※ 半角英数字
 年 ~ 
検索結果: 386 件中 1件目~20件目を表示


Initialising ...



Initialising ...


Initialising ...


Initialising ...


Initialising ...


Initialising ...


Initialising ...


Initialising ...



Short- and middle-ranges order structures of KNbO$$_3$$ nanocrystals

米田 安宏; 國定 諒一*; 近田 司*; 上野 慎太郎*; 藤井 一郎*; 永田 肇*; 尾原 幸治*; 和田 智志*

Japanese Journal of Applied Physics, 58(SL), p.SLLA03_1 - SLLA03_7, 2019/11

We studied KNbO$$_3$$ nanocrystals grown by a solvothermal method. Average and local structures were refined by combining Rietveld and PDF analysis. We found that a rhombohedrally distorted NbO$$_6$$ octahedron was maintained in short-range order region, even in the nanocrystals with a cubic average structure. The cubic structure of KNbO$$_3$$ nanocrystals were observed as a disordered phase of the rhombohedral structure. The disordered feature can be understood that the structural transformation owing to the particle-size effect is analogous to the temperature-driven phase transition.


Colossal barocaloric effects in plastic crystals

Li, B.*; 川北 至信; 河村 聖子; 菅原 武*; Wang, H.*; Wang, J.*; Chen, Y.*; 河口 沙織*; 河口 彰吾*; 尾原 幸治*; et al.

Nature, 567(7749), p.506 - 510, 2019/03



Unique helical magnetic order and field-induced phase in trillium lattice antiferromagnet EuPtSi

金子 耕士; Frontzek, M. D.*; 松田 雅昌*; 中尾 朗子*; 宗像 孝司*; 大原 高志; 垣花 将司*; 芳賀 芳範; 辺土 正人*; 仲間 隆男*; et al.

Journal of the Physical Society of Japan, 88, p.013702_1 - 013702_5, 2019/01

 被引用回数:1 パーセンタイル:14.05(Physics, Multidisciplinary)

Magnetic transitions in chiral antiferromagnet EuPtSi were investigated by means of single crystal neutron diffraction. In the ground state, magnetic peaks emerge at positions represented by $$q_{1}$$=$$(0.2, 0.3, 0)$$. Upon heating, an additional magnetic peak splitting around 2.5 K was uncovered, indicating a presence of a first-order transition with $$q^*_{1}$$=$$(0.2, 0.3, {delta})$$. An half-polarized neutron scattering for polarization parallel to Q reveled that polarization antiparallel to Q has stronger intensity in both magnetic phases. This feature clarifies single chiral character of helical structure with moments normal to the ordering vector in both ordered states. Under vertical magnetic field along [1,1,1] in the $$A$$ phase, magnetic peaks form hexagonal patterns in the equatorial scattering plane around nuclear. An ordering vector $$q_{A}$$ of the $$A$$-phase has the similar size in the periodicity to $$q_{1}$$, and could be a hallmark of a formation of skyrmion lattice in EuPtSi.


Local structure and phase transitions of KNbO$$_3$$

米田 安宏; 尾原 幸治*; 永田 肇*

Japanese Journal of Applied Physics, 57(11S), p.11UB07_1 - 11UB07_6, 2018/11

 パーセンタイル:100(Physics, Applied)



Numerical simulation on self-leveling behavior of mixed particle beds using multi-fluid model coupled with DEM

Phan, L. H. S.*; 大原 陽平*; 河田 凌*; Liu, X.*; Liu, W.*; 守田 幸路*; Guo, L.*; 神山 健司; 田上 浩孝

Proceedings of 12th International Topical Meeting on Nuclear Reactor Thermal-Hydraulics, Operation and Safety (NUTHOS-12) (USB Flash Drive), 12 Pages, 2018/10



Structure analysis and derivation of deformed electron density distribution of polydiacetylene giant single crystal by the combination of X-ray and neutron diffraction data

田代 孝二*; 日下 勝弘*; 細谷 孝明*; 大原 高志; 塙坂 真*; 吉澤 功徳*; 山元 博子*; 新村 信雄*; 田中 伊知朗*; 栗原 和男*; et al.

Macromolecules, 51(11), p.3911 - 3922, 2018/06

 パーセンタイル:100(Polymer Science)

The crystal structure of polydiacetylene giant single crystal has been analyzed on the basis of the two different methods of wide-angle neutron diffraction and X-ray diffraction. The X-ray result gives us the total electron density distribution. The neutron result tells the positions of atomic nuclei. As a result, the so-called bonded (or deformed) electron density, i.e., the electron density distribution due to the conjugation among the covalently bonded atoms along the polymer chain, can be estimated using the two information. The present report is the first example of the application of X-N method to the synthetic polymer species.


Local structure analysis of KNbO$$_3$$ nanocrystals with cubic shape

米田 安宏; 國定 諒一*; 近田 司*; 上野 慎太郎*; 尾原 幸治*; 和田 智志*

Transactions of the Materials Research Society of Japan, 43(2), p.93 - 96, 2018/04



Liquid-like thermal conduction in intercalated layered crystalline solids

Li, B.; Wang, H.*; 川北 至信; Zhang, Q.*; Feygenson, M.*; Yu, H. L.*; Wu, D.*; 尾原 幸治*; 菊地 龍弥*; 柴田 薫; et al.

Nature Materials, 17(3), p.226 - 230, 2018/03

 被引用回数:18 パーセンタイル:1.81(Chemistry, Physical)

As a generic property, all substances transfer heat through microscopic collisions of constituent particles. A solid conducts heat through both transverse and longitudinal acoustic phonons, but a liquid employs only longitudinal vibrations. As a result, a solid is usually thermally more conductive than a liquid. In canonical viewpoints, such a difference also serves as the dynamic signature distinguishing a solid from a liquid. Here, we report liquid-like thermal conduction observed in the crystalline AgCrSe$$_{2}$$. The transverse acoustic phonons are completely suppressed by the ultrafast dynamic disorder while the longitudinal acoustic phonons are strongly scattered but survive, and are thus responsible for the intrinsically ultralow thermal conductivity. This scenario is applicable to a wide variety of layered compounds with heavy intercalants in the van der Waals gaps, manifesting a broad implication on suppressing thermal conduction. These microscopic insights might reshape the fundamental understanding on thermal transport properties of matter and open up a general opportunity to optimize performances of thermoelectrics.


Neutron scattering study of yttrium iron garnet

社本 真一; 伊藤 孝; 大西 弘明; 山内 宏樹; 稲村 泰弘; 松浦 直人*; 赤津 光洋*; 樹神 克明; 中尾 朗子*; 茂吉 武人*; et al.

Physical Review B, 97(5), p.054429_1 - 054429_9, 2018/02

 被引用回数:1 パーセンタイル:100(Materials Science, Multidisciplinary)




桜井 弘*; 篠原 厚*; 小浦 寛之; 上垣外 修一*; 森本 幸司*; 羽場 宏光*; 延輿 秀人*

Isotope News, (特別号2), p.2 - 14, 2018/01

日本アイソトープ協会発行の協会誌「Isotope News」における新春座談会(2018年1月1日誌上掲載)に登壇する。「ニホニウムとその次の元素へ・・・」という座談会のタイトルで、ニホニウム(超重元素)の発見の歴史や今後の超重元素発見にむけての展望など、(1)理論、(2)加速器、(3)実験、(4)周期表を話題の中心として夢のある内容を紹介する。特に原子核物理・理論の観点から座談を展開する。


Materials and Life Science Experimental Facility (MLF) at the Japan Proton Accelerator Research Complex, 2; Neutron scattering instruments

中島 健次; 川北 至信; 伊藤 晋一*; 阿部 淳*; 相澤 一也; 青木 裕之; 遠藤 仁*; 藤田 全基*; 舟越 賢一*; Gong, W.*; et al.

Quantum Beam Science (Internet), 1(3), p.9_1 - 9_59, 2017/12



Numerical simulation of solid-particle sedimentation behavior using a multi-fluid model coupled with DEM

河田 凌*; 大原 陽平*; Sheikh, Md. A. R.*; Liu, X.*; 松元 達也*; 守田 幸路*; Guo, L.*; 神山 健司; 鈴木 徹

Proceedings of 17th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-17) (USB Flash Drive), 14 Pages, 2017/09

Numerical simulations of various thermal-hydraulic phenomena with multiphase and multicomponent flows in postulated core disruptive accidents (CDAs) are regarded as particular difficulties in the safety analysis of liquid-metal cooled reactors. In a material relocation phase of CDAs, core debris may settle on the core-support structure and/or in the lower inlet plenum of the reactor vessel and then form the debris bed. In particular, the shape of debris bed is crucial for the relocation of molten core and heat-removal capability of the debris bed as well as re-criticality. In the present study, a hybrid numerical simulation method, which couples the multi-fluid model of the 3D fast reactor safety analysis code SIMMER-IV with the discrete element method (DEM), was applied to analyze sedimentation and bed formation behaviors of core debris. In the present study, 3D simulations were performed for a series of particle sedimentation experiments with gravity driven discharge of solid particles into a quiescent cylindrical water pool. The present simulation predicts the sedimentation behavior of mixed particles with different density or particle size as well as homogeneous particles. The simulation results on bed shapes and particle distribution in the bed agree well with the experimental ones. They demonstrate the fundamental applicability of the present hybrid method to solid-particle sedimentation and bed formation simulations.


Magnetic structure of divalent europium compound EuGa$$_{4}$$ studied by single-crystal time-of-flight neutron diffraction

川崎 卓郎; 金子 耕士; 仲村 愛*; 阿曽 尚文*; 辺土 正人*; 仲間 隆男*; 大原 高志; 鬼柳 亮嗣; 及川 健一; 田村 格良; et al.

Journal of the Physical Society of Japan, 85(11), p.114711_1 - 114711_5, 2016/11

 パーセンタイル:100(Physics, Multidisciplinary)

The magnetic structure of the intermetallic compound EuGa$$_{4}$$ was investigated using single-crystal neutron diffraction with TOF Laue technique on the new diffractometer SENJU at MLF of J-PARC. Despite of the high neutron absorption of Eu, a vast number of diffraction spots were observed without isotope enrichment. The magnetic reflections appeared at $$h + k + l$$ $$neq$$ 2$$n$$ below 16 K, indicating that the ordering vector is $$q$$ = (0, 0, 0). The continuous evolution of the magnetic reflection intensity below T$$_{N}$$ follows a squared Brillouin function for $$S$$ = 7/2. By adopting a wavelength-dependent absorption collection, the magnetic structure of EuGa$$_{4}$$ revealed that a nearly full magnetic moment of 6.4 $$mu$$B of Eu lies within the basal plane of the lattice.


SENJU; A New time-of-flight single-crystal neutron diffractometer at J-PARC

大原 高志; 鬼柳 亮嗣; 及川 健一; 金子 耕士; 川崎 卓郎; 田村 格良; 中尾 朗子*; 花島 隆泰*; 宗像 孝司*; 茂吉 武人*; et al.

Journal of Applied Crystallography, 49(1), p.120 - 127, 2016/02

 被引用回数:13 パーセンタイル:11.41(Chemistry, Multidisciplinary)

SENJU, a time-of-flight Laue-type single-crystal neutron diffractometer, was developed at the Materials and Life Science Experimental Facility (MLF) of the Japan Accelerator Research Complex (J-PARC). Molecular structure analysis of a sub-millimeter taurine crystal and magnetic structure analysis of a MnF$$_{2}$$ crystal were performed to evaluate its performance.


Development of laser beam injection system for the Edge Thomson Scattering (ETS) in ITER

谷塚 英一; 波多江 仰紀; 水藤 哲*; 小原 美由紀*; 萩田 浩二*; 井上 和典*; Bassan, M.*; Walsh, M.*; 伊丹 潔

Journal of Instrumentation (Internet), 11(1), p.C01006_1 - C01006_12, 2016/01

 被引用回数:4 パーセンタイル:51.49(Instruments & Instrumentation)

In the ITER Edge Thomson Scattering, the penetration in the port plug allows the laser beams to be injected into the plasma. The penetration has to be as small as possible to reduce neutron streaming from the plasma-side. In ITER, multiple laser systems are needed for high availability of Thomson scattering diagnostics. A new type of beam combiner was developed to obtain collinear, i.e. smallest footprint because of the common path, and fixed polarization from multiple laser beams using a rotating half-wave-plate. The rotating half-wave-plate method does not induce misalignment even if the rotating mechanism defects. The combined beam is injected into plasma and is absorbed at the beam dump. The beam alignment system was designed to hit the laser beam onto the center of the beam dump. The beam position at the beam dump head is monitored by multiple alignment laser beams which are collinear with the diagnostic YAG laser beam and an imaging system installed outside the diagnostic port.



篠原 孝司; 林 伸彦; 諫山 明彦; 宮戸 直亮; 浦野 創; 相羽 信行

プラズマ・核融合学会誌, 91(12), p.797 - 800, 2015/12



Integrated modelling of toroidal rotation with the 3D non-local drift-kinetic code and boundary models for JT-60U analyses and predictive simulations

本多 充; 佐竹 真介*; 鈴木 康浩*; 吉田 麻衣子; 林 伸彦; 神谷 健作; 松山 顕之; 篠原 孝司; 松永 剛; 仲田 資季; et al.

Nuclear Fusion, 55(7), p.073033_1 - 073033_11, 2015/07

 被引用回数:5 パーセンタイル:55.24(Physics, Fluids & Plasmas)

The integrated simulation framework for toroidal momentum transport is developed, which self-consistently calculates the neoclassical toroidal viscosity (NTV), the radial electric field $$E_r$$ and the resultant toroidal rotation $$V_phi$$ together with the scrape-off-layer(SOL)-physics based boundary model. The coupling of three codes, the 1.5D transport code, TOPICS, the 3D equilibrium code, VMEC and the 3D $$delta f$$ drift-kinetic equation solver, FORTEC-3D, makes it possible to calculate the NTV due to the non-axisymmetric perturbed magnetic field caused by toroidal field coils. Analyses reveal that the NTV significantly influences $$V_phi$$ in JT-60U and $$E_r$$ holds the key to determine the NTV profile. The sensitivity of the $$V_phi$$ profile to the boundary rotation necessitates a boundary condition modelling for toroidal momentum. Owing to the high-resolution measurement system in JT-60U, the $$E_r$$ gradient is found to be virtually zero at the separatrix regardless of toroidal rotation velocities. Focusing on $$E_r$$, the boundary model of toroidal momentum is developed in conjunction with the SOL/divertor plasma code D5PM. This modelling realizes self-consistent predictive simulations for operation scenario development in ITER.



篠原 孝司; 諫山 明彦; 鈴木 隆博; 吉田 麻衣子

プラズマ・核融合学会誌, 91(7), p.494 - 496, 2015/07


2015年の春季に国際トカマク物理活動(ITPA)に関する全4グループの会合が各グループ独立に開催された。「高エネルギー粒子物理」はフランスのITER機構で開催し日本からは2名の参加があった。「MHD安定性」はフランスのITER機構で開催し日本からは1名の参加があった。「統合運転シナリオ」はスペインのFusion for Energyで開催し日本からは3名の参加があった。「輸送と閉じ込め物理」はフランスのITER機構で開催し日本からは2名(TV会議参加)の参加があった。それぞれ、各極の関係者と国際装置間比較実験、ITERの物理に関する今後の課題、及び、各グループの活動計画の議論が行われた。これらの会合の概要をまとめて報告する。なお、次回会合は2015年の秋季に各グループ独立に開催する予定である。


Production of $$^{88}$$Nb and $$^{170}$$Ta for chemical studies of element 105, Db, using the GARIS gas-jet system

Huang, M.*; 羽場 宏光*; 村上 昌史*; 浅井 雅人; 加治 大哉*; 金谷 淳平*; 笠松 良崇*; 菊永 英寿*; 菊谷 有希*; 小森 有希子*; et al.

Journal of Radioanalytical and Nuclear Chemistry, 304(2), p.845 - 849, 2015/05

 被引用回数:3 パーセンタイル:66.76(Chemistry, Analytical)



Effects of the radial electric field on the confinement of fast ions in ITER

谷 啓二*; 本多 充; 及川 聡洋*; 篠原 孝司; 草間 義紀; 杉江 達夫

Nuclear Fusion, 55(5), p.053010_1 - 053010_15, 2015/05


 被引用回数:1 パーセンタイル:90.9(Physics, Fluids & Plasmas)


386 件中 1件目~20件目を表示