JOPSS:検索結果一覧

検索結果：　101 件中 1件目～20件目を表示

発表形式

Initialising ...

選択項目を絞り込む

掲載資料名

Initialising ...

発表会議名

Initialising ...

筆頭著者名

Initialising ...

キーワード

Initialising ...

使用言語

Initialising ...

発行年

Initialising ...

開催年

Initialising ...

論文

Influence of pulse duration on mechanical properties and dislocation density of dry laser peened aluminum alloy using ultrashort pulsed laser-driven shock wave

吉田雅幸*; 西端樹*; 松田朋己*; 伊藤佑介*; 杉田直彦*; 城鮎美*; 菖蒲敬久; 荒河一渡*; 廣瀬明夫*; 佐野智一*

Journal of Applied Physics, 132(7), p.075101_1 - 075101_9, 2022/08

https://doi.org/10.1063/5.0083511

被引用回数：5 パーセンタイル：67.2(Physics, Applied)

This study aims to investigate the influence of the pulse duration on the mechanical properties and dislocation density of a aluminum alloy treated using dry laser peening. The results of the micro-Vickers hardness test, residual stress measurement, and dislocation density measurement demonstrate that over a pulse duration range of 180 fs to 10 ps, the maximum peening effects are achieved with a pulse duration of 1 ps. Moreover, the most significant dry laser peening effects are obtained by choosing a pulse duration that achieves a laser intensity that simultaneously generates the strongest shock pressure, suppresses optical nonlinear effects, and realizes the least thermal effects, which weaken the shock effects.

論文

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

https://doi.org/10.1103/PhysRevMaterials.6.044405

被引用回数：5 パーセンタイル：59.75(Materials Science, Multidisciplinary)

This study focuses on an inverse-type Heusler alloy, Mn $_{2-delta}$ CoGa $_{1+delta}$ (MCG), with a small off-stoichiometry (), showing perpendicular magnetic anisotropy (PMA). We observed a relatively large uniaxial magnetocrystalline anisotropy constant ( $K_mathrm{u}$ ) on the order of 10 J/m 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 - and the unoccupied -spin states is responsible for the PMA of the MCG films.

論文

Improving the safety of the high temperature gas-cooled reactor "HTTR" based on Japan's new regulatory requirements

濱本真平; 清水厚志; 猪井宏幸; 栃尾大輔; 本間史隆; 澤畑洋明; 関田健司; 渡辺周二; 古澤孝之; 飯垣和彦; et al.

Nuclear Engineering and Design, 388, p.111642_1 - 111642_11, 2022/03

https://doi.org/10.1016/j.nucengdes.2021.111642

被引用回数：2 パーセンタイル：53.91(Nuclear Science & Technology)

日本原子力研究開発機構は、2011年の福島第一原子力発電所事故を契機に作られ2013年12月に施行された新しい規制要件に、高温工学試験研究炉(HTTR)を適合させた。様々な高温ガス炉(HTTR)安全試験を通じて得られたHTGRに関する知見を基に、既存の構造物,系統及び機器の安全性及び耐震分類が議論された。防護の対象となる構築物,系統及び機器が再検討し、安全機能に影響を及ぼす内的・外的脅威への対策が強化された。さらに、設計基準を超える事故として、多量の放射性物質が放出されるおそれのある事故に対する措置を講じた。我々のこの対応が、新しい規制要求に適合していることを、原子力規制委員会は厳格かつ適切に審査した。2014年11月に提出したHTTRの設置許可変更申請書は、9回の修正を経て2020年6月に承認された。この対応は、高温ガス炉の特性を反映すれば、強化された規制要件を満たすためでも合理的に設計できることを示しており、今後の高温ガス炉の開発の参考になると考える。

論文

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

https://doi.org/10.3390/nano11071723

被引用回数：2 パーセンタイル：17.84(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.

論文

Unveiling spin-dependent unoccupied electronic states of Co $_{2}$ MnGe (Ga) film via Ge (Ga) $L_{2,3}$ absorption spectroscopy

吉川智己*; Antonov, V. N.*; 河野嵩*; 鹿子木将明*; 角田一樹; 宮本幸治*; 竹田幸治; 斎藤祐児; 後藤一希*; 桜庭裕弥*; et al.

Physical Review B, 102(6), p.064428_1 - 064428_7, 2020/08

https://doi.org/10.1103/PhysRevB.102.064428

被引用回数：2 パーセンタイル：12.9(Materials Science, Multidisciplinary)

X-ray absorption spectroscopy (XAS) and X-ray magnetic circular dichroism (XMCD) spectroscopy were applied at the Ge (Ga) $L_{2,3}$ edge to unravel the spin-resolved unoccupied electronic states of Co $_{2}$ MnGe (Ga). Complicated spectral features were observed in both XAS and XMCD spectra. For their interpretation, we compared the experimental XAS and XMCD spectra with the calculated Ge (Ga) 4 and 4 orbital partial density of states. The comparison enabled a qualitative explanation of the XMCD spectra as the difference between the majority and minority-spin unoccupied density of states summed over the 4 and 4 orbitals. Our finding provides a new approach to uncover the spin-split partial density of states above the Fermi level.

論文

Nature of the Dirac gap modulation and surface magnetic interaction in axion antiferromagnetic topological insulator MnBi $_{2}$ Te $_{4}$

Shikin, A. M.*; Estyunin, D. A.*; Klimovskikh, I. I.*; Filnov, S. O.*; Kumar, S.*; Schwier, E. F.*; 宮本幸治*; 奥田太一*; 木村昭夫*; 黒田健太*; et al.

Scientific Reports (Internet), 10, p.13226_1 - 13226_13, 2020/08

https://doi.org/10.1038/s41598-020-70089-9

被引用回数：59 パーセンタイル：96.43(Multidisciplinary Sciences)

Modification of the gap at the Dirac point (DP) in axion antiferromagnetic topological insulator MnBi $_{2}$ Te $_{4}$ and its electronic and spin structure have been studied by angle- and spin-resolved photoemission spectroscopy (ARPES) under laser excitation at various temperatures, light polarizations and photon energies. We have distinguished both large and reduced gaps at the DP in the ARPES dispersions, which remain open above the Nel temperature of $T_textrm{N}$ = 24.5 K. We propose that the gap above $T_textrm{N}$ remains open due to a short-range magnetic field generated by chiral spin fluctuations. Spin-resolved ARPES, XMCD and circular dichroism ARPES measurements show a surface ferromagnetic ordering for the large gap sample and apparently significantly reduced effective magnetic moment for the reduced gap sample.

論文

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

https://doi.org/10.1103/PhysRevB.101.104401

被引用回数：18 パーセンタイル：73.04(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 , and the saturation magnetization reaches a minimum value at .

論文

Improving fatigue performance of laser-welded 2024-T3 aluminum alloy using dry laser peening

佐野智一*; 詠村嵩之*; 廣瀬明夫*; 川人洋介*; 片山聖二*; 荒河一渡*; 政木清孝*; 城鮎美*; 菖蒲敬久; 佐野雄二*

Metals, 9(11), p.1192_1 - 1192_13, 2019/11

AA2019-0690.pdf:3.91MB

https://doi.org/10.3390/met9111192

被引用回数：15 パーセンタイル：65.54(Materials Science, Multidisciplinary)

本研究の目的は、ドライレーザーピーニング(DryLP)の有効性を検証することである。DryLPは、大気条件下でフェムト秒レーザーパルスを使用して、加工合金中の硬度,残留応力,疲労性能などの機械的特性を改善するピーニング技術である。レーザー溶接された2024アルミニウム合金にDryLP処理を施すと軟化した溶接金属は母材の元の硬度に回復し、溶接金属と熱影響部の残留引張応力は圧縮応力に変わった。疲労寿命は180MPaの引張圧縮試験でほぼ2倍になり、120MPaでは50倍以上増加した。以上から、DryLPは低応力振幅での溶接欠陥のあるレーザー溶接アルミニウム試験片の疲労性能を改善するのにより効果的であることを明らかにした。

論文

Element-specific density of states of Co $_{2}$ MnGe revealed by resonant photoelectron spectroscopy

河野嵩*; 鹿子木将明*; 吉川智己*; Wang, X.*; 角田一樹*; 宮本幸治*; 室隆桂之*; 竹田幸治; 斎藤祐児; 後藤一希*; et al.

Physical Review B, 100(16), p.165120_1 - 165120_6, 2019/10

https://doi.org/10.1103/PhysRevB.100.165120

被引用回数：5 パーセンタイル：27.67(Materials Science, Multidisciplinary)

Resonant photoelectron spectroscopy at the Co and Mn 2 core absorption edges of half-metallic Co $_{2}$ MnGe has been performed to determine the element-specific density of states (DOS). A significant contribution of the Mn 3 partial DOS near the Fermi level ( $E_{F}$ ) was clarified by measurement at the Mn 2 absorption edge. Further analysis by first-principles calculation revealed that it has $t_{2g}$ symmetry, which must be responsible for the electrical conductivity along the line perpendicular to the film plane. The dominant normal Auger contribution observed at the Co 2 absorption edge indicates delocalization of photoexcited Co 3 electrons. The difference in the degrees of localization of the Mn 3 and Co 3 electrons in Co $_{2}$ MnGe is explained by the first-principles calculation.

論文

Magnetic-impurity-induced modifications to ultrafast carrier dynamics in the ferromagnetic topological insulators Sb $_{2-x}$ V $_{x}$ Te $_{3}$

角田一樹*; 鹿子木将明*; Reimann, J.*; Nurmamat, M.*; 後藤伸一*; 竹田幸治; 斎藤祐児; Kokh, K. A.*; Tereshchenko, O. E.*; Gdde, J.*; et al.

New Journal of Physics (Internet), 21(9), p.093006_1 - 093006_8, 2019/09

https://doi.org/10.1088/1367-2630/ab3ac6

被引用回数：11 パーセンタイル：65.02(Physics, Multidisciplinary)

We systematically investigate the magnetic, structural and electronic properties and the ultrafast carrier dynamics in a series of V-doped Sb $_{2}$ Te $_{3}$ samples of composition Sb $_{2-x}$ V $_{x}$ Te $_{3}$ with x = 0, 0.015 and 0.03. Element specific X-ray magnetic circular dichroism signifies that the ferromagnetism of V-doped Sb $_{2}$ Te $_{3}$ is governed by the p-d hybridization between the host carrier and the magnetic dopant. Time- and angle-resolved photoemission spectroscopy has revealed that the V impurity induced states underlying the topological surface state (TSS) add scattering channels that significantly shorten the duration of transient surface electrons down to 100 fs scale. This is in a sharp contrast to the prolonged duration reported for pristine samples though the TSS is located inside the bulk energy gap of the host in either magnetic or non-magnetic cases. It implies the presence of a mobility gap in the bulk energy gap region of the host material.

論文

Negative Te spin polarization responsible for ferromagnetic order in the doped topological insulator V $_{0.04}$ (Sb $_{1-x}$ Bi $_{x}$ ) $_{1.96}$ Te $_{3}$

Ye, M.*; Xu, T.*; Li, G.*; Qiao, S.*; 竹田幸治; 斎藤祐児; Zhu, S.-Y.*; Nurmamat, M.*; 角田一樹*; 石田行章*; et al.

Physical Review B, 99(14), p.144413_1 - 144413_7, 2019/04

AA2018-0697.pdf:1.89MB

https://doi.org/10.1103/PhysRevB.99.144413

被引用回数：12 パーセンタイル：56.27(Materials Science, Multidisciplinary)

We investigate the microscopic origin of ferromagnetism coupled with topological insulators in V-doped (Sb,Bi) $_{2}$ Te $_{3}$ employing X-ray magnetic circular dichroism and angle-resolved two-photon photoemission spectroscopies, combined with first-principles calculations. We found an magnetic moment at the Te site anti-parallel to that of the V and Sb sites, which plays a key role in the ferromagnetic order. We ascribe it to the hybridization between Te 5 and V 3 majority spin states at the Fermi energy, consistent with the Zener-type - exchange interaction scenario. The substitution of Bi for Sb suppresses the bulk ferromagnetism by introducing extra electron carriers in the majority spin channel of the Te states that compensates the antiparallel magnetic moment on the Te site. Our findings reveal important clues to designing magnetic topological insulators with higher Curie temperature that work under ambient conditions.

論文

Dirac gap opening and Dirac-fermion-mediated magnetic coupling in antiferromagnetic Gd-doped topological insulators and their manipulation by synchrotron radiation

Shikin, A. M.*; Estyunin, D. A.*; Surnin, Yu. I.*; Koroleva, A. V.*; Shevchenko, E. V.*; Kokh, K. A.*; Tereshchenko, O. E.*; Kumar, S.*; Schwier, E. F.*; 島田賢也*; et al.

Scientific Reports (Internet), 9(1), p.4813_1 - 4813_17, 2019/03

https://doi.org/10.1038/s41598-019-41137-w

被引用回数：19 パーセンタイル：71.48(Multidisciplinary Sciences)

A new kind of magnetically-doped antiferromagnetic (AFM) topological insulators (TIs), Bi $_{1.09}$ Gd $_{0.06}$ Sb $_{0.85}$ Te $_{3}$ , has been studied by angle-resolved photoemission, superconducting magnetometry (SQUID) and X-ray magnetic circular dichroism (XMCD). It has been shown that this TI is characterized by the Dirac gap at the Fermi level. In the paramagnetic phase, a surface magnetic layer is supposed to develop, where the coupling between the Gd magnetic moments is mediated by the topological surface states (TSSs). This assumption can be confirmed by opening a gap at the Dirac point indicated by the surface-sensitive ARPES, a weak hysteresis loop measured by SQUID, the XMCD showing a surface magnetic moment and the temperature dependence of electrical resistance demonstrating a mid-gap semiconducting behavior, which correlates with the temperature dependence of the surface magnetization and confirms the conclusion that only TSSs are located at the Fermi level.

論文

Preferred site occupation of 3 atoms in Ni $_{x}$ Fe $_{4-x}$ N ( = 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

https://doi.org/10.1103/PhysRevMaterials.2.024407

被引用回数：14 パーセンタイル：48.52(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 ( = 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 at face-centered (II) sites and N 2 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.

論文

平成28年度技術士試験「原子力・放射線部門」対策講座; 平成27年度技術士二次試験「原子力・放射線部門」; そのポイントを探る全体解説、必須科目及び選択科目の設問と解説

高橋直樹; 芳中一行; 原田晃男; 山中淳至; 上野隆; 栗原良一; 鈴木惣十; 高松操; 前田茂貴; 井関淳; et al.

日本原子力学会ホームページ(インターネット), 64 Pages, 2016/00

本資料は、平成28年度技術士試験(原子力・放射線部門)の受験を志す者への学習支援を目的とし、平成27年度技術士試験(原子力・放射線部門)の出題傾向分析や学習方法等についての全体解説、必須科目の解答と解説及び選択科目の模範解答や解答作成にあたってのポイント解説を行うものである。なお、本資料は技術士制度の普及と技術士育成を目的とした日本原子力学会から日本技術士会(原子力・放射線部会)への依頼に基づき、原子力機構所属の技術士及び社内外の各分野における専門家により作成を行ったものである。

論文

Carrier-mediated ferromagnetism in the magnetic topological insulator Cr-doped (Sb,Bi) $_{2}$ Te $_{3}$

Ye, M.*; Li, W.*; Zhu, S.-Y.*; 竹田幸治; 斎藤祐児; Wang, J.*; Pan, H.*; Nurmamat, M.*; 角田一樹*; Ji, F.*; et al.

Nature Communications (Internet), 6, p.8913_1 - 8913_7, 2015/11

AA2015-0647.pdf:0.64MB

https://doi.org/10.1038/ncomms9913

被引用回数：52 パーセンタイル：89.95(Multidisciplinary Sciences)

磁性元素を添加したトポロジカル絶縁体は、量子異常ホール効果や無散逸伝導などの魅力的な現象の発現が予言され、低消費電力スピンデバイスの開発につながっていくものと期待されている。既に、いくつかの磁性添加トポロジカル絶縁体で長距離磁気秩序が確認されている。しかし、量子異常ホール効果の発現は、極低温におけるCrを添加した(Sb,Bi) $_{2}$ Te $_{3}$ 系に限られており、強磁性の微視的な起源はほとんど分かっていない。そこで、今回、X線磁気円二色性実験による元素選択的研究を行うことにより、本物質系の強磁性は、母体の正孔キャリアーを媒介としたものであり、Crの3d電子とSbやTeのp電子の相互作用が極めて重要であることを明らかにした。この結果は、異常量子ホール素子の実現に向けても重要である。

論文

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

https://doi.org/10.1063/1.4921431

被引用回数：14 パーセンタイル：52.35(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 $^{ast}$ 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 $^{ast}$ and $^{ast}$ anti-bondings between the Fe 3d and N 2p orbitals.

論文

Spectroscopic evidence of band Jahn-Teller distortion upon martensitic phase transition in Heusler-type Ni-Fe(Co)-Ga ferromagnetic shape-memory alloy films

角田一樹*; 白井開渡*; Zhu, S.-Y.*; 谷口雅樹*; Ye, M.*; 上田茂典*; 竹田幸治; 斎藤祐児; Aseguinolaza, I. R.*; Barandiarn, J. M.*; et al.

Physical Review B, 91(13), p.134417_1 - 134417_6, 2015/04

https://doi.org/10.1103/PhysRevB.91.134417

被引用回数：6 パーセンタイル：27.97(Materials Science, Multidisciplinary)

The temperature evolution of the electronic structure of a Ni-Fe(Co)-Ga/MgO(100), Heusler-type, ferromagnetic shape-memory alloy thin film has been followed by a bulk-sensitive hard X-ray photoelectron spectroscopy, element-selective soft X-ray magnetic circular dichroism, and first-principles calculation. The reversible changes of the electronic states near the Fermi energy show a hysteresis associated with the martensitic phase transition (MPT), where the pseudogap opens on cooling and closes again on warming. In addition, the Ni 3d spin magnetic moment increases by approximately two times across the MPT, whereas the change of Fe 3d moment is moderate. By comparing the experimental results with the calculated spin-resolved density of states, we conclude that the band Jahn-Teller effect of Ni 3d and Fe 3d orbitals is responsible for MPT.

報告書

原子力緊急時支援・研修センターの活動(平成25年度)

佐藤猛; 武藤重男; 秋山聖光; 青木一史; 岡本明子; 川上剛; 久米伸英; 中西千佳; 小家雅博; 川又宏之; et al.

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

JAEA-Review-2014-048.pdf:13.91MB

日本原子力研究開発機構は、災害対策基本法及び武力攻撃事態対処法に基づき、「指定公共機関」として、国及び地方公共団体その他の機関に対し、災害対策又は武力攻撃事態等への対処において、原子力機構の防災業務計画及び国民保護業務計画に則り、技術支援をする責務を有している。原子力緊急時支援・研修センターは、緊急時には、全国を視野に入れた専門家の派遣、防災資機材の提供、防護対策のための技術的助言等の支援活動を行う。また、平常時には、我が国の防災対応体制強化・充実のために、自らの訓練・研修のほか、国、地方公共団体、警察、消防、自衛隊等の原子力防災関係者のための実践的な訓練・研修、原子力防災に関する調査研究及び国際協力を実施する。平成25年度においては、原子力機構の年度計画に基づき、以下の業務を推進した。(1)国, 地方公共団体等との連携を図った指定公共機関としての技術支援活動、(2)国, 地方公共団体等の原子力防災関係者の人材育成及び研修・訓練、(3)原子力防災に係る調査・研究の実施及び情報発信、(4)国際機関と連携を図ったアジア諸国への原子力防災に係る国際貢献。また、指定公共機関としてこれまでに培った経験及び福島事故への初動時からの対応等を活かし、国レベルでの防災対応基盤の強化に向け、専門家として技術的な支援を行うとともに、支援・研修センターの機能の維持・運営及び国との連携を図った自らの対応能力強化などに重点的に取り組んだ。

論文

Development of a fiber-coupled laser-induced breakdown spectroscopy instrument for analysis of underwater debris in a nuclear reactor core

佐伯盛久; 岩撫暁生; 伊藤主税; 若井田育夫; Thornton, B.*; 作花哲夫*; 大場弘則

Journal of Nuclear Science and Technology, 51(7-8), p.930 - 938, 2014/07

https://doi.org/10.1080/00223131.2014.917996

被引用回数：70 パーセンタイル：98.67(Nuclear Science & Technology)

高放射線環境下でかつ水中に存在する固体試料を遠隔元素分析するための、ファイバーカップリングレーザー誘起ブレークダウン(LIBS)分光装置を設計・開発した。通常水中でLIBSを行うと、レーザーアブレーションにより生成したプラズマが水によりすぐ冷却されてしまうため、そこからの発光を効率よく観測することができない。そこで我々は、ガスフローシステムまたはダブルレーザーパルスシステムをLIBSシステムに取り入れることにより、レーザーアブレーションプラズマの周辺だけに擬大気環境を発生させ、水中でも効率よくLIBS測定ができるようにした。また、放射線照射した時のファイバーの光学透過特性試験を行い、放射線照射前後において近赤外(700-1100nm)領域では透過特性が変化しないことを見出した。さらに、分析を行うために最低必要なレーザーパワーを測定し、その結果を基にLIBSシステムの要であるレーザーを小型なもので置き換えることに成功した。以上の結果を基に、可搬型のファイバーカップリングレーザーLIBS分析システムを試作し、その性能評価を行った。

論文

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

https://doi.org/10.1063/1.4862517

被引用回数：18 パーセンタイル：60.33(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 $_{B}$ per atom, and that of Co atoms to be 1.47 $_{B}$ per atom in Co $_{3}$ FeN at 300 K. These values are close to 1.87 $_{B}$ per Fe atom in Fe $_{4}$ N and 1.43 $_{B}$ 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.