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Journal Articles

Long-term density-dependent groundwater flow analysis and its effect on nuclide migration for safety assessment of high-level radioactive waste disposal with consideration of interaction between fractures and matrix of rock formation in coastal crystalline groundwater systems

Park, Y.-J.*; Sawada, Atsushi; Ozutsumi, Takenori*; Tanaka, Tatsuya*; Hashimoto, Shuji*; Morita, Yutaka*

Proceedings of 3rd International Conference on Discrete Fracture Network Engineering (DFNE 2022) (Internet), 8 Pages, 2022/00

Safety analysis for underground disposal facilities for high-level radioactive waste requires thorough understanding of long-term groundwater flow and nuclide migration processes in geologic media. In the coastal subsurface systems, groundwater flow is defined by the complex interactions between freshwater of meteoric origin and denser saline water from the sea. In addition, sea levels are expected to fluctuate significantly due to a transgression and regression of the sea over the millions of years for safety analysis. This study presents long-term evolution of groundwater environment such as salinity concentration and flow velocity with focus of the interaction between fractures and matrix blocks in regional and near-field scale analysis framework for groundwater flow and nuclide migration for underground disposal facilities in hypothetical fractured crystalline coastal systems.

Journal Articles

Thermally altered subsurface material of asteroid (162173) Ryugu

Kitazato, Kohei*; Milliken, R. E.*; Iwata, Takahiro*; Abe, Masanao*; Otake, Makiko*; Matsuura, Shuji*; Takagi, Yasuhiko*; Nakamura, Tomoki*; Hiroi, Takahiro*; Matsuoka, Moe*; et al.

Nature Astronomy (Internet), 5(3), p.246 - 250, 2021/03

 Times Cited Count:30 Percentile:96.87(Astronomy & Astrophysics)

Here we report observations of Ryugu's subsurface material by the Near-Infrared Spectrometer (NIRS3) on the Hayabusa2 spacecraft. Reflectance spectra of excavated material exhibit a hydroxyl (OH) absorption feature that is slightly stronger and peak-shifted compared with that observed for the surface, indicating that space weathering and/or radiative heating have caused subtle spectral changes in the uppermost surface. However, the strength and shape of the OH feature still suggests that the subsurface material experienced heating above 300 $$^{circ}$$C, similar to the surface. In contrast, thermophysical modeling indicates that radiative heating does not increase the temperature above 200 $$^{circ}$$C at the estimated excavation depth of 1 m, even if the semimajor axis is reduced to 0.344 au. This supports the hypothesis that primary thermal alteration occurred due to radiogenic and/or impact heating on Ryugu's parent body.

Journal Articles

The Surface composition of asteroid 162173 Ryugu from Hayabusa2 near-infrared spectroscopy

Kitazato, Kohei*; Milliken, R. E.*; Iwata, Takahiro*; Abe, Masanao*; Otake, Makiko*; Matsuura, Shuji*; Arai, Takehiko*; Nakauchi, Yusuke*; Nakamura, Tomoki*; Matsuoka, Moe*; et al.

Science, 364(6437), p.272 - 275, 2019/04

 Times Cited Count:233 Percentile:99.74(Multidisciplinary Sciences)

The near-Earth asteroid 162173 Ryugu, the target of Hayabusa2 sample return mission, is believed to be a primitive carbonaceous object. The Near Infrared Spectrometer (NIRS3) on Hayabusa2 acquired reflectance spectra of Ryugu's surface to provide direct measurements of the surface composition and geological context for the returned samples. A weak, narrow absorption feature centered at 2.72 micron was detected across the entire observed surface, indicating that hydroxyl (OH)-bearing minerals are ubiquitous there. The intensity of the OH feature and low albedo are similar to thermally- and/or shock-metamorphosed carbonaceous chondrite meteorites. There are few variations in the OH-band position, consistent with Ryugu being a compositionally homogeneous rubble-pile object generated from impact fragments of an undifferentiated aqueously altered parent body.

Journal Articles

Conceptual uncertainties in modelling the interaction between engineered and natural barriers of nuclear waste repositories in crystalline rocks

Finsterle, S.*; Lanyon, B.*; ${AA}$kesson, M.*; Baxter, S.*; Bergstr$"o$m, M.*; Bockg${aa}$rd, N.*; Dershowitz, W.*; Dessirier, B.*; Frampton, A.*; Fransson, ${AA}$.*; et al.

Geological Society, London, Special Publications, No.482, p.261 - 283, 2019/00

 Times Cited Count:8 Percentile:67.25

Nuclear waste disposal in geological formations relies on a multi-barrier concept that includes engineered components which in many cases includes a bentonite buffer surrounding waste packages and the host rock. An SKB's (Swedish Nuclear Fuel and Waste Management Co.) Modelling Task Force project facilitated to improve the overall understanding of rock - bentonite interactions, as 11 teams used different conceptualisations and modelling tools to analyse the in-situ experiment at the $"A$ps$"o$ Hard Rock Laboratory. The exercise helped identify conceptual uncertainties that led to different assessments of the relative importance of the engineered and natural barrier subsystems and of aspects that need to be better understood to arrive at reliable predictions of bentonite wetting.

Journal Articles

Evidence of electronic polarization of the As ion in the superconducting phase of F-doped LaFeAsO

Kim, J.*; Fujiwara, Akihiko*; Sawada, Tomohiro*; Kim, Y.*; Sugimoto, Kunihisa*; Kato, Kenichi*; Tanaka, Hiroshi*; Ishikado, Motoyuki*; Shamoto, Shinichi; Takata, Masaki*

IUCrJ, 1(3), p.155 - 159, 2014/05

 Times Cited Count:2 Percentile:21.58(Chemistry, Multidisciplinary)

Using a charge density analysis based on synchrotron radiation X-ray powder diffraction data, we found that the charge carriers only accumulated in the iron layer of the superconducting phase of LaFeAsO$$_{1-x}$$F$$_{x}$$ at low temperatures. Analysis of the electrostatic potential distribution revealed the concerted enhancement of the electronic polarization of the As ions and the carrier redistribution.

Journal Articles

Event structure and double helicity asymmetry in jet production from polarized $$p + p$$ collisions at $$sqrt{s}$$ = 200 GeV

Adare, A.*; Afanasiev, S.*; Aidala, C.*; Ajitanand, N. N.*; Akiba, Y.*; Al-Bataineh, H.*; Alexander, J.*; Aoki, K.*; Aphecetche, L.*; Armendariz, R.*; et al.

Physical Review D, 84(1), p.012006_1 - 012006_18, 2011/07

 Times Cited Count:28 Percentile:72.42(Astronomy & Astrophysics)

We report on the event structure and double helicity asymmetry ($$A_{LL}$$) of jet production in longitudinally polarized $$p + p$$ collisions at $$sqrt{s}$$ = 200 GeV. Photons and charged particles were measured by the PHENIX experiment. Event structure was compared with the results from PYTHIA event generator. The production rate of reconstructed jets is satisfactorily reproduced with the next-to-leading-order perturbative QCD calculation. We measured $$A_{LL}$$ = -0.0014 $$pm$$ 0.0037 at the lowest $$P_T$$ bin and -0.0181 $$pm$$ 0.0282 at the highest $$P_T$$ bin. The measured $$A_{LL}$$ is compared with the predictions that assume various $$Delta G(x)$$ distributions.

Journal Articles

Identified charged hadron production in $$p + p$$ collisions at $$sqrt{s}$$ = 200 and 62.4 GeV

Adare, A.*; Afanasiev, S.*; Aidala, C.*; Ajitanand, N. N.*; Akiba, Yasuyuki*; Al-Bataineh, H.*; Alexander, J.*; Aoki, Kazuya*; Aphecetche, L.*; Armendariz, R.*; et al.

Physical Review C, 83(6), p.064903_1 - 064903_29, 2011/06

 Times Cited Count:176 Percentile:99.41(Physics, Nuclear)

Transverse momentum distributions and yields for $$pi^{pm}, K^{pm}, p$$, and $$bar{p}$$ in $$p + p$$ collisions at $$sqrt{s}$$ = 200 and 62.4 GeV at midrapidity are measured by the PHENIX experiment at the RHIC. We present the inverse slope parameter, mean transverse momentum, and yield per unit rapidity at each energy, and compare them to other measurements at different $$sqrt{s}$$ collisions. We also present the scaling properties such as $$m_T$$ and $$x_T$$ scaling and discuss the mechanism of the particle production in $$p + p$$ collisions. The measured spectra are compared to next-to-leading order perturbative QCD calculations.

Journal Articles

Azimuthal correlations of electrons from heavy-flavor decay with hadrons in $$p+p$$ and Au+Au collisions at $$sqrt{s_{NN}}$$ = 200 GeV

Adare, A.*; Afanasiev, S.*; Aidala, C.*; Ajitanand, N. N.*; Akiba, Yasuyuki*; Al-Bataineh, H.*; Alexander, J.*; Aoki, Kazuya*; Aphecetche, L.*; Aramaki, Y.*; et al.

Physical Review C, 83(4), p.044912_1 - 044912_16, 2011/04

 Times Cited Count:7 Percentile:49.81(Physics, Nuclear)

Measurements of electrons from the decay of open-heavy-flavor mesons have shown that the yields are suppressed in Au+Au collisions compared to expectations from binary-scaled $$p+p$$ collisions. Here we extend these studies to two particle correlations where one particle is an electron from the decay of a heavy flavor meson and the other is a charged hadron from either the decay of the heavy meson or from jet fragmentation. These measurements provide more detailed information about the interaction between heavy quarks and the quark-gluon matter. We find the away-side-jet shape and yield to be modified in Au+Au collisions compared to $$p+p$$ collisions.

Journal Articles

Measurement of neutral mesons in $$p$$ + $$p$$ collisions at $$sqrt{s}$$ = 200 GeV and scaling properties of hadron production

Adare, A.*; Afanasiev, S.*; Aidala, C.*; Ajitanand, N. N.*; Akiba, Y.*; Al-Bataineh, H.*; Alexander, J.*; Aoki, K.*; Aphecetche, L.*; Armendariz, R.*; et al.

Physical Review D, 83(5), p.052004_1 - 052004_26, 2011/03

 Times Cited Count:169 Percentile:98.47(Astronomy & Astrophysics)

The PHENIX experiment at RHIC has measured the invariant differential cross section for production of $$K^0_s$$, $$omega$$, $$eta'$$ and $$phi$$ mesons in $$p + p$$ collisions at $$sqrt{s}$$ = 200 GeV. The spectral shapes of all hadron transverse momentum distributions are well described by a Tsallis distribution functional form with only two parameters, $$n$$ and $$T$$, determining the high $$p_T$$ and characterizing the low $$p_T$$ regions for the spectra, respectively. The integrated invariant cross sections calculated from the fitted distributions are found to be consistent with existing measurements and with statistical model predictions.

Journal Articles

Polymer electrolyte membranes having sulfoalkyl grafts into ETFE film prepared by radiation-induced copolymerization of methyl acrylate and methyl methacrylate

Hanh, T. T.*; Takahashi, Shuichi; Chen, J.; Sawada, Shinichi; Maekawa, Yasunari

Journal of Applied Polymer Science, 114(1), p.231 - 237, 2009/06

 Times Cited Count:6 Percentile:21.71(Polymer Science)

Polymer electrolyte membranes (PEMs) containing alkylsulfonic acid grafts can be prepared by radiation-induced graft copolymerization of methyl acrylate (MA) and methyl methacrylate (MMA) into a poly(ethylene-co-tetrafluoroethylene) (ETFE) film followed by sulfonation of the MA units in the copolymer grafts using an equimolar complex of chlorosulfonic acid and 1,4-dioxane (ClSO$$_{3}$$H-Complex). The grafted films with 33-79 % MA units are treated with ClSO$$_{3}$$H-Complex to obtain PEMs with IEC of 0.36-0.81 mmol/g and proton conductivity of 0.04-0.065 S/cm. The PEMs with higher MMA content showed higher durability in water (80 $$^{circ}$$C) and under oxidative conditions (3% H$$_{2}$$O$$_{2}$$) at 60 $$^{circ}$$C. This is because the PMMA grafts in the PEMs have no proton at an $$alpha$$-carbonyl carbon, which is considered to be a trigger of the degradation of grafting polymers.

JAEA Reports

Development of measurement system of aperture and tracer concentration distribution in a single fracture by optical visualization method

Sato, Hisashi; Xiao, J.; Sawada, Atsushi

JAEA-Research 2007-006, 53 Pages, 2007/03

JAEA-Research-2007-006.pdf:6.15MB

It is important to investigate fracture aperture distribution in order to study the influences of heterogeneous aperture distribution onto the fracture hydraulic and mass transport properties. There are several aperture measurement methods, but an optical method has an advantage that measurement resolution is high and tracer movement can be observed. We have developed aperture measurement and tracer movement measuring system by optical method, and have made transparent replica, and measured aperture distribution and tracer concentration distribution. As a result, the optical method was able to confirm the effectiveness of aperture measurement. In addition, the optical method could acquire the tracer concentration distribution which was not disturbed by the influence of heterogeneous aperture distribution.

Journal Articles

Visualization and quantitative evaluation of aperture distribution, fluid flow and tracer transport in a variable aperture fracture

Xiao, J.; Sato, Hisashi*; Sawada, Atsushi; Takebe, Atsuji*

Proceedings of 4th Asian Rock Mechanics Symposium (ARMS 2006) (CD-ROM), 8 Pages, 2006/11

The heterogeneous void geometries (aperture distribution) in a single fracture have a strong influence on fluid flow process and the solute transport. In order to understand and to predict flow and transport phenomenon through fracture, this paper describes newly developed method for the simultaneous evaluations of fracture aperture, concentration distribution of tracers and fluid velocity in a fracture by means of Light-emitting diode (LED) transmission measurement and Particle Image Velocity (PIV) combine system. It was utilized to accomplish the visualization of flow and solute transport, and to evaluate quantitatively the effect of fracture aperture correlation on temporal flow and transport process through fracture.

Journal Articles

Improving the realism of the cellular Potts model in simulations of biological cells

Ouchi, Noriyuki; Glazier, J. A.*; Rieu, J.-P*; Upadhyaya, A.*; Sawada, Yasuji*

Physica A, 329(3-4), p.451 - 458, 2003/11

 Times Cited Count:82 Percentile:91.44(Physics, Multidisciplinary)

Because the extended large-Q Potts model captures effectively the global features of tissue rearrangement experiments, including cell sorting and tissue engulfment, it has become a common technique for cell level simulation of tissues. It agrees qualitatively with experiments. However, standard simulations using positive surface energies fail to describe correctly the dynamics of single cells moving within an aggregate. In particular, the hierarchy of diffusion constants is reversed compared to experiments. The standard model also suffers from numerical instabilities. In this letter, we show how to modify the Hamiltonian using negative surface energies and a spin flip energy threshold to improve the correspondence to experiments. We also investigate diffusion constant dependence on model parameters.

Journal Articles

Completion of the ITER CS model coil-outer module fabrication

Ando, Toshinari; Hiyama, Tadao; Takahashi, Yoshikazu; Nakajima, Hideo; Kato, Takashi; Isono, Takaaki; Sugimoto, Makoto; Kawano, Katsumi; Koizumi, Norikiyo; Nunoya, Yoshihiko; et al.

IEEE Transactions on Applied Superconductivity, 10(1), p.568 - 571, 2000/03

 Times Cited Count:10 Percentile:53.58(Engineering, Electrical & Electronic)

no abstracts in English

Journal Articles

Present status of R&D for the superconducting proton linac at JAERI

Mizumoto, Motoharu; Kusano, Joichi; Hasegawa, Kazuo; Ouchi, Nobuo; Oguri, Hidetomo; Ichihara, Masahiro; Tomisawa, Tetsuo; Ito, Takashi; Chishiro, Etsuji*; Ikegami, Masanori*; et al.

KEK Proceedings 99-25, p.3 - 5, 2000/02

no abstracts in English

Journal Articles

Fabrication of ITER central solenoid model coil-outer module

Ando, Toshinari; Hiyama, Tadao; Takahashi, Yoshikazu; Nakajima, Hideo; Kato, Takashi; Sugimoto, Makoto; Isono, Takaaki; Kawano, Katsumi; Koizumi, Norikiyo; Hamada, Kazuya; et al.

IEEE Transactions on Applied Superconductivity, 9(2), p.628 - 631, 1999/06

 Times Cited Count:8 Percentile:51.51(Engineering, Electrical & Electronic)

no abstracts in English

JAEA Reports

A Conceptual design of the RF system for the NSP high intensity proton accelerator at JAERI

Chishiro, Etsuji*; Touchi, Y.*; Kaneko, H.*; Takado, H.*; Sawada, J.*; Kusano, Joichi; Mizumoto, Motoharu

JAERI-Tech 99-020, 56 Pages, 1999/03

JAERI-Tech-99-020.pdf:2.22MB

no abstracts in English

Oral presentation

Development of the safe and non-electric power type explosion prevention system with hydrogen storage materials, 3; Preparation and evaluation of hydrogen

Maekawa, Yasunari; Hasegawa, Shin; Sawada, Shinichi; Chen, J.; Hashimoto, Naoyuki*; Isobe, Shigehito*

no journal, , 

For establishing a safe and non-electric power type explosion prevention system with hydrogen storage materials, hydrogen permselective membranes against oxygen and water vapor have been developed. Using a radiation-induced grafting method, 4-trimethoxysilylstyrene (STMS) and acrylic acid (AAc) monomers were introduced onto porous poly(vinylidene fluoride) (PVDF) films to obtain STMS- and AAc-grafted PVDF membranes with grafting degrees of 23 and 24%. The STMS- and AAc-grafted PVDF membranes showed permeabilities of hydrogen 8.1 and 12 time higher than those of water vapor. The above results indicated that radiation-grafting of porous films should be very effective method to obtain hydrogen permselective membranes.

Oral presentation

Imaging of Li distribution in Li ion batteries by direct elemental detection technique of PIGE and NRA combined with proton microbeam at TIARA

Yamazaki, Akiyoshi*; Kamiya, Tomihiro; Sato, Takahiro; Mima, Kunioki*; Fujita, Kazuhisa*; Okuda, Chikaaki*; Sawada, Hiroshi*; Saito, Tsohiya*; Gonzales, R.*; Perlado, J. M.*; et al.

no journal, , 

Oral presentation

Development of the safe and non-electric power type explosion prevention system with hydrogen storage materials, 2-3; Preparation and evaluation of hydrogen permselective membranes

Maekawa, Yasunari; Hasegawa, Shin; Sawada, Shinichi; Chen, J.; Hashimoto, Naoyuki*; Isobe, Shigehito*

no journal, , 

no abstracts in English

Oral presentation

Spectral characteristics of asteroid (162173) Ryugu with Hayabusa2 NIRS3

Takir, D.*; Kitazato, Kohei*; Milliken, R. E.*; Iwata, Takahiro*; Abe, Masanao*; Otake, Makiko*; Matsuura, Shuji*; Arai, Takehiko*; Nakauchi, Yusuke*; Nakamura, Tomoki*; et al.

no journal, , 

JAXA spacecraft and sample return mission Hayabusa2 has arrived at the near-Earth asteroid 162173 Ryugu, which is classified a primitive carbonaceous object. Here we report recent results of near-infrared spectrometer (NIRS3) on the Hayabusa2 spacecraft. The observations provide direct measurements of the surface composition of Ryugu and context for the returned samples. NIRS3 has detected a weak and narrow absorption feature centered at 2.72 micrometer across entire observed surface. This absorption feature is attributed to the presence of OH-bearing minerals. The NIRS3 observations also revealed that Ryugu is the darkest object to be observed up-close by a visiting spacecraft. The intensity of the OH feature and low albedo are consistent with thermally-and/or shock-metamorphosed, and/or carbon-rich space-weathered primitive and hydrated carbonaceous chondrites.

21 (Records 1-20 displayed on this page)