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
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.
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
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.
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
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。
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.
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
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 GdO 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 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.
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
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.
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
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 -AlO(0001). In the atomic arrangement analysis of single-layer graphene on -AlO(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 -AlO(0001), as evidenced by the short vertical distance between graphene and -AlO(0001) surface. The interfacial interactions are shown to be dominated by the electrostatic force involved in the graphene -system and the unsaturated electrons of the topmost O layer of -AlO(0001) rather than the van der Waals interactions. Such feature causes hole doping into graphene, which gives graphene a chance to slide on the -AlO(0001) surface with a small energy barrier despite the strong interfacial interactions.
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
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.
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
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.
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
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
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 -d hybridization at the interface as well as out-of-plane spin polarization at the band region of graphene. The present study indicates the importance of the interface design at the atomic layer level for graphene-based spintronics.
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
A process of tunneling conduction and the spin-dependent resistivity change (so-called tunneling magnetoresitance effect) in the Fe-doped C 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 interface is much higher than that in Fe crystal at low temperature in a similar fashion to that at the Co/C interface in the Co-doped C 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 in the C-Fe compound.
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
Atomic and electronic structure of graphene/Ni(111), -BN/Ni(111) and graphene/-BN/Ni(111) nanocomposites with different numbers of graphene and -BN layers and in different mutual arrangements of graphene/Ni and -BN/Ni at the interfaces was studied using LDA/PBC/PW technique. For the sake of comparison, corresponding graphene, -BN and graphene/-BN structures without the Ni plate were calculated using the same technique. It was suggested that C-:C- and N-:B- configurations are energetically favorable for the graphene/Ni and -BN/Ni interfaces, respectively. The Ni plate was found to induce a significant degree of spin polarization in graphene and -BN caused by direct exchange interactions of the electronic states located on different fragments.
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, 3(15), p.2003 - 2008, 2012/08
The atomic and electronic structure of narrow zigzag nanoribbons with finite length, consisting of graphene terminated by fluorine on one side, hexagonal ()-BN, and -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.
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
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.
境 誠司; 三谷 誠司*; 松本 吉弘; 圓谷 志郎; Avramov, P.; 大伴 真名歩; 楢本 洋*; 高梨 弘毅
Journal of Magnetism and Magnetic Materials, 324(12), p.1970 - 1974, 2012/06
Voltage-dependence of the tunneling magnetoresistance effect in the granular C-Co films has been investigated under the current-perpendicular-to-plane geometry. The transport measurements demonstrate that the granular C-Co films show unusually an exponential MR-V dependence. Small characteristic energies of less than 10's meV are derived from the temperature dependences of the characteristic voltage in the exponential relationship. Considering the voltage drops between Co nanoparticles and also the effect of cotunneling on the energy values, the characteristic energies for the voltage-induced degradation of the spin polarization are found to show a satisfactory agreement with that for the thermally-induced one. It can reasonably be expected that the onset of magnetic disorder to the localized d-electron spins at the interface region of the C-Co compound with Co nanoparticles will lead to the unusual voltage and temperature dependence of the MR ratio and the spin polarization.
圓谷 志郎; 松本 吉弘; 大伴 真名歩; Avramov, P.; 楢本 洋*; 境 誠司
Journal of Applied Physics, 111(6), p.064324_1 - 064324_6, 2012/03
北条 育子*; 小出 明広*; 松本 吉弘; 丸山 喬*; 永松 伸一*; 圓谷 志郎; 境 誠司; 藤川 高志*
Journal of Electron Spectroscopy and Related Phenomena, 185(1-2), p.32 - 38, 2012/03
In this work we have measured Co K- and L-edge X-ray absorption near edge structure (XANES) and Co L-edge X-ray magnetic circular dichroism (XMCD) spectra, and also carried out their calculations for CCo compounds. The observed XANES and XMCD are sensitive to the Co concentration. In the low density region (=1.0-1.5), one Co is surrounded by three C balls. The Co L-edge XMCD analyses gives the spin magnetic moment on Co in the range 0.5-0.9 .
西内 満美子; Pirozhkov, A. S.; 榊 泰直; 小倉 浩一; Esirkepov, T. Z.; 谷本 壮; 金崎 真聡; 余語 覚文; 堀 利彦; 匂坂 明人; et al.
Physics of Plasmas, 19(3), p.030706_1 - 030706_4, 2012/03
松本 吉弘; 境 誠司; 圓谷 志郎; 高木 康多*; 中川 剛志*; 楢本 洋*; Avramov, P.; 横山 利彦*
Chemical Physics Letters, 511(1-3), p.68 - 72, 2011/07