 45, 2016/06


 Times Cited Count:4 Percentile:22.77(Materials Science, Multidisciplinary)

We investigated the magnetization process of Fe (110) film using the field dependence of magnetic Compton scattering and M$"o$ssbauer spectroscopy. From the magnetic Compton profiles, the spin and orbital magnetic moment specific magnetization versus magnetizing field curves were obtained. From the M$"o$ssbauer spectra, the angles between the magnetizing field and the magnetic moment were obtained. It was found that the magnetizing field dependence of the ratio between orbital moment and spin moment was related to the angles between the magnetizing field and the magnetic moment. We indicate that the magnetic field dependence of the orbital magnetic moment plays a role in the magnetization process.

JAEA Reports

Annual report of Nuclear Emergency Assistance and Training Center (April 1, 2013 - March 31, 2014)

Sato, Takeshi; Muto, Shigeo; Akiyama, Kiyomitsu; Aoki, Kazufumi; Okamoto, Akiko; Kawakami, Takeshi; Kume, Nobuhide; Nakanishi, Chika; Koie, Masahiro; Kawamata, Hiroyuki; et al.

JAEA-Review 2014-048, 69 Pages, 2015/02


JAEA was assigned as a designated public institution under the Disaster Countermeasures Basic Act and under the Armed Attack Situations Response Act. Based on these Acts, the JAEA has the responsibility of providing technical support to the national government and/or local governments in case of disaster responses or response in the event of a military attack, etc. In order to fulfill the tasks, the JAEA has established the Emergency Action Plan and the Civil Protection Action Plan. In case of a nuclear emergency, NEAT dispatches specialists of JAEA, supplies the national government and local governments with emergency equipment and materials, and gives technical advice and information. In normal time, NEAT provides various exercises and training courses concerning nuclear disaster prevention to those personnel taking an active part in emergency response institutions of the national and local governments, police, fire fighters, self-defense forces, etc. in addition to the JAEA itself. The NEAT also researches nuclear disaster preparedness and response, and cooperates with international organizations. In the FY2013, the NEAT accomplished the following tasks: (1) Technical support activities as a designated public institution in cooperation with the national and local governments, etc. (2) Human resource development, exercise and training of nuclear emergency response personnel for the national and local governments, etc. (3) Researches on nuclear disaster preparedness and response, and sending useful information (4) International contributions to Asian countries on nuclear disaster preparedness and response in collaboration with the international organizations

Journal Articles

The Result of beam commissioning in J-PARC 3-GeV RCS

Harada, Hiroyuki; Hotchi, Hideaki; Saha, P. K.; Shobuda, Yoshihiro; Hayashi, Naoki; Yamamoto, Kazami; Yoshimoto, Masahiro; Tamura, Fumihiko; Yamamoto, Masanobu; Kinsho, Michikazu; et al.

Proceedings of 52nd ICFA Advanced Beam Dynamics Workshop on High-Intensity and High-Brightness Hadron Beams (HB 2012) (Internet), p.339 - 343, 2012/09

J-PARC 3-GeV RCS has started the beam commissioning since Oct. 2007. In the beam commissioning, the beam tuning for basic parameters and high-intensity operation has been continuously performed. This presentation will describe the results of the beam-loss reduction and minimization for high-intensity operation.

Journal Articles

Beam commissioning and operation of the Japan Proton Accelerator Research Complex 3-GeV rapid cycling synchrotron

Hotchi, Hideaki; Harada, Hiroyuki; Hayashi, Naoki; Kinsho, Michikazu; Saha, P. K.; Shobuda, Yoshihiro; Tamura, Fumihiko; Yamamoto, Kazami; Yamamoto, Masanobu; Yoshimoto, Masahiro; et al.

Progress of Theoretical and Experimental Physics (Internet), 2012(1), p.02B003_1 - 02B003_26, 2012/00

 Times Cited Count:16 Percentile:66.98(Physics, Multidisciplinary)

The J-PARC 3-GeV RCS is a high-power pulsed proton driver aiming at 1 MW output beam power. The RCS was beam commissioned in October 2007 and made available for user operation in December 2008 with an output beam power of 4 kW. Since then, the output beam power of the RCS has been steadily increasing as per progressions of beam tuning and hardware improvements. So far, the RCS has successfully achieved high-intensity beam trials of up to 420 kW at a low-level intensity loss of less than 1%, and the output beam power for the routine user program has been increased to 210 kW. The most important issues in increasing the output beam power are the control and minimization of beam loss to maintain machine activation within the permissible level. This paper presents the recent progress in the RCS beam power ramp-up scenario, with particular emphasis on our efforts for beam loss issues.

Journal Articles

Ablation of insulators under the action of short pulses of X-ray plasma lasers and free-electron lasers

Inogamov, N. A.*; Anisimov, S. I.*; Petrov, Y. V.*; Khokhlov, V. A.*; Zhakhovskii, V. V.*; Faenov, A. Ya.*; Pikuz, T.; Fortov, V. E.*; Skobelev, I. Y.*; Kato, Yoshiaki*; et al.

Journal of Optical Technology, 78(8), p.473 - 480, 2011/08

 Times Cited Count:5 Percentile:29.38(Optics)

Journal Articles

Current status of the control system for J-PARC accelerator complex

Yoshikawa, Hiroshi; Sakaki, Hironao; Sako, Hiroyuki; Takahashi, Hiroki; Shen, G.; Kato, Yuko; Ito, Yuichi; Ikeda, Hiroshi*; Ishiyama, Tatsuya*; Tsuchiya, Hitoshi*; et al.

Proceedings of International Conference on Accelerator and Large Experimental Physics Control Systems (ICALEPCS '07) (CD-ROM), p.62 - 64, 2007/10

J-PARC is a large scale facility of the proton accelerators for the multi-purpose of scientific researches in Japan. This facility consists of three accelerators and three experimental stations. Now, J-PARC is under construction, and LINAC is operated for one year, 3GeV synchrotron has just started the commissioning in this October the 1st. The completion of this facility will be next summer. The control system of accelerators established fundamental performance for the initial commissioning. The most important requirement to the control system of this facility is to minimize the activation of accelerator devices. In this paper, we show that the performances of each layer of this control system have been achieved in the initial stage.

Journal Articles

Separation behaviors of actinides from rare-earths in molten salt electrorefining using saturated liquid cadmium cathode

Kato, Tetsuya*; Inoue, Tadashi*; Iwai, Takashi; Arai, Yasuo

Journal of Nuclear Materials, 357(1-3), p.105 - 114, 2006/10

 Times Cited Count:101 Percentile:98.85(Materials Science, Multidisciplinary)

Electrorefining in the molten LiCl-KCl eutectic salt containing actinides(An) and rare-earths(RE) was conducted to recover up to 10 wt% An into liquid Cd cathode, which is much higher than the solubility of An in liquid Cd at the experimental temperature. In the saturated Cd cathode, An and RE were recovered to form a compound of the PuCd$$_{11}$$ lattice, MCd$$_{11}$$. The separation factors of RE against Pu were defined as (RE/Pu in the Cd cathode)/(RE/Pu in the salt) and calculated for the saturated Cd alloy including MCd$$_{11}$$. The separation factors for the Cd cathodes were a little larger than the equilibrium values.

Journal Articles

Distillation of cadmium from uranium-plutonium-cadmium alloy

Kato, Tetsuya*; Iizuka, Masatoshi*; Inoue, Tadashi*; Iwai, Takashi; Arai, Yasuo

Journal of Nuclear Materials, 340(2-3), p.259 - 265, 2005/04

 Times Cited Count:23 Percentile:81.68(Materials Science, Multidisciplinary)

no abstracts in English

JAEA Reports

Material Properties of Oxide Dispersion Strengthened (ODS) Ferritic Steels for Core Materials of FBR; Mechanical Strength Properties of Sodium Exposed and Nickel Diffused Materials [Interim Report]

Kato, Shoichi; Sakurai, Tadashi*; Yoshida, Eiichi

JNC TN9400 2003-107, 127 Pages, 2004/02


An oxide dispersion strengthened(ODS) ferritic steel have excellent resistance to swelling and superior creep strength, they are expected to be used as a long-life cladding material in future advallced fast reactor. In this study, sodium environmental effect on the ODS steel developed by JNC were clarified through tensile test after sodium exposure for maximum 10,000hrs and creep-rupture test in sodium at elevated temperature. The exposure to sodium was conducted using a sodium test loop constituted by austenitic steels. For the conditions of sodium exposure test, the sodium temperatures were 923K and 973K, the oxygen concentration in sodium was below 2ppm and sodium flow rate on the surface of specimen was less than 1$$times$$10 sup-4 m/s. Further the specimen with the nickel diffused was prepared, which is simulate to nickel diffusing through sodium from the surface of structural stainless steels. The main results obtained were as follows;(1)The results showed excellent sodium-resistance up to a high temperature of about 973K in stagnant sodium conditions, and its considered that the effects of sodium environment on tensile properties were negligible. In case of stagnant sodium condition, creep-rupture strength in sodium was equal to the in argon gas, and no sodium environmental effect was observed. The same is true for the creep-rupture ductility. (2)The tensile properties of nickel diffused test specimens at high temperatures simulating microstructure change were equal to that of the thermal aging process specimens. These tensile tests suggest that sodium environmental effects can be ignored. However, the effect of nickel diffusion on creep strength are not clear at present and experimental investigation are being conducted. (3)The coefficient of nickel diffusion in the ODS steel can be estimated based on the results of nickel concentration measurement. This value is larger than that of the diffusion coefficient for typical alpha-Fe steel at temperature below 973

Journal Articles

Electrochemical behaviors of uranium and plutonium at simultaneous recoveries into liquid cadmium cathodes

Uozumi, Koichi*; Iizuka, Masatoshi*; Kato, Tetsuya*; Inoue, Tadashi*; Shirai, Osamu*; Iwai, Takashi; Arai, Yasuo

Journal of Nuclear Materials, 325(1), p.34 - 43, 2004/02

 Times Cited Count:108 Percentile:98.72(Materials Science, Multidisciplinary)

Experiments were conducted on simultaneous recovering of uranium and plutonium electrochemically into laboratory scale liquid cadomium cathodes(LCCs) at different U/Pu ratios in the salt phase. The influence of the salt composition on the recovered amount of uranium and plutonium, the morphology of uranium and plutonium in the LCCs, and the behavior of americium were examined. It was shouwn that there is a threshold in the U/Pu ratio in the salt phase for the successful simultaneous recovery of uranium and plutonium up to 10wt% in high current efficiencies.

Journal Articles

Recovery of plutonium and uranium into liquid cadmium cathodes at high current densities

Kato, Tetsuya*; Uozumi, Koichi*; Inoue, Tadashi*; Shirai, Osamu*; Iwai, Takashi; Arai, Yasuo

Proceedings of GLOBAL2003 Atoms for Prosperity; Updating Eisenhower's Global Vision for Nuclear Energy (CD-ROM), p.1591 - 1595, 2003/11

Electrolysis experiments were carried to recover plutonium and uranium into liquid cadmium cathodes from molten salt at high cathode current densities. In the electrolysis at 101mA/cm$$^{2}$$, 10.4wt.% of heavy metals in the cathode was recovered at almost 100% of current efficiency. In the electrolysis at 156mA/cm$$^{2}$$, the cathode potential ascended after approximately 8wt.% of heavy metals was recovered and some deposit was observed outside of the crucible.

Journal Articles

Solid spallation target materials development

Kawai, Masayoshi*; Furusaka, Michihiro; Li, J.-F.*; Kawasaki, Akira*; Yamamura, Tsutomu*; Mehmood, M.*; Kurishita, Hiroaki*; Kikuchi, Kenji; Takenaka, Nobuyuki*; Kiyanagi, Yoshiaki*; et al.

Proceedings of ICANS-XVI, Volume 3, p.1087 - 1096, 2003/07

In order to establish the technique fabricating a thin target slab with a real size, thin tantalum-clad tungsten slab with a hole for a thermocouple was fabricated with the high-precision machinery techniques and the HIP'ing method. The ultrasonic diagnostic showed that tantalum and tungsten bond was perfect. The HIP optimum condition was certified by means of the small punch test as already reported. The electrolytic coating technique in a molten salt was developed to make a thinner tantalum cladding on a tungsten target with a complicated shape, in order to reduce radioactivity from tantalum in an irradiated target.

Journal Articles

Measurement of thermal property for tungsten-stainless steel alloy and high purity tungsten

Kawai, Masayoshi*; Li, J.*; Watanabe, Ryuzo*; Kurishita, Hiroaki*; Kikuchi, Kenji; Igarashi, Tadashi*; Kato, Masahiro*

Dai-23-Kai Nihon Netsu Bussei Shimpojiumu Koen Rombunshu, p.313 - 315, 2002/11

The objective of the present study is to develop the stainless-steel-bonded tungsten alloys by powder metallurgy processes. Commercially available tungsten powders and stainless steel (SUS304L) powder were used as the raw materials and mixed by ball milling at the ratios of 97mass% W -3% SUS and 93mass% W -7mass% SUS. Powder compacts were formed by die pressing and cold isostatic pressing (CIP), then sintered mainly in vacuum at the temperatures above the melting point of the stainless steel phase. Some samples were fabricated by glass-encapsulated hot isostatic pressing (HIPing) at lower temperatures. The microstructural observation was made by scanning electron microscopy (SEM). The thermal properties of the produced alloy and various tungsten materials supplied from Allied Material Corp. was measured with the laser-frash method. It was found that stable liquid-phase-sintered microstructures were not easily formed in the tungsten-stainless steel system. The electron probe microanalysis (EPMA) revealed that tungsten was considerably dissolved in the stainless steel phase during sintering. Therefore, thermal conductivity of the W/7 mass% SUS alloy was 22.8-53.5 W/m/K that was very lower than theoretical value calculated from those of pure tungsten and stainless steel. Its temperature dependence is resembled to that of stainless steel, i.e., thermal conductivity increased with the specimen temperature as like stainless steel. The diffusivity of pure tungsten is compared with those of tungsten alloys.

Journal Articles

Radiation-induced reactions $$via$$ the lowest excited states in cinnamic acid crystals

Maekawa, Yasunari; Inaba, Tomonori; Hobo, Hiroki; Narita, Tadashi*; Koshikawa, Hiroshi; Moon, S.; Kato, Jun; Yoshida, Masaru

Chemical Communications, (18), p.2088 - 2089, 2002/09

Radiation-induced reactions of cinnamic acid derivatives have been examined and compared them with photoreactions in the crystalline states; all the reaction products were exactly the same as those of the photoreactions, indicating that the reactions proceed only via the lowest excited state to give [2+2]cycloadducts, E/Z isomerization products, or starting molecules.

Journal Articles

Development of Neutron Multiplicity Measurement Method in ($$gamma$$,xn)Reactions

Harada, Hideo; Furutaka, Kazuyoshi; Shcherbakov, O.; Kinoshita, Tadashi*; Kato, Atsushi*; Katsuyama, Tomoyoshi*

Kakuriken Kenkyu Hokoku, 35, p.18 - 22, 2002/00


JAEA Reports

Development of the simulation monitoring system

Kato, Katsumi*; Watanabe, Tadashi; Kume, Etsuo

JAERI-Tech 2000-077, 50 Pages, 2001/01


no abstracts in English

Journal Articles

Completion of CS insert fabrication

Sugimoto, Makoto; Isono, Takaaki; Nunoya, Yoshihiko; Koizumi, Norikiyo; Nakajima, Hideo; Kato, Takashi; Matsukawa, Makoto; Hamada, Kazuya; Matsui, Kunihiro; Nishijima, Gen; et al.

IEEE Transactions on Applied Superconductivity, 10(1), p.564 - 567, 2000/03

 Times Cited Count:22 Percentile:71.36(Engineering, Electrical & Electronic)

no abstracts in English

JAEA Reports

Parallel computation of a lattice-gas two-phase flow simulation code on a workstation cluster

Watanabe, Tadashi; Ebihara, Kenishi; Kato, Katsumi*

JAERI-Data/Code 99-029, 38 Pages, 1999/05


no abstracts in English

38 (Records 1-20 displayed on this page)