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論文

Nuclear structure of $$^{76}$$Ni from the ($$p$$,$$2p$$) reaction

Elekes, Z.*; Kripk$'o$, $'A$*; Sohler, D.*; Sieja, K.*; 緒方 一介*; 吉田 数貴; Doornenbal, P.*; Obertelli, A.*; Authelet, G.*; 馬場 秀忠*; et al.

Physical Review C, 99(1), p.014312_1 - 014312_7, 2019/01

 パーセンタイル:100(Physics, Nuclear)

($$p$$,$$2p$$)反応による$$^{76}$$Niの核構造の探索実験を行った。Lenzi, Nowacki, Poves, Sieja相互作用を用いた殻模型計算では実験結果を説明しうる陽子空孔状態が得られており、理論的な断面積計算は実験値とよい一致を与えた。実験で得られたすべての状態を理論的に一意に決定することはできなかったが、過去の実験結果と同様にNi同位体でのZ = 28の大きなshell gapを示す結果が得られた。

論文

Evaluation of residual stress relaxation in a rolled joint by neutron diffraction

林 眞琴*; Root, J. H.*; Rogge, R. B.*; 徐 平光

Quantum Beam Science (Internet), 2(4), p.21_1 - 21_16, 2018/12

The rolled joint of pressure tube, consisting of three axial symmetric parts, modified SUS403 stainless steel, Zr-2.5Nb pressure tube and Inconel-718, has been examined by neutron diffraction for residual stresses. It was heat treated at 350$$^{circ}$$C for 30, 130 and 635 hours to simulate the thermal aging of the rolled joint over the lifetime of the advanced thermal reactor at 288$$^{circ}$$C for 1, 5 and 30 years. The crystal lattice strains at various locations in the rolled joint before and after the aging treatments were measured by neutron diffraction and the residual stress distribution in the rolled joint was evaluated by using the Kroner elastic model and the generalized Hooke's law. In the crimp region of the rolled joint, it was found that the aging treatment had weak effect on the residual stresses in the Inconel and the SUS403. In the non-aged Zr-2.5Nb, the highest residual stresses were found near its interface with the SUS430. In the Zr-2.5Nb in the crimp region near its interface with the SUS430, the average compressive axial stress was -440 MPa, having no evident change during the long-time aging. In the Zr-2.5Nb outside closest to the crimp region, the tensile axial and hoop stresses were relieved during the 30 hours aging. The hoop stresses in the crimp region evolved from an average tensile stress of 80 MPa to an average compressive stress of 230 MPa after the 635 hours aging, suggesting that the rolled joint had a good long-term sealing ability against the leakage of high temperature water.

論文

A Fluorometric skin-interfaced microfluidic device and smartphone imaging module for ${{it in situ}}$ quantitative analysis of sweat chemistry

関根 由莉奈; Kim, S. B.*; Zhang, Y.*; Bandodkar, A. J.*; Xu, S.*; Choi, J.*; 入江 将大*; Ray, T. R.*; Kohli, P.*; 香西 直文; et al.

Lab on a Chip, 18(15), p.2178 - 2186, 2018/08

近年、スウェットに含まれる代謝産物やイオン等を用いたPoint of Careが高く注目されている。本研究では、それらのバイオマーカーを効果的にその場で検出することを目的として、ソフトで薄いウェアラブルマイクロ流路デバイスとスマートフォンを基盤とした蛍光イメージングシステムを提案する。精密に設計されたマイクロ流路は、皮膚から汗を時間シーケンス制御で集めることを可能にした。また、集められた汗から蛍光検出剤によって検出された塩化物,ナトリウム,亜鉛濃度をスマートフォンを基盤とした蛍光イメージングシステムで正確に定量分析することに成功した。このシステムを実際に試験したところ、正確に効率よく作動することを確認した。

論文

Nuclear moments of the low-lying isomeric $$1^+$$ state of $$^{34}$$Al; Investigation on the neutron $$1p1h$$ excitation across $$N=20$$ in the island of inversion

Xu, Z. Y.*; Heylen, H.*; 旭 耕一郎*; Boulay, F.*; Daugas, J. M.*; de Groote, R. P.*; Gins, W.*; Kamalou, O.*; Koszor$'u$s, $'A$.*; Lykiardopoupou, M.*; et al.

Physics Letters B, 782, p.619 - 626, 2018/07

 パーセンタイル:100(Astronomy & Astrophysics)

GANIL研究所において、$$^{36}$$Sからのフラグメンテーション反応によって中性子過剰核$$^{34}$$Alにおける核異性体である$$1^+$$状態を生成し、その磁気双極子モーメントと電気的四重極モーメント(Qモーメント)をそれぞれ$$beta$$-NMR法および$$beta$$-NQR法を用いて測定した。この状態は中性子数20の殻ギャップを越えて励起したものであり、その性質を実験的に押さえることは、この原子核の周辺で知られている逆転の島(基底状態で既に殻ギャップを越えた励起が起こるとされる原子核の一団)の発現のメカニズムを解明するための有益な情報を与える。測定されたg因子の絶対値は$$1.757pm 0.014$$、Qモーメントの絶対値は38(5)mbとなった。これらの値は、大規模殻模型計算による予言値に近く、模型の高い記述能力を確かめることができた。

論文

High stereographic resolution texture and residual stress evaluation using time-of-flight neutron diffraction

徐 平光; Harjo, S.; 小島 真由美*; 鈴木 裕士; 伊藤 崇芳*; Gong, W.; Vogel, S. C.*; 井上 純哉*; 友田 陽*; 相澤 一也; et al.

Journal of Applied Crystallography, 51(3), p.746 - 760, 2018/06

 被引用回数:1 パーセンタイル:47.84(Chemistry, Multidisciplinary)

Neutron diffraction texture measurements provide bulk textures with excellent grain statistics even for large grained materials, together with the crystallographic parameters and microstructure information such as phase fractions, coherent crystallite size, root mean square microstrain, macroscopic/intergranular stress/strain. The procedure for high stereographic resolution texture and residual stress evaluation was established at the TAKUMI engineering materials diffractometer. The pole figure evaluation of a limestone standard sample with a trigonal crystal structure suggested that the obtained precision for texture measurement is comparable with the oversea well-established neutron beam lines utilized for texture measurements. A high strength martensite-austenite multilayered steel was employed for further verification of the reliability of simultaneous Rietveld analysis of multiphase textures and macro stress tensors. By using a geometric mean micro-mechanical model, the macro stress tensor analysis with a plane stress assumption showed a RD-TD in-plane compressive stress (about -330 MPa) in martensite layers and a RD-TD in-plane tensile stress (about 320 MPa) in austenite layers. The phase stress partitioning was ascribed to the additive effect of volume expansion during martensite transformation and the linear contraction misfit during water quenching.

論文

Developing reliable reaction gamma-ray data

Dimitriou, P.*; Belgya, T.*; Cho, Y.-S.*; Filipescu, D.*; Firestone, R.*; Goriely, S.*; 岩本 信之; 河野 俊彦*; Kopecky, J.*; Krticka, M.*; et al.

EPJ Web of Conferences (Internet), 178, p.06005_1 - 06005_3, 2018/05

測定や既存のデータ評価・編集、また基礎科学や応用への利用に向けた巨大双極子共鳴パラメータ等のテーブル作成を基にした光核反応断面積や光子強度関数の開発について報告する。

論文

Comparison of heavy-ion transport simulations; Collision integral in a box

Zhang, Y.-X.*; Wang, Y,-J.*; Colonna, M.*; Danielewicz, P.*; 小野 章*; Tsang, M. B.*; Wolter, H.*; Xu, J.*; Chen, L.-W.*; Cozma, D.*; et al.

Physical Review C, 97(3), p.034625_1 - 034625_20, 2018/03

 被引用回数:16 パーセンタイル:1.01(Physics, Nuclear)

2017年4月に開催された国際会議Transport2017において、重イオン核反応モデルの国際的な比較が議論された。重イオン加速器の安全評価や宇宙飛行士の被ばく評価等で重要な役割を果たすため、世界中で重イオン核反応の様々な理論モデルが開発されている。本研究はモデル間の共通点と差異を明らかにし、各モデルの問題点を明らかにした。比較において、辺の長さが20fmの直方体に320個の中性子と320個の陽子をランダム配置し、それらが時間発展に伴って起こす散乱の回数や散乱時のエネルギーなどを計算する条件が設定された。また、結果以外にも、理論モデルを構成するアルゴリズムについても比較を行った。発表者は重イオン核反応モデルJQMD(JAERI Quantum Molecular Dynamics)を用いて計算を行い、世界で開発されている15の計算コードによる計算結果と比較した。コードアルゴリズムの比較では、JQMDは必ず陽子から 優先的に衝突確率を計算し、その後に中性子の衝突を計算するため、物理描像の妥当性が指摘された。一方、JQMDは他のモデルとほぼ同じ計算結果を出すことも判明した。衝突回数や運動量の計算値が平均から2倍以上乖離するモデルもある中で、JQMDは本計算条件で安定した性能を発揮することが確認された。

論文

Shell evolution beyond $$Z$$=28 and $$N$$=50; Spectroscopy of $$^{81,82,83,84}$$Zn

Shand, C. M.*; Podoly$'a$k, Zs.*; G$'o$rska, M.*; Doornenbal, P.*; Obertelli, A.*; Nowacki, F.*; Otsuka, T.*; Sieja, K.*; Tostevin, J. A.*; Tsunoda, T.*; et al.

Physics Letters B, 773, p.492 - 497, 2017/10

 被引用回数:8 パーセンタイル:14.67(Astronomy & Astrophysics)

Low-lying states in neutron-rich $$^{81,82.83.84}$$Zn nuclei were measured for the first time via in-beam $$gamma$$-ray spectroscopy at RIKEN. These include the 4$$_1^+$$ to 2$$_1^+$$ in $$^{82}$$Zn and the 2$$_1^+$$ to 0$$_1^+$$ and 4$$_1^+$$ to 2$$_1^+$$ in $$^{84}$$Zn. The reduced E($$2^+$$) energies and increased E(4$$^+$$)/E(2$$^+$$) ratios at $$N$$=52,54 compared to $$^{80}$$Zn attest that the magicity is confined just on the neutron number $$N$$=50 only. The levels observed in $$^{84}$$Zn suggest the onset of deformation towards heavier Zn isotopes. The data were compared to state-of-the-art shell model calculations.

論文

種々な方法によるMn-Si-C鋼の残留オーステナイト体積率測定の比較

友田 陽*; 関戸 信彰*; 徐 平光; 川崎 卓郎; Harjo, S.; 田中 雅彦*; 篠原 武尚; Su, Y.; 谷山 明*

鉄と鋼, 103(10), p.570 - 578, 2017/10

 被引用回数:1 パーセンタイル:76.21(Metallurgy & Metallurgical Engineering)

Various methods were employed to measure the austenite volume fraction in a 1.5Mn-1.5Si-0.2C steel. It has been confirmed that the volume fractions determined by transmission electron microscopy, scanning electron microscopy/electron back scatter diffraction, X-ray diffraction and neutron diffraction exhibit a general trend to become larger in this order, although the values obtained by X-ray and neutron diffraction are similar in the present steel because austenite is relatively stable. The austenite volume fractions determined by diffraction methods have been found to be affected by the measuring specimen direction, i.e., texture, even by applying the conventional correcting procedure. To avoid this influence, it is recommended to measure both of volume fraction and texture simultaneously using neutron diffraction. Although synchrotron X-ray shows higher angle resolution, its small incident beam size brings poor statistic reliability. The influence of texture cannot be avoided for transmission Bragg edge measurement, either, which must be overcome to realize 2D or 3D volume fraction mapping.

論文

Observation of a $$gamma$$-decaying millisecond isomeric state in $$^{128}$$Cd$$_{80}$$

Jungclaus, A.*; Grawe, H.*; 西村 俊二*; Doornenbal, P.*; Lorusso, G.*; Simpson, G. S.*; S$"o$derstr$"o$m, P.-A.*; 炭竃 聡之*; Taprogge, J.*; Xu, Z. Y.*; et al.

Physics Letters B, 772, p.483 - 488, 2017/09

 被引用回数:4 パーセンタイル:30.79(Astronomy & Astrophysics)

A new high-spin isomer in the neutron-rich nucleus $$^{128}$$Cd was populated in the projectile fission of a $$^{238}$$U beam at the Radioactive Isotope Beam Factory at RIKEN. A half-life of T$$_{1/2}$$ = 6.3(8) ms was measured for the new state which was tentatively assigned a spin/parity of (15$$^-$$). The isomeric state decays via the emission of a 309-keV $$gamma$$ ray with $$E3$$ multipolarity. The experimental results are compared to shell model calculations performed using state-of-the-art realistic effective interactions and to the neighbouring nucleus $$^{129}$$Cd. The comparison with calculations shows that adjustments of the pairing and multipole parts of the effective interaction derived from the CD-Bonn nucleon-nucleon potential are required in order to describe the properties of nuclei in the region around $$^{132}$$Sn.

論文

Quantitative evaluation of texture and dislocations during annealing after hot deformation in austenitic steel using neutron diffraction

友田 陽*; 佐藤 成男*; Uchida, M.*; 徐 平光; Harjo, S.; Gong, W.; 川崎 卓郎

Materials Science Forum, 905, p.25 - 30, 2017/08

Microstructural change during hot compressive deformation at 700 $$^{circ}$$C followed by isothermal annealing for a Fe-32Ni austnitic alloy was monitored using ${it in situ}$ neutron diffraction. The evolution of deformation texture with 40% compression and its change to recrystallization texture during isothermal annealing were presented by inverse pole figures for the axial and radial directions. The change in dislocation density was tracked using the convolutional muli-profile whole profile fitting method. To obtain the fitting results with good statistics, at least 60 s time-slicing for the event-mode recorded data was needed. The average dislocation density in 60 s after hot compression was determined to be 2.8 $$times$$ 10$$^{14}$$ m$$^{-2}$$ that decreased with increasing of annealing time.

論文

Shape evolution in neutron-rich krypton isotopes beyond N=60; First spectroscopy of $$^{98,100}$$Kr

Flavigny, F.*; Doornenbal, P.*; Obertelli, A.*; Delaroche, J.-P.*; Girod, M.*; Libert, J.*; Rodriguez, T. R.*; Authelet, G.*; Baba, H.*; Calvet, D.*; et al.

Physical Review Letters, 118(24), p.242501_1 - 242501_6, 2017/06

 被引用回数:14 パーセンタイル:9.07(Physics, Multidisciplinary)

The first $$gamma$$-ray spectroscopy of very neutron rich $$^{98,100}$$Kr isotopes was carried out at the RIBF at RIKEN Nishina center. Excited states in these isotopes were populated via (p,2p) reactions using radioactive $$^{99,101}$$Rb beams accelerated to 220 MeV/nucleon. The new data show a significant increase in deformation beyond N=60, as well as competing configurations (shape-coexistence) at low energy. The data were compared with beyond-mean-field calculations which predict level energies in good agreement with observation, and suggest oblate-prolate shape coexistence.

論文

放射光X線回折法を用いた積層型高強度鋼板におけるマルテンサイト層の局所変形挙動評価

小島 真由美*; 城 鮎美*; 鈴木 裕士; 井上 純哉*; 菖蒲 敬久; 徐 平光; 秋田 貢一; 南部 将一*; 小関 敏彦*

材料, 66(6), p.420 - 426, 2017/06

The strain distribution in a multilayered steel composite, which consists of martensite and austenite layers, was evaluated by energy dispersive X-ray diffraction to investigate the homogeneity of deformation in the martensite layer under uniaxial loading. A dog-bone shape specimen with a martensite layer with 0.2 mm in a thickness, sandwiching by austenite layers with 0.4 mm in thickness, was utilized in this study. A change in strains as a function of tensile loading was measured at the center of the martensite layer as well as near the interface between the martensite and austenite layers. Furthermore, the residual strain distributions were measured in the martensite layer of the unloaded specimens after different applied strains. As a result, slight inhomogeneous deformation was found at the beginning of the plastic deformation in the martensite layer although no local deformation was recognized even near the interface between austenite and martensite layers. After further deformation, mismatch of plastic deformation between austenite and martensite layers was reduced, and the martensite layer deformed homogeneously. Therefore, an unstable interface phenomenon might not be caused by the intrinsic factors with a mesoscopic scale discussed in this experiment.

論文

Evaluation of austenite volume fraction in TRIP steel sheets using neutron diffraction

徐 平光; 友田 陽*; 新垣 優; Harjo, S.; 末吉 仁*

Materials Characterization, 127, p.104 - 110, 2017/05

 被引用回数:10 パーセンタイル:5.06(Materials Science, Multidisciplinary)

The volume fractions of austenite ($$f_{rm A}$$) in TRIP steels were evaluated using time-of-flight neutron diffraction through four methods. They include the analysis method with random texture assumption, the correction method of ($$hkl$$) peak intensities, the Rietveld refinement method using the summed spectrum without distinguishing the specimen orientations, and the combined Rietveld analysis method for textures and volume fractions. It was found that for a near-random spectrum obtained by the summation of all the measured neutron spectra, the Rietveld refinement provided a satisfactory precision for $$f_{rm A}$$. Moreover, the precision was further improved through the combined Rietveld analysis method. If the texture measurement is unavailable, it is suggested to measure the neutron spectrum along the transverse direction, and to analyze the $$f_{rm A}$$ using conventional correction method of ($$hkl$$) peak intensities. It was also confirmed that the increment of $$f_{rm A}$$ evidently improved the combinations of tensile strength and uniform elongation (TS$$times$$UEl).

論文

$$gamma$$ decay of unbound neutron-hole states in $$^{133}$$Sn

Vaquero, V.*; Jungclaus, A.*; Doornenbal, P.*; Wimmer, K.*; Gargano, A.*; Tostevin, J. A.*; Chen, S.*; N$'a$cher, E.*; Sahin, E.*; 志賀 慶明*; et al.

Physical Review Letters, 118(20), p.202502_1 - 202502_5, 2017/05

 被引用回数:8 パーセンタイル:18.97(Physics, Multidisciplinary)

Excited states in $$^{133}$$Sn were populated following one-neutron knockout reaction from an unstable $$^{134}$$Sn beam at the RIBF laboratory in RIKEN. In addition to the already known $$gamma$$ rays, additional $$gamma$$ strength was observed for the first time in the excitation-energy range 3.5-5.5 MeV. Since the neutron separation energy of $$^{133}$$Sn is low, this observation provides direct evidence for the radioactive decay of neutron-unbound states in this nucleus. The ability of $$gamma$$ decay to compete with neutron emission was attributed to a mismatch between the wave functions of the initial and final states in the neutron emission case. These findings suggest that in the region south-east of $$^{132}$$Sn, nuclear structure effects play a significant role in the decay of unbound states, which are instead usually ignored in the evaluation of neutron-emission probabilities in astrophysical simulations.

論文

Low-lying structure and shape evolution in neutron-rich Se isotopes

Chen, S.*; Doornenbal, P.*; Obertelli, A.*; Rodriguez, T. R.*; Authelet, G.*; Baba, H.*; Calvet, D.*; Ch$^a$teau, F.*; Corsi, A.*; Delbart, A.*; et al.

Physical Review C, 95(4), p.041302_1 - 041302_6, 2017/04

 被引用回数:11 パーセンタイル:8.11(Physics, Nuclear)

Neutron-rich isotopes of selenium, $$^{88,90,92,94}$$Se, where studied via in beam $$gamma$$-ray spectroscopy after nucleon removal reactions at RIBF in RIKEN. The low-energy excitations of these nuclei were investigated using $$gamma$$-$$gamma$$ coincidences, and the first and second excited 2$$^+$$ states were found at remarkably low energies. The analysis and comparison with self-consistent beyond-mean field calculations suggest that both shape coexistence and triaxiality are needed to describe these isotopes.

論文

Type II shell evolution in $$A=70$$ isobars from the $$N geq 40$$ island of inversion

Morales, A. I.*; Benzoni, G.*; Watanabe, H.*; 角田 佑介*; Otsuka, T.*; 西村 俊二*; Browne, F.*; Daido, R.*; Doornenbal, P.*; Fang, Y.*; et al.

Physics Letters B, 765, p.328 - 333, 2017/02

 被引用回数:10 パーセンタイル:8.11(Astronomy & Astrophysics)

The level schemes of neutron-rich isotopes $$^{70}$$Co and $$^{70}$$Ni were populated in the $$beta$$ decay of $$^{70}$$Fe and studied using $$beta$$-delayed $$gamma$$-ray spectroscopy of the $$beta$$ decay, at the RIBF in RIKEN, Japan. The experimental results were compared to state-of-the-art shell-model calculations, and indicate a dominance of prolate deformation in the low-lying states, coexisting with spherical states. The $$beta$$ decay of the $$A=70$$ isobars is shown to progress in accordance to a new type of shell evolution, the so-called Type II, which involves many particle-hole excitations across energy gaps.

論文

Are there signatures of harmonic oscillator shells far from stability?; First spectroscopy of $$^{110}$$Zr

Paul, N.*; Corsi, A.*; Obertelli, A.*; Doornenbal, P.*; Authelet, G.*; Baba, H.*; Bally, B.*; Bender, M.*; Calvet, D.*; Ch$^a$teau, F.*; et al.

Physical Review Letters, 118(3), p.032501_1 - 032501_7, 2017/01

 被引用回数:14 パーセンタイル:9.07(Physics, Multidisciplinary)

The first measurement of $$gamma$$ rays emitted by the very neutron rich nuclei $$^{112}$$Mo (Z=42) and $$^{110}$$Zr (Z=40) was carried out at the RIBF facility at RIKEN. These data shine light on the postulated N=70 harmonic oscillator shell. If the spin-orbit splitting which gives rise to the N=82 shell gap is reduced in very neutron-rich nuclei, the harmonic oscillator gap at N=70 should open instead. However, both the measured energy of the first excited state $$^{112}$$Mo and $$^{110}$$Zr, respectively 235(7) keV and 185(11) keV, and their E(4$$^+$$)/E(2$$^+$$) ratio, indicate that these nuclei are good rotors, and exclude the shell stabilization scenario at Z=40 and N=70. These results were compared to state-of-the-art density functional theoretical calculations using Gogny and Skyrme effective interactions.

論文

Effect of storage environment on hydrogen generation by the reaction of Al with water

Wang, Y.-Q.*; Gai, W.-Z.*; Zhang, X.-Y.*; Pan, H.-Y.*; Cheng, Z.-X.*; 徐 平光; Deng, Z.-Y.*

RSC Advances (Internet), 7(4), p.2103 - 2109, 2017/01

AA2016-0521.pdf:1.55MB

 被引用回数:3 パーセンタイル:60.18(Chemistry, Multidisciplinary)

Al powder was stored in saturated water vapor, oxygen, nitrogen and drying air separately for a time period up to about six months, the degradation behavior of Al activity was characterized by the reaction of Al with water. It was found that water vapor decreased the induction time for the beginning of Al-water reaction and reduced the total hydrogen generation per unit weight of Al, while oxygen increased the induction time and retarded the Al-water reaction. In contrast, the effect of nitrogen and drying air on Al activity was weak. The mechanism analyses indicated that water vapor promoted the hydration of Al surface passive oxide film and speeded up the reaction of Al with water, while oxygen thickened the passive oxide film of Al surface and prolonged its hydration process. These imply that water vapor rather than oxygen is responsible for the degradation of Al activity during storage under ambient condition.

論文

中性子回折によるA1050アルミニウムの集合組織測定

徐 平光; Harjo, S.; 小貫 祐介*

加工と熱処理による優先方位制御, p.1 - 6, 2016/11

金属材料の加工性などの材料特性を考察するためには、材料全体の平均的な集合組織を明らかにする必要がある。高い透過能を有する中性子線を用いた集合組織測定では、材料全体の平均情報を一度に測定できる利点があり、研究用原子炉JRR-3の残留応力解析装置RESA-1や、大強度陽子加速器施設J-PARCにおける工学中性子回折装置TAKUMIとiMATERIAで実施可能である。本研究では、軽金属学会軽金属部会の共通アルミニウム合金試料を用いて、TAKUMIとiMATERIA装置による検出器パネルを分割した高精度集合組織測定技術の妥当性を検討した。両装置から得られた集合組織結果がX線回折結果とほぼ一致していることなどを示した。

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