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Journal Articles

A Quasiclassical trajectory calculation to compute the reaction cross section and thermal rate constant for the cesium exchange reaction $$^{133}$$CsI + $$^{135}$$Cs $$rightarrow$$ $$^{133}$$Cs + I$$^{135}$$Cs

Kobayashi, Takanori*; Matsuoka, Leo*; Yokoyama, Keiichi

Computational and Theoretical Chemistry, 1150, p.40 - 48, 2019/02

One of important research targets in the development of cesium isotope separation system is design of recovery process of cesium atom. Relevant to this research target, the reaction cross section and reaction rate constant of a cesium exchange reaction through collision of the cesium iodide molecules with cesium atoms are calculated by a quasi-classical trajectory calculation based on a potential energy surface obtained by quantum chemistry calculations. Consequently, the rate constant is calculated to be 3.6 $$times$$ 10$$^{-10}$$ cm$$^{3}$$molecule$$^{-1}$$s$$^{-1}$$, as large as collision rate in the present condition. In addition, slightly positive temperature dependence is observed in the rate constant. This behavior is explained with the long-range attractive force and effect of subsequent dissociation process.

JAEA Reports

Progress of general control system for Materials and Life Science Experimental Facility at J-PARC

Sakai, Kenji; Oi, Motoki; Takada, Hiroshi; Kai, Tetsuya; Nakatani, Takeshi; Kobayashi, Yasuo*; Watanabe, Akihiko*

JAEA-Technology 2018-011, 57 Pages, 2019/01

JAEA-Technology-2018-011.pdf:4.98MB

For safely and efficiently operating a spallation neutron source and a muon target, a general control system (GCS) operates within Materials and Life Science Experimental Facility (MLF). GCS administers operation processes and interlocks of many instruments. It consists of several subsystems such as an integral control system (ICS), interlock systems (ILS), shared servers, network system, and timing distribution system (TDS). Although GCS is an independent system that controls the target stations, it works closely with the control systems of the accelerators and other facilities in J-PARC. Since the first beam injection, GCS has operated stably without any serious troubles after modification based on commissioning for operation and control. Then, significant improvements in GCS such as upgrade of ICS by changing its framework software and function enhancement of ILS were proceeded until 2015. In this way, many modifications have been proceeded in the entire GCS during a period of approximately ten years after start of beam operation. Under these situation, it is important to comprehend upgrade history and present status of GCS in order to decide its upgrade plan. This report summarizes outline, structure, roles and functions of GCS in 2017.

JAEA Reports

Proceedings of the User Group Meeting on MLF Spectrometers (DIRECTION 2018); October 11, 2018, Ibaraki Quantum Beam Research Center (Tokai, Ibaraki, Japan)

Kajimoto, Ryoichi; Yokoo, Tetsuya*; Matsuura, Masato*

JAEA-Review 2018-024, 78 Pages, 2019/01

JAEA-Review-2018-024.pdf:76.52MB

The joint user meeting for the neutron spectrometers in the Materials and Life Science Experimental Facility (MLF) at J-PARC, "DIRECTION 2018", was held jointly by J-PARC MLF, KEK-IMSS, and CROSS. This meeting was purposed to encourage users' activities and collaborations between users and instruments on six beamlines BL01 (4SEASONS), BL02 (DNA), BL06 (VIN ROSE), BL12 (HRC), BL14 (AMATERAS), and BL23 (POLANO). In this meeting, 14 talks and 21 posters were presented, which reported recent research activities using the instruments, and the current status of the instruments and sample environments. This report compiles the presentation materials and their abstracts.

Journal Articles

A Telescoping view of solute architectures in a complex fluid system

Motokawa, Ryuhei; Kobayashi, Toru; Endo, Hitoshi; Mu, J.*; Williams, C. D.*; Masters, A. J.*; Antonio, M. R.*; Heller, W. T.*; Nagao, Michihiro*

ACS Central Science, 5(1), p.85 - 96, 2019/01

We present a hierarchical aggregate model of an organic phase containing a coordination species that acts as a fundamental building unit of higher-order structures formed in the organic phase. We aimed to elucidate the fundamental aspects of the microscopic structure and phase separation occurring in ionic separation and recovery systems during solvent extraction. The coordination species aggregate through a hydrogen-bonding network formed by interaction between the hydrophilic part of the coordination species with extracted water and acid molecules. This reduces the hydrophilic surface area, resulting in subsequent formation of small primal clusters of 2 to 3 nm in diameter. The primal clusters further aggregate due to van der Waals interaction to form large aggregates of $$<$$ 10 nm in diameter. The size of the primal cluster does not depend on the concentration of the coordination species, whereas the size of the large aggregate increases as the aggregation number of the primal clusters increases. We conclude that hybrid interaction is a key driving force in the formation and growth of the hierarchical aggregate and the induction of phase separation of the organic phase.

Journal Articles

Invariant incommensurate coherence length in spin-density-wave excitation of Cr$$_{0.99}$$Fe$$_{0.01}$$

Hiraka, Haruhiro*; Yano, Shinichiro*; Fukuda, Tatsuo

Journal of Magnetism and Magnetic Materials, 469, p.629 - 632, 2019/01

Low-energy magnetic excitation of spin-density wave (SDW) in a single crystal of Cr$$_{0.99}$$Fe$$_{0.01}$$ was measured using cold neutron triple-axis spectroscopy. Because of the unchanged incommensurability and the constant line width in 2.5 $$leqslanthbaromegaleqslant$$ 6 meV, the magnetic excitation could not be explained with a conventional dispersion of $$hbaromega_qpropto q$$. In this paper, we conjectured the presence of standing waves, which would be excited in local spin matrices. The effectively vertical dispersion was attributed to the longitudinal spin fluctuation in the spin matrices. A series of low-energy magnetic excitations in Cr alloys could be understood with the coexistence of the standing waves and progressive waves such as spin waves.

Journal Articles

Unique helical magnetic order and field-induced phase in trillium lattice antiferromagnet EuPtSi

Kaneko, Koji; Frontzek, M. D.*; Matsuda, Masaaki*; Nakao, Akiko*; Munakata, Koji*; Ohara, Takashi; Kakihana, Masashi*; Haga, Yoshinori; Hedo, Masato*; Nakama, Takao*; et al.

Journal of the Physical Society of Japan, 88, p.013702_1 - 013702_5, 2019/01

Magnetic transitions in chiral antiferromagnet EuPtSi were investigated by means of single crystal neutron diffraction. In the ground state, magnetic peaks emerge at positions represented by $$q_{1}$$=$$(0.2, 0.3, 0)$$. Upon heating, an additional magnetic peak splitting around 2.5 K was uncovered, indicating a presence of a first-order transition with $$q^*_{1}$$=$$(0.2, 0.3, {delta})$$. An half-polarized neutron scattering for polarization parallel to Q reveled that polarization antiparallel to Q has stronger intensity in both magnetic phases. This feature clarifies single chiral character of helical structure with moments normal to the ordering vector in both ordered states. Under vertical magnetic field along [1,1,1] in the $$A$$ phase, magnetic peaks form hexagonal patterns in the equatorial scattering plane around nuclear. An ordering vector $$q_{A}$$ of the $$A$$-phase has the similar size in the periodicity to $$q_{1}$$, and could be a hallmark of a formation of skyrmion lattice in EuPtSi.

Journal Articles

Manifestation of electron correlation effect in 5$$f$$ states of uranium compounds revealed by 4$$d$$-5$$f$$ resonant photoelectron spectroscopy

Fujimori, Shinichi; Kobata, Masaaki; Takeda, Yukiharu; Okane, Tetsuo; Saito, Yuji; Fujimori, Atsushi; Yamagami, Hiroshi; Haga, Yoshinori; Yamamoto, Etsuji; Onuki, Yoshichika*

Physical Review B, 99(3), p.035109_1 - 035109_5, 2019/01

In the present study, we have elucidated the nature of the electron correlation effect in uranium compounds by imaging the partial $$mathrm{U}~5f$$ density of states (pDOS) of typical itinerant, localized, and heavy fermion uranium compounds by using the $$mathrm{U}$$ 4$$d$$-5$$f$$ resonant photoemission spectroscopy. Obtained $$mathrm{U}~5$$ pDOS exhibit a systematic trend depending on the physical properties of compounds: Although the coherent peak at the Fermi level can be explained by the band-structure calculation, an incoherent peak emerges on the higher binding energy side ($$lesssim 1~mathrm{eV}$$) in the cases of localized and heavy fermion compounds. The intensity and energy position of the incoherent peak is increased and shifted to a higher binding energy as the localization of the $$mathrm{U}~5$$ state increases. These behaviors are consistent with the prediction of the Mott metal-insulator transition, suggesting that the Hubbard-$$U$$ type mechanism takes an essential role in the $$5f$$ electronic structure of actinide materials.

Journal Articles

Battery-free, skin-interfaced microfluidic/electronic systems for simultaneous electrochemical, colorimetric, and volumetric analysis of sweat

Bandodkar, A. J.*; Gutruf, P.*; Choi, J.*; Lee, K.-H.*; Sekine, Yurina; Reeder, J. T.*; Jeang, W. J.*; Aranyosi, A. J.*; Lee, S. P.*; Model, J. B.*; et al.

Science Advances (Internet), 5(1), p.eaav3294_1 - eaav3294_15, 2019/01

Interest in advanced wearable technologies increasingly extends beyond systems for biophysical measurements to those that enable continuous, non-invasive monitoring of biochemical markers in biofluids. Here, we introduce battery-free, wireless microelectronic platforms that perform sensing via schemes inspired by the operation of biofuel cells. Combining these systems in a magnetically releasable manner with chrono-sampling microfluidic networks that incorporate assays based on colorimetric sensing yields thin, flexible, lightweight, skin-interfaced technologies with broad functionality in sweat analysis. A demonstration device allows simultaneous monitoring of sweat rate/loss, along with quantitative measurements of pH and of lactate, glucose and chloride concentrations using biofuel cell and colorimetric approaches.

Journal Articles

Provision of laser irradiation conditions for melting and solidification processes using computational science simulation code SPLICE

Muramatsu, Toshiharu

Sumato Purosesu Gakkai-Shi, 8(1), p.4 - 8, 2019/01

本解説論文では、加工材料にレーザー光が照射されてから加工が完了するまでの複合物理過程を定量的に取扱えるようにするために開発中の計算科学シミュレーションコードSPLICEの概要と各種レーザー加工プロセスへの適用例を実験結果などとともに紹介する。さらに、加工プロセスに対する設計空間を可視化することにより、レーザー加工に付随するオーバーヘッドを大幅に低減させ得る方法として、SPLICEコードをディジタルモックアップ装置として利用するフロントローディングツールとして効果的であることを述べる。

Journal Articles

Quasielastic neutron scattering of brucite to analyse hydrogen transport on the atomic scale

Okuchi, Takuo*; Tomioka, Naotaka*; Purevjav, N.*; Shibata, Kaoru

Journal of Applied Crystallography, 51, p.1564 - 1570, 2018/12

It is demonstrated that quasielastic neutron scattering (QENS) is a novel and effective method to analyse atomic scale hydrogen transport processes occurring within a mineral crystal lattice. The method was previously characterized as sensitive for analysing the transport frequency and distance of highly diffusive hydrogen atoms or water molecules in condensed matter. Here are shown the results of its application to analyse the transport of much slower hydrogen atoms which are bonded into a crystal lattice as hydroxyls. Two types of hydrogen transport process were observed in brucite, Mg(OH)$$_{2}$$ : a jump within a single two-dimensional layer of the hydrogen lattice and a jump into the next nearest layer of it. These transport processes observed within the prototypical structure of brucite have direct implications for hydrogen transport phenomena occurring within various types of oxides and minerals having layered structures.

Journal Articles

Structure of active sites of Fe-N-C nano-catalysts for alkaline exchange membrane fuel cells

Kishi, Hirofumi*; Sakamoto, Tomokazu*; Asazawa, Koichiro*; Yamaguchi, Susumu*; Kato, Takeshi*; Zulevi, B.*; Serov, A.*; Artyushkova, K.*; Atanassov, P.*; Matsumura, Daiju; et al.

Nanomaterials, 8(12), p.965_1 - 965_13, 2018/12

Platinum group metal-free catalysts based on transition metal-nitrogen-carbon nanomaterials have been studied by a combination of in situ X-ray spectroscopy techniques, high-resolution transmission electron microscope, M$"o$ssbauer spectroscopy, electrochemical methods and density functional theory. Fe-N-C oxygen reduction reaction electrocatalysts were synthesized by varying several synthetic parameters to obtain nanomaterials with different composition and morphology. Associated with Fe-N$$_x$$ motive and the presence of Fe metallic particles in the electrocatalysts showed the clear differences in the variation of composition; processing and treatment conditions of sacrificial support method. From the results of material characterization; catalytic activity and theoretical studies; Fe metallic particles (coated with carbon) are main contributors into the HO$$_{2}$$$$^{-}$$ generation.

Journal Articles

High-energy magnetic excitations in lightly oxygen-doped lanthanum nickel oxides

Nakajima, Kenji; Kajimoto, Ryoichi

Physica B; Condensed Matter, 551, p.142 - 145, 2018/12

We will report on magnetic excitations in lightly oxygen doped lanthanum nickel oxide, La$$_{2}$$NiO$$_{4+delta}$$. By introducing slightly excessive oxygen atoms in the system, magnetic excitations in La$$_{2}$$NiO$$_{4}$$ drastically changes its picture. In lower energy region, spin-wave stiffness strongly suppressed. On the other hand, in the higher energy region, spin-wave dispersion curve is almost same as in the stoichiometric system, while excitations show considerable broadening. Alternation of the character of the excitations by changing energy is also reported in hole doped cuprates and cobalates. We consider that this behavior is one of key clues to understand magnetism and transport properties in carrier doped layered transition metal oxides. We investigated detail of magnetic excitations in two different lightly doped systems, La$$_{2}$$NiO$$_{4.02}$$ and La$$_{2}$$NiO$$_{4.11}$$ in wide momentum and energy transfer space by using time-of-flight spectrometers at J-PARC. Observed doping effects in magnetic excitations will be discussed by comparing them to those reported in other related layered transition metal oxides.

Journal Articles

Performances of oscillating radial collimator for the Fermi chopper spectrometer 4SEASONS at J-PARC

Nakamura, Mitsutaka; Kambara, Wataru*; Iida, Kazuki*; Kajimoto, Ryoichi; Kamazawa, Kazuya*; Ikeuchi, Kazuhiko*; Ishikado, Motoyuki*; Aoyama, Kazuhiro*

Physica B; Condensed Matter, 551, p.480 - 483, 2018/12

Recently there has been an increasing need for inelastic neutron scattering experiments under some special environments such as magnetic fields, pressure and high temperatures. In order to obtain high quality data, the unnecessary scattering caused by sample environmental apparatus should be suppressed as much as possible. We have developed an oscillating radial collimator with a view to satisfying users' needs, which is specialized for the Fermi chopper spectrometer 4SEASONS at J-PARC.4SEASONS provides relatively high incident energies, and thus we chose hydrogen free metal sheets as the collimator blades. The control system of this oscillating radial collimator enables us to flexibly tune the oscillating pattern, such as the oscillating speed and oscillating angle. In this presentation, we report the performances and remaining issues of the newly developed oscillating radial collimator for 4SEASONS.

Journal Articles

Phonon dynamics of NaI investigated by G($$r,E$$) analysis

Nakamura, Mitsutaka; Kikuchi, Tatsuya*; Kamazawa, Kazuya*; Kawakita, Yukinobu

Physica B; Condensed Matter, 551, p.351 - 354, 2018/12

The dynamic structure function in real space G($$r,E$$) is deduced from the dynamical structure factor S($$Q,E$$) which can be obtained from inelastic neutron scattering measurement. In this study, we applied the G($$r,E$$) analysis to NaI which is a typical alkali halide crystal. The optic and acoustic phonons of NaI are widely separated in energy because the difference in mass between the constituent atoms is large. These characteristic properties certainly help us to evaluate the G($$r,E$$) features associated with the phonon modes. We measured the S($$Q,E$$) for NaI powder using the Fermi chopper spectrometer 4SEASONS at J-PARC, and converted S($$Q,E$$) into G($$r,E$$) by newly developed software which utilizes the maximum entropy method. Our analysis clearly demonstrated the G($$r,E$$) of TO mode oscillates out of phase with that of LA mode, which is physically reasonable. Further analyses will be given in the presentation.

Journal Articles

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

Kai, Tetsuya; Sato, Setsuo*; Hiroi, Kosuke; Su, Y.; Segawa, Mariko; Parker, J. D.*; Matsumoto, Yoshihiro*; Hayashida, Hirotoshi*; Shinohara, Takenao; Oikawa, Kenichi; 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.

Journal Articles

Local structure study of the iron-based systems of BaFe$$_2$$As$$_2$$ and LiFeAs by X-ray PDF and XAFS analyses

Li, S.*; Toyoda, Masayuki*; Kobayashi, Yoshiaki*; Ito, Masayuki*; Ikeuchi, Kazuhiko*; Yoneda, Yasuhiro; Otani, Akira*; Matsumura, Daiju; Asano, Shun*; Mizuki, Junichiro*; et al.

Physica C, 555, p.45 - 53, 2018/12

${it T}$-dependence of local distortions in BaFe$$_2$$As$$_2$$ and LiFeAs by X-ray PDF and XAFS methods. Although PDF data exhibit anomaly at the structure transition temperature, EXAFS data exhibit no anomaly. Data supporting the local orthorhombicity at 300 K in the tetragonal phase for BaFe$$_2$$As$$_2$$. Arguments on the origins of the 4-fold symmetry breaking in the ground average structure of the tetragonal phase.

Journal Articles

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

Hayashi, Makoto*; Root, J. H.*; Rogge, R. B.*; Xu, P. G.

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.

Journal Articles

X-ray absorption study of platinum nanoparticles on an ion-irradiated carbon support

Kakitani, Kenta*; Kimata, Tetsuya*; Yamaki, Tetsuya*; Yamamoto, Shunya*; Matsumura, Daiju; Taguchi, Tomitsugu*; Terai, Takayuki*

Radiation Physics and Chemistry, 153, p.152 - 155, 2018/12

The chemical state and local structure of 2.6-nm-sized platinum (Pt) nanoparticles on an ion-irradiated glassy carbon (GC) substrate were investigated by X-ray absorption fine structure measurements. The partial oxidation of the Pt nanoparticles was confirmed by the peak intensity in the near-edge region of the absorption spectrum. The analysis of the extended region revealed a higher coordination number and shorter bond length of Pt-Pt compared to those of the Pt nanoparticles on the non-ion-irradiated GC. Thus, Pt nanoparticles on the ionirradiated GC substrate were found to hold a rigid metallic coordination during the oxidation.

Journal Articles

Nanoscopic structural investigation of nanogels for drug delivery application

Sekine, Yurina

Shiki, 41, P. 4, 2018/12

This article described the detailed structure of a nanogel formed by self-association of polysaccharides determined by contrast variation small-angle neutron scattering.

Journal Articles

Local disorder in proton conductor BaSn$$_{0.5}$$In$$_{0.5}$$O$$_{2.75}$$ analyzed by neutron diffraction/ atomic pair distribution function

Igawa, Naoki; Kodama, Katsuaki; Taguchi, Tomitsugu*; Yoshida, Yukihiko*; Matsukawa, Takeshi*; Hoshikawa, Akinori*; Ishigaki, Toru*

Transactions of the Materials Research Society of Japan, 43(6), p.329 - 332, 2018/12

For the understanding of the crystal structural effect on the electrical properties, the local disorder in BaSn$$_{0.5}$$In$$_{0.5}$$O$$_{2.75}$$ which is one of the excellent proton conductors for solid oxide fuel cells was estimated by using the Atomic Pair Distribution Function (PDF) analysis method with the neutron diffraction. The local structure is almost the same as the average structure which was estimated by the Rietveld analysis using the cubic crystal structure (space group, $${it Pm}$$$$overline{3}$$$${it m}$$) in the atomic distance range of ${it r}$ $$>$$ 6${AA}$. The PDF profile was fitted better using the tetragonal crystal structure with the space group of ${it P}$4/${it mmm}$ than those with $${it Pm}$$$$overline{3}$$$${it m}$$ in the range ${it r}$ $$<$$ 6${AA}$. Those results indicate the presence of the local disorder in the lattice. In this work, the relationship between the average and local structures of BaSn$$_{0.5}$$In$$_{0.5}$$O$$_{2.75}$$ will be discussed.

18101 (Records 1-20 displayed on this page)