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The Analytical study of inventories and physicochemical configuration of spallation products produced in Lead-Bismuth Eutectic of Accelerator Driven System

宮原 信哉*; 大平 直也*; 有田 裕二*; 前川 藤夫; 松田 洋樹; 佐々 敏信; 明午 伸一郎

Nuclear Engineering and Design, 352, p.110192_1 - 110192_8, 2019/10

 被引用回数:0 パーセンタイル:100(Nuclear Science & Technology)

鉛ビスマス共晶(LBE)合金は加速器駆動システム(ADS)の核破砕中性子ターゲットや冷却材として用いられ、核破砕生成物として多くの元素が生成するため、その放出および輸送挙動を評価することが重要である。そこで、J-PARCのADSターゲット試験施設(TEF-T)のLBEループについて、LBE中に生成する核破砕生成物のインベントリおよび物理化学的組成について検討した。LBE内の核破砕生成物インベントリは、PHITSコードを使用して評価した。LBE中の核破砕生成物の物理化学的組成は、350$$^{circ}$$C$$sim$$500$$^{circ}$$CのLBE運転温度及びLBE中の酸素濃度10ppb$$sim$$1ppmの条件下、Thermo-Calcコードを用いて計算した。計算の結果、Rb, Tl, Tc, Os, Ir, Pt, Au, Hgの8元素がすべての条件下でLBEに可溶であり、化合物は形成されなかった。Ce, Sr, Zr及びYの酸化物はLBE中でCeO$$_{2}$$, SrO, ZrO$$_{2}$$およびY$$_{2}$$O$$_{3}$$として安定であることが示唆された。


Magnetic, thermal, and neutron diffraction studies of a coordination polymer; bis(glycolato)cobalt(II)

中根 僚宏*; 米山 翔太*; 兒玉 健*; 菊地 耕一*; 中尾 朗子*; 大原 高志; 東中 隆二*; 松田 達磨*; 青木 勇二*; 藤田 渉*

Dalton Transactions (Internet), 48(1), p.333 - 338, 2019/01

 被引用回数:1 パーセンタイル:74.85(Chemistry, Inorganic & Nuclear)

The two-dimensional quadratic lattice magnet, bis(glycolato)cobalt(II) ([Co(HOCH$$_{2}$$CO$$_{2}$$)$$_{2}$$]), showed anti-ferromagnetic ordering at 15.0 K and an abrupt increase in magnetisation at H = 22 600 Oe and 2 K, thereby acting as a metamagnet. Neutron diffraction studies suggested that the magnetic moment vectors of the Co(II) ions had an amplitude of 3.59 mB and were not aligned in a fully antiparallel fashion to those of their neighbours, which caused canting between the magnetic moment vectors in the sheet. The canting angle was determined to be 7.1deg. Canting induced net magnetisation in the sheet, but this magnetisation was cancelled between sheets. The magnetisations in the sheets were oriented parallel to the magnetic field at the critical magnetic field.


Element-specific observation of the ferromagnetic ordering process in UCoAl via soft X-ray magnetic circular dichroism

竹田 幸治; 斎藤 祐児; 岡根 哲夫; 山上 浩志; 松田 達磨*; 山本 悦嗣; 芳賀 芳範; 大貫 惇睦*

Physical Review B, 97(18), p.184414_1 - 184414_7, 2018/05


 被引用回数:1 パーセンタイル:87.78(Materials Science, Multidisciplinary)

We have performed soft X-ray magnetic circular dichroism (XMCD) experiments on the itinerant-electron metamagnet UCoAl at the U 4$$d$$-5$$f$$ ($$N_mathrm{4, 5}$$) and Co 2$$p$$-3$$d$$ ($$L_mathrm{2, 3}$$) absorption edges in order to investigate the magnetic properties of the U 5$$f$$ and Co 3$$d$$ electrons separately. From the line shape of the XMCD spectrum, it is deduced that the orbital magnetic moment of the Co 3$$d$$ electrons is unusually large. Through the systematic temperature ($$T$$)- and magnetic field ($$H$$)-dependent XMCD measurements, we have obtained two types of the magnetization curve as a function of $$H$$ and $$T$$ (M-H curve and M-T curve, respectively). The metamagnetic transition from a paramagnetic state to a field-induced ferromagnetic state was observed clearly under 15 K at $$H_mathrm{M}$$. The value of the $$H_mathrm{M}$$ and its $$T$$-dependence agree well between the U and Co sites, and the bulk magnetization. Whereas, we have discovered the remarkable differences in the M-H and M-T curves between the U and Co sites. The present findings show clearly that the role of the Co 3$$d$$ electrons should be considered more carefully in order to understand the origin of the magnetic ordering in UCoAl.


New precise measurement of muonium hyperfine structure interval at J-PARC

上野 恭裕*; 青木 正治*; 深尾 祥紀*; 東 芳隆*; 樋口 嵩*; 飯沼 裕美*; 池戸 豊*; 石田 啓一*; 伊藤 孝; 岩崎 雅彦*; et al.

Hyperfine Interactions, 238(1), p.14_1 - 14_6, 2017/11

 被引用回数:3 パーセンタイル:6.76

MuSEUM is an international collaboration aiming at a new precise measurement of the muonium hyperfine structure at J-PARC (Japan Proton Accelerator Research Complex). Utilizing its intense pulsed muon beam, we expect a ten-fold improvement for both measurements at high magnetic field and zero magnetic field. We have developed a sophisticated monitoring system, including a beam profile monitor to measure the 3D distribution of muonium atoms to suppress the systematic uncertainty.


Maximizing $$T_c$$ by tuning nematicity and magnetism in FeSe$$_{1-x}$$S$$_x$$ superconductors

松浦 康平*; 水上 雄太*; 新井 佑基*; 杉村 優一*; 前島 尚行*; 町田 晃彦*; 綿貫 徹*; 福田 竜生; 矢島 健*; 広井 善二*; et al.

Nature Communications (Internet), 8, p.1143_1 - 1143_6, 2017/10

 被引用回数:37 パーセンタイル:9.91(Multidisciplinary Sciences)

A fundamental issue concerning iron-based superconductivity is the roles of electronic nematicity and magnetism in realising high transition temperature ($$T_c$$). To address this issue, FeSe is a key material, as it exhibits a unique pressure phase diagram involving nonmagnetic nematic and pressure-induced antiferromagnetic ordered phases. However, as these two phases in FeSe have considerable overlap, how each order affects superconductivity remains perplexing. Here we construct the three-dimensional electronic phase diagram, temperature ($$T$$) against pressure ($$P$$) and iso-valent S-substitution ($$x$$), for FeSe$$_{1-x}$$S$$_x$$. By simultaneously tuning chemical and physical pressures, against which the chalcogen height shows a contrasting variation, we achieve a complete separation of nematic and antiferromagnetic phases. In between, an extended nonmagnetic tetragonal phase emerges, where $$T_c$$ shows a striking enhancement. The completed phase diagram uncovers that high-$$T_c$$ superconductivity lies near both ends of the dome-shaped antiferromagnetic phase, whereas $$T_c$$ remainslow near the nematic critical point.


Benchmark study of the recent version of the PHITS code

岩元 洋介; 佐藤 達彦; 橋本 慎太郎; 小川 達彦; 古田 琢哉; 安部 晋一郎; 甲斐 健師; 松田 規宏; 細山田 龍二*; 仁井田 浩二*

Journal of Nuclear Science and Technology, 54(5), p.617 - 635, 2017/05

 被引用回数:24 パーセンタイル:1.13(Nuclear Science & Technology)



New muonium HFS measurements at J-PARC/MUSE

Strasser, P.*; 青木 正治*; 深尾 祥紀*; 東 芳隆*; 樋口 嵩*; 飯沼 裕美*; 池戸 豊*; 石田 啓一*; 伊藤 孝; 岩崎 雅彦*; et al.

Hyperfine Interactions, 237(1), p.124_1 - 124_9, 2016/12

 被引用回数:5 パーセンタイル:7.43

At the Muon Science Facility (MUSE) of J-PARC (Japan Proton Accelerator Research Complex), the MuSEUM collaboration is planning new measurements of the ground state hyperfine structure (HFS) of muonium both at zero field and at high magnetic field. The previous measurements were performed both at LAMPF (Los Alamos Meson Physics Facility) with experimental uncertainties mostly dominated by statistical errors. The new high intensity muon beam that will soon be available at MUSE H-Line will provide an opportunity to improve the precision of these measurements by one order of magnitude. An overview of the different aspects of these new muonium HFS measurements, the current status of the preparation, and the results of a first commissioning test experiment at zero field are presented.


Fermi surface of ThRu$$_{2}$$Si$$_{2}$$ as a reference to the strongly correlated isostructural metals investigated by quantum oscillations

松本 裕司*; 芳賀 芳範; 立岩 尚之; 青木 晴善*; 木村 憲彰*; 山村 朝雄*; 山本 悦嗣; 松田 達磨*; Fisk, Z.*; 山上 浩志*

Journal of the Physical Society of Japan, 85(10), p.104709_1 - 104709_7, 2016/10

 被引用回数:2 パーセンタイル:71.88(Physics, Multidisciplinary)

dHvA oscillations were detected on an actinide compound ThRu$$_2$$Si$$_2$$ which is regarded as a reference to strongly correlated electron systems URu$$_2$$Si$$_2$$ and CeRu$$_2$$Si$$_2$$. Observed Fermi surfaces well coincides with the band structure calculations, as well as experimentally obtained ones for a heavy fermion compound CeRu$$_2$$Si$$_2$$. On the other hand, Fermi surfaces of URu$$_2$$Si$$_2$$ have significantly different characteristics, suggesting an itinerant ground state of 5f electrons.


Colossal thermomagnetic response in the exotic superconductor URu$$_2$$Si$$_2$$

山下 卓也*; 下山 祐介*; 芳賀 芳範; 松田 達磨*; 山本 悦嗣; 大貫 惇睦; 住吉 浩明*; 藤本 聡*; Levchenko, A.*; 芝内 孝禎*; et al.

Nature Physics, 11(1), p.17 - 20, 2015/01

 被引用回数:32 パーセンタイル:11.24(Physics, Multidisciplinary)

Observation of a colossal Nernst signal is reported. URu$$_2$$Si$$_2$$ is known as a heavy fermion superconductor. The superconductivity coexists with the so-called hidden-order phase. The Nernst coefficient is enhanced by as large as million times over the theoretically expected value within the standard framework of superconducting fluctuations. Moreover, contrary to the conventional wisdom, the enhancement is more significant with the reduction of the impurity scattering rate. This anomalous Nernst effect intimately reflects the highly unusual superconducting state in URu$$_2$$Si$$_2$$.


Single-crystal growth and de Haas-van Alphen effect study of ThRu$$_2$$Si$$_2$$

松本 裕司*; 芳賀 芳範; 立岩 尚之; 青木 晴善*; 木村 憲彰*; 松田 達磨*; 山本 悦嗣; Fisk, Z.; 山上 浩志*

JPS Conference Proceedings (Internet), 3, p.011096_1 - 011096_5, 2014/06

Electronic differences between heavy Fermion CeRu$$_2$$Si$$_2$$ and isoelectronic nonmagnetic ThRu$$_2$$Si$$_2$$ have been investigated. We succeeded in observing the de Haas-van Alphen oscillation in a high quality single crystal of ThRu$$_2$$Si$$_2$$. The mean free path of conduction carriers has been estimated as 6400 ${AA}$, indicating the high quality of the present sample.


Direct observation of lattice symmetry breaking at the hidden-order transition in URu$$_2$$Si$$_2$$

利根川 翔*; 笠原 成*; 福田 竜生; 杉本 邦久*; 安田 伸広*; 鶴原 悠悟*; 渡邊 大樹*; 水上 雄太*; 芳賀 芳範; 松田 達磨*; et al.

Nature Communications (Internet), 5, p.4188_1 - 4188_7, 2014/06

 被引用回数:46 パーセンタイル:8.41(Multidisciplinary Sciences)

We report on the observation of lattice symmetry breaking from the fourfold to twofold structure by high-resolution synchrotron X-ray diffraction measurements at zero field. Small orthorhombic symmetry-breaking distortion sets in at the transition temperature with a jump, uncovering the weakly first-order nature of the hidden-order transition. This distortion is observed only in ultra pure samples, implying a highly unusual coupling nature between the electronic pneumaticity and underlying lattice.


Magnetic-field-induced charge order in the filled skutterudite SmRu$$_{4}$$P$$_{12}$$; Evidence from resonant and nonresonant X-ray diffraction

松村 武*; 道村 真司*; 稲見 俊哉; 林 佑弥*; 伏屋 健吾*; 松田 達磨*; 東中 隆二*; 青木 勇二*; 菅原 仁*

Physical Review B, 89(16), p.161116_1 - 161116_5, 2014/04

 被引用回数:12 パーセンタイル:42.82(Materials Science, Multidisciplinary)

SmRu$$_4$$P$$_{12}$$$$T_{rm MI}=16.5$$K以下の反強磁性相と$$T_{rm MI}$$$$T^*$$(=14K)間の中間相を共鳴と非共鳴のX線回折法で研究した。中間相では非共鳴の$$q$$=(1,0,0)のThomson散乱が磁場によって誘起される。この現象は理論的に予言されている$$p$$バンドの電荷秩序を反映した原子変位によって引き起こされている。同時にSmの磁場方向の反強磁性モーメントが強調され、これは$$Gamma_7-Gamma_8$$結晶場状態の交互配列を反映していると考えられる。この結果は、軌道に依存した$$p$$-$$f$$混成とpバンドのネスティング不安定性がPrRu$$_4$$P$$_{12}$$やPrFe$$_4$$P$$_{12}$$と同様な非従来型電荷秩序を引き起こしていることを示している。


Cyclotron resonance study of quasiparticle mass and scattering rate in the hidden-order and superconducting phases of URu$$_2$$Si$$_2$$

利根川 翔*; 橋本 顕一郎*; 井加田 洸輔*; 鶴原 悠悟*; Lin, Y.-H.*; 宍戸 寛明*; 芳賀 芳範; 松田 達磨; 山本 悦嗣; 大貫 惇睦; et al.

Physical Review B, 88(24), p.245131_1 - 245131_13, 2013/12

 被引用回数:11 パーセンタイル:46.27(Materials Science, Multidisciplinary)

Detailed analyses of the cyclotron resonance lines in a uranium compound URu$$_2$$Si$$_2$$ are reported. The analyses of the resonance profiles reveals that the heavier branch of the split line has a larger scattering rate, providing evidence for the existence of hot-spot along the [110] direction. The result is consistent with the broken fourfold symmetry in the hidden-order phase.


$$^{29}$$Si-NMR study of antiferromagnet CeRh$$_2$$Si$$_2$$ using single crystals

酒井 宏典; 徳永 陽; 神戸 振作; 松本 裕司; 松田 達磨; 芳賀 芳範

Journal of the Korean Physical Society, 63(3), p.352 - 355, 2013/08

 被引用回数:2 パーセンタイル:76.54(Physics, Multidisciplinary)



Single crystal growth and physical properties of UT$$_2$$Al$$_{20}$$ (T = transition metal)

松本 裕司; 松田 達磨; 立岩 尚之; 山本 悦嗣; 芳賀 芳範; Fisk, Z.

Journal of the Korean Physical Society, 63(3), p.363 - 366, 2013/08

 被引用回数:6 パーセンタイル:50.8(Physics, Multidisciplinary)

We have studied single crystal growth and physical properties of the UT$$_2$$Al$$_{20}$$ system. We have successfully grown UT$$_2$$Al$$_{20}$$ (T = Cr, Ti, W and Mo) using Al self flux and characterized the crystals using electron probe microanalyzer (EPAM) and X-ray diffraction, and measured their magnetic and electric properties. The ground states of UT$$_2$$Al$$_{20}$$ (T = Cr, Mo and W) are Pauli paramagnetic as is likely also in UTi$$_2$$Al$$_{20}$$. The effective masses of UCr$$_2$$Al$$_{20}$$ and UTi$$_2$$Al$$_{20}$$ are only weakly enhanced.


Separation of magnetic properties at uranium and cobalt sites in UCoAl using soft X-ray magnetic circular dichroism

竹田 幸治; 斎藤 祐児; 岡根 哲夫; 山上 浩志; 松田 達磨*; 山本 悦嗣; 芳賀 芳範; 大貫 惇睦; Fisk, Z.

Physical Review B, 88(7), p.075108_1 - 075108_6, 2013/08

 被引用回数:9 パーセンタイル:52.55(Materials Science, Multidisciplinary)



Single-crystal growth and physical properties of URhIn$$_5$$

松本 裕司*; 芳賀 芳範; 立岩 尚之; 酒井 宏典; 松田 達磨; 山本 悦嗣; Fisk, Z.

Physical Review B, 88(4), p.045120_1 - 045120_6, 2013/07

 被引用回数:6 パーセンタイル:64.56(Materials Science, Multidisciplinary)

We have grown the new uranium compound URhIn$$_5$$ with the tetragonal HoCoGa$$_5$$-type by the In self flux method. In contrast to the nonmagnetic ground state of the isoelectronic analogue URhGa$$_5$$, URhIn$$_5$$ is an antiferromagnet with antiferromagnetic transition temperature $$T_{rm N}$$ = 98 K. The moderately large electronic specific heat coefficient $$gamma$$ = 50 mJ/K$$^2$$mol demonstrates the contribution of 5f electrons to the conduction band.



芝内 孝禎*; 笠原 成*; 松田 祐司*; 福田 竜生; 杉本 邦久*

日本結晶学会誌, 55(2), p.128 - 134, 2013/04



Observation of bulk band dispersions of YbRh$$_2$$Si$$_2$$ using soft X-ray angle-resolved photoemission spectroscopy

保井 晃*; 斎藤 祐児; 藤森 伸一; 川崎 郁斗*; 岡根 哲夫; 竹田 幸治; Lapertot, G.*; Knebel, G.*; 松田 達磨*; 芳賀 芳範; et al.

Physical Review B, 87(7), p.075131_1 - 075131_6, 2013/02

 被引用回数:5 パーセンタイル:69.41(Materials Science, Multidisciplinary)

YbRh$$_2$$Si$$_2$$に対して軟X線角度分解光電子分光(ARPES)測定を行い、その3次元バルク価電子帯構造を明らかにした。15 Kで測定したARPESスペクトルには、Yb$$ ^{3+}$$マルチプレットピークだけではなく、有限のYb$$ ^{2+}$$ピークを持っており、この化合物が価数揺動状態にあることに対応している。これは、$$T_{rm K}$$において、この化合物中のYbの4f電子が遍歴的な性質を持っていることを意味している。分散のないYb 4fバンド以外のバンド構造は、YbRh$$_2$$Si$$_2$$よりもむしろLuRh$$_2$$Si$$_2$$と一致していることが明らかとなった。さらに、Yb 3d-4f共鳴光電子分光スペクトルはYb 5d電子状態が価電子に存在していることを示唆している。これらの結果から、Yb 4fからYb 5d電子状態への電荷移動が重要であることが示唆される。


Magnetic excitation in totally symmetric staggered ordered phase of PrFe$$_4$$P$$_{12}$$

岩佐 和晃*; Hao, L.*; 神木 正史*; 桑原 慶太郎*; Mignot, J.-M.*; 菅原 仁*; 青木 勇二*; 松田 達磨; 佐藤 英行*

Journal of the Physical Society of Japan, 81(9), p.094711_1 - 094711_9, 2012/09

 被引用回数:7 パーセンタイル:48.6(Physics, Multidisciplinary)

We report inelastic neutron scattering results for single-crystalline samples of PrFe$$_4$$P$$_{12}$$, which undergoes a transition from the heavy-electron phase to the antiferro-type nonmagnetic ordered phase. In contrast to the quasielastic magnetic response observed in the heavy electron phase, the well-defined inelastic peaks located at 1.5 and 3 meV are superimposed in the ordered phase. The maximum spectral intensity appears at the Brillouin zone center for the original $$Imbar{3}$$ structure, and the minimum spectral intensity appears at the zone boundaries including the ordering vector $$q_0$$ = (1,0,0). The spectra are consistent with the recently proposed staggered ordering of a Pr site with well-localized $$f$$-electrons and that with a Kondo-singlet-like state, which are represented as the totally symmetric state accompanied by the charge modulation of carriers.

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