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Journal Articles

Non-aqueous selective synthesis of orthosilicic acid and its oligomers

Igarashi, Masayasu*; Matsumoto, Tomohiro*; Yagihashi, Fujio*; Yamashita, Hiroshi*; Ohara, Takashi; Hanashima, Takayasu*; Nakao, Akiko*; Moyoshi, Taketo*; Sato, Kazuhiko*; Shimada, Shigeru*

Nature Communications (Internet), 8, p.140_1 - 140_8, 2017/07

 Times Cited Count:25 Percentile:64.07(Multidisciplinary Sciences)

Journal Articles

Observation of a $$p$$-wave one-neutron halo configuration on $$^{37}$$Mg

Kobayashi, Nobuyuki*; Nakamura, Takashi*; Kondo, Yosuke*; Tostevin, J. A.*; Utsuno, Yutaka; Aoi, Nori*; Baba, Hidetada*; Barthelemy, R.*; Famiano, M. A.*; Fukuda, Naoki*; et al.

Physical Review Letters, 112(24), p.242501_1 - 242501_5, 2014/06

 Times Cited Count:89 Percentile:94.33(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

Deformation-driven $$p$$-wave halos at the drip-line; $$^{31}$$Ne

Nakamura, Takashi*; Kobayashi, Nobuyuki*; Kondo, Yosuke*; Sato, Yoshiteru*; Tostevin, J. A.*; Utsuno, Yutaka; Aoi, Nori*; Baba, Hidetada*; Fukuda, Naoki*; Gibelin, J.*; et al.

Physical Review Letters, 112(14), p.142501_1 - 142501_5, 2014/04

 Times Cited Count:62 Percentile:91.13(Physics, Multidisciplinary)

no abstracts in English

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:29 Percentile:72.31(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:184 Percentile:99.44(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:8 Percentile:49.7(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:175 Percentile:98.48(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

Effects of ferromagnetic materials on plasma control

Oyama, Naoyuki; Sato, Masayasu; Shinohara, Koji

Purazuma, Kaku Yugo Gakkai-Shi, 87(3), p.195 - 198, 2011/03

Reduced activation ferritc/martensitic steel has been considered as a candidate of the structural material for DEMO reactor. Since effects of its strong magnetism on plasma production, plasma control and compatibility with high performance plasmas have been concerned, AMTEX project in JFT-2M demonstrates that the toroidal field (TF) ripple can be reduced by the ferritc steel tiles (FSTs) and there is no bad effect on the compatibility with high performance plasmas. Based on these results, the FSTs have been installed in JT-60U in order to improve the plasma performance through the reduction of the TF ripple. Then, it is confirmed that the effect of the error field due to the FSTs can be corrected so as to control the plasma. Although these experimental results indicate that the effect of the FSTs on plasma control seems to be small, the effect of the ferromagnetic materials inside the test blanket module for ITER on the plasma confinement has recently been concerned.

Journal Articles

Feasibility study of ECE measurement in JT-60SA

Sato, Masayasu; Isayama, Akihiko

Nuclear Instruments and Methods in Physics Research A, 623(2), p.653 - 655, 2010/11

 Times Cited Count:0 Percentile:0.01(Instruments & Instrumentation)

no abstracts in English

JAEA Reports

Conceptual design of the SlimCS fusion DEMO reactor

Tobita, Kenji; Nishio, Satoshi*; Enoeda, Mikio; Nakamura, Hirofumi; Hayashi, Takumi; Asakura, Nobuyuki; Uto, Hiroyasu; Tanigawa, Hiroyasu; Nishitani, Takeo; Isono, Takaaki; et al.

JAEA-Research 2010-019, 194 Pages, 2010/08


This report describes the results of the conceptual design study of the SlimCS fusion DEMO reactor aiming at demonstrating fusion power production in a plant scale and allowing to assess the economic prospects of a fusion power plant. The design study has focused on a compact and low aspect ratio tokamak reactor concept with a reduced-sized central solenoid, which is novel compared with previous tokamak reactor concept such as SSTR (Steady State Tokamak Reactor). The reactor has the main parameters of a major radius of 5.5 m, aspect ratio of 2.6, elongation of 2.0, normalized beta of 4.3, fusion out put of 2.95 GW and average neutron wall load of 3 MW/m$$^{2}$$. This report covers various aspects of design study including systemic design, physics design, torus configuration, blanket, superconducting magnet, maintenance and building, which were carried out increase the engineering feasibility of the concept.

Journal Articles

Halo structure of the island of inversion nucleus $$^{31}$$Ne

Nakamura, Takashi*; Kobayashi, Nobuyuki*; Kondo, Yosuke*; Sato, Yoshiteru*; Aoi, Nori*; Baba, Hidetada*; Deguchi, Shigeki*; Fukuda, Naoki*; Gibelin, J.*; Inabe, Naoto*; et al.

Physical Review Letters, 103(26), p.262501_1 - 262501_4, 2009/12

 Times Cited Count:198 Percentile:97.53(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

Analysis of residual gas by high-resolution mass spectrometry during helium glow discharge cleaning in JT-60U

Hayashi, Takao; Kaminaga, Atsushi; Arai, Takashi; Sato, Masayasu

Fusion Engineering and Design, 84(2-6), p.908 - 910, 2009/06

 Times Cited Count:3 Percentile:24.52(Nuclear Science & Technology)

The residual gas analysis has been conducted by high-resolution mass spectrometry which can discriminate between D$$_{2}$$ and He gas species during helium glow discharge cleaning (He-GDC) in JT-60U in order to investigate the effect of He-GDC. The residual gas analyzer was able to distinguish between D$$_{2}$$ and He peaks during He-GDC. Since the He-GDC started, the partial pressure of D$$_{2}$$ gas increases with time and reached its highest pressure (3.8 $$times$$ 10$$^{-4}$$ Pa), which is about ten times larger than that before the He-GDC (3.5 $$times$$ 10$$^{-5}$$ Pa). The total amount of D$$_{2}$$, which was released during the He-GDC (7 hours), was evaluated as 4 Pa m$$^{3}$$. The pressure of D$$_{2}$$ (5.7 $$times$$ 10$$^{-6}$$ Pa) about 7 hours after the He-GDC (7 hours) is significantly lower than before the He-GDC, which indicates the He-GDC is effective to remove the deuterium from plasma facing components.

Journal Articles

Hydrogen isotope retention in the outboard first wall tiles of JT-60U

Yoshida, Masafumi; Tanabe, Tetsuo*; Nobuta, Yuji*; Hayashi, Takao; Masaki, Kei; Sato, Masayasu

Journal of Nuclear Materials, 390-391, p.635 - 638, 2009/06

 Times Cited Count:9 Percentile:53.3(Materials Science, Multidisciplinary)

We have investigated hydrogen isotopes retention in the outboard first wall tiles of JT-60U by means of TDS, SIMS and SEM. The outboard first wall tiles of JT-60U are mostly eroded. The total retention (H+D) normalized by a unit area and integrated NBI time in the eroded first wall tiles and the eroded divertor tiles were nearly the same, in spite of the lower temperature of the first wall. Differently from divertor tiles, in which H retention was dominated owing to HH discharges preformed after DD discharges, deuterium is dominated in hydrogen isotopes retention and penetrates deeper from the surface. This is attributed to injection of high energy D and difficulty of isotopic replacement owing to their lower temperature. The integrated amount over the whole surface could be appreciably large. This type of hydrogen retention could be also possible for the metallic wall.

Journal Articles

Retention and depth profile of hydrogen isotopes in gaps of the first wall in JT-60U

Nobuta, Yuji*; Arai, Takashi; Yagyu, Junichi; Masaki, Kei; Sato, Masayasu; Tanabe, Tetsuo*; Yamauchi, Yuji*; Hino, Tomoaki*

Journal of Nuclear Materials, 390-391, p.643 - 646, 2009/06

 Times Cited Count:5 Percentile:35.97(Materials Science, Multidisciplinary)

The hydrogen and deuterium retention in gap side surfaces of the first wall tiles exposed to DD and HH discharges in JT-60U were investigated. The hydrogen and deuterium retention and boron deposition increased with the gap width. The depth profile of deuterium was very similar to that of boron, indicating that deuterium was incorporated with boron. Thick carbon deposition layer ($$sim$$ 1e$$^{-5}$$m) was observed in the gap of inboard tile and the atomic ratio in (H+D)/C at the carbon layer was estimated to be approximately 0.15. This value is higher than that observed in the divertor region. In this study, the H+D amount in gap side surfaces of the first wall was of the order of 1e23 $$sim$$ 1e24m$$^{-2}$$.

Journal Articles

Tritium removal by isotopic exchange

Tanabe, Tetsuo*; Sugiyama, Kazuyoshi*; Shibahara, Takahiro*; Hirohata, Yuko*; Yoshida, Masafumi; Masaki, Kei; Sato, Masayasu

Journal of Nuclear Materials, 390-391, p.705 - 708, 2009/06

 Times Cited Count:8 Percentile:49.52(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Deuterium depth profiling in graphite tiles not exposed to hydrogen discharges before air ventilation of JT-60U

Hayashi, Takao; Sugiyama, Kazuyoshi*; Mayer, M.*; Krieger, K.*; Masaki, Kei; Tanabe, Tetsuo*; Sato, Masayasu

Journal of Nuclear Materials, 390-391, p.667 - 670, 2009/05

 Times Cited Count:1 Percentile:10.22(Materials Science, Multidisciplinary)

Absolute concentrations and the depth profiles of D in plasma-facing graphite tiles used in JT-60U were determined by means of the D($$^{3}$$He, p)$$^{4}$$He resonant nuclear reaction. The analyzed samples were not exposed to H discharges before air ventilation. The maximum depth of analysis is about 1.4 $$times$$ 10$$^{24}$$ carbon (C) atoms/m$$^{2}$$, corresponding to a linear depth of 16 $$mu$$m for the density of 1.7 $$times$$ 10$$^{3}$$ kg/m$$^{3}$$. The highest D concentration was found at the inboard mid-plane of first wall area. The maximum D concentration is D/C=0.13, and the concentration decrease with the depth. The D retention within 16 $$mu$$m is 1.9 $$times$$ 10$$^{22}$$ D atoms/m$$^{2}$$. The D retentions in this paper were about 2$$sim$$9 times larger than previous samples, which were located on the same area and exposed to the hydrogen discharges. This indicates the H plasma discharges were effective to remove the D (and T) from graphite tiles in the first wall area.

Journal Articles

Localized tungsten deposition in divertor region in JT-60U

Ueda, Yoshio*; Fukumoto, Masakatsu*; Watanabe, Jun*; Otsuka, Yusuke*; Arai, Takashi; Asakura, Nobuyuki; Nobuta, Yuji*; Sato, Masayasu; Nakano, Tomohide; Yagyu, Junichi; et al.

Proceedings of 22nd IAEA Fusion Energy Conference (FEC 2008) (CD-ROM), 8 Pages, 2008/10

Deposition profiles of tungsten released from the outer divertor were studied in JT-60U. A neutron activation method was used for the first time to accurately measure deposited tungsten. Surface density of tungsten in the thick carbon deposition layer can be measured by this method. Tungsten was mainly deposited on the inner divertor (around inner strike points) and on the outer wing of the dome. Toroidal distribution of the W deposition was significantly localized near the tungsten released position, while other metallic impurities such as Fe, Cr, Ni were distributed more uniformly. These data indicate that inward drift in the divertor region played a significant role in tungsten transport in JT-60U.

Journal Articles

Effects of relativistic and absorption on ECE spectra in high temperature tokamak plasma

Sato, Masayasu; Isayama, Akihiko

Plasma and Fusion Research (Internet), 2, p.S1029_1 - S1029_5, 2007/11

Using the extended Trubnikov's expression for the fully relativistic Maxwellian in the case of oblique propagation to the magnetic field ($$B$$$$_{t}$$), electron cyclotron emission (ECE) spectra are calculated in a high temperature ($$T$$$$_{t}$$) tokamak plasma. We investigate the ECE by changing the angles between the sight line and the equatorial plane or $$B$$$$_{t}$$ direction. Feature of ECE spectra can be interpreted from the viewpoints of relativistic, Doppler and absorption effects. The downshift frequency variation due to the relativistic effect in the high field side (HFS) observation is bigger than that in the low field side observation. Absorption at the HFS plasma results in the deep dip at the HFS of fundamental, second and third harmonics in the ECE spectra. For the vertical observation, in the case of optically thin case, ECE spectra are similar to the emissivity profile, and when electron density ($$n$$$$_{e}$$) is higher, ECE spectra are modified due to the absorption in plasma. Since the $$B$$$$_{t}$$, $$n$$$$_{e}$$, $$T$$$$_{e}$$ increase in the case of the SlimCS DEMO reactor, the ECE spectra expands to high frequency emission (2000 GHz). So, ECE detector in the case of Fourier transform spectrometer system should be modified from present liquid He cooled InSb detector because of the detection of high frequency emission.

Journal Articles

Evaluation of extended trubnikov emissivity to the oblique propagation and application to electron temperature measurement in a reactor-grade tokamak

Sato, Masayasu; Isayama, Akihiko

Fusion Science and Technology, 52(2), p.169 - 175, 2007/08

 Times Cited Count:1 Percentile:11.32(Nuclear Science & Technology)

no abstracts in English

Journal Articles

SlimCS; Compact low aspect ratio DEMO reactor with reduced-size central solenoid

Tobita, Kenji; Nishio, Satoshi; Sato, Masayasu; Sakurai, Shinji; Hayashi, Takao; Shibama, Yusuke; Isono, Takaaki; Enoeda, Mikio; Nakamura, Hirofumi; Sato, Satoshi; et al.

Nuclear Fusion, 47(8), p.892 - 899, 2007/08

 Times Cited Count:57 Percentile:86.6(Physics, Fluids & Plasmas)

The concept for a compact DEMO reactor named "SlimCS" is presented. Distinctive features of the concept is low aspect ratio ($$A$$ = 2.6) and use of a reduced-size center solenoid (CS) which has a function of plasma shaping rather than poloidal flux supply. The reduced-size CS enables us to introduce a thin toroidal field (TF) coil system which contributes to reducing the weight and construction cost of the reactor. SlimCS is as compact as advanced commercial reactor designs such as ARIES-RS and produces 1 GWe in spite of moderate requirements for plasma parameters. Merits of low-$$A$$, i.e. vertical stability for high elongation and high beta limit are responsible for such reasonable physics requirements.

165 (Records 1-20 displayed on this page)