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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

Introduction to plasma fusion energy

Takamura, Shuichi*; Kado, Shinichiro*; Fujii, Takashi*; Fujiyama, Hiroshi*; Takabe, Hideaki*; Adachi, Kazuo*; Morimiya, Osamu*; Fujimori, Naoji*; Watanabe, Takayuki*; Hayashi, Yasuaki*; et al.

Kara Zukai, Purazuma Enerugi No Subete, P. 164, 2007/03

no abstracts in English

Journal Articles

Overview of national centralized tokamak program; Mission, design and strategy to contribute ITER and DEMO

Ninomiya, Hiromasa; Akiba, Masato; Fujii, Tsuneyuki; Fujita, Takaaki; Fujiwara, Masami*; Hamamatsu, Kiyotaka; Hayashi, Nobuhiko; Hosogane, Nobuyuki; Ikeda, Yoshitaka; Inoue, Nobuyuki; et al.

Journal of the Korean Physical Society, 49, p.S428 - S432, 2006/12

To contribute DEMO and ITER, the design to modify the present JT-60U into superconducting coil machine, named National Centralized Tokamak (NCT), is being progressed under nationwide collaborations in Japan. Mission, design and strategy of this NCT program is summarized.

Journal Articles

The Upper pliocene diatom zone and fission-track age of the upper Koetoi Formation around the Sarobetsu anticline, northern Hokkaido

Yasue, Kenichi; Akiba, Fumio*; Ohira, Hiroto*; Ishii, Eiichi

Chishitsugaku Zasshi, 112(4), p.284 - 293, 2006/04

The Upper Pliocene Neodenticula koizumii Zone was recognized near the boundary between the Koetoi and Yuchi Formations in the western part of the Horonobe area, northern Hokkaido. In previous studies, numerous reworked fossil diatoms from underlying strata have obscured the recognition of the zone. However, this study samples include commonly both N. seminae and N. koizumii as probable autochthonous diatoms and almost no reworked fossil diatoms. Therefore, the samples belong obviously to the Neodenticula koizumii Zone. In addition, fission track ages of zircon crystals from a tuff between the diatom samples show 2.2$$pm$$0.1 Ma and 2.3$$pm$$0.1 Ma (2.5$$pm$$0.1 Ma:). The diatoms and FT age data indicate that the depositional age around the boundary between the Koetoi and Yuchi Formations in the study area is 2.1-2.4 Ma. The age is younger than that in the eastern part of the Horonobe area for about one million years, which is concordant with the previously suggested westward migration of the Tenpoku Basin after Pliocene.

Journal Articles

Overview of the national centralized tokamak programme

Kikuchi, Mitsuru; Tamai, Hiroshi; Matsukawa, Makoto; Fujita, Takaaki; Takase, Yuichi*; Sakurai, Shinji; Kizu, Kaname; Tsuchiya, Katsuhiko; Kurita, Genichi; Morioka, Atsuhiko; et al.

Nuclear Fusion, 46(3), p.S29 - S38, 2006/03

 Times Cited Count:13 Percentile:41.76(Physics, Fluids & Plasmas)

The National Centralized Tokamak (NCT) facility program is a domestic research program for advanced tokamak research to succeed JT-60U incorporating Japanese university accomplishments. The mission of NCT is to establish high beta steady-state operation for DEMO and to contribute to ITER. The machine flexibility and mobility is pursued in aspect ratio and shape controllability, feedback control of resistive wall modes, wide current and pressure profile control capability for the demonstration of the high-b steady state.

Journal Articles

Engineering design and control scenario for steady-state high-beta operation in national centralized tokamak

Tsuchiya, Katsuhiko; Akiba, Masato; Azechi, Hiroshi*; Fujii, Tsuneyuki; Fujita, Takaaki; Fujiwara, Masami*; Hamamatsu, Kiyotaka; Hashizume, Hidetoshi*; Hayashi, Nobuhiko; Horiike, Hiroshi*; et al.

Fusion Engineering and Design, 81(8-14), p.1599 - 1605, 2006/02

 Times Cited Count:1 Percentile:9.98(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Design study of national centralized tokamak facility for the demonstration of steady state high-$$beta$$ plasma operation

Tamai, Hiroshi; Akiba, Masato; Azechi, Hiroshi*; Fujita, Takaaki; Hamamatsu, Kiyotaka; Hashizume, Hidetoshi*; Hayashi, Nobuhiko; Horiike, Hiroshi*; Hosogane, Nobuyuki; Ichimura, Makoto*; et al.

Nuclear Fusion, 45(12), p.1676 - 1683, 2005/12

 Times Cited Count:15 Percentile:45.53(Physics, Fluids & Plasmas)

Design studies are shown on the National Centralized Tokamak facility. The machine design is carried out to investigate the capability for the flexibility in aspect ratio and shape controllability for the demonstration of the high-beta steady state operation with nation-wide collaboration, in parallel with ITER towards DEMO. Two designs are proposed and assessed with respect to the physics requirements such as confinement, stability, current drive, divertor, and energetic particle confinement. The operation range in the aspect ratio and the plasma shape is widely enhanced in consistent with the sufficient divertor pumping. Evaluations of the plasma performance towards the determination of machine design are presented.

Journal Articles

Heating and current drive by N-NBI in JT-60U and LHD

Kaneko, Osamu*; Yamamoto, Takumi; Akiba, Masato; Hanada, Masaya; Ikeda, Katsunori*; Inoue, Takashi; Nagaoka, Kenichi*; Oka, Yoshihide*; Osakabe, Masaki*; Takeiri, Yasuhiko*; et al.

Fusion Science and Technology, 44(2), p.503 - 507, 2003/09

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

High energy negative-ion-based neutral beam injection (N-NBI) is expected as an efficient and reliable tool of heating and current driving for reactor plasmas such as ITER. A world wide activity on developing technology of negative ion production and beam formation started in 1980's and the great progress has been achieved up to now. In particular, Japan has two large projects that planned adopting N-NBI for real plasma experiments; the JT-60U tokamak and the LHD heliotron, which further motivated the R&D activity. These R&D programs were carried out at JAERI and NIFS separately in Japan, and both were successfully done. The first beam injection experiment was made on the JT-60U in 1996, followed by the LHD in 1998. They were the first experiments on heating plasma by high energy beam in tokamaks and in stellerators, and the obtained results were very promising.

Journal Articles

Fusion reactor technology; Challenge to future energy

Seki, Masahiro; Hishinuma, Akimichi; Kurihara, Kenichi; Akiba, Masato; Abe, Tetsuya; Ishitsuka, Etsuo; Imai, Tsuyoshi; Enoeda, Mikio; Ohira, Shigeru; Okumura, Yoshikazu; et al.

Kaku Yugoro Kogaku Gairon; Mirai Enerugi Eno Chosen, 246 Pages, 2001/09

no abstracts in English

Journal Articles

Construction of a fast real-time visualization system for JT-60 plasma shape

Hoshi, Y.*; Miura, Yushi; Ouchi, K.*; Kakefuda, Toyokazu*; Akiba, K.*; *; Kawamata, Yoichi; Kurihara, Kenichi

Heisei-12-Nendo Tohoku Daigaku Gijutsu Kenkyukai Hokoku, p.425 - 427, 2001/03

no abstracts in English

Journal Articles

Plasma real-time control system for advanced tokamak operation scenarios in JT-60

Kurihara, Kenichi; Kawamata, Yoichi; Akiba, K.*; Miura, Yushi; Akasaka, Hiromi; Adachi, H.*; Hoshi, Y.*; Fukuda, Takeshi; Oikawa, Toshihiro

IEEE Transactions on Nuclear Science, 47(2), p.205 - 209, 2000/04

no abstracts in English

Journal Articles

Development of the real-time plasma shape visualization system in JT-60

Kurihara, Kenichi; Kawamata, Yoichi; Akiba, K.*; Adachi, H.*; Hoshi, Y.*; Kimura, Toyoaki

Purazuma, Kaku Yugo Gakkai-Shi (CD-ROM), 75(10), 12 Pages, 1999/10

no abstracts in English

Journal Articles

Ion-exchange properties of potassium nickel hexacyanoferrate(II) compounds

; Miyamoto, Yoichi; Akiba, Kenichi*

Solvent Extraction and Ion Exchange, 16(4), p.1013 - 1031, 1998/00

None

Journal Articles

Ion-exchange properties of potassium nickel hexacyanoferrate(II) compounds

; Miyamoto, Yoichi; Akiba, Kenichi*

Solvent Extraction and Ion Exchange, 16(4), p.1013 - 1031, 1998/00

 Times Cited Count:24 Percentile:69.73(Chemistry, Multidisciplinary)

None

Journal Articles

JT-60U plasma control system

Kimura, Toyoaki; Kurihara, Kenichi; Kawamata, Yoichi; Akiba, K.*; ; Terakado, Tsunehisa; Yoshino, Ryuji

Fusion Technology, 32(3), p.404 - 415, 1997/11

no abstracts in English

JAEA Reports

Development of the real-time plasma shape visualization system in JT-60

Kurihara, Kenichi; Kawamata, Yoichi; Akiba, K.*; Adachi, H.*; Kimura, Toyoaki

JAERI-Research 97-055, 23 Pages, 1997/08

JAERI-Research-97-055.pdf:1.38MB

no abstracts in English

JAEA Reports

None

Akiba, Kenichi*

PNC TJ1601 97-002, 79 Pages, 1997/03

PNC-TJ1601-97-002.pdf:1.35MB

None

24 (Records 1-20 displayed on this page)