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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:140 Percentile:99.81(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

Can the decision way by the "veil of ignorance" promote public acceptance?; A Hypothetical scenario survey about selecting a candidate site for geological disposal of high level radioactive waste in Japan

Onuma, Susumu*; Hirose, Yukio*; Osawa, Hideaki; Otomo, Shoji*; Yokoyama, Miki*

Nihon Risuku Kenkyu Gakkai Dai-31-Kai Nenji Taikai Koen Rombunshu (USB Flash Drive), 6 Pages, 2018/11

One reason of not being decided a candidate site for geological disposal of high level radioactive waste is that strong opposition occurs once a name of the place where residents live even if they can understand the necessity of the facility. Therefore, we hypothesized that people would accept the decision if they consent the decision way beforehand under the condition everyone can be involved in as a potential interest party (the ignorance of veil). A hypothetical scenario survey was conducted in Japan. The results revealed that the decision way and the decision under the ignorance of veil were likely to be accepted more than the current decision way even if they became candidate site. Moreover, the decision way under the ignorance of veil was evaluated higher procedural fairness, while the current way was low procedural fairness.

Journal Articles

Quantum beams open up the future, 3

Oyama, Yukio; Ikeda, Yujiro; Arai, Masatoshi; Morii, Yukio

Nihon Genshiryoku Gakkai-Shi ATOMO$$Sigma$$, 51(1), p.14 - 19, 2009/01

The beam commissioning of the J-PARC facilities of which the construction was started in 2001 is now progressed toward completion at the end of JFY2008. Of the J-PARC facilities, especially the pulsed neutron source with the world highest performance is able to open a new era of neutron application research. In this article, the outline of J-PARC, the pulsed neutron source which will start the user operation on December 2008, and their neutron instruments which is under construction are introduced. The neutron research is one of the important applications of quantum beam technology and expected to expand to broad research area such as bio-science, materials science, industrial use, etc. by start of J-PARC utilization. The latest achievement of neutron research mostly conducted at the JRR-3 research reactor in operation and future prospect are overviewed.

Journal Articles

Report on ITPA (International Tokamak Physics Activity) meeting, 22

Takenaga, Hidenobu; Ogawa, Yuichi*; Takizuka, Tomonori; Yagi, Masatoshi*; Yamada, Hiroshi*; Sakamoto, Yoshiteru; Toi, Kazuo*; Fukuda, Takeshi*; Fukuyama, Atsushi*; Fujita, Takaaki; et al.

Purazuma, Kaku Yugo Gakkai-Shi, 84(7), p.465 - 467, 2008/07

no abstracts in English

Journal Articles

Report of meetings of ITPA (International Tokamak Physics Activity), 19

Sasao, Mamiko*; Kusama, Yoshinori; Kawano, Yasunori; Kawahata, Kazuo*; Mase, Atsushi*; Sugie, Tatsuo; Fujita, Takaaki; Fukuda, Takeshi*; Fukuyama, Atsushi*; Sakamoto, Yoshiteru; et al.

Purazuma, Kaku Yugo Gakkai-Shi, 83(9), p.779 - 782, 2007/09

This is a report of highlights from 2007 spring meetings of seven Topical Groups (TG) of International Tokamak Physics Activity (ITPA). In each meeting, high priority issues in physics of International Thermonuclear Experimental Reactor (ITER) and other burning plasma experiments have been discussed and investigated. Twenty-seven scientists from Japan have participated in those meetings. Dates and places of the meetings are shown below. (1) Diagnostics TG: 26-30 March, Princeton (USA), (2) Transport Physics TG: 7-10 May, Lausanne (Switzerland), (3) Confinement Database and Modeling TG: 7-10 May, Lausanne (Switzerland), (4) Edge Pedestal Physics TG: 7-10 May, Garching (Germany) (5) Steady State Operation TG: 9-11 May, Daejeon (South Korea), (6)MHD TG: 21-24 May, San Diego (USA), (7) Scrape-off-layer and Divertor Physics TG: 7-10 May, Garching (Germany).

Journal Articles

Andreev bound states and tunneling characteristics of a noncentrosymmetric superconductor

Iniotakis, C.*; Hayashi, Nobuhiko; Sawa, Yasuo*; Yokoyama, Takehito*; May, U.*; Tanaka, Yukio*; Sigrist, M.*

Physical Review B, 76(1), p.012501_1 - 012501_4, 2007/07

 Times Cited Count:83 Percentile:92.73(Materials Science, Multidisciplinary)

The tunneling characteristics of planar junctions between a normal metal and a noncentrosymmetric superconductor such as CePt$$_3$$Si are examined. It is shown that the superconducting phase with mixed parity can give rise to characteristic zero-bias anomalies in certain junction directions. Andreev bound states at the interface are the origin of these zero-bias anomalies. The tunneling characteristics for different directions allow us to test the structure of the parity-mixed pairing state.

Journal Articles

Ultrarelativistic electron generation during the intense, ultrashort laser pulse interaction with clusters

Fukuda, Yuji; Akahane, Yutaka; Aoyama, Makoto; Hayashi, Yukio; Homma, Takayuki; Inoue, Norihiro*; Kando, Masaki; Kanazawa, Shuhei; Kiriyama, Hiromitsu; Kondo, Shuji; et al.

Physics Letters A, 363(2-3), p.130 - 135, 2007/02

Collimated relativistic electrons up to 58 MeV with an electron charge of 2.1 nC were generated by the interaction of intense laser pulses with the Ar cluster target at the laser intensity of 3.5$$times$$10$$^{19}$$W/cm$$^{2}$$. The resulting spectrum does not fit a Maxwellian distribution, but is well described by a two-temperature Maxwellian, which indicates two mechanisms of the electron acceleration. Two dimensional particle-in-cell simulations demonstrate an important role of clusters. The higher energy electrons are injected when they are expelled from the clusters by the laser pulse field. They then gain their energy during the direct acceleration by the laser pulse, whose phase velocity in the underdense plasma is larger than speed of light in vacuum. The lower energy electrons, which are injected during the plasma wave breaking, are accelerated by the wakefield.

Journal Articles

Report on ITPA (International Tokamak Physics Activity) meeting, 18

Kawahata, Kazuo*; Kawano, Yasunori; Kusama, Yoshinori; Mase, Atsushi*; Sasao, Mamiko*; Sugie, Tatsuo; Fujita, Takaaki; Fukuda, Takeshi*; Fukuyama, Atsushi*; Sakamoto, Yoshiteru; et al.

Purazuma, Kaku Yugo Gakkai-Shi, 83(2), p.195 - 198, 2007/02

no abstracts in English

Journal Articles

Optimization for SEU/SET immunity on 0.15 $$mu$$m fully depleted CMOS/SOI digital logic devices

Makihara, Akiko*; Asai, Hiroaki*; Tsuchiya, Yoshihisa*; Amano, Yukio*; Midorikawa, Masahiko*; Shindo, Hiroyuki*; Kuboyama, Satoshi*; Onoda, Shinobu; Hirao, Toshio; Nakajima, Yasuhito*; et al.

Proceedings of 7th International Workshop on Radiation Effects on Semiconductor Devices for Space Application (RASEDA-7), p.95 - 98, 2006/10

no abstracts in English

Journal Articles

Construction of High Intensity Proton Accelerator Facility (J-PARC)

Oyama, Yukio

Kensa Gijutsu, 11(9), p.1 - 7, 2006/09

The construction of J-PARC (Japan Proton Accelerator Reserach Complex) is being progressed jointly by Japan Atomic Energy Agency and High Energy Accelerator Reseach Organization. The outline and present status of the project are described.

Journal Articles

Report of ITPA (International Tokamak Physics Activity) meetings, 17

Asakura, Nobuyuki; Kato, Takako*; Nakano, Tomohide; Takamura, Shuichi*; Tanabe, Tetsuo*; Iio, Shunji*; Nakajima, Noriyoshi*; Ono, Yasushi*; Ozeki, Takahisa; Takechi, Manabu; et al.

Purazuma, Kaku Yugo Gakkai-Shi, 82(7), p.448 - 450, 2006/07

no abstracts in English

Journal Articles

J-PARC and new era of science

Oyama, Yukio

Nuclear Instruments and Methods in Physics Research A, 562(2), p.548 - 552, 2006/06

 Times Cited Count:10 Percentile:59.81(Instruments & Instrumentation)

High Intensity Proton Accelerator Project promoted jointly by Japan Atomic Energy research Institute (JAERI) and High Energy Accelerator Research Organization (KEK), named as J-PARC was started on April 1, 2001. The project was merged from the projects promoted by the both institutes, called Neutron Science Project and Japan Hadron Project, respectively. The accelerator complex of J-PARC consists of three accelerators: 400 MeV Linac, 3 GeV rapid cycle synchrotron and 50 GeV synchrotron, and four major experimental facilities: Material & Life Science Facility, Nuclear & Particle Physics (Hadron) Facility, Neutrino Facility and Nuclear Transmutation Experiment Facility. The present construction phase, Phase-I, excludes nuclear transmutation facility. The accelerators will be completed in 2007 with 200 MeV Linac, and an operation will start. The Neutrino facility will be completed in 2008 and the 200-400 MeV Linac will be constructed in 2008-2010.

Journal Articles

Report on ITPA (International Tokamak Physics Activity) meeting, 16

Sakamoto, Yoshiteru; Toi, Kazuo*; Fukuda, Takeshi*; Fukuyama, Atsushi*; Fujita, Takaaki; Ogawa, Yuichi*; Takizuka, Tomonori; Takenaga, Hidenobu; Yagi, Masatoshi*; Yamada, Hiroshi*; et al.

Purazuma, Kaku Yugo Gakkai-Shi, 82(2), p.109 - 110, 2006/02

no abstracts in English

Journal Articles

Measurement of radiolytic yield of nitric acid in air

Kanda, Yukio*; Oki, Yuichi*; Yokoyama, Sumi; Sato, Kaoru; Noguchi, Hiroshi; Tanaka, Susumu*; Iida, Takao*

Radiation Physics and Chemistry, 74(5), p.338 - 340, 2005/12

 Times Cited Count:5 Percentile:37.38(Chemistry, Physical)

The operation of high-energy accelerators leads to the production of radiolytic noxious gases, such as ozone and nitrogen compounds in the air of the beam-line tunnels. Among nitrogen compounds, nitric acid is a principal radiolytic compound produced in large quantities. In the high-intensity proton accelerator, such as J-PARC, a very strong radiation environment leads to an abundant production of nitric acid. A quantitative assessment of the damage due to corrosion with nitric acid is essential for machine maintenance and information concerning the formation of nitric acid is a requisite for that. In this work, the G-value for nitric acid production was measured by irradiating atmospheric air with 48MeV-protons. The G-value was obtained to be 1.46$$pm$$0.12. The G-value for nitric acid production obtained in this experiment was larger than the estimated value, but very close to the value of 1.5 given by irradiating the air with Co-60-$$gamma$$rays.

Journal Articles

Characterization of radionuclides formed by high-energy neutron irradiation

Yokoyama, Sumi; Sato, Kaoru; Noguchi, Hiroshi; Tanaka, Susumu; Iida, Takao*; Furuichi, Shinya*; Kanda, Yukio*; Oki, Yuichi*; Kaneto, Taihei*

Radiation Protection Dosimetry, 116(1-4), p.401 - 405, 2005/12

 Times Cited Count:1 Percentile:11.17(Environmental Sciences)

The physicochemical property of radionuclides suspended in the air is an important parameter to evaluate internal doses due to the inhalation of the airborne radionuclides and to develop the air monitoring system in high-energy proton accelerator facilities. This study focuses on the property of radioactive airborne chlorine ($$^{38}$$Cl and $$^{39}$$Cl) and sulfur ($$^{38}$$S) formed from Ar gas by irradiation with high-energy neutrons. As a result of the irradiation to a mixture of Ar gas and dry air, $$^{38}$$Cl and $$^{39}$$Cl existed as non-acidic gas and $$^{38}$$S was present as acidic gas. Further, it was found that in the high-energy neutron irradiation to aerosol containing-Ar gas, the higher the amount of radioactive aerosols becomes, the lower that of radioactive acidic gas becomes.

Journal Articles

Neutron facility at high intensity proton accelerator project

Oyama, Yukio; Ikeda, Yujiro

Hoshasen To Sangyo, (107), p.45 - 51, 2005/09

JAERI and KEK are jointly conducting high intensity proton accelerator project (J-PARC). The outline of the J-PARC project and a design concept of the neutron source facility at J-PARC are described in detail.

Journal Articles

Report on ITPA (International Tokamak Physics Activity) meeting, 14

Sakamoto, Yoshiteru; Toi, Kazuo*; Fukuda, Takeshi*; Fukuyama, Atsushi*; Fujita, Takaaki; Ogawa, Yuichi*; Takizuka, Tomonori; Takenaga, Hidenobu; Yagi, Masatoshi*; Yamada, Hiroshi*; et al.

Purazuma, Kaku Yugo Gakkai-Shi, 81(8), p.626 - 627, 2005/08

no abstracts in English

Journal Articles

Analysis of neutronic experiment on a simulated mercury spallation neutron target assembly bombarded by Giga-electron-Volt protons

Maekawa, Fujio; Meigo, Shinichiro; Kasugai, Yoshimi; Takada, Hiroshi; Ino, Takashi*; Sato, Setsuo*; Jerde, E.*; Glasgow, D.*; Niita, Koji*; Nakashima, Hiroshi; et al.

Nuclear Science and Engineering, 150(1), p.99 - 108, 2005/05

 Times Cited Count:6 Percentile:42.45(Nuclear Science & Technology)

A neutronic benchmark experiment on a simulated spallation neutron target assembly with 1.94, 12 and 24 GeV proton beams conducted by using the AGS accelerator at BNL/US was analyzed to investigate validity of neutronics calculations on proton accelerator driven spallation neutron sources. Monte Carlo particle transport calculation codes NMTC/JAM, MCNPX and MCNP-4A with associated cross section data in JENDL and LA-150 were used for the analysis. As a result, although the overall energy range was encompassed from GeV to meV, i.e., more than 12 orders of magnitude, calculated fast and thermal neutron fluxes agreed approximately within $$pm$$ 40 % with the experiments. Accordingly, it was concluded that neutronics calculations with these codes and cross section data were adequate for estimating nuclear properties in spallation neutron sources.

Journal Articles

New-type neutron source with proton accelerator and its application

Hino, Ryutaro; Yokomizo, Hideaki; Yamazaki, Yoshishige; Hasegawa, Kazuo; Suzuki, Hiromitsu; Soyama, Kazuhiko; Hayashi, Makoto*; Haga, Katsuhiro; Kaminaga, Masanori; Sudo, Yukio*; et al.

Nihon Kikai Gakkai-Shi, 107(1032), p.851 - 882, 2004/11

no abstracts in English

Journal Articles

Optimal control of ultrafast selection

Yokoyama, Keiichi; Teranishi, Yoshiaki; Toya, Yukio; Shirai, Toshizo; Fukuda, Yuji; Aoyama, Makoto; Akahane, Yutaka; Inoue, Norihiro*; Ueda, Hideki; Yamakawa, Koichi; et al.

Journal of Chemical Physics, 120(20), p.9446 - 9449, 2004/05

 Times Cited Count:6 Percentile:19.84(Chemistry, Physical)

Optimal laser control for ultrafast selection of closely-lying excited states, whose energy separation is smaller than the laser bandwidth, is reported on the two-photon transition of atomic cesium; Cs(6S $$rightarrow$$ 7D$$_{J}$$, J = 5/2 and 3/2). Selective excitation was carried out by pulse shaping of ultrashort laser pulses which were adaptively modulated in a closed-loop learning system handling eight parameters representing the electric field. Two-color fluorescence from the respective excited states was monitored to measure the selectivity. The fitness used in the learning algorithm was evaluated from the ratio of the fluorescence yield. After fifty generations, a pair of nearly transform-limitted pulses were obtained as an optimal pulse shape, proving the effectiveness of "Ramsey fringes" mechanism. The contrast of the selection ratio was improved by $$sim$$ 30 % from the simple "Ramsey fringes" experiment.

190 (Records 1-20 displayed on this page)