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論文

Development of three-dimensional distribution visualization technology for boron using energy resolved neutron-imaging system (RADEN)

阿部 雄太; 土川 雄介; 甲斐 哲也; 松本 吉弘*; Parker, J. D.*; 篠原 武尚; 大石 佑治*; 加美山 隆*; 永江 勇二; 佐藤 一憲

Proceedings of 2020 International Conference on Nuclear Engineering (ICONE 2020) (Internet), 6 Pages, 2020/08

Boron carbide is used as a neutron-absorbing material in Fukushima-Daiichi Nuclear Power Station (1F), producing borides that are twice as hard as oxides (such as UO$$_{2}$$ and ZrO$$_{2}$$). The high neutron absorption of boron affects the evaluation of re-criticality during the process of debris retrieval. Therefore, it is important not only to determine the presence of boron but also to investigate the distribution of boron inside the material in a non-destructive manner during decommissioning. To address the uncertainties in the core material relocation behavior of boiling water reactor (BWR) during a severe accident (SA), solidified melt specimens of a simulated fuel assembly were prepared by plasma heating. If core material melting and relocation (CMMR) specimens can be used to estimate the B distribution in 1F Unit-3, that will provide valuable information in the decommissioning of 1F. To address this, the authors focused on the energy-resolved neutron imaging system, RADEN, which utilizes a wide energy range, from meV to keV. This is an innovative three-dimensional analysis technology for boride distribution that affects the evaluation of hardness and re-criticality. In the calibration standard samples (Zr$$_{x}$$B$$_{1-x}$$ and Fe$$_{x}$$B$$_{1-x}$$), there was a good correlation between boron concentration and the energy-dependence of the cross sections of cold and epi-thermal neutrons. In the CMMR specimens, boron distribution was confirmed from the contrast difference between cold and epi-thermal neutrons. In the future, the results of calibration standard samples will be applied to the results of CMMR specimens. With this method, three-dimensional boron distribution will be measured, and the understanding of boride distribution 1F Unit-3 will be improved, which may be reflected in an improved SA code.

論文

The Energy-resolved neutron imaging system, RADEN

篠原 武尚; 甲斐 哲也; 及川 健一; 中谷 健; 瀬川 麻里子; 廣井 孝介; Su, Y.; 大井 元貴; 原田 正英; 飯倉 寛; et al.

Review of Scientific Instruments, 91(4), p.043302_1 - 043302_20, 2020/04

 被引用回数:1 パーセンタイル:30.41(Instruments & Instrumentation)

The energy-resolved neutron imaging system, RADEN, has been installed at the pulsed neutron source in the Materials and Life Science Experimental Facility of the Japan Proton Accelerator Research Complex. In addition to conventional neutron radiography and tomography, RADEN, the world's first imaging beam-line at a pulsed neutron source, provides three main options for new, quantitative neutron imaging techniques: Bragg-edge imaging to visualize the spatial distribution of crystallographic information, resonance absorption imaging for elemental composition and temperature information, and polarized neutron imaging for magnetic field information. This paper describes the results of characterization studies of the neutronic performance and installed devices at RADEN and shows the results of several demonstration studies for pulsed neutron imaging.

論文

中性子イメージング装置RADEN(螺鈿)の活用

甲斐 哲也; 篠原 武尚; 松本 吉弘*

検査技術, 25(2), p.1 - 5, 2020/02

J-PARC物質・生命科学実験施設に設置されたエネルギー分析型中性子イメージング装置RADENは、エネルギー分析を行わない中性子ラジオグラフィ/トモグラフィの利用でも相応の役割を果たしている。本稿では、検査技術の一つとしての検討材料を提供するため、これまでにRADENで中性子ラジオグラフィ/トモグラフィの利用で得られた成果について紹介する。

論文

Pulsed neutron imaging based crystallographic structure study of a Japanese sword made by Sukemasa in the Muromachi period

及川 健一; 鬼柳 善明*; 佐藤 博隆*; 大前 良磨*; Pham, A.*; 渡辺 賢一*; 松本 吉弘*; 篠原 武尚; 甲斐 哲也; Harjo, S.; et al.

Materials Research Proceedings, Vol.15, p.207 - 213, 2020/02

Japanese swords are very attractive not only as a work of art but also a metallurgical point of view. Since Japanese vintage swords became valuable, it is indispensable to establish non-destructive analysis method to identify some peculiar characteristics. Bragg edge imaging gives real-space distributions of bulk information in a crystalline material as well as neutron tomography. In this work, we investigated crystallographic information of a Japanese sword made by Sukemasa in Izumi province in the first quarter of the 16th century. The experiments have been performed at RADEN at J-PARC. The Sukemasa sword was measured with a counting-type 2D detector and with a CCD camera. We are now analyzing the measured 2D-transmission spectra using RITS code to obtain spatial distribution of the crystallite size, the texture variation, the d110 shift and its broadening. Complementary data analysis using white beam tomography is also on going. Detailed analysis results will be presented.

論文

Feasibility study of two-dimensional neutron-resonance thermometry using molybdenum in 316 stainless-steel

甲斐 哲也; 廣井 孝介; Su, Y.; 瀬川 麻里子; 篠原 武尚; 松本 吉弘*; Parker, J. D.*; 林田 洋寿*; 及川 健一

Materials Research Proceedings, Vol.15, p.149 - 153, 2020/02

A two-dimensional thermometry technique based on neutron resonance reactions derives the temperature of specified elements in an object by analyzing the Doppler broadening of a neutron resonance measured by a time-analyzing neutron imaging-detector. This technique is expected to be one of the important applications of the energy-resolved neutron imaging system, RADEN, at J-PARC. The authors focused on molybdenum contained in 316 stainless-steel (with a weight fraction of 2-3 wt%). Energy-dependent transmitted neutrons were measured through a 3 mm thick 316 stainless-steel plate placed in a heater at temperatures between 23 and 500 degrees Celsius at RADEN using a gas-electron multiplier (GEM) detector. Thermal and cold neutrons were eliminated from the incident beam by a cadmium filter. The sample area within the neutron beam was 30 by 50 mm$$^2$$. The feasibility is discussed in the presentation.

論文

Recent progress on practical materials study by Bragg edge imaging at J-PARC

及川 健一; Su, Y.; 鬼柳 亮嗣; 川崎 卓郎; 篠原 武尚; 甲斐 哲也; 廣井 孝介; Harjo, S.; Parker, J. D.*; 松本 吉弘*; et al.

Physica B; Condensed Matter, 551, p.436 - 442, 2018/12

 被引用回数:1 パーセンタイル:87.78(Physics, Condensed Matter)

We are promoting for practical product observation by the energy-resolved neutron imaging method using high-intensity pulsed neutrons at J-PARC, under the Photon and Quantum Basic Research Coordinated Development Program from the Ministry of Education, Culture, Sports, Science and Technology, Japan. Bragg edge imaging, one of the energy-resolved neutron imaging methods for visualizing material properties, was applied to feasibility study of the temperature distribution of copper rod, complementary study of the texture and strain distribution of bent steel plates using neutron diffraction and EBSD, and so on. Outline of results obtained by these imaging experiments will be presented.

論文

Characteristics of the 2012 model lithium-6 time-analyzer neutron detector (LiTA12) system as a high efficiency detector for resonance absorption imaging

甲斐 哲也; 佐藤 節夫*; 廣井 孝介; Su, Y.; 瀬川 麻里子; Parker, J. D.*; 松本 吉弘*; 林田 洋寿*; 篠原 武尚; 及川 健一; et al.

Physica B; Condensed Matter, 551, p.496 - 500, 2018/12

 被引用回数:1 パーセンタイル:87.78(Physics, Condensed Matter)

The 2012 model lithium-6 time-analyzer neutron detector (LiTA12) system, based on a lithium glass scintillator and multi-anode photomultiplier tube, has the highest neutron efficiency among the detectors for pulsed neutron imaging together with a flexibility of the efficiency by changing the thickness of the lithium glass. The authors expect this detector system could become a main detector system for the energy-resolved neutron imaging system, RADEN, at J-PARC, and have started evaluation of the LiTA12 system. For example, spatial resolution for resonance absorption imaging was evaluated by using a line-pair pattern made by 3 micro meter thick gold on a quartz plate. Less than 1 mm width line pairs were resolved at an 8 Mcps neutron counting rate and around 5 eV neutron energy.

論文

Effect of upstream beam collimation on neutron phase imaging with a Talbot-Lau interferometer at the RADEN beam line in J-PARC

關 義親; 篠原 武尚; 上野 若菜; Parker, J. D.*; 松本 吉弘*

Physica B; Condensed Matter, 551, p.512 - 516, 2018/12

 被引用回数:3 パーセンタイル:65.86(Physics, Condensed Matter)

3枚の格子からなる中性子タルボ・ロー干渉計は高機能なイメージング装置であり、通常の吸収コントラスト像に加えて、微分位相コントラスト像とビジビリティコントラスト像も同時に取得することができる。我々はJ-PARC MLF RADENビームラインにおいて波長分解型のタルボ・ロー干渉計の開発を進めている。干渉パターンの波長分解解析を行うことで、白色ビーム測定で生じていた色収差による系統誤差を排除するとともに、より定量的な情報を引き出すことが可能になる。この波長分解測定・解析法を前提として、RADENビームラインの波長スペクトルに最適化した干渉計の設計(中心波長・格子周期・格子間距離)を決定した。

論文

Spatial resolution test targets made of gadolinium and gold for conventional and resonance neutron imaging

瀬川 麻里子; 及川 健一; 甲斐 哲也; 篠原 武尚; 林田 洋寿*; 松本 吉弘*; Parker, J. D.*; 中谷 健; 廣井 孝介; Su, Y.; et al.

JPS Conference Proceedings (Internet), 22, p.011028_1 - 011028_8, 2018/11

We have fabricated and utilized spatial resolution test targets made of gadolinium and gold for conventional and resonance neutron imaging performed at RADEN, located at beam line BL22 of the J-PARC Materials and Life Science Experimental Facility (MLF). RADEN covers a broad energy range from cold neutrons to high-energy neutrons with energy of several tens keV and was designed to perform energy-resolved neutron imaging utilizing two-dimensional detectors combined with the accurate measurement of neutron energy by the time-of-flight method. The test targets were designed to verify the spatial resolution and image uniformity of two kinds of neutron detectors, counting-type detectors and camera-type detectors. In this presentation, we report the details of these two-dimensional test targets, and the results of demonstrations using the test targets with our neutron imaging detectors. This work was supported in part by the Photon and Quantum Basic Research Coordinated Development Program from the Ministry of Education, Culture, Sports, Science and Technology, Japan.

論文

Deformation analysis of reinforced concrete using neutron imaging technique

小山 拓*; 上野 一貴*; 関根 麻里子*; 松本 吉弘*; 甲斐 哲也; 篠原 武尚; 飯倉 寛; 鈴木 裕士; 兼松 学*

Materials Research Proceedings, Vol.4, p.155 - 160, 2018/05

 被引用回数:0 パーセンタイル:100

We developed, in this study, a novel method to observe internal deformation of concrete by the neutron transmission imaging technique. In order to visualize the internal deformation of concrete, the cement paste markers containing Gd$$_{2}$$O$$_{3}$$ powder were two-dimensionally dispersed around the ferritic deformed rebar in the reinforced concrete. This experiment was conducted using BL22, RADEN, in the Material and Life Science Experimental Facility of the Japan Proton Accelerator Research Complex. The transmission images of the reinforced concrete sample were taken at several positions on the vertical sample stage, and the displacement of the marker from the initial position was successfully evaluated within approximately $$pm$$0.1 mm accuracy by image analysis for selected markers with higher contrast and circularity. Furthermore, concrete deformation under pull-out loading to the embedded rebar was evaluated by the same way, and its reaction compressive deformation was successfully observed by analyzing the displacement of the markers. The results obtained in this study bring beneficial knowledge that the measurement accuracy of the marker displacement can be improved more by choosing a spherical shape of the marker and by increasing the contrast of the marker.

論文

Reliability estimation of neutron resonance thermometry using tantalum and tungsten

甲斐 哲也; 廣井 孝介; Su, Y.; 篠原 武尚; Parker, J. D.*; 松本 吉弘*; 林田 洋寿*; 瀬川 麻里子; 中谷 健; 及川 健一; et al.

Physics Procedia, 88, p.306 - 313, 2017/06

 被引用回数:3 パーセンタイル:6.96

Neutron resonance thermometry, which measures material temperature by analyzing the Doppler broadening of a neutron resonance peak, is one of the applications of energy-resolved neutron imaging at RADEN of J-PARC. Although this technique is promising, advantages and disadvantages have not been discussed in practical applications. The authors measured neutron transmission rates of tantalum and tungsten foils in a heater chamber up to 300 degrees Celsius at RADEN. The energy-dependent neutron transmission rates with different statistics were obtained after the measurements by selecting arbitrary measuring intervals from one measurement, and the temperatures of the foils were estimated from those transmission rates with different statistics. The reliability of the neutron resonance thermometry with statistical accuracy, irradiation time and spatial resolution are discussed.

論文

Contracted interlayer distance in graphene/sapphire heterostructure

圓谷 志郎; Antipina, L. Y.*; Avramov, P.*; 大伴 真名歩*; 松本 吉弘*; 平尾 法恵; 下山 巖; 楢本 洋*; 馬場 祐治; Sorokin, P. B.*; et al.

Nano Research, 8(5), p.1535 - 1545, 2015/05

 被引用回数:20 パーセンタイル:25.92(Chemistry, Physical)

Direct growth of graphene on insulators is expected to yield significant improvements in performance of graphene-based electronic and spintronic devices. In this study, we successfully reveal atomic arrangement and electronic properties of the coherent heterostructure of single-layer graphene and $$alpha$$-Al$$_{2}$$O$$_{3}$$(0001). In the atomic arrangement analysis of single-layer graphene on $$alpha$$-Al$$_{2}$$O$$_{3}$$(0001), we observed apparently contradicting results. The in-plane analysis shows that single-layer graphene grows not in the single-crystalline epitaxial manner but in the polycrystalline form with two strongly pronounced preferred orientations. This suggests the relatively weak interfacial interactions to be operative. But, we demonstrate that there exists unusually strong physical interactions between graphene and $$alpha$$-Al$$_{2}$$O$$_{3}$$(0001), as evidenced by the short vertical distance between graphene and $$alpha$$-Al$$_{2}$$O$$_{3}$$(0001) surface. The interfacial interactions are shown to be dominated by the electrostatic force involved in the graphene $$pi$$-system and the unsaturated electrons of the topmost O layer of $$alpha$$-Al$$_{2}$$O$$_{3}$$(0001) rather than the van der Waals interactions. Such feature causes hole doping into graphene, which gives graphene a chance to slide on the $$alpha$$-Al$$_{2}$$O$$_{3}$$(0001) surface with a small energy barrier despite the strong interfacial interactions.

論文

Contact-induced spin polarization in BNNT(CNT)/TM (TM=Co, Ni)nanocomposites

Kuzubov, A. A.*; Kovaleva, E. A.*; Avramov, P. V.*; Kuklin, A. V.*; Mikhaleva, N. S.*; Tomilin, F. N.*; 境 誠司; 圓谷 志郎; 松本 吉弘*; 楢本 洋*

Journal of Applied Physics, 116(8), p.084309_1 - 084309_4, 2014/08

 被引用回数:8 パーセンタイル:56.45(Physics, Applied)

The interaction between carbon and BN nanotubes (NT) and transition metal Co and Ni supports was studied using electronic structure calculations. Several configurations of interfaces were considered, and the most stable ones were used for electronic structure analysis. All NT/Co interfaces were found to be more energetically favorable than NT/Ni, and conductive carbon nanotubes demonstrates lightly stronger bonding than semiconducting ones. The presence of contact-induced spin polarization was established for all nanocomposites. It was found that the contact-induced polarization of BNNT leads to the appearance of local conductivity in the vicinity of the interface while the rest of the nanotube lattice remains to be insulating.

論文

Atomic structure and physical properties of fused porphyrin nanoclusters

Avramov, P. V.*; Kuzubov, A. A.*; 境 誠司; 大伴 真名歩*; 圓谷 志郎; 松本 吉弘*; Eleseeva, N. S.*; Pomogaev, V. A.*; 楢本 洋*

Journal of Porphyrins and Phthalocyanines, 18(7), p.552 - 568, 2014/07

 被引用回数:1 パーセンタイル:93.19(Chemistry, Multidisciplinary)

A wide variety of planar and curved fused porphyrin/metalloporphyrin nanoclusters have been studied at the LC-GGA DFT level. It was found that curved and hollow-caged 0D and 1D nanoclusters are metastable and bear unique atomic and electronic structure and mechanical properties. Under different types of mechanical loads the nanoclusters display ultrastrong and superelastic properties. The curvature of the hollow cage nanoclusters leads to the redistribution of the metal d states near the Fermi level. The extremely high spin states allow one to use Fe-porphyrin nanoclusters as molecular supermagnets and logic quantum gates for holonomic quantum computations.

論文

Contact-induced spin polarization of monolayer hexagonal boron nitride on Ni(111)

大伴 真名歩; 山内 泰*; Kuzubov, A. A.*; Eliseeva, N. S.*; Avramov, P.*; 圓谷 志郎; 松本 吉弘; 楢本 洋*; 境 誠司

Applied Physics Letters, 104(5), p.051604_1 - 051604_4, 2014/02

 被引用回数:10 パーセンタイル:49.05(Physics, Applied)

六方晶窒化ホウ素(h-BN)はグラフェン・スピントロニクスのトンネルバリア材料として有望視されている。本研究ではスピン偏極準安定ヘリウム脱励起分光法(SPMDS)を用いて、Ni(111)上の単層h-BNのスピン分解バンド構造を調べた。SPMDSの最表面敏感性により、Ni 3$$d$$ピークの重複を受けずに部分的に占有されたギャップ内順位を検出できた。さらにこのギャップ内順位は大きなスピン偏極を持ち、Niの多数スピン側に偏極していることが示された。この正のスピン偏極は、h-BN/Ni(111)界面における$$pi$$-$$d$$軌道混成によるものであると帰属できた。

論文

Spin orientation transition across the single-layer graphene/nickel thin film interface

松本 吉弘; 圓谷 志郎; 小出 明広*; 大伴 真名歩; Avramov, P.; 楢本 洋*; 雨宮 健太*; 藤川 高志*; 境 誠司

Journal of Materials Chemistry C, 1(35), p.5533 - 5537, 2013/09

 被引用回数:20 パーセンタイル:28.43(Materials Science, Multidisciplinary)

The spin-electronic structures across the interface between single-layer graphene and a Ni(111) thin film are explored by employing the depth-resolved X-ray absorption and magnetic circular dichroism spectroscopy with the atomic layer resolution. The depth-resolved Ni L-edge analysis clarifies that the Ni atomic layers adjacent to the interface show a transition of the spin orientation to the perpendicular one in contrast with the in-plane one in the bulk region. The C K-edge analysis reveals the intensifying of the spin-orbital interactions induced by the $$Pi$$-d hybridization at the interface as well as out-of-plane spin polarization at the $$Pi$$ band region of graphene. The present study indicates the importance of the interface design at the atomic layer level for graphene-based spintronics.

論文

High spin polarization at the Fe/C$$_{60}$$ interface in the Fe-doped C$$_{60}$$ film

境 誠司; 松本 吉弘; 大伴 真名歩; 圓谷 志郎; Avramov, P.; Sorokin, P. B.*; 楢本 洋*

Synthetic Metals, 173, p.22 - 25, 2013/06

 被引用回数:2 パーセンタイル:87.01(Materials Science, Multidisciplinary)

A process of tunneling conduction and the spin-dependent resistivity change (so-called tunneling magnetoresitance effect) in the Fe-doped C$$_{60}$$ film with a granular structure is investigated for the current-into-plane device. Cooperative tunneling (cotunneling) through several Fe nanoparticles is suggested to be operative at temperatures lower than 20 K. By considering the effect of cotunneling on the magnetoresistance ratio, it is successfully shown that the spin polarization of tunneling electrons generated at the Fe/C$$_{60}$$ interface is much higher than that in Fe crystal at low temperature in a similar fashion to that at the Co/C$$_{60}$$ interface in the Co-doped C$$_{60}$$ films. A strong temperature dependence of spin polarization is observed, suggesting possible influences by the thermally-induced disorders ascribed in the Fe atoms bonded with C$$_{60}$$ in the C$$_{60}$$-Fe compound.

論文

Contact-induced spin polarization in graphene/$$h$$-BN/Ni nanocomposites

Avramov, P.; Kuzubov, A. A.*; 境 誠司; 大伴 真名歩; 圓谷 志郎; 松本 吉弘; 楢本 洋*; Eliseeva, N. S.*

Journal of Applied Physics, 112(11), p.114303_1 - 114303_10, 2012/12

 被引用回数:15 パーセンタイル:39.49(Physics, Applied)

Atomic and electronic structure of graphene/Ni(111), $$h$$-BN/Ni(111) and graphene/$$h$$-BN/Ni(111) nanocomposites with different numbers of graphene and $$h$$-BN layers and in different mutual arrangements of graphene/Ni and $$h$$-BN/Ni at the interfaces was studied using LDA/PBC/PW technique. For the sake of comparison, corresponding graphene, $$h$$-BN and graphene/$$h$$-BN structures without the Ni plate were calculated using the same technique. It was suggested that C-$$top$$:C-$$fcc$$ and N-$$top$$:B-$$fcc$$ configurations are energetically favorable for the graphene/Ni and $$h$$-BN/Ni interfaces, respectively. The Ni plate was found to induce a significant degree of spin polarization in graphene and $$h$$-BN caused by direct exchange interactions of the electronic states located on different fragments.

論文

Intrinsic edge asymmetry in narrow zigzag hexagonal heteroatomic nanoribbons causes their subtle uniform curvature

Avramov, P.; Fedorov, D. G.*; Sorokin, P. B.*; 境 誠司; 圓谷 志郎; 大伴 真名歩; 松本 吉弘; 楢本 洋*

Journal of Physical Chemistry Letters (Internet), 3(15), p.2003 - 2008, 2012/08

 被引用回数:29 パーセンタイル:19.98(Chemistry, Physical)

The atomic and electronic structure of narrow zigzag nanoribbons with finite length, consisting of graphene terminated by fluorine on one side, hexagonal ($$h$$)-BN, and $$h$$-SiC were studied with density functional theory. It is found that the asymmetry of nanoribbon edges causes a uniform curvature of the ribbons due to structural stress in the aromatic ring plane. Narrow graphene nanoribbons terminated with fluorine on one side demonstrate a considerable out-of-plane bend, suggesting that the nanoribbon is a fraction of a conical surface. It is shown that the intrinsic curvature of the narrow nanoribbons destroys the periodicity and results in a systematic cancellation of the dipole moment. The in- and out-of-plane curvature of thin arcs allows their closure in nanorings or cone fragments of giant diameter.

論文

High hydrogen-adsorption-rate material based on graphane decorated with alkali metals

Antipina, L. Y.*; Avramov, P.; 境 誠司; 楢本 洋*; 大伴 真名歩; 圓谷 志郎; 松本 吉弘; Sorokin, P. B.*

Physical Review B, 86(8), p.085435_1 - 085435_7, 2012/08

 被引用回数:41 パーセンタイル:12.91(Materials Science, Multidisciplinary)

The graphane with chemically bonded alkali metals (Li, Na, K) was considered as potential material for hydrogen storage. The ab initio calculations show that such material can adsorb as many as four hydrogen molecules per Li, Na, and K metal atom. These values correspond to 12.20, 10.33, and 8.56 wt% of hydrogen, respectively, and exceed the DOE requirements. The thermodynamic analysis shows that Li-graphane complex is the most promising for hydrogen storage with ability to adsorb three hydrogen molecules per metal atom at 300 K and pressure in the range of 5-250 atm.

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