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Intruder configurations in $$^{29}$$Ne at the transition into the island of inversion; Detailed structure study of $$^{28}$$Ne

Wang, H.*; 安田 昌弘*; 近藤 洋介*; 中村 隆司*; Tostevin, J. A.*; 緒方 一介*; 大塚 孝治*; Poves, A.*; 清水 則孝*; 吉田 数貴; et al.

Physics Letters B, 843, p.138038_1 - 138038_9, 2023/08

$$^{29}$$Neからの1中性子除去反応を用いて、$$^{28}$$Neの詳細な$$gamma$$線分光を行った。平行運動量分布の解析に基づき、$$^{28}$$Neの準位構造とスピンパリティを決定し、初めて負のパリティ状態を同定した。測定された断面積と運動量分布から、N=20とN=28のシェルギャップの消失の証拠となる有意なintruder p-wave強度が明らかになった。束縛状態については、弱いf-waveの可能性のある強度が観測された。いくつかの有効相互作用を用いた大規模殻模型計算では、実験的に観測された大きなp-wave強度と小さなf-wave強度は再現されず、Ne同位体に沿った反転の島への遷移の完全な理論的記述への挑戦が続いていることを示している。


Magnetoelastic anisotropy in Heusler-type Mn$$_{2-delta}$$CoGa$$_{1+delta}$$ films

窪田 崇秀*; 高野 大地*; 小田 洋平*; Mohanty, S.*; 伊藤 啓太*; 松木 充弘*; 林田 誠弘*; Sun, M.*; 竹田 幸治; 斎藤 祐児; et al.

Physical Review Materials (Internet), 6(4), p.044405_1 - 044405_12, 2022/04

 被引用回数:1 パーセンタイル:25.64(Materials Science, Multidisciplinary)

This study focuses on an inverse-type Heusler alloy, Mn$$_{2-delta}$$CoGa$$_{1+delta}$$ (MCG), with a small off-stoichiometry ($$delta$$), showing perpendicular magnetic anisotropy (PMA). We observed a relatively large uniaxial magnetocrystalline anisotropy constant ($$K_mathrm{u}$$) on the order of 10$$^5$$ J/m$$^3$$ at room temperature in the MCG films with a small tetragonal distortion of a few percent. X-ray magnetic circular dichroism (XMCD) was employed to get insight into the origin for the PMA. Negligible angular variation of the orbital magnetic moment evaluated using the XMCD spectra suggested a minor role of the so-called Bruno's term to $$K_mathrm{u}$$. The origin of the PMA was discussed based on the second-order perturbation theory in terms of the spin-orbit coupling, and first principles calculations, claiming that the mixing of the occupied $$uparrow$$- and the unoccupied $$downarrow$$-spin states is responsible for the PMA of the MCG films.


Fundamental study on scheduling of inspection process for fast reactor plants

鈴木 正昭*; 伊藤 真理*; 橋立 竜太; 高橋 慧多; 矢田 浩基; 高屋 茂

2020 9th International Congress on Advanced Applied Informatics (IIAI-AAI 2020), p.797 - 801, 2021/07

To realize the reasonable and effective maintenance of nuclear power plants, it is essential to optimize the maintenance scheduling management from the viewpoints of both safety and efficiency. As a fundamental study, we propose an inspection-process-scheduling model that minimizes the total number of inspections in a fast reactor. In this study, we formulate the inspection-process-scheduling problem as an integer programming problem. Computing the inspection-process schedules for a simplified fast reactor plant model, we verified that the proposed model can provide the optimal schedule automatically.


Microstructures and interface magnetic moments in Mn$$_{2}$$VAl/Fe layered films showing exchange bias

窪田 崇秀*; 嶋田 雄介*; 土屋 朋生*; 吉川 智己*; 伊藤 啓太*; 竹田 幸治; 斎藤 祐児; 今野 豊彦*; 木村 昭夫*; 高梨 弘毅*

Nanomaterials (Internet), 11(7), p.1723_1 - 1723_11, 2021/07

 被引用回数:2 パーセンタイル:22.96(Chemistry, Multidisciplinary)

Heusler alloys exhibit various magnetic properties. In this study, a layered sample consisting of a Heusler alloy, Mn$$_{2}$$VAl and a ferromagnet, Fe, is selected as a material system exhibiting exchange bias. Although the fully ordered Mn$$_{2}$$VAl is known as a ferrimagnet, the Mn$$_{2}$$VAl/Fe layered structure exhibits exchange bias. The high-angle annular dark field STEM images demonstrated the formation of Mn$$_{2}$$VAl clusters with the L2$$_{1}$$ phase distributed only around the interface to the Fe layer in the sample. Furthermore, the antiferromagnetic coupling between the Mn- and Fe-moments were observed in element specific hysteresis loops measured using XMCD. The locally ordered L2$$_{1}$$ phase and antiferromagnetic Mn-moments in the Mn$$_{2}$$VAl layer are important for the exchange bias.


Controlled growth of boron-doped epitaxial graphene by thermal decomposition of a B$$_{4}$$C thin film

乗松 航*; 松田 啓太*; 寺澤 知潮; 高田 奈央*; 増森 淳史*; 伊藤 圭太*; 小田 晃司*; 伊藤 孝寛*; 遠藤 彰*; 舟橋 良次*; et al.

Nanotechnology, 31(14), p.145711_1 - 145711_7, 2020/04

 被引用回数:6 パーセンタイル:43.55(Nanoscience & Nanotechnology)

炭化珪素(SiC)基板上にエピタキシャル成長した炭化ホウ素(B$$_{4}$$C)薄膜の熱分解によって、ホウ素をドープしたエピタキシャルグラフェンが成長することを示した。SiC上のB$$_{4}$$CとB$$_{4}$$C上のグラフェンの界面は、一定の方位関係を持ち、ダングリングボンドのない安定した構造を局所的に持っていた。B$$_{4}$$Cの最初の炭素層はバッファー層として機能し、その上にグラフェンが積層していた。B$$_{4}$$C上のグラフェンは、ホウ素が高濃度にドープされており、正孔濃度は2$$times$$10$$^{13}$$ - 2$$times$$10$$^{15}$$ cm$$^{-2}$$の広い範囲で制御できた。高濃度にホウ素をドープしたグラフェンはスピングラス挙動を示し、これはスピンフラストレーションシステムにおける局所的な反強磁性秩序の存在を示唆している。炭化物の熱分解は、さまざまな用途向けの新しいの機能エピタキシャルグラフェンをウェーハスケールで得るための技術であると期待できる。


Manipulation of saturation magnetization and perpendicular magnetic anisotropy in epitaxial Co$$_{x}$$Mn$$_{4-x}$$N films with ferrimagnetic compensation

伊藤 啓太*; 安富 陽子*; Zhu, S.*; Nurmamat, M.*; 田原 昌樹*; 都甲 薫*; 秋山 了太*; 竹田 幸治; 斎藤 祐児; 小口 多美夫*; et al.

Physical Review B, 101(10), p.104401_1 - 104401_8, 2020/03

 被引用回数:14 パーセンタイル:73.18(Materials Science, Multidisciplinary)

Spintronics devices utilizing a magnetic domain wall motion have attracted increasing attention, and ferrimagentic materials with almost compensated magnetic moments are highly required to realize the fast magnetic domain wall motion. Here, we report a key function for this purpose in anti-perovskite Co$$_{x}$$Mn$$_{4-x}$$N films. Perpendicular magnetization emerges for $$0.8 leq x$$, and the saturation magnetization reaches a minimum value at $$x = 0.8$$.


Enhancement of element production by incomplete fusion reaction with weakly bound deuteron

Wang, H.*; 大津 秀暁*; 千賀 信幸*; 川瀬 頌一郎*; 武内 聡*; 炭竃 聡之*; 小山 俊平*; 櫻井 博儀*; 渡辺 幸信*; 中山 梓介; et al.

Communications Physics (Internet), 2(1), p.78_1 - 78_6, 2019/07

 被引用回数:7 パーセンタイル:55.1(Physics, Multidisciplinary)



Isotope-selective microscale imaging of radioactive Cs without isobaric interferences using sputtered neutral mass spectrometry with two-step resonant ionization employing newly-developed Ti:Sapphire lasers

坂本 哲夫*; 森田 真人*; 金成 啓太*; 富田 英生*; Sonnenschein, V.*; 齊藤 洸介*; 大橋 雅也*; 加藤 弘太郎*; 井口 哲夫*; 河合 利秀*; et al.

Analytical Sciences, 34(11), p.1265 - 1270, 2018/11

 被引用回数:8 パーセンタイル:34.16(Chemistry, Analytical)

Characterization of radionuclides in Fukushima is important to determine their origins and current state in the environment. Radionuclides exist as fine particles and are mixed with other constituents. A measurement method with both micro-imaging capability and highly selective element detection is necessary to analyze these particles. We developed such an imaging technique using a time-of-flight secondary ion mass spectrometry and wavelength tunable Ti:Sapphire lasers for resonance ionization of target elements without mass interference. This is called resonant laser ionization sputtered neutral mass spectrometry. The instrument has high lateral resolution and higher ionization selectivity using two-step resonance excitation of Cs with two lasers at different wavelengths. Optimization of the wavelength for resonance ionization using a Cs compound was performed, and a real environmental particle containing radioactive Cs was analyzed. Isotope images of three kinds of Cs were successfully obtained without interfere from Ba isotopes for the first time.


Preferred site occupation of 3$$d$$ atoms in Ni$$_{x}$$Fe$$_{4-x}$$N (${it x}$ = 1 and 3) films revealed by X-ray absorption spectroscopy and magnetic circular dichroism

高田 郁弥*; 伊藤 啓太*; 竹田 幸治; 斎藤 祐児; 高梨 弘毅*; 木村 昭夫*; 末益 崇*

Physical Review Materials (Internet), 2(2), p.024407_1 - 024407_5, 2018/02

 被引用回数:14 パーセンタイル:51.11(Materials Science, Multidisciplinary)

X-ray absorption spectroscopy (XAS) and X-ray magnetic circular dichroism measurements were performed at the Ni and Fe $$L_{2,3}$$ absorption edges for Ni$$_{x}$$Fe$$_{4-x}$$N (${it x}$ = 1 and 3) epitaxial films. Shoulders at approximately 2 eV above the Ni $$L_{2,3}$$ main peaks in the XAS spectrum of Ni$$_{3}$$FeN were interpreted to originate from hybridization of orbitals between Ni 3$$d$$ at face-centered (II) sites and N 2$$p$$ at body-centered sites, while such features were missing in NiFe$$_{3}$$N film. Similar shoulders were observed at Fe $$L_{2,3}$$ edges in both films. Hence, Ni atoms preferentially occupied corner (I) sites, where the hybridization was weak because of the relatively long distance between Ni at I sites and N atoms. The relatively large magnetic moment deduced from sum-rule analysis of NiFe$$_{3}$$N also showed a good agreement with the presence of Ni atoms at I sites.


Structure of the magnetic excitations in the spin-1/2 triangular-lattice Heisenberg antiferromagnet Ba$$_{3}$$CoSb$$_{2}$$O$$_{9}$$

伊藤 沙也*; 栗田 伸之*; 田中 秀数*; 河村 聖子; 中島 健次; 伊藤 晋一*; 桑原 慶太郎*; 加倉井 和久*

Nature Communications (Internet), 8, p.235_1 - 235_6, 2017/08

 被引用回数:67 パーセンタイル:93.64(Multidisciplinary Sciences)

A spin-1/2 triangular-lattice Heisenberg antiferromagnet (TLHAF) is a prototypical frustrated quantum magnet, which exhibits remarkable quantum many-body effects that arise from the synergy between spin frustration and quantum fluctuation. The ground-state properties of a spin-1/2 TLHAF are theoretically well understood. However, magnetic excitations are less well understood and the theoretical consensus is limited. The experimental study of the magnetic excitations in spin-1/2 TLHAFs has also been limited. Here we show the whole picture of magnetic excitations in the spin-1/2 TLHAF Ba$$_{3}$$CoSb$$_{2}$$O$$_{9}$$ investigated by inelastic neutron scattering. Significantly different from the theory, the excitation spectra have a three-stage energy structure. The lowest first stage is composed of dispersion branches of single-magnon excitations. The second and third stages are dispersive continua accompanied by columnar continuum extending above 10 meV, which is six times larger than the exchange interaction J=1.67 meV. Our results indicate the necessity of a new theoretical framework.


Universal scaling for the spin-electricity conversion on surface states of topological insulators

山本 敬太*; 塩見 雄毅*; 瀬川 耕司*; 安藤 陽一*; 齊藤 英治

Physical Review B, 94(2), p.024404_1 - 024401_6, 2016/05

 被引用回数:17 パーセンタイル:62.66(Materials Science, Multidisciplinary)



Science from the initial operation of HRC

伊藤 晋一*; 横尾 哲也*; 益田 隆嗣*; 吉澤 英樹*; 左右田 稔*; 池田 陽一*; 井深 壮史*; 川名 大地*; 佐藤 卓*; 南部 雄亮*; et al.

JPS Conference Proceedings (Internet), 8, p.034001_1 - 034001_6, 2015/09

Since the installation of the High Resolution Chopper Spectrometer, HRC, experiments using the HRC are being conducted to observe the dynamics in wide range of physics. Scientific results during the period since the initial construction are summarized.


Local electronic states of Fe$$_{4}$$N films revealed by X-ray absorption spectroscopy and X-ray magnetic circular dichroism

伊藤 啓太*; 都甲 薫*; 竹田 幸治; 斎藤 祐児; 小口 多美夫*; 末益 崇*; 木村 昭夫*

Journal of Applied Physics, 117(19), p.193906_1 - 193906_6, 2015/05

 被引用回数:14 パーセンタイル:53.5(Physics, Applied)

We performed XAS and XMCD measurements at Fe L$$_{2,3}$$ and N K-edges for Fe$$_{4}$$N epitaxial films grown by MBE. We compared experimental XAS and XMCD spectra with those simulated by a combination of a first-principles calculation and Fermi's golden rule. We revealed that the shoulders observed at Fe L$$_{2,3}$$-edges in the XAS and XMCD spectra were due to the electric dipole transition from the Fe 2p core-level to the hybridization state generated by $$sigma$$$$^{ast}$$ anti-bonding between the orbitals of N 2p at the body-centered site and Fe 3d on the face-centered (II) sites. Thus, the observed shoulders were attributed to the local electronic structure of Fe atoms at II sites. As to the N K-edge, the line shape of the obtained spectra was explained by the dipole transition from the N 1s core-level to the hybridization state formed by $$pi$$$$^{ast}$$ and $$sigma$$$$^{ast}$$ anti-bondings between the Fe 3d and N 2p orbitals.


X-ray magnetic circular dichroism for Co$$_{x}$$Fe$$_{4-x}$$N (x = 0, 3, 4) films grown by molecular beam epitaxy

伊藤 啓太*; 佐内 辰徳*; 安富 陽子*; Zhu, S.-Y.*; 都甲 薫*; 竹田 幸治; 斎藤 祐児; 木村 昭夫*; 末益 崇*

Journal of Applied Physics, 115(17), p.17C712_1 - 17C712_3, 2014/05

 被引用回数:18 パーセンタイル:61.39(Physics, Applied)

We evaluated orbital ($$m_{rm orb}$$) and spin magnetic moments ($$m_{rm spin}$$) of Co$$_{x}$$Fe$$_{4-x}$$N (x = 0, 3, 4) epitaxial thin films grown by molecular beam epitaxy using X-ray magnetic circular dichroism, and discussed the dependence of these values on x. Site-averaged $$m_{rm spin}$$ value of Fe atoms was deduced to be 1.91 $$mu$$$$_{B}$$ per atom, and that of Co atoms to be 1.47 $$mu$$$$_{B}$$ per atom in Co$$_{3}$$FeN at 300 K. These values are close to 1.87 $$mu$$$$_{B}$$ per Fe atom in Fe$$_{4}$$N and 1.43 $$mu$$$$_{B}$$ per Co atom in Co$$_{4}$$N, respectively. This result implies that the Fe and Co atoms in the Co$$_{3}$$FeN films were located both at corner and face-centered sites in the anti-perovskite lattice. Spin magnetic moments per unit cell were decreased linearly with increasing x in Co$$_{x}$$Fe$$_{4-x}$$N. This tendency is in good agreement with theory predicted by the first-principle calculation.


超深地層研究所計画 年度報告書(2012年度)

濱 克宏; 見掛 信一郎; 西尾 和久; 松岡 稔幸; 石橋 正祐紀; 笹尾 英嗣; 引間 亮一*; 丹野 剛男*; 真田 祐幸; 尾上 博則; et al.

JAEA-Review 2013-050, 114 Pages, 2014/02




Development of small specimen test techniques for the IFMIF test cell

若井 栄一; Kim, B. J.; 野澤 貴史; 菊地 孝行; 平野 美智子*; 木村 晃彦*; 笠田 竜太*; 横峯 健彦*; 吉田 崇英*; 野上 修平*; et al.

Proceedings of 24th IAEA Fusion Energy Conference (FEC 2012) (CD-ROM), 6 Pages, 2013/03

Recent progress of small specimen test technique and the engineering design and engineering validation tests of high flux test module (HFTM) for the IFMIF test cell is mainly summarized and evaluated in the IFMIF/EVEDA (Engineering validation and engineering design activities) projects under Broader Approach Agreement between EURATOM and Japan. Effects of specimen size on mechanical properties such as impact properties and ductile-to-brittle transition temperature are known to occur in ferritic/martensitic steels, and some parts of them have been prepared in the guideline and standard of mechanical tests by ASTM-international and ISO. However, our research of ferritic/martensitic steel F82H showed that it did not match with our data, i.e., master curve method for fracture in ductile-to-brittle transition behaviour of F82H steel. Accordingly, we need to modify and develop these standards for the tests including small size specimens of fusion materials in IFMIF. Also, some designs were prepared in the design of HFTM.


超深地層研究所計画 年度報告書(2010年度)

國丸 貴紀; 見掛 信一郎; 西尾 和久; 鶴田 忠彦; 松岡 稔幸; 石橋 正祐紀; 上野 孝志; 徳安 真吾; 大丸 修二; 竹内 竜史; et al.

JAEA-Review 2012-020, 178 Pages, 2012/06


日本原子力研究開発機構東濃地科学センターでは、「地層処分技術に関する研究開発」のうち深地層の科学的研究(地層科学研究)の一環として、結晶質岩(花崗岩)を対象とした超深地層研究所計画を進めている。本計画は、「第1段階; 地表からの調査予測研究段階」、「第2段階; 研究坑道の掘削を伴う研究段階」、「第3段階; 研究坑道を利用した研究段階」の3段階からなり、2010年度は、第2段階である「研究坑道の掘削を伴う研究段階」を進めるとともに、第3段階(研究坑道を利用した研究段階)の調査研究を開始した。本報告書は、2002年2月に改訂した「超深地層研究所地層科学研究基本計画」に基づき、超深地層研究所計画の第2段階「研究坑道の掘削を伴う研究段階」及び第3段階(研究坑道を利用した研究段階)における2010年度に実施した(1)調査研究、(2)施設建設、(3)共同研究等の成果を取りまとめたものである。


Dehydration process of fish analyzed by neutron beam imaging

田野井 慶太朗*; 濱田 洋祐*; 瀬山 祥平*; 斉藤 貴之*; 飯倉 寛; 中西 友子*

Nuclear Instruments and Methods in Physics Research A, 605(1-2), p.179 - 184, 2009/06

 被引用回数:3 パーセンタイル:28.49(Instruments & Instrumentation)

Since regulation of water content of the dried fish is an important factor for the quality of the fish, water-losing process during dryin (squid and Japanese horse mackerel) was analyzed through neutron beam imaging. The neutron image showed that around the shoulder of mackerel, there was a part where water content was liable to maintain high during drying. To analyze water-losing process more in detail, spatial image was produced. From the images, it was clearly indicated that the decrease of water content was regulated around the shoulder part. It was suggested that to prevent deterioration around the shoulder part of the dried fish is an important factor to keep quality of the dried fish in the storage.



木下 博久; 野原 壯; 中田 高*; 池田 安隆*; 伊藤 潔*; 大槻 憲四郎*; 鷺谷 威*; 高田 圭太*; 遠田 晋次*

活断層研究, (25), p.27 - 37, 2005/06



Development of environment for remote participation in fusion research on JT-60

大島 貴幸; 内藤 磨; 濱松 清隆; 射場 克幸; 佐藤 稔; 坂田 信也; 次田 友宣; 松田 俊明; 岩崎 慶太*; 軽部 行洋*; et al.

Fusion Engineering and Design, 71(1-4), p.239 - 244, 2004/06

 被引用回数:5 パーセンタイル:35.58(Nuclear Science & Technology)

原研JT-60では、全国に分散した大学及び他研究機関の核融合研究のエキスパートを結集し、JT-60に遠隔研究参加し、遠隔実験,遠隔解析,遠隔計測を行える階層的遠隔研究システムの構築を進めている。遠隔研究参加環境として、ビデオ会議システム,実験風景ストリーミングシステム,遠隔計測システム,遠隔プラズマ解析システムを開発及び運用している。ビデオ会議システムは、H.320プロトコルを用いたISDN回線を使ったもので、海外との運用実績が数多くある。現在は、H.323プロトコルを用いたインターネット上でのテレビ会議システムに移行しつつある。また、ストリーミングシステムはReal Systemを使用しJT-60中央制御室の様子を配信している。遠隔計測は、WSで構成される遠隔計測システムに置き換え、Xウィンドウ機能を使って外部からアクセスが可能となった。また、VizAnalysisとVizSquareとよばれる、遠隔解析のためのソフトウェアシステムを開発した。現在は、コンピュータネットワーク上のセキュリティ対策や新たな通信ツールを開発し、最終的にはITERの遠隔実験参加を視野に入れたシステムの開発を行っている。

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