2021/10/28 更新

写真a

ヨシムラ コウジ
吉村 浩司
YOSHIMURA Koji
所属
異分野基礎科学研究所 教授
職名
教授

学位

  • 博士(理学) ( 1995年3月   東京大学 )

研究分野

  • 自然科学一般 / 半導体、光物性、原子物理

  • 自然科学一般 / 素粒子、原子核、宇宙線、宇宙物理にする実験

学歴

  • 東京大学   理学系研究科   博士課程

    1991年4月 - 1995年1月

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    備考: 単位取得退学

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  • 東京大学   理学系研究科   修士課程

    1989年4月 - 1991年3月

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  • 東京大学   工学系研究科   修士課程

    1986年4月 - 1988年3月

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  • 東京大学   理科I類 / 工学部  

    1982年4月 - 1986年3月

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経歴

  • 岡山大学   異分野基礎科学研究所   教授

    2016年4月 - 現在

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  • 岡山大学   極限量子研究コア   教授

    2013年5月 - 2016年3月

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  • 高エネルギー加速器研究機構   素粒子原子核研究所   准教授

    2001年1月 - 2013年5月

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  • 東京大学   素粒子物理国際研究センター   助手

    1995年1月 - 2000年12月

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所属学協会

 

論文

  • Estimation of radiative half-life of Th229m by half-life measurement of other nuclear excited states in Th229

    Y. Shigekawa, A. Yamaguchi, K. Suzuki, H. Haba, T. Hiraki, H. Kikunaga, T. Masuda, S. Nishimura, N. Sasao, A. Yoshimi, K. Yoshimura

    Physical Review C   104 ( 2 )   2021年8月

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:American Physical Society (APS)  

    DOI: 10.1103/physrevc.104.024306

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    その他リンク: http://harvest.aps.org/v2/journals/articles/10.1103/PhysRevC.104.024306/fulltext

  • Suppression of the optical crosstalk in a multi-channel silicon photomultiplier array

    Takahiko Masuda, Daniel G. Ang, Nicholas R. Hutzler, Cole Meisenhelder, Noboru Sasao, Satoshi Uetake, Xing Wu, David DeMille, Gerald Gabrielse, John M. Doyle, Koji Yoshimura

    Optics Express   29 ( 11 )   16914 - 16914   2021年5月

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:The Optical Society  

    DOI: 10.1364/oe.424460

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  • Simulation Study of Laser Ionization of Muonium by 1S-2S Excitation for the Muon g − 2/EDM Experiment at J-PARC

    Ce Zhang, Hideaki Hara, Takahiro Hiraki, Yutaka Ikedo, Yasutaka Imai, Katsuhiko Ishida, Saeid Kamal, Naritoshi Kawamura, Akihiro Koda, Yajun Mao, Takahiko Masuda, Tsutomu Mibe, Yasuhiro Miyake, Yuki Miyamoto, Yu Oishi, Masashi Otani, Patrick Strasser, Koichiro Shimomura, Kazuhito Suzuki, Satoshi Uetake, Takayuki Yamazaki, Shinsuke Yamamoto, Koji Yoshimura, Mitsuhiro Yoshida

    Proceedings of the 3rd J-PARC Symposium (J-PARC2019)   2021年3月

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    掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:Journal of the Physical Society of Japan  

    DOI: 10.7566/jpscp.33.011125

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  • Absolute X-ray energy measurement using a high-accuracy angle encoder

    Takahiko Masuda, Tsukasa Watanabe, Kjeld Beeks, Hiroyuki Fujimoto, Takahiro Hiraki, Hiroyuki Kaino, Shinji Kitao, Yuki Miyamoto, Koichi Okai, Noboru Sasao, Makoto Seto, Thorsten Schumm, Yudai Shigekawa, Kenji Tamasaku, Satoshi Uetake, Atsushi Yamaguchi, Yoshitaka Yoda, Akihiro Yoshimi, Koji Yoshimura

    Journal of Synchrotron Radiation   28 ( 1 )   111 - 119   2021年1月

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    掲載種別:研究論文(学術雑誌)   出版者・発行元:International Union of Crystallography (IUCr)  

    This paper presents an absolute X-ray photon energy measurement method that uses a Bond diffractometer. The proposed system enables the prompt and rapid <italic>in situ</italic> measurement of photon energies over a wide energy range. The diffractometer uses a reference silicon single-crystal plate and a highly accurate angle encoder called SelfA. The performance of the system is evaluated by repeatedly measuring the energy of the first excited state of the potassium-40 nuclide. The excitation energy is determined as 29829.39 (6) eV, and this is one order of magnitude more accurate than the previous measurement. The estimated uncertainty of the photon energy measurement was 0.7 p.p.m. as a standard deviation and the maximum observed deviation was 2 p.p.m.

    DOI: 10.1107/s1600577520014526

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  • Development of a measurement system enabling the reconstruction of gamma-ray time spectra by simultaneous recording of energy and time information

    Hiroyuki Tajima, Shinji Kitao, Ryo Masuda, Yasuhiro Kobayashi, Takahiko Masuda, Koji Yoshimura, Makoto Seto

    JAPANESE JOURNAL OF APPLIED PHYSICS   58 ( 10 )   2019年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IOP PUBLISHING LTD  

    We developed a measurement system that enables the reconstruction of gamma-ray time spectra in cascade decay schemes with 0.3 ns time resolution, which is sufficient for nuclear decay with more than nanoseconds half-life. As this system records all the time and energy information of gamma-rays, the energy regions for the gamma-ray identification can be optimized after the measurement. Moreover, this system has five timing inputs and thus we can record the timing data of external perturbations; we can investigate the responses to the perturbation afterward. This property fulfills the demands required for quantum information research with gamma-rays. (C) 2019 The Japan Society of Applied Physics

    DOI: 10.7567/1347-4065/ab3f19

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    arXiv

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    その他リンク: http://arxiv.org/pdf/1905.11029v1

  • X-ray pumping of the Th-229 nuclear clock isomer

    Takahiko Masuda, Akihiro Yoshimi, Akira Fujieda, Hiroyuki Fujimoto, Hiromitsu Haba, Hideaki Hara, Takahiro Hiraki, Hiroyuki Kaino, Yoshitaka Kasamatsu, Shinji Kitao, Kenji Konashi, Yuki Miyamoto, Koichi Okai, Sho Okubo, Noboru Sasao, Makoto Seto, Thorsten Schumm, Yudai Shigekawa, Kenta Suzuki, Simon Stellmer, Kenji Tamasaku, Satoshi Uetake, Makoto Watanabe, Tsukasa Watanabe, Yuki Yasuda, Atsushi Yamaguchi, Yoshitaka Yoda, Takuya Yokokita, Motohiko Yoshimura, Koji Yoshimura

    NATURE   573 ( 7773 )   238 - +   2019年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:NATURE PUBLISHING GROUP  

    Thorium-229 is a unique case in nuclear physics: it presents a metastable
    first excited state Th-229m, just a few electronvolts above the nuclear ground
    state. This so-called isomer is accessible by VUV lasers, which allows
    transferring the amazing precision of atomic laser spectroscopy to nuclear
    physics. Being able to manipulate the Th-229 nuclear states at will opens up a
    multitude of prospects, from studies of the fundamental interactions in physics
    to applications as a compact and robust nuclear clock. However, direct optical
    excitation of the isomer or its radiative decay back to the ground state has
    not yet been observed, and a series of key nuclear structure parameters such as
    the exact energies and half-lives of the low-lying nuclear levels of Th-229 are
    yet unknown. Here we present the first active optical pumping into Th-229m. Our
    scheme employs narrow-band 29 keV synchrotron radiation to resonantly excite
    the second excited state, which then predominantly decays into the isomer. We
    determine the resonance energy with 0.07 eV accuracy, measure a half-life of
    82.2 ps, an excitation linewidth of 1.70 neV, and extract the branching ratio
    of the second excited state into the ground and isomeric state respectively.
    These measurements allow us to re-evaluate gamma spectroscopy data that have
    been collected over 40~years.

    DOI: 10.1038/s41586-019-1542-3

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    arXiv

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    その他リンク: http://arxiv.org/pdf/1902.04823v1

  • Coherent two-photon emission from hydrogen molecules excited by counter- propagating laser pulses

    Takahiro Hiraki, Hideaki Hara, Yuki Miyamoto, Kei Imamura, Takahiko Masuda, Noboru Sasao, Satoshi Uetake, Akihiro Yoshimi, Koji Yoshimura, Motohiko Yoshimura

    JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS   52 ( 4 )   2019年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IOP PUBLISHING LTD  

    We observed two-photon emission (TPE) signal from the first vibrationally excited state of parahydrogen gas coherently excited by counter-propagating laser pulses. A single narrow-linewidth laser source has roles in the excitation of the parahydrogen molecules and the induction of the TPE process. We measured dependences of the signal energy on the detuning, target gas pressure, and input pulse energies. These results are qualitatively consistent with those obtained by numerical simulations based on Maxwell-Bloch equations with one spatial dimension and one temporal dimension. This study of the TPE process in the counterpropagating injection scheme is an important step toward neutrino mass spectroscopy.

    DOI: 10.1088/1361-6455/aafbd0

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    arXiv

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    その他リンク: http://arxiv.org/pdf/1806.04005v2

  • Energy response of X-rays under high flux conditions using a thin APD for the energy range of 6-33 keV

    T. Masuda, T. Hiraki, H. Kaino, S. Kishimoto, Y. Miyamoto, K. Okai, S. Okubo, R. Ozaki, N. Sasao, K. Suzuki, S. Uetake, A. Yoshimi, K. Yoshimura

    NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT   913   72 - 77   2019年1月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    This paper reports on the demonstration of a high-rate energy measurement technique using a thin depletion layer silicon avalanche photodiode (Si-APD). A dedicated amplitude-to-time converter is developed to realize simultaneous energy and timing measurement in a high rate condition. The energy response of the system is systematically studied by using monochromatic X-ray beam with an incident energy ranging from 6 to 33 keV. The obtained energy spectra contain clear peaks and tail distributions. The peak fraction monotonously decreases as the incident photon energy increases. This phenomenon can be explained by considering the distribution of the energy deposit in silicon, which is investigated by using a Monte Carlo simulation.

    DOI: 10.1016/j.nima.2018.10.029

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  • Sigma p scattering experiment at J-PARC - results of commissioning run -

    K. Miwa, J. K. Ahn, Y. Akazawa, T. Aramaki, S. Ashikaga, S. Callier, N. Chiga, S. W. Choi, H. Ekawa, P. Evtoukhovitch, N. Fujioka, M. Fujita, S. Hasegawa, S. Hayakawa, R. Honda, S. Hoshino, K. Hosomi, M. Ichikawa, Y. Ichikawa, M. Ieiri, M. Ikeda, K. Imai, Y. Ishikawa, S. Ishimoto, W. S. Jung, H. Kanauchi, H. Kanda, B. M. Kang, H. Kawai, S. H. Kim, K. Kobayashi, T. Koike, K. Matsuda, Y. Matsumoto, R. Nagatomi, Y. Nakada, M. Nakagawa, I. Nakamura, T. Nanamura, M. Naruki, S. Ozawa, L. Raux, A. Sakaguchi, H. Sako, S. Sato, T. Shiozaki, K. Shirotori, K. Suzuki, S. Suzuki, M. Tabata, C. d. L. Taille, H. Takahashi, T. Takahashi, T. N. Takahashi, H. Tamura, Z. Tsamalaidze, H. Umetsu, M. Ukai, T. O. Yamamoto, K. Yoshimura

    13TH INTERNATIONAL CONFERENCE ON HYPERNUCLEAR AND STRANGE PARTICLE PHYSICS (HYP2018)   2130   2019年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:AMER INST PHYSICS  

    The Sigma p scattering experiment has just been started at J-PARC this year (2018). We made "Sigma beam factory" a reality where a beam with an intensity of more than 5x10(5) Sigma(-) beam per day could be produced by using 20 M/spill pi(-) beam. The CATCH system, which is a dedicated system to detect recoil proton from the Sigma p scattering, operated stably under the high counting rate, and its successful operation was confirmed by identifying the pp scattering events in J-PARC. In the June beam time, the production run of the Sigma(-)p scattering was carried out for 2 days, which was just 10% of the requested beam time. The remaining beam time of the Sigma(-)p channel and the Sigma(+)p channel will take place in the spring of 2019.

    DOI: 10.1063/1.5118374

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  • Geometry-dependent spectra and coherent-transient measurement of nearly degenerate four-wave mixing using two-photon resonance

    Hideaki Hara, Yuki Miyamoto, Takahiro Hiraki, Kei Imamura, Takahiko Masuda, Noboru Sasao, Satoshi Uetake, Akihiro Yoshimi, Koji Yoshimura, Motohiko Yoshimura

    JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS   52 ( 23 )   2018年10月

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    記述言語:英語   出版者・発行元:IOP PUBLISHING LTD  

    We study nearly degenerate four-wave mixing using a two-photon-allowed
    vibrational transition of parahydrogen. A signal photon is generated by a
    trigger photon and coherence among parahydrogen, which is prepared by two
    counterpropagating pump pulses. The dependence of the signal pulse energy on
    the trigger frequency are investigated. The measured spectra vary depending on
    the geometry. They shift depending on the direction of the signal pulse and on
    the small angle formed by the counterpropagating pump pulses. Furthermore, the
    dependence of signal pulse energy on the incident time of the trigger pulse is
    investigated. The measured signal pulse energy is high if the trigger pulse is
    slightly delayed with respect to the pump pulses. We demonstrate that these
    geometry-dependent spectra and coherent-transient response can be explained by
    using simple models.

    DOI: 10.1088/1361-6455/ab4a6e

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    arXiv

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    その他リンク: http://arxiv.org/pdf/1810.13120v1

  • Multi-MW accelerator target material properties under proton irradiation at Brookhaven National Laboratory linear isotope producer

    N. Simos, H. Ludewig, H. Kirk, E. Dooryhee, S. Ghose, Z. Zhong, H. Zhong, S. Makimura, K. Yoshimura, J. R. J. Bennett, G. Kotsinas, Z. Kotsina, K. T. McDonald

    PHYSICAL REVIEW ACCELERATORS AND BEAMS   21 ( 5 )   2018年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER PHYSICAL SOC  

    The effects of proton beams irradiating materials considered for targets in high-power accelerator experiments have been studied using the Brookhaven National Laboratory's (BNL) 200 MeV proton linac. A wide array of materials and alloys covering a wide range of the atomic number (Z) are being scoped by the high-power accelerator community prompting the BNL studies to focus on materials representing each distinct range, i.e. low-Z, mid-Z and high-Z. The low range includes materials such as beryllium and graphite, the midrange alloys such as Ti-6Al-4V, gum metal and super-Invar and finally the high-Z range pure tungsten and tantalum. Of interest in assessing proton irradiation effects are (a) changes in physiomechanical properties which are important in maintaining high-power target functionality, (b) identification of possible limits of proton flux or fluence above which certain materials cease to maintain integrity, (c) the role of material operating temperature in inducing or maintaining radiation damage reversal, and (d) phase stability and microstructural changes. The paper presents excerpt results deduced from macroscopic and microscopic post-irradiation evaluation (PIE) following several irradiation campaigns conducted at the BNL 200 MeV linac and specifically at the isotope producer beam-line/target station. The microscopic PIE relied on high energy x-ray diffraction at the BNL NSLS X17B1 and NSLS II XPD beam lines. The studies reveal the dramatic effects of irradiation on phase stability in several of the materials, changes in physical properties and ductility loss as well as thermally induced radiation damage reversal in graphite and alloys such as super-Invar.

    DOI: 10.1103/PhysRevAccelBeams.21.053001

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  • Nuclear resonant scattering experiment with fast time response: Photonuclear excitation of Hg-201

    A. Yoshimi, H. Hara, T. Hiraki, Y. Kasamatsu, S. Kitao, Y. Kobayashi, K. Konashi, R. Masuda, T. Masuda, Y. Miyamoto, K. Okai, S. Okubo, R. Ozaki, N. Sasao, O. Sato, M. Seto, T. Schumm, Y. Shigekawa, S. Stellmer, K. Suzuki, S. Uetake, M. Watanabe, A. Yamaguchi, Y. Yasuda, Y. Yoda, K. Yoshimura, M. Yoshimura

    PHYSICAL REVIEW C   97 ( 2 )   2018年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER PHYSICAL SOC  

    Nuclear resonant excitation and detection of its decay signal for the 26.27-keV level of Hg-201 is demonstrated with high-brilliance synchrotron radiation (SR) and a fast x-ray detector system. This SR-based photonuclear excitation scheme, known as nuclear resonant scattering (NRS) in the field of materials science, is also useful for investigating nuclear properties, such as the half-lives and radiative widths of excited nuclear levels. To date, because of the limited time response of the x-ray detector, the nuclear levels to which this method could be applied have been limited to the one whose half-lives are longer than similar to 1 ns. The faster time response of the NRS measurement makes possible NRS experiments on nuclear levels with much shorter half-lives. We have fabricated an x-ray detector system that has a time resolution of 56 ps and a shorter tail function than that reported previously. With the implemented detector system, the NRS signal of the 26.27-keVstate of Hg-201 could be clearly discriminated from the electronic scattering signal at an elapsed time of 1 ns after the SR pulse. The half-life of the state was determined as 629 +/- 18 ps, which has better precision by a factor of three compared with that reported to date obtained from nuclear decay spectroscopy.

    DOI: 10.1103/PhysRevC.97.024607

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  • Vibrational excitation of hydrogen molecules by two-photon absorption and third-harmonic generation

    Yuki Miyamoto, Hideaki Hara, Takahiro Hiraki, Takahiko Masuda, Noboru Sasao, Satoshi Uetake, Akihiro Yoshimi, Koji Yoshimura, Motohiko Yoshimura

    JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS   51 ( 1 )   2018年1月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IOP PUBLISHING LTD  

    We report the coherent excitation of the vibrational state of hydrogen molecules by two-photon absorption and the resultant third-harmonic generation (THG). Parahydrogen molecules cooled by liquid nitrogen are irradiated by mid-infrared nanosecond pulses at 4.8 mu m with a nearly Fourier-transform-limited linewidth. The first excited vibrational state of parahydrogen is populated by two-photon absorption of the mid-infrared photons. Because of the narrow linewidth of the mid-infrared pulses, coherence between the ground and excited states is sufficient to induce higher-order processes. Near-infrared photons from the THG are observed at 1.6 mu m. The dependence of the intensity of the near-infrared radiation on mid-infrared pulse energy, target pressure, and cell length is determined. We used a simple formula for THG with consideration of realistic experimental conditions to explain the observed results.

    DOI: 10.1088/1361-6455/aa9782

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  • Frequency dependence of coherently amplified two-photon emission from hydrogen molecules

    Hideaki Hara, Yuki Miyamoto, Takahiro Hiraki, Takahiko Masuda, Noboru Sasao, Satoshi Uetake, Akihiro Yoshimi, Koji Yoshimura, Motohiko Yoshimura

    PHYSICAL REVIEW A   96 ( 6 )   2017年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER PHYSICAL SOC  

    We investigate how the efficiency of coherently amplified two-photon emission depends on the frequency of one of the two emitted photons, namely the signal photon. This is done over the wavelength range of 5.048-10.21 mu m by using the vibrational transition of parahydrogen. The efficiency increases with the frequency of the signal photon. Considering experimental errors, our results are consistent with the theoretical prediction for the present experimental conditions. This study is an experimental demonstration of the frequency dependence of coherently amplified two-photon emission, and also presents its potential as a light source.

    DOI: 10.1103/PhysRevA.96.063827

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  • The results from BESS-Polar experiment

    K. Abe, H. Fuke, S. Haino, T. Hams, M. Hasegawa, K. C. Kim, M. H. Lee, Y. Makida, J. W. Mitchell, J. Nishimura, M. Nozaki, R. Orito, J. F. Ormes, N. Picot-Clemente, K. Sakai, M. Sasaki, E. S. Seo, R. E. Streitmatter, J. Suzuki, K. Tanaka, N. Thakur, A. Yamamoto, T. Yoshida, K. Yoshimura

    ADVANCES IN SPACE RESEARCH   60 ( 4 )   806 - 814   2017年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCI LTD  

    The balloon-borne experiment with a superconducting spectrometer (BESS) instrument was developed as a high-resolution, high-geometric-acceptance magnetic-rigidity spectrometer for sensitive measurements of cosmic-ray antiparticles, searches for antinuclei, and precise measurements of the absolute fluxes of light GCR elements and isotopes. The original BESS experiment flew 8 times over Lynn Lake, Canada and once from Fort Sumner, USA during the period of 1993 through 2002, with continuous improvement in the instrument. Based on the instrument concept inherited from the BESS spectrometer, a very low instrumental energy cutoff for antiprotons was achieved with a new thin-walled superconducting magnet and removal of the outer pressure vessel for BESS-Polar project. The first and second scientific flights called BESS-Polar I/II were successfully performed, over Antarctica in 2004 December and 2007 December respectively. We report the scientific results, focusing on the long-duration flights of BESS-Polar I (2004) and BESS-Polar II (2007-2008). (C) 2017 COSPAR. Published by Elsevier Ltd. All rights reserved.

    DOI: 10.1016/j.asr.2016.11.004

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  • Fast x-ray detector system with simultaneous measurement of timing and energy for a single photon

    T. Masuda, S. Okubo, H. Hara, T. Hiraki, S. Kitao, Y. Miyamoto, K. Okai, R. Ozaki, N. Sasao, M. Seto, S. Uetake, A. Yamaguchi, Y. Yoda, A. Yoshimi, K. Yoshimura

    REVIEW OF SCIENTIFIC INSTRUMENTS   88 ( 6 )   2017年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER INST PHYSICS  

    We developed a fast X-ray detector system for nuclear resonant scattering (NRS) experiments. Our system employs silicon avalanche photo-diode (Si-APD) as a fast X-ray sensor. The system is able to acquire both timing and energy of a single X-ray photon simultaneously in a high rate condition, 106 counts per second for one Si-APD. The performance of the system was investigated in SPring-8, a synchrotron radiation facility in Japan. Good time resolution of 120 ps (FWHM) was achieved with a slight tail distribution in the time spectrum by a level of 10(-9) at 1 ns apart from the peak. Using this system, we successfully observed the NRS from the 26.27-keV level of mercury-201, which has a half-life of 630(50) ps. We also demonstrated the reduction of background events caused by radioactive decays in a radioactive sample by discriminating photon energy. Published by AIP Publishing.

    DOI: 10.1063/1.4989405

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  • Vibrational two-photon emission from coherently excited solid parahydrogen

    Yuki Miyamoto, Hideaki Hara, Takahiko Masuda, Noboru Sasao, Satoshi Uetake, Akihiro Yoshimi, Koji Yoshimura, Motohiko Yoshimura

    JOURNAL OF PHYSICAL CHEMISTRY A   121 ( 20 )   3943 - 3951   2016年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER CHEMICAL SOC  

    We report observation of two-photon emission from coherently excited
    vibrational state of solid parahydrogen, known as one of quantum solids. The
    coherent state between the ground and the excited states is prepared by
    stimulated Raman scattering using two visible laser pulses. The two-photon
    emission is triggered by another mid-infrared laser pulse. The observed
    two-photon emission persists even when the trigger pulse is injected long after
    the excitation. The observed phenomenon is due to a long decoherence time of
    the vibrational states of solid parahydrogen, which is attributed to special
    nature as quantum solid. Dependence of the decoherence on target temperature
    and residual orthohydrogen concentration are studied along with its time
    evolution. It is found that the emission intensity increases even after the
    excitation pulses pass through the target completely. The coherence development
    is highly suppressed at high target temperature and high residual orthohydrogen
    concentration. Effects of target annealing and laser-induced damage on the
    target are also observed.

    DOI: 10.1021/acs.jpca.7b02011

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    arXiv

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    その他リンク: http://arxiv.org/pdf/1612.05600v1

  • MEASUREMENTS OF COSMIC-RAY PROTON AND HELIUM SPECTRA FROM THE BESS-POLAR LONG-DURATION BALLOON FLIGHTS OVER ANTARCTICA

    K. Abe, H. Fuke, S. Haino, T. Hams, M. Hasegawa, A. Horikoshi, A. Itazaki, K. C. Kim, T. Kumazawa, A. Kusumoto, M. H. Lee, Y. Makida, S. Matsuda, Y. Matsukawa, K. Matsumoto, J. W. Mitchell, Z. Myers, J. Nishimura, M. Nozaki, R. Orito, J. F. Ormes, N. Picot-Clemente, K. Sakai, M. Sasaki, E. S. Seo, Y. Shikaze, R. Shinoda, E. Streitmatter, J. Suzuki, Y. Takasugi, K. Takeuchi, K. Tanaka, N. Thakur, T. Yamagami, A. Yamamoto, T. Yoshida, K. Yoshimura

    ASTROPHYSICAL JOURNAL   822 ( 2 )   2016年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IOP PUBLISHING LTD  

    The BESS-Polar Collaboration measured the energy spectra of cosmic-ray protons and helium during two long-duration balloon flights over Antarctica in 2004 December and 2007 December at substantially different levels of solar modulation. Proton and helium spectra probe the origin and propagation history of cosmic rays in the galaxy, and are essential to calculations of the expected spectra of cosmic-ray antiprotons, positrons, and electrons from interactions of primary cosmic-ray nuclei with the interstellar gas, and to calculations of atmospheric muons and neutrinos. We report absolute spectra at the top of the atmosphere for cosmic-ray protons in the kinetic energy range 0.2-160 GeV and helium nuclei in the range 0.15-80 GeV/nucleon. The corresponding magnetic-rigidity ranges are 0.6-160 GV for protons and 1.1-160 GV for helium. These spectra are compared to measurements from previous BESS flights and from ATIC-2, PAMELA, and AMS-02. We also report the ratio of the proton and helium fluxes from 1.1 to 160 GV and compare this to the ratios from PAMELA and AMS-02.

    DOI: 10.3847/0004-637X/822/2/65

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  • Review of the theoretical and experimental status of dark matter identification with cosmic-ray antideuterons

    T. Aramaki, S. Boggs, S. Bufalino, L. Dal, P. von Doetinchem, F. Donato, N. Fornengo, H. Fuke, M. Grefe, C. Hailey, B. Hamilton, A. Ibarra, J. Mitchell, I. Mognet, R. A. Ong, R. Pereira, K. Perez, A. Putze, A. Raklev, P. Salati, M. Sasaki, G. Tarle, A. Urbano, A. Vittino, S. Wild, W. Xue, K. Yoshimura

    PHYSICS REPORTS-REVIEW SECTION OF PHYSICS LETTERS   618   1 - 37   2016年3月

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    記述言語:英語   出版者・発行元:ELSEVIER  

    Recent years have seen increased theoretical and experimental effort towards the first ever detection of cosmic-ray antideuterons, in particular as an indirect signature of dark matter annihilation or decay. In contrast to indirect dark matter searches using positrons, antiprotons, or gamma-rays, which suffer from relatively high and uncertain astrophysical backgrounds, searches with antideuterons benefit from very suppressed conventional backgrounds, offering a potential breakthrough in unexplored phase space for dark matter. This article is based on the first dedicated cosmic-ray antideuteron workshop, which was held at UCLA in June 2014. It reviews broad classes of dark matter candidates that result in detectable cosmic-ray antideuteron fluxes, as well as the status and prospects of cur rent experimental searches. The coalescence model of antideuteron production and the influence of antideuteron measurements at particle colliders are discussed. This is followed by a review of the modeling of antideuteron propagation through the magnetic fields, plasma currents, and molecular material of our Galaxy, the solar system, the Earth's geomagnetic field, and the atmosphere. Finally, the three ongoing or planned experiments that are sensitive to cosmic-ray antideuterons, BESS, AMS-02, and GAPS, are detailed. As cosmic-ray antideuteron detection is a rare event search, multiple experiments with orthogonal techniques and backgrounds are essential. Therefore, the combination of AMS-02 and GAPS antideuteron searches is highly desirable. Many theoretical and experimental groups have contributed to these studies over the last decade, this review aims to provide the first coherent discussion of the relevant dark matter theories that antideuterons probe, the challenges to predictions and interpretations of antideuteron signals, and the experimental efforts toward cosmic antideuteron detection. (C) 2016 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.physrep.2016.01.002

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  • Simultaneous Measurements of Superradiance at Multiple Wavelength from Helium Excited States: II. Analysis

    Chiaki Ohae, James R. Harries, Hiroshi Iwayama, Kentarou Kawaguchi, Susumu Kuma, Yuki Miyamoto, Mitsuru Nagasono, Kyo Nakajima, Itsuo Nakano, Eiji Shigemasa, Noboru Sasao, Satoshi Uetake, Tomonari Wakabayashi, Akihiro Yoshimi, Koji Yoshimura, Motohiko Yoshimura

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   85 ( 3 )   2016年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    Previous experimental studies of superradiance (SR) in multi-level systems have been explainable using the predictions of the well-known simple two-level SR model. However our recent study [K. Nakajima et al., J. Phys. Soc. Jpn. 84, 054301 (2015)] using EUV free-electron laser excitation of helium atoms, where SR was observed at wavelengths of 502, 668, and 728 nm, revealed behaviour which necessitates a full multi-level treatment of the SR development. In this paper, we report simulations of the initial excitation by the FEL pulses, and the subsequent development of multi-level SR. The results of the simulation reproduce the experimental findings, and reveal that competitive SR on two transitions with a common upper level plays an important role in the development of the system.

    DOI: 10.7566/JPSJ.85.034301

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  • Recent progress of SPAN towards neutrino mass spectroscopy

    T. Masuda, H. Hara, Y. Miyamoto, N. Sasao, M. Tanaka, S. Uetake, A. Yoshimi, K. Yoshimura, M. Yoshimura

    XIV INTERNATIONAL CONFERENCE ON TOPICS IN ASTROPARTICLE AND UNDERGROUND PHYSICS (TAUP 2015), PTS 1-7   718   2016年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:IOP PUBLISHING LTD  

    SPAN (SPectroscopy of Atomic Neutrino) project aims to determine the absolute neutrino mass. The process we plan to use is a cooperative de-excitation of atoms in a metastable level emitting a neutrino pair associated with a photon. The photon energy spectrum of this process contains information on the absolute mass of neutrino. Key items of this experiment are a rate amplification using macro-coherence in a target medium in case of plural particles emission and an external triggering of the emission in order to scan the spectrum. We have demonstrated the rate amplification in two-photon emission from para-hydrogen gas which was coherently excited to its first vibrationally excited state. The coherence in the medium was generated by irradiating two driving laser pulses. The emission was stimulated by irradiating a mid-infrared laser pulse. The enhancement factor of more than 10(18) with respect to the spontaneous emission was achieved. This paper briefly summarizes the results.

    DOI: 10.1088/1742-6596/718/6/062043

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  • Towards a measurement of the nuclear clock transition in Th-229

    Simon Stellmer, Matthias Schreal, Georgy Kazakov, Koji Yoshimura, Thorsten Schumm

    8TH SYMPOSIUM ON FREQUENCY STANDARDS AND METROLOGY 2015   723   2016年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:IOP PUBLISHING LTD  

    We investigate a potential candidate for a future optical clock: the nucleus of the isotope Th-229. Over the past 40 years of research, various experiments have found evidence for the existence of an isomeric state at an energy of a few eV. So far, neither the energy nor the lifetime of the isomer have been determined directly. As the scene is not yet prepared for direct laser excitation, other means of populating the isomer need to be explored. We investigate three different approaches, all of which rely on CaF2 crystals doped with Th-229 or U-233. Various kinds of crystal luminescence are discussed in detail.

    DOI: 10.1088/1742-6596/723/1/012059

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  • 固体パラ水素振動準位を用いたコヒーレント二光子放出の観測

    宮本 祐樹, 原 秀明, 増田 孝彦, 植竹 智, 笹尾 登, 吉見 彰洋, 吉村 浩司, 吉村 太彦

    日本物理学会講演概要集   71   577 - 577   2016年

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    記述言語:日本語   出版者・発行元:一般社団法人 日本物理学会  

    <p>二光子吸収は良く知られた二光子過程であるが、逆過程である二光子放出の、特に固体中での報告は少ない。本研究では、固体パラ水素の振動準位をラマン過程によりコヒーレントに励起、さらに中赤外レーザーを照射することで二光子放出のレートを増幅し、観測することに成功した。固体パラ水素の振動状態は長いデコヒーレンス時間を持つため、中赤外レーザーを励起から100ns以上後に入射しても二光子放出が観測された。</p>

    DOI: 10.11316/jpsgaiyo.71.2.0_577

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  • トリウム229極低エネルギーアイソマー準位探索の進展

    大久保 翔, 岡井 晃一, 岩崎 達郎, 原 秀明, 宮本 祐樹, 増田 孝彦, 植竹 智, 吉見 彰洋, 笹尾 登, 吉村 太彦, 吉村 浩司, 山口 敦史, 瀬戸 誠, 北尾 真司, 小林 康浩, 増田 亮, 依田 芳卓, 笠松 良崇, 重河 優大, 安田 勇輝, 小無 健司, 渡部 信, Stellmer Simon, Schumm Thorsten

    日本物理学会講演概要集   71   181 - 181   2016年

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    記述言語:日本語   出版者・発行元:一般社団法人 日本物理学会  

    <p>Th-229の原子核はeV程度の非常に低いアイソマー準位を持つ。レーザー励起できる唯一の原子核として原子時計や基礎物理への応用が期待されるが、レーザー励起をするためには準位の決定精度が十分でなく、またこれまで脱励起光を直接観測した例はない。この準位を高精度で決定するため、SPring-8の高輝度放射光を用いた核共鳴散乱の手法によりアイソマー準位の一つ上の準位へ励起を行い、その脱励起によるアイソマー準位からの脱励起光の直接観測を行っている。本講演では実験の現状と高時間分解能検出器を用いた核共鳴散乱のデータ取得法について報告する。</p>

    DOI: 10.11316/jpsgaiyo.71.2.0_181

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  • Rate amplification of the two photon emission from para-hydrogen toward the neutrino mass measurement

    Takahiko Masuda, Hideaki Hara, Yuki Miyamoto, Susumu Kuma, Itsuo Nakano, Chiaki Ohae, Noboru Sasao, Minoru Tanaka, Satoshi Uetake, Akihiro Yoshimi, Koji Yoshimura, Motohiko Yoshimura

    HYPERFINE INTERACTIONS   236 ( 1-3 )   73 - 77   2015年11月

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:SPRINGER INTERNATIONAL PUBLISHING AG  

    We recently reported an experiment which focused on demonstrating the macro-coherent amplification mechanism. This mechanism, which was proposed for neutrino mass measurements, indicates that a multi-particle emission rate should be amplified by coherence in a suitable medium. Using a para-hydrogen molecule gas target and the adiabatic Raman excitation method, we observed that the two photon emission rate was amplified by a factor of more than 10(15) from the spontaneous emission rate. This paper briefly summarizes the previous experimental result and presents the current status and the future prospect.

    DOI: 10.1007/s10751-015-1177-1

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  • A 64ch readout module for PPD/MPPC/SiPM using EASIROC ASIC

    Isamu Nakamura, N. Ishijima, K. Hanagaki, K. Yoshimura, Y. Nakai, K. Ueno

    NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT   787   376 - 379   2015年7月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    A readout module for PPD/MPPC/GAPD/SiPM is developed using EASIROC ASIC. The module can handle 64 PPDs and has on-board bias power supply, ADC for energy measurement, 1 ns TDC on FPGA as well as 64ch Logic output for external trigger. Controls and data transfer are through SiTCP technology implemented in FPGA. The module has NIM format for convenience, but can be operated without crate with 5 V AC/DC converter. Basic performance of production module was tested and the results are presented in the poster. (C) 2015 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.nima.2015.01.098

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  • Externally triggered coherent two-photon emission from hydrogen molecules

    Yuki Miyamoto, Hideaki Hara, Takahiko Masuda, Noboru Sasao, Minoru Tanaka, Satoshi Uetake, Akihiro Yoshimi, Koji Yoshimura, Motohiko Yoshimura

    PROGRESS OF THEORETICAL AND EXPERIMENTAL PHYSICS   2015 ( 8 )   2015年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:OXFORD UNIV PRESS INC  

    We report coherent enhancement of two-photon emission from the excited
    vibrational state of molecular hydrogen triggered by irradiating mid-infrared
    pulses externally. We previously observed the two-photon emission triggered by
    the internally generated fourth Stokes photons. By injecting independent
    mid-infrared pulses externally, it is possible to control experimental
    parameters and investigate the mechanism in more detail. In this article, we
    describe the two-photon emission using the external trigger pulses. Its
    spectrum and dependence on the energy and timing of the trigger pulse are
    presented along with numerical simulations based on the Maxwell-Bloch
    equations. The measured number of emitted photons is 6 10^11 photons/pulse and
    the resulting enhancement factor from the spontaneous emission is more than
    10^18. This value is three orders of magnitude higher than that of the previous
    experiment. External control of emission process is expected to be essential
    for observation of weaker process of radiative emission of neutrino pair.

    DOI: 10.1093/ptep/ptv103

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    その他リンク: http://arxiv.org/pdf/1505.07663v1

  • 22pAG-7 水素分子振動準位間のコヒーレント2光子放出III

    植竹 智, 原 秀明, 増田 孝彦, 宮本 祐樹, 中野 逸夫, 笹尾 登, 田中 実, 吉見 彰洋, 吉村 浩司, 吉村 太彦

    日本物理学会講演概要集   70   668 - 668   2015年

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    記述言語:日本語   出版者・発行元:一般社団法人日本物理学会  

    DOI: 10.11316/jpsgaiyo.70.1.0_668

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  • 22aDF-11 SPAN(原子を用いたニュートリノ質量分光実験)のためのマクロコヒーレント増幅機構の詳細研究II

    原 秀明, 増田 孝彦, 宮本 祐樹, 中野 逸夫, 笹尾 登, 田中 実, 植竹 智, 吉見 彰洋, 吉村 浩司, 吉村 太彦

    日本物理学会講演概要集   70   86 - 86   2015年

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    記述言語:日本語   出版者・発行元:一般社団法人日本物理学会  

    DOI: 10.11316/jpsgaiyo.70.1.0_86

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  • Observation of coherent two-photon emission from the first vibrationally-excited state of hydrogen molecules

    Yuki Miyamoto, Hideaki Hara, Susumu Kuma, Takahiko Masuda, Masayuki Katsuragawa, Itsuo Nakano, Chiaki Ohae, Noboru Sasao, Minoru Tanaka, Satoshi Uetake, Akihiro Yoshimi, Koji Yoshimura, Motohiko Yoshimura

    PROGRESS OF THEORETICAL AND EXPERIMENTAL PHYSICS   2014 ( 11 )   2014年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:OXFORD UNIV PRESS INC  

    In this paper, we describe an experiment which was conducted to explore the
    macro-coherent amplification mechanism using a two-photon emission process from
    the first vibrationally-excited state of para-hydrogen molecule. Large
    coherence in the initial state was prepared by the adiabatic Raman population
    transfer method, and the lowest Stokes sideband was used as a trigger field. We
    observed the coherent two-photon emission consistent with the expectation of
    the paired super-radiance master equation.

    DOI: 10.1093/ptep/ptu152

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    その他リンク: http://arxiv.org/pdf/1406.2198v2

  • Time variations of cosmic-ray helium isotopes with BESS-Polar I

    K. Abe, H. Fuke, S. Haino, T. Hams, M. Hasegawa, A. Horikoshi, A. Itazaki, K. C. Kim, T. Kumazawa, A. Kusumoto, M. H. Lee, Y. Makida, S. Matsuda, Y. Matsukawa, K. Matsumoto, J. W. Mitchell, A. A. Moiseev, J. Nishimura, M. Nozaki, R. Orito, J. F. Ormes, N. Picot-Clemente, K. Sakai, M. Sasaki, E. S. Seo, Y. Shikaze, R. Shinoda, R. E. Streitmatter, J. Suzuki, Y. Takasugi, K. Takeuchi, K. Tanaka, N. Thakur, T. Yamagami, A. Yamamoto, T. Yoshida, K. Yoshimura

    ADVANCES IN SPACE RESEARCH   53 ( 10 )   1426 - 1431   2014年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCI LTD  

    The Balloon-borne Experiment with a Superconducting Spectrometer (BESS) is configured with a solenoidal superconducting magnet and a suite of precision particle detectors, including time-of-flight hodoscopes based on plastic scintillators, a silica-aerogel Cherenkov detector, and a high resolution tracking system with a central jet-type drift chamber. The charges of incident particles are determined from energy losses in the scintillators. Their magnetic rigidities (momentum/charge) are measured by reconstructing each particle trajectory in the magnetic field, and their velocities are obtained by using the time-of-flight system. Together, these measurements can accurately identify helium isotopes among the incoming cosmic-ray helium nuclei up to energies in the GeV per nucleon region. The BESS-Polar I instrument flew for 8.5 days over Antarctica from December 13th to December 21st, 2004. Its long-duration flight and large geometric acceptance allow the time variations of isotopic fluxes to be studied for the first time. The time variations of helium isotope fluxes are presented here for rigidities from 1.2 to 2.5 GV and results are compared to previously reported proton data and neutron monitor data. Published by Elsevier Ltd. on behalf of COSPAR.

    DOI: 10.1016/j.asr.2013.09.028

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  • Production of Ba Metastable State via Superradiance

    Chiaki Ohae, Atsushi Fukumi, Susumu Kuma, Yuki Miyamoto, Kyo Nakajima, Itsuo Nakano, Hajime Nanjo, Noboru Sasao, Satoshi Uetake, Tomonari Wakabayashi, Akihiro Yoshimi, Koji Yoshimura, Motohiko Yoshimura

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   83 ( 4 )   2014年4月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PHYSICAL SOC JAPAN  

    We describe in this paper a fast and efficient method of producing a high density of barium (Ba) atoms in the D-1(2) metastable state, which is a candidate initial state for a new class of cooperative and coherent optical process called paired superradiance (PSR). In the experiment, Ba atoms are excited first by laser light to the P-1(1) state and then brought to the desired state D-1(2) via radiative transition in the superradiance (SR) mode. It is found that a production efficiency (from S-1(0) to D-1(2)) of more than similar to 30% is achieved within a time interval of a few nanoseconds for a Ba density n > 10(19) m(-3). Several key features of SR important for future PSR experiments are also studied.

    DOI: 10.7566/JPSJ.83.044301

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  • Cosmic ray H-2/H-1 ratio measured from BESS in 2000 during solar maximum

    K. C. Kim, K. Abe, H. Fuke, T. Hams, M. H. Lee, Y. Makida, S. Matsuda, J. W. Mitchell, J. Nishimura, J. F. Ormes, M. Sasaki, E. S. Seo, Y. Shikaze, R. E. Streitmatter, J. Suzuki, K. Tanaka, T. Yamagami, A. Yamamoto, T. Yoshida, K. Yoshimura

    ADVANCES IN SPACE RESEARCH   51 ( 2 )   234 - 237   2013年1月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCI LTD  

    The Balloon-borne Experiment with a Superconducting Spectrometer (BESS) was flown from Lynn Lake, Manitoba, Canada in August, 2000, during the maximum solar modulation period, with an average residual atmospheric overburden of 4.3 g/cm(2). Precise spectral measurements of cosmic ray hydrogen isotopes from 0.178 GeV/n to 1.334 GeV/n were made during the 28.7 h of flight. This paper presents the measured energy spectra and their ratio, H-2/H-1. The results are also compared with previous measurements and theoretical predictions. (c) 2012 COSPAR. Published by Elsevier Ltd. All rights reserved.

    DOI: 10.1016/j.asr.2012.01.015

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  • Search for cosmic-ray antiproton origins and for cosmological antimatter with BESS

    A. Yamamoto, J. W. Mitchell, K. Yoshimura, K. Abe, H. Fuke, S. Haino, T. Hams, M. Hasegawa, A. Horikoshi, A. Itazaki, K. C. Kim, T. Kumazawa, A. Kusumoto, M. H. Lee, Y. Makida, S. Matsuda, Y. Matsukawa, K. Matsumoto, A. A. Moiseev, Z. Myers, J. Nishimura, M. Nozaki, R. Orito, J. F. Ormes, K. Sakai, M. Sasaki, E. S. Seo, Y. Shikaze, R. Shinoda, R. E. Streitmatter, J. Suzuki, Y. Takasugi, K. Takeuchi, K. Tanaka, T. Taniguchi, N. Thakur, T. Yamagami, T. Yoshida

    ADVANCES IN SPACE RESEARCH   51 ( 2 )   227 - 233   2013年1月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCI LTD  

    The balloon-borne experiment with a superconducting spectrometer (BESS) has performed cosmic-ray observations as a US-Japan cooperative space science program, and has provided fundamental data on cosmic rays to study elementary particle phenomena in the early Universe. The BESS experiment has measured the energy spectra of cosmic-ray antiprotons to investigate signatures of possible exotic origins such as dark matter candidates or primordial black holes, and searched for heavier antinuclei that might reach Earth from antimatter domains formed in the early Universe. The apex of the BESS program was reached with the Antarctic flight of BESS-Polar II, during the 2007-2008 Austral Summer, that obtained over 4.7 billion cosmic-ray events from 24.5 days of observation. The flight took place at the expected solar minimum, when the sensitivity of the low-energy antiproton measurements to a primary source is greatest. Here, we report the scientific results, focusing on the long-duration flights of BESS-Polar I (2004) and BESS-Polar II (2007-2008). (c) 2011 COSPAR. Published by Elsevier Ltd. All rights reserved.

    DOI: 10.1016/j.asr.2011.07.012

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  • Development of a tracking detector system with multichannel scintillation fibers and PPD

    R. Honda, S. Callier, S. Hasegawa, M. Ieiri, Y. Matsumoto, K. Miwa, I. Nakamura, L. Raux, C. De La Taille, M. Tanaka, T. Uchida, K. Yoshimura

    NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT   695   206 - 209   2012年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    For the J-PARC E40 experiment which aims to measure differential cross-sections of Sigma p scatterings, a system to detect scattered proton from Sigma p scatterings is under development. The detection system consists of scintillation fibers with a MPPC readout. A prototype and a readout electronics for MPPC have already been developed. The prototype consisting of a scintillation fiber tracker and a BGO calorimeter was tested with a proton beam of 80 MeV. Energy resolutions of the tracker of 22.0% (sigma) and the calorimeter of 1.0% (sigma) were obtained for 1 MeV and 70 MeV energy deposit, respectively. The prototype readout electronics has an ASIC for multichannel operation. EASIROC, and a Silicon TCP (SiTCP) interface to communicate with a DAQ system. Its data transfer rate measured was 14 kHz. Required performances for the prototype system have been achieved except for the energy resolution of the prototype fiber tracker. (C) 2011 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.nima.2011.10.005

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  • Multi-wavelength study of PPDs using an OPO tunable pulse laser microscope system

    Koji Yoshimura, Isamu Nakamura

    NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT   695   197 - 201   2012年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    We have developed a new pulsed laser microscope system whose wavelength is continuously tunable from 410 nm to 2200 nm by using an optical parametric oscillator (OPO) laser system. The laser spot can be focused to similar to 2 mu m diameter, small enough to measure pixel-by-pixel performance of PPDs (pixelated photon detectors). Using multi-wavelength laser light, we plan to probe PPDs at various depths, thanks to their different penetration lengths in the silicon layer. In this paper, details of the commissioning of the laser microscope system and pilot measurements on a PPD at several wavelengths will be presented. (C) 2011 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.nima.2011.11.053

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  • The MICE Muon Beam on ISIS and the beam-line instrumentation of the Muon Ionization Cooling Experiment

    M. Bogomilov, Y. Karadzhov, D. Kolev, I. Russinov, R. Tsenov, G. Vankova-Kirilova, L. Wang, F. Y. Xu, S. X. Zheng, R. Bertoni, M. Bonesini, F. Ferri, G. Lucchini, R. Mazza, F. Paleari, F. Strati, V. Palladino, G. Cecchet, A. de Bari, M. Capponi, A. Cirillo, A. Iaciofano, A. Manfredini, M. Parisi, D. Orestano, F. Pastore, A. Tonazzo, L. Tortora, Y. Mori, Y. Kuno, H. Sakamoto, A. Sato, T. Yano, M. Yoshida, S. Ishimoto, S. Suzuki, K. Yoshimura, F. Filthaut, R. Garoby, S. Gilardoni, P. Gruber, K. Hanke, H. Haseroth, P. Janot, A. Lombardi, S. Ramberger, M. Vretenar, P. Bene, A. Blondel, F. Cadoux, J. -S. Graulich, V. Grichine, E. Gschwendtner, F. Masciocchi, R. Sandstrom, V. Verguilov, H. Wisting, C. Petitjean, R. Seviour, J. Alexander, G. Charnley, N. Collomb, S. Griffiths, B. Martlew, A. Moss, I. Mullacrane, A. Oates, P. Owens, C. White, S. York, D. Adams, R. Apsimon, P. Barclay, D. E. Baynham, T. W. Bradshaw, M. Courthold, P. Drumm, R. Edgecock, T. Hayler, M. Hills, Y. Ivaniouchenkov, A. Jones, A. Lintern, C. MacWaters, C. Nelson, A. Nichols, R. Preece, S. Ricciardi, J. H. Rochford, C. Rogers, W. Spensley, J. Tarrant, K. Tilley, S. Watson, A. Wilson, D. Forrest, F. J. P. Soler, K. Walaron, P. Cooke, R. Gamet, A. Alekou, M. Apollonio, G. Barber, R. Beuselinck, D. Clark, I. Clark, D. Colling, A. Dobbs, P. Dornan, S. Fayer, A. Fish, R. Hare, S. Greenwood, A. Jamdagni, V. Kasey, M. Khaleeq, J. Leaver, K. Long, E. McKigney, T. Matsushita, J. Pasternak, T. Sashalmi, T. Savidge, M. Takahashi, V. Blackmore, T. Carlisle, J. H. Cobb, W. Lau, M. Rayner, C. D. Tunnell, H. Witte, S. Yang, C. N. Booth, P. Hodgson, L. Howlett, R. Nicholson, E. Overton, M. Robinson, P. Smith, D. Adey, J. Back, S. Boyd, P. Harrison, M. Ellis, P. Kyberd, M. Littlefield, J. J. Nebrensky, A. D. Bross, S. Geer, D. Neuffer, A. Moretti, M. Popovic, M. A. C. Cummings, T. J. Roberts, A. DeMello, M. A. Green, D. Li, S. Virostek, M. S. Zisman, B. Freemire, P. Hanlet, D. Huang, G. Kafka, D. M. Kaplan, P. Snopok, Y. Torun, S. Blot, Y. K. Kim, U. Bravar, Y. Onel, D. Cline, Y. Fukui, K. Lee, X. Yang, R. A. Rimmer, L. M. Cremaldi, G. Gregoire, T. L. Hart, D. A. Sanders, D. J. Summers, L. Coney, R. Fletcher, G. G. Hanson, C. Heidt, J. Gallardo, S. Kahn, H. Kirk, R. B. Palmer

    JOURNAL OF INSTRUMENTATION   7   2012年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IOP PUBLISHING LTD  

    The international Muon Ionization Cooling Experiment (MICE), which is under construction at the Rutherford Appleton Laboratory (RAL), will demonstrate the principle of ionization cooling as a technique for the reduction of the phase-space volume occupied by a muon beam. Ionization cooling channels are required for the Neutrino Factory and the Muon Collider. MICE will evaluate in detail the performance of a single lattice cell of the Feasibility Study 2 cooling channel. The MICE Muon Beam has been constructed at the ISIS synchrotron at RAL, and in MICE Step I, it has been characterized using the MICE beam-instrumentation system. In this paper, the MICE Muon Beam and beam-line instrumentation are described. The muon rate is presented as a function of the beam loss generated by the MICE target dipping into the ISIS proton beam. For a 1 V signal from the ISIS beam-loss monitors downstream of our target we obtain a 30 KHz instantaneous muon rate, with a neglible pion contamination in the beam.

    DOI: 10.1088/1748-0221/7/05/P05009

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  • Search for Antihelium with the BESS-Polar Spectrometer

    K. Abe, H. Fuke, S. Haino, T. Hams, M. Hasegawa, A. Horikoshi, A. Itazaki, K. C. Kim, T. Kumazawa, A. Kusumoto, M. H. Lee, Y. Makida, S. Matsuda, Y. Matsukawa, K. Matsumoto, J. W. Mitchell, Z. Myers, J. Nishimura, M. Nozaki, R. Orito, J. F. Ormes, K. Sakai, M. Sasaki, E. S. Seo, Y. Shikaze, R. Shinoda, R. E. Streitmatter, J. Suzuki, Y. Takasugi, K. Takeuchi, K. Tanaka, N. Thakur, T. Yamagami, A. Yamamoto, T. Yoshida, K. Yoshimura

    PHYSICAL REVIEW LETTERS   108 ( 13 )   2012年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER PHYSICAL SOC  

    In two long-duration balloon flights over Antarctica, the Balloon-borne Experiment with a Superconducting Spectrometer (BESS) collaboration has searched for antihelium in the cosmic radiation with the highest sensitivity reported. BESS-Polar I flew in 2004, observing for 8.5 days. BESS-Polar II flew in 2007-2008, observing for 24.5 days. No antihelium candidate was found in BESS-Polar I data among 8.4 x 10(6) vertical bar Z vertical bar = 2 nuclei from 1.0 to 20 GV or in BESS-Polar II data among 4: 0 x 10(7) vertical bar Z vertical bar = 2 nuclei from 1.0 to 14 GV. Assuming antihelium to have the same spectral shape as helium, a 95% confidence upper limit to the possible abundance of antihelium relative to helium of 6.9 x 10(-8) was determined combining all BESS data, including the two BESS-Polar flights. With no assumed antihelium spectrum and a weighted average of the lowest antihelium efficiencies for each flight, an upper limit of 1.0 x 10(-7) from 1.6 to 14 GV was determined for the combined BESS-Polar data. Under both antihelium spectral assumptions, these are the lowest limits obtained to date.

    DOI: 10.1103/PhysRevLett.108.131301

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  • Measurement of the Cosmic-Ray Antiproton Spectrum at Solar Minimum with a Long-Duration Balloon Flight over Antarctica

    K. Abe, H. Fuke, S. Haino, T. Hams, M. Hasegawa, A. Horikoshi, K. C. Kim, A. Kusumoto, M. H. Lee, Y. Makida, S. Matsuda, Y. Matsukawa, J. W. Mitchell, J. Nishimura, M. Nozaki, R. Orito, J. F. Ormes, K. Sakai, M. Sasaki, E. S. Seo, R. Shinoda, R. E. Streitmatter, J. Suzuki, K. Tanaka, N. Thakur, T. Yamagami, A. Yamamoto, T. Yoshida, K. Yoshimura

    PHYSICAL REVIEW LETTERS   108 ( 5 )   2012年1月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER PHYSICAL SOC  

    The energy spectrum of cosmic-ray antiprotons ((p) over bar 's) from 0.17 to 3.5 GeV has been measured using 7886 (p) over bar 's detected by BESS-Polar II during a long-duration flight over Antarctica near solar minimum in December 2007 and January 2008. This shows good consistency with secondary (p) over bar calculations. Cosmologically primary (p) over bar 's have been investigated by comparing measured and calculated (p) over bar spectra. BESS-Polar II data show no evidence of primary (p) over bar 's from the evaporation of primordial black holes.

    DOI: 10.1103/PhysRevLett.108.051102

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  • The design, construction and performance of the MICE scintillating fibre trackers

    M. Ellis, P. R. Hobson, P. Kyberd, J. J. Nebrensky, A. Bross, J. Fagan, T. Fitzpatrick, R. Flores, R. Kubinski, J. Krider, R. Rucinski, P. Rubinov, C. Tolian, T. L. Hart, D. M. Kaplan, W. Luebke, B. Freemire, M. Wojcik, G. Barber, D. Clark, I. Clark, P. J. Dornan, A. Fish, S. Greenwood, R. Hare, A. Jamdagni, V. Kasey, M. Khaleeq, J. Leaver, K. R. Long, E. McKigney, T. Matsushita, C. Rogers, T. Sashalmi, P. Savage, M. Takahashi, A. Tapper, K. Yoshimura, P. Cooke, R. Gamet, H. Sakamoto, Y. Kuno, A. Sato, T. Yano, M. Yoshida, C. MacWaters, L. Coney, G. Hanson, A. Klier, D. Cline, X. Yang, D. Adey

    NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT   659 ( 1 )   136 - 153   2011年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    Charged-particle tracking in the international Muon Ionisation Cooling Experiment (MICE) will be performed using two solenoidal spectrometers, each instrumented with a tracking detector based on 350 mu m diameter scintillating fibres. The design and construction of the trackers is described along with the quality-assurance procedures, photon-detection system, readout electronics, reconstruction and simulation software and the data-acquisition system. Finally, the performance of the MICE tracker, determined using cosmic rays, is presented. (C) 2011 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.nima.2011.04.041

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  • Search for Novel Origins of Cosmic-ray Antiprotons and Antimatter with BESS-Polar Flight over Antarctica.

    Koji Yoshimura, S. Haino, M. Hasegawa, A. Horikoshi, T. Kumazawa, Y. Makida, S. Matsuda, K. Matsumoto, M. Nozaki, J. Suzuki, K. Tanaka, A. Yamamoto, T. Hams, J. W. Mitchell, A. A. Moiseev, R. E. Streitmatter, M. Sasaki, K. Abe, Itazaki, Y. Matsukawa, Y. Shikaze, R. Orito, Y. Takasugi, K. Takeuchi, H. Fuke, T. Yamagami, T. Yoshida, K. C. Kim, M. H. Lee, Z. Myers, E. S. Seo, J. Nishimura, K. Sakai, R. Shinoda, J. F. Ormes, N. Thakur

    35TH INTERNATIONAL CONFERENCE OF HIGH ENERGY PHYSICS (ICHEP 2010)   2010年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:SCUOLA INT SUPERIORE STUDI AVANZATI-SISSA  

    The primary aims of the BESS-Polar program are precise measurements of the low-energy antiproton spectrum and search for cosmologically significant antimatter, which would provide new clues to understand the early Universe. The second flight (BESS-Polar II) over Antarctica was successfully carried out in Dec 2007 - Jan 2008. We performed 24.5days scientific observation just at the solar minimum. The payload worked well during the flight and 4.7 billion cosmic-ray events were collected. Based on the BESS-Polar II data, we present recent preliminary results of cosmic-ray antiproton measurements and sensitive search for antimatter.

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  • Accelerator design concept for future neutrino facilities

    M. Apollonio, J. S. Berg, A. Blondel, A. Bogacz, S. Brooks, J. -E. Campagne, D. Caspar, C. Cavata, P. Chimenti, J. Cobb, M. Dracos, R. Edgecock, I. Efthymiopoulos, A. Fabich, R. Fernow, F. Filthaut, J. Gallardo, R. Garoby, S. Geer, F. Gerigk, G. Hanson, R. Johnson, C. Johnstone, D. Kaplan, E. Keil, H. Kirk, A. Klier, A. Kurup, J. Lettry, K. Long, S. Machida, K. McDonald, F. Meot, Y. Mori, D. Neuffer, V. Palladino, R. Palmer, K. Paul, A. Poklonskiy, M. Popovic, C. Prior, G. Rees, C. Rossi, T. Rovelli, R. Sandstroem, R. Sevior, P. Sievers, N. Simos, Y. Torun, M. Vretenar, K. Yoshimura, M. S. Zisman

    JOURNAL OF INSTRUMENTATION   4   2009年7月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IOP PUBLISHING LTD  

    This document summarizes the work of the Accelerator Working Group (AWG) of the International Scoping Study (ISS) of a Future Neutrino Factory and Superbeam Facility. The main goal of the activity was to reach consensus on a baseline design for a Neutrino Factory complex, including proton driver parameters, choice of target, front-end design, acceleration system design, and decay ring geometry. Another goal was to explore the commonality, if any, between the proton driver for a Neutrino Factory and those for a Superbeam or Beta Beam facility. In general, the requirements for either of the latter facilities are less stringent than those for a Neutrino Factory. Here, we discuss concepts, parameters, and expected performance of the required subsystems for our chosen baseline design of a Neutrino Factory. We also give an indication of the main R&D tasks-many of which are already under way-that must be carried out to finalize facility design approaches.

    DOI: 10.1088/1748-0221/4/07/P07001

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  • The BESS-Polar Ultra-Thin Superconducting Solenoid Magnet and Its Operational Characteristics During Long-Duration Scientific Ballooning Over Antarctica

    Yasuhiro Makida, Akira Yamamoto, Koji Yoshimura, Ken-ichi Tanaka, Jun'ichi Suzuki, Shinya Matsuda, Masata Hasegawa, Atsushi Horikoshi, Ryoko Shinoda, Kenichi Sakai, Shoichi Mizumaki, Reiko Orito, Yousuke Matsukawa, Akira Kusumoto, John W. Mitchell, Robert E. Streitmatter, Thomas Hams, Makoto Sasaki, Neeharika Thakur

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   19 ( 3 )   1315 - 1319   2009年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC  

    An ultra-thin superconducting solenoid has been developed for a cosmic-ray spectrometer ballooning over Antarctica, which is named BESS-Polar II. The coil with a diameter of 0.9 m, a length of 1.4 m and a thickness of 3.5 mm, is wound with high-strength aluminum stabilized superconductor and provides 0.8 T in the spectrometer. Based on the experience at the BESS-Polar-I solenoid flight for nine days in 2004, the BESS-Polar-II solenoid, which was cryogenically improved, realized a persistent current mode operation for 25 days in the second flight campaign in December 2007 though January 2008. It has contributed to accumulate the cosmic-ray observation data with 4700 million events and 16 terabyte in a hard disk unit. This report will describe the second solenoid performance during the flight.

    DOI: 10.1109/TASC.2009.2017946

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  • Measurement of the cosmic-ray low-energy antiproton spectrum with the first BESS-Polar Antarctic flight

    K. Abe, H. Fuke, S. Haino, T. Hams, A. Itazaki, K. C. Kim, T. Kumazawa, M. H. Lee, Y. Makida, S. Matsuda, K. Matsumoto, J. W. Mitchell, A. A. Moiseev, Z. Myers, J. Nishimura, M. Nozaki, R. Orito, J. F. Ormes, M. Sasaki, E. S. Seo, Y. Shikaze, R. E. Streitmatter, J. Suzuki, Y. Takasugi, K. Takeuchi, K. Tanaka, T. Yamagami, A. Yamamoto, T. Yoshida, K. Yoshimura

    PHYSICS LETTERS B   670 ( 2 )   103 - 108   2008年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER  

    The BESS-Polar spectrometer had its first successful balloon flight over Antarctica in December 2004. During the 8.5-day long-duration flight, almost 0.9 billion events were recorded and 1,520 antiprotons were detected in the energy range 0.1-4.2 GeV. In this Letter, we report the antiproton spectrum obtained, discuss the origin of cosmic-ray antiprotons, and use antiproton data to probe the effect of charge-sign-dependent drift in the solar modulation. (C) 2008 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.physletb.2008.10.053

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  • BESS-Polar experiment: Progress and future prospects

    K. Yoshimura, K. Abe, H. Fuke, S. Haino, T. Hams, M. Hasegawa, A. Horikoshi, K. C. Kim, T. Kumazawa, A. Kusumoto, M. -H. Lee, Y. Makida, S. Matsuda, Y. Matsukawa, J. W. Mitchell, A. A. Moiseev, J. Nishimura, M. Nozaki, R. Orito, J. F. Ormes, K. Sakai, M. Sasaki, E. S. Seo, Y. Shikaze, R. Shinoda, R. E. Streitmatter, J. Suzuki, K. Takeuchi, N. Thakur, K. Tanaka, T. Yamagami, A. Yamamoto, T. Yoshida

    ADVANCES IN SPACE RESEARCH   42 ( 10 )   1664 - 1669   2008年11月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCI LTD  

    The first scientific flight of the BESS-Polar balloon-borne experiment was successfully carried out in December 2004 from Antarctica with the primary scientific objectives of searching for primordial antiparticles from the universe and making precision measurements of primary cosmic-ray fluxes. During the 8.5 day flight, the newly developed BESS-Polar spectrometer worked well and gathered data from 9 x 10(8) cosmic-ray events, showing its capability for making long-duration science observations. We have already started hardware development for the second experiment, which is expected to be a flight of more than 20 days during the next solar minimum period with the upgraded spectrometer. In this manuscript, progress on and prospects for the BESS-Polar experiment are described. (C) 2008 Published by Elsevier Ltd on behalf of COSPAR.

    DOI: 10.1016/j.asr.2007.05.048

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  • Search for antihelium: Progress with BESS

    M. Sasaki, S. Haino, K. Abe, H. Fuke, T. Hams, K. C. Kim, M. H. Lee, Y. Makida, S. Matsuda, J. W. Mitchell, A. A. Moiseev, J. Nishimura, M. Nozaki, S. Orito, J. F. Ormes, T. Sanuki, E. S. Seo, Y. Shikaze, R. E. Streitmatter, J. Suzuki, K. Tanaka, T. Yamagami, A. Yamamoto, T. Yoshida, K. Yoshimura

    ADVANCES IN SPACE RESEARCH   42 ( 3 )   450 - 454   2008年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCI LTD  

    In this paper, we report searches for antilielium in cosmic rays using two recently flown magnetic rigidity spectrometers. BESS-TeV had extended rigidity with all MDR of 1.4 TV and had a flight duration of one day. BESS-Polar was optimized for collecting power. It was flown for 8.5 days and had an MDR of 240 GV. Tile former flight allows us to explore a previously unexplored rigidity band and the latter flight yields a factor of three improvement in the overall BESS limit. No antilielium candidate was found in the rigidity ranges of 1-500 GV, and 0.6-20 GV, among 7 x 10(4) events taken with BESS-TeV, and 8 X 10(6) events taken with BESS-Polar, respectively. (c) 2007 COSPAR. Published by Elsevier Ltd. All rights reserved.

    DOI: 10.1016/j.asr.2007.09.012

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  • Search for primordial antiparticles with BESS

    A. Yamamoto, K. Abe, H. Fuke, S. Haino, T. Hams, M. Hasegawa, A. Horikoshi, K. C. Kim, A. Kusumoto, M. H. Lee, Y. Makida, S. Matsuda, Y. Matsukawa, J. W. Mitchell, A. Moiseev, J. Nishimura, M. Nozaki, R. Orito, S. Orito, J. F. Ormes, K. Sakai, T. Sanuki, M. Sasaki, E. S. Seo, Y. Shikaze, R. Shinoda, R. E. Streitmatter, J. Suzuki, K. Tanaka, N. Thakur, T. Yamagami, T. Yoshida, K. Yoshimura

    ADVANCES IN SPACE RESEARCH   42 ( 3 )   442 - 449   2008年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCI LTD  

    The Balloon-borne Experiment with a Superconducting Spectrometer (BESS) has been carried out to search for primordial antiparticles in cosmic rays. In ten flights from 1993 to 2004, it measured the cosmic-ray.antiproton spectrum in the energy range 0.1-4.2 GeV at various solar activity conditions. It also searched for antideuterons and antilielium nuclei, and it made precise measurement of cosmicray particle spectra. The BESS program has been extended to long duration balloon (LDB) flights in Antarctica (BESS-Polar) with the goal of achieving unprecedented sensitivity in the search for primordial antiparticles. This report describes recent results from BESS and progress of the BESS-Polar program. (c) 2008 Published by Elsevier Ltd on behalf of COSPAR.

    DOI: 10.1016/j.asr.2007.04.069

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  • Irradiation damage studies of high power accelerator materials

    N. Simos, H. G. Kirk, P. Thieberger, H. Ludewig, J. O. Conor, L. Mausner, P. -T. Trung, K. T. McDonald, K. Yoshimura, J. R. J. Bennett

    JOURNAL OF NUCLEAR MATERIALS   377 ( 1 )   41 - 51   2008年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    High-performance production targets and other critical accelerator components intercepting intense, energetic proton beams are essential as the accelerator community envisions the next generation, multi-MW accelerators. Materials that have served the nuclear sector well may not be suitable to play such a role which demands that the material comprising the beam-intercepting element must, in addition to the long exposure which leads to accumulated irradiation damage, also endure short exposure that manifests itself as thermo-mechanical shock. The ability of materials to resist irradiation-induced degradation of its properties that control shock and fatigue is of primary interest. The need for such materials that extend beyond resistance to the neutron-driven irradiation damage of reactor components has led to an extensive search and experimentation with new alloys and composites. These new high-performance materials, which appear to possess the right combination of mechanical and physical properties, are explored through a multi-phased experimental study at Brookhaven National Laboratory (BNL). This study, which brings together the interest in accelerator targets of different facilities around the world, seeks to simulate conditions of both short and long exposure to proton beams to assess the survivability potential of these new alloys and composite materials. While thermo-mechanical shock effects have been studied in the early stages of this comprehensive effort, it is irradiation damage that is currently the focus of the study and results to-date are presented in this paper along with the status and objectives of ongoing studies. Of special interest are results depicting damage reversal through post-irradiation annealing in some of the materials. High fluences of 200 and/or 117 MeV protons provided by the BNL Linac beam that serves the isotope Production Facility were used to assess irradiation damage in these new composites and alloys. (c) 2008 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.jnucmat.2008.02.074

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  • Search for fractionally charged particles in cosmic rays with the BESS spectrometer

    H. Fuke, Y. Tasaki, K. Abe, S. Haino, Y. Makida, S. Matsuda, J. W. Mitchell, A. A. Molseev, J. Nishimura, M. Nozaki, S. Orito, J. F. Ormes, M. Sasaki, E. S. Seo, Y. Shikaze, R. E. Streitmatter, J. Suzuki, K. Tanaka, T. Yamagami, A. Yamamoto, T. Yoshida, K. Yoshimura

    ADVANCES IN SPACE RESEARCH   41 ( 12 )   2050 - 2055   2008年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCI LTD  

    Historically, there are been many searches for fractionally charged particles in the cosmic radiation. However, few searches have been performed near the top of the atmosphere. We performed a search for relativistic 2/3e charged particles in cosmic rays using data collected during four BESS balloon flights from 1997 to 2000 carried out in northern Canada. The data were analyzed by examining energy deposition in the time-of-flight scintillator hodoscopes. No candidate was found. We derive an upper limit of 4.5 x 10(-7) (cm(2) s sr)(-1) for the flux of 2,e charged particles, at the 90% confidence level. (C) 2007 COSPAR. Published by Elsevier Ltd. All rights reserved.

    DOI: 10.1016/j.asr.2007.02.042

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  • Development and study of the multi pixel photon counter

    S. Gomi, H. Hano, T. Iijima, S. Itoh, K. Kawagoe, S. H. Kim, T. Kubota, T. Maeda, T. Matsumura, Y. Mazuka, K. Miyabayashi, H. Miyata, T. Murakami, T. Nakadaira, T. Nakaya, H. Otono, E. Sano, T. Shinkawa, Y. Sudo, T. Takeshita, M. Taguchi, T. Tsubokawa, S. Uozumi, M. Yamaoka, H. Yamazaki, M. Yokoyama, K. Yoshimura, T. Yoshioka

    NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT   581 ( 1-2 )   427 - 432   2007年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    The Multi pixel Photon Counter is a novel semiconductor photon sensor which consist of 100-1600 micro APD pixels. Each piel works in limited Geiger mode with an inverse bias voltage around 80 V. The MPPC has many remarkable features such as high gain, large photon detection efficiency, low cost and tolerance for magnetic field. Fundamental properties, such as the gain, dark noise rate and inter-pixel cross-talk, have been measured with three different samples which have 100, 400, and 1600 pixels. Variation of the gain over 750 samples, and uniformity of the gain and photon sensitivity within one pixel are also evaluated. As the result of the tests, it is confirmed that the MPPC has satisfactory performance for many appplications, not only for high energy physics experiments but also for medical engineering systems. (C) 2007 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.nima.2007.08.020

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  • Measurements of 0.2-20 GeV/n cosmic-ray proton and helium spectra from 1997 through 2002 with the BESS spectrometer

    Y. Shikaze, S. Haino, K. Abe, H. Fuke, T. Hams, K. C. Kim, Y. Makida, S. Matsuda, J. W. Mitchell, A. A. Moiseev, J. Nishimura, M. Nozaki, S. Orito, J. F. Ormes, T. Sanuki, M. Sasaki, E. S. Seo, R. E. Streitmatter, J. Suzuki, K. Tanaka, T. Yamagami, A. Yamamoto, T. Yoshida, K. Yoshimura

    ASTROPARTICLE PHYSICS   28 ( 1 )   154 - 167   2007年9月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER  

    We measured low energy cosmic-ray proton and helium spectra in the kinetic energy range 0.215-21.5 GeV/n at different solar activities during a period from 1997 to 2002. The observations were carried out with the BESS spectrometer launched on a balloon at Lynn Lake, Canada. A calculation for the correction of secondary particle backgrounds from the overlying atmosphere was improved by using the measured spectra at small atmospheric depths ranging from 5 through 37 g/cm(2). The uncertainties including statistical and systematic errors of the obtained spectra at the top of atmosphere are 5-7% for protons and 6-9% for helium nuclei in the energy range 0.5-5 GeV/n. (C) 2007 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.astropartphys.2007.05.001

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  • The BESS program

    A. Yamamoto, K. Abe, H. Fuke, S. Haino, T. Hams, K. Kim, M. H. Lee, Y. Makida, S. Matsuda, J. W. Mitchell, A. Moiseev, J. Nishimura, M. Nozaki, R. Orito, S. Orito, J. F. Ormes, K. Sakai, T. Sanuki, M. Sasaki, E. S. Seo, Y. Shikaze, R. E. Streitmatter, J. Suzuki, K. Tanaka, N. Thakur, T. Yamagami, T. Yoshida, K. Yoshimura

    NUCLEAR PHYSICS B-PROCEEDINGS SUPPLEMENTS   166   62 - 67   2007年4月

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:ELSEVIER  

    The Balloon-Born Experiment with a Superconducting Spectrometer (BESS) has measured cosmic-ray spectra blow 1 TeV and searched for antiparticle of novel cosmic origin. The BESS program is extended to long duration balloon (LDB) flights in Antarctica (BESS-Polar) aiming at unprecedented sensitivity to search for primordial antiparticles. This report describes recent results from BESS and the progress in the BESS-Polar program.

    DOI: 10.1016/j.nuclphysbps.2006.12.092

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  • Measurements of proton, helium and muon spectra at small atmospheric depths with the BESS spectrometer (vol 564, pg 8, 2003)

    K. Abe, T. Sanuki, K. Anraku, Y. Asaoka, H. Fuke, S. Haino, N. Ikeda, M. Imori, K. Izumi, T. Maeno, Y. Makida, S. Matsuda, N. Matsui, T. Matsukawa, H. Matsumoto, J. W. Mitchell, A. A. Moiseev, J. Nishimura, M. Nozaki, S. Orito, J. E. Ormes, M. Sasaki, E. S. Seo, Y. Shikaze, T. Sonoda, R. E. Streitmatter, J. Suzuki, K. Tanaka, K. Tanizaki, T. Yamagami, A. Yamamoto, Y. Yamamoto, K. Yamato, T. Yoshida, K. Yoshimura

    PHYSICS LETTERS B   645 ( 5-6 )   472 - 475   2007年2月

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    記述言語:英語   出版者・発行元:ELSEVIER SCIENCE BV  

    DOI: 10.1016/j.physletb.2006.12.046

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  • Solid target studies for muon colliders and neutrino beams

    N Simos, H Kirk, H Ludewig, P Thieberger, WT Weng, PT Trung, K McDonald, J Sheppard, K Yoshimura, Y Hayato

    NUCLEAR PHYSICS B-PROCEEDINGS SUPPLEMENTS   155   288 - 290   2006年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    This paper presents preliminary results from an ongoing post-irradiation analysis of materials that have been irradiated at the Brookhaven National Laboratory (BNL) Isotope facility. The effort is part of an experimental study that focuses on how prone to irradiation damage these materials are and thus what is their potential in playing the role of high power targets in the neutrino superbeam and the muon collider initiatives.

    DOI: 10.1016/j.nuclphysbps.2006.02.077

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  • Measurements of atmospheric antiprotons

    K Yamato, K Abe, H Fuke, S Haino, Y Makida, S Matsuda, H Matsumoto, JW Mitchell, AA Moiseev, J Nishimura, M Nozaki, S Orito, JF Ormes, T Sanuki, M Sasaki, ES Seo, Y Shikaze, RE Streitmatter, J Suzuki, K Tanaka, T Yamagami, A Yamamoto, T Yoshida, K Yoshimura

    PHYSICS LETTERS B   632 ( 4 )   475 - 479   2006年1月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER  

    We measured atmospheric antiproton spectra in the energy range 0.2 to 3.4 GeV, at sea level and at balloon altitude in the atmospheric depth range 4.5 to 26 g/cm(2). The observed energy spectra, including our previous measurements at mountain altitude, were compared with estimated spectra calculated on various assumptions regarding the energy distribution of antiprotons that interacted with air nuclei. (c) 2005 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.physletb.2005.11.042

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  • Development of multi-pixel photon counters

    S. Gomi, M. Taguchi, H. Hano, S. Itoh, T. Kubota, X. Maeda, Y. Mazuka, H. Otono, E. Sano, Y. Sudo, T. Tsubokawa, M. Yamaoka, H. Yamazaki, S. Uozumi, T. Yoshioka, T. Lijima, K. Kawagoe, S. H. Kim, T. Matsumura, K. Miyabayashi, T. Murakami, T. Nakadaira, T. Nakaya, T. Shinkawa, T. Takeshita, M. Yokoyama, K. Yoshimura

    IEEE Nuclear Science Symposium Conference Record   2   1105 - 1111   2006年

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    掲載種別:研究論文(国際会議プロシーディングス)  

    The multi-pixel photon counter (MPPC) is a newly developed photodetector with an excellent photon counting capability. It also has many attractive features such as small size, high gain, low operation voltage and power consumption, and capability of operating in magnetic fields and in room temperature. The basic performance of samples has been measured. A gain of ∼10 is achieved with a noise rate less than 500 kHz with 1 p.e. threshold, and cross-talk probability of less than 40% at room temperature. The photon detection efficiency for green light is twice or more that of the photomultiplier tubes. It is found that the basic performance of the MPPC is satisfactory for use in real experiments. © 2006 IEEE. 6

    DOI: 10.1109/NSSMIC.2006.356040

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  • Target material irradiation studies for high-intensity accelerator beams

    N Simos, H Kirk, H Ludewig, P Thieberger, WT Weng, K McDonald, J Sheppard, G Evangelakis, K Yoshimura

    NUCLEAR PHYSICS B-PROCEEDINGS SUPPLEMENTS   149   259 - 261   2005年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    This paper presents results of recent experimental studies focusing on the behavior of special materials and composites under irradiation conditions and their potential use as accelerator targets. The paper also discusses the approach and goals of on-going investigations on an expanded material matrix geared toward the neutrino superbeam and muon collider initiatives.

    DOI: 10.1016/j.nuclphysbps.2005.05.033

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  • Conducting pulsed target

    K Yoshimura, Y Yamanoi, P Sievers, B Autin

    NUCLEAR PHYSICS B-PROCEEDINGS SUPPLEMENTS   149   265 - 267   2005年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    Conducting pulsed target scheme has been studied as an alternative targetry solution used for a dedicated high-intense and bright muon source (PRISM). We made a conceptual design and have developed a pulse power supply and a mercury loop to be used for the proof-of-principle test.

    DOI: 10.1016/j.nuclphysbps.2005.05.035

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  • R&D works on high-power targetry for neutrino factories

    K Yoshimura

    JOURNAL OF NUCLEAR MATERIALS   343 ( 1-3 )   14 - 20   2005年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    High power targetry is one of the major technical challenges to realize neutrino factories based on muon storage rings. Various R&D works have been carried out in the framework of international collaboration. Recent progress in a free mercury jet, material studies, and capture/focusing devices are discussed. Future prospects for R&D are briefly described. (c) 2005 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.jnucmat.2005.02.009

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  • Search for cosmic-ray antideuterons

    H Fuke, T Maeno, K Abe, S Haino, Y Makida, S Matsuda, H Matsumoto, JW Mitchell, AA Moiseev, J Nishimura, M Nozaki, S Orito, JF Ormes, M Sasaki, ES Seo, Y Shikaze, RE Streitmatter, J Suzuki, K Tanaka, K Tanizaki, T Yamagami, A Yamamoto, Y Yamamoto, K Yamato, T Yoshida, K Yoshimura

    PHYSICAL REVIEW LETTERS   95 ( 8 )   2005年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMERICAN PHYSICAL SOC  

    We performed a search for cosmic-ray antideuterons using data collected during four BESS balloon flights from 1997 to 2000. No candidate was found. We derived, for the first time, an upper limit of 1.9x10(-4) (m(2)s sr GeV/nucleon)(-1) for the differential flux of cosmic-ray antideuterons, at the 95% confidence level, between 0.17 and 1.15 GeV/nucleon at the top of the atmosphere.

    DOI: 10.1103/PhysRevLett.95.081101

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  • Measurement of radiation heating induced by secondary particles from 12-GeV primary proton-beam interactions

    H Ohnishi, K Yoshimura, T Nakamoto, A Yamamoto, Y Ajima, M Aoki, N Fukasawa, K Ishibashi, Y Kuno, T Miura, K Nakahara, N Nosaka, M Numajiri, T Ogitsu, A Sato

    NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT   545 ( 1-2 )   88 - 96   2005年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    We measured radiation heating induced by secondary particles from 12-GeV primary proton beam interactions. A newly developed "cryogenic calorimeter" technique was employed to precisely Measure heat fluxes of 0.2.1 W deposited in a large copper absorber. The results were compared with calculations by using Monte-Carlo codes, MARS and PHITS. (c) 2005 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.nima.2005.03.001

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  • Flight performance of the BESS-Polar aerogel Cherenkov counter

    T. Hams, K. Abe, H. Fuke, S. Haino, K. C. Kim, T. Kumazawa, M. H. Lee, Y. Makida, S. Matsuda, H. Matsumoto, K. Matsumoto, J. W. Mitchell, A. A. Moiseev, Z. D. Myers, J. Nishimura, M. Nozaki, A. Ogata, M. Oikawa, J. F. Ormes, M. Sasaki, E. S. Seo, Y. Shikaze, R. E. Streitmatter, J. Suzuki, K. Takeuchi, K. Tanaka, T. Taniguci, T. Yamagami, A. Yamamoto, T. Yoshida, K. Yoshimura

    Proceedings of the 29th International Cosmic Ray Conference, Vol 3: OG1   69 - 72   2005年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:TATA INST FUNDAMENTAL RESEARCH  

    The BESS-Polar balloon payload had its first flight on December 13th-21st, 2004 (UTC) from McMurdo Station, Antarctica. The flight duration was over eight days and more than 9 x 108 cosmic-ray events were recorded. An overview of the BESS-Polar flight, the status of the antiproton analysis, and a discussion of the low-power readout electronics and data acquisition system can be found elsewhere in these proceedings. In this paper we discuss the design, testing, and flight performance of the BESS-Polar Cherenkov counter, which operated in ambient conditions outside a pressure vessel. The silica-aerogel Cherenkov radiator had a nominal index-of-refraction, n = 1.02, yielding an lower limit for the most likely photoelectron (PE) number of 7 in the center of the counter and 9 near the photomultiplier tubes.

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  • Precise measurements of the cosmic ray antiproton spectrum with BESS including the effects of solar modulation

    JW Mitchell, K Abe, K Anraku, Y Asaoka, M Fujikawa, H Fuke, S Haino, T Hams, N Ikeda, M Imori, A Itazaki, K Izumi, MH Lee, T Maeno, Y Makida, S Matsuda, N Matsui, T Matsukawa, H Matsumoto, H Matsunaga, T Mitsui, A Moiseev, M Motoki, J Nishimura, M Nozaki, H Omiya, S Orito, JF Ormes, T Saeki, T Sanuki, M Sasaki, ES Seo, Y Shikaze, T Sonoda, SA Stephens, RE Streitmatter, J Suzuki, Y Takasugi, K Tanaka, K Tanizaki, Ueda, I, JZ Wang, Y Yajima, T Yamagami, A Yamamoto, Y Yamamoto, K Yamato, T Yoshida, K Yoshimura

    MARS INTERNATIONAL REFERENCE ATMOSPHERE, LIVING WITH A STAR AND FUNDAMENTAL PHYSICS   35 ( 1 )   135 - 141   2005年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD  

    The Balloon Borne Experiment with a Superconducting Spectrometer (BESS) has measured the energy spectrum of cosmic-ray antiprotons between 0.18 and 4.20 GeV in eight flights between 1993 and 2002. Above about I GeV, models in which antiprotons are secondary products of the interactions of primary cosmic rays with the interstellar gas agree with the BESS antiproton spectrum. Below I GeV, the data show a possible excess antiproton flux compared to secondary model predictions, suggesting the presence of an additional source of antiprotons. The antiproton/proton ratios measured between 1993 and 1999, during the Sun's positive-polarity phase, are consistent with simple models of solar modulation. However, results from the 2000 flight, following the solar magnetic field reversal, show a sudden increase in the antiproton/proton ratio and tend to favor a charge-sign-dependent drift model. To extend BESS measurements to lower energies, an evolutionary instrument, BESS-Polar, is under construction for polar flight in 2004. Published by Elsevier Ltd on behalf of COSPAR.

    DOI: 10.1016/j.asr.2003.08.044

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  • Observation of low energy antiprotons at the 2004 BESS-Polar flight in Antarctica

    S. Matsuda, S. Haino, K. Abe, H. Fuke, T. Hams, K. C. Kim, T. Kumazawa, M. H. Lee, Y. Makida, H. Matsumoto, K. Matsumoto, J. W. Mitchell, A. A. Moiseev, Z. D. Myers, J. Nishimura, M. Nozaki, A. Ogata, M. Oikawa, J. F. Ormes, M. Sasaki, E. S. Seo, Y. Shikaze, R. E. Streitmatter, J. Suzuki, K. Takeuchi, K. Tanaka, T. Yamagami, A. Yamamoto, T. Yoshida, K. Yoshimura

    Proceedings of the 29th International Cosmic Ray Conference, Vol 3: OG1   25 - 28   2005年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:TATA INST FUNDAMENTAL RESEARCH  

    A flatter spectrum of low-energy cosmic ray antiprotons below 1 GeV measured by the BESS experiment in the last solar minimum period suggests the existence of possible novel and exotic sources of cosmic-ray antiprotons, such as evaporation of primordial black holes and annihilation of supersymmetric dark matter. In order to investigate these antiproton sources and to search for antimatter in the cosmic radiation, the BESS-Polar experiment was carried out with a NASA long duration balloon flight over Antarctica in December 2004. During this 8.5-day flight, the BESS-Polar superconducting spectrometer gathered 900 million cosmic-ray events. The data show that the newly developed particle detector system functioned well enough to observe the low energy antiprotons during the entire flight. Thus' we can expect to derive a precise energy spectrum of the low-energy antiprotons with several-times higher statistics than that from the flight of the previous solar minimum period.

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  • Isotope measurements of cosmic-ray hydrogen and helium during the 2000 solar maximum

    K. C. Kim, E. S. Seo, K. Abe, H. Fuke, S. Haino, T. Maeno, Y. Makida, S. Matsuda, H. Matsumoto, J. W. Mitchell, A. A. Moiseev, J. Nishimura, M. Nozaki, S. Orito, J. F. Ornes, T. Sanuki, M. Sasaki, Y. Shikaze, R. E. Streitmatter, J. Suzuki, K. Tanaka, T. Yamagami, A. Yamamoto, T. Yoshida, K. Yoshimura

    Proceedings of the 29th International Cosmic Ray Conference, Vol 3: OG1   77 - 80   2005年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:TATA INST FUNDAMENTAL RESEARCH  

    The isotopic composition measurements of cosmic-ray hydrogen and helium were made during the most recent period of solar maximum using the Balloon-borne Experiment with a Superconducting Spectrometer (BESS). The data selection procedure and the mass histograms for proton, helium and their isotopes of BESS-2000 are presented in this paper.

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  • Post-irradiation properties of candidate materials for high-power targets

    HG Kirk, H Ludewig, L Mausner, N Simos, P Thieberger, KT McDonald, JC Sheppard, LP Trung, Y Hayato, K Yoshimura

    2005 IEEE PARTICLE ACCELERATOR CONFERENCE (PAC), VOLS 1-4   1329 - 1331   2005年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:IEEE  

    The desire of the high-energy-physics community for more intense secondary particle beams motivates the development of multi-megawatt, pulsed proton sources. T e targets needed to produce these secondary particle beams must be sufficiently robust to withstand the intense pressure waves arising from the high peak-energy deposition which an intense pulsed beam will deliver. In addition, the materials used for the targets must continue to perform in a severe radiation environment. The effect of the beam-induced pressure waves can be mitigated by use of target materials with high-yield strength and/or low coefficient of thermal expansion (CTE) [1, 2, 3]. We report here first results of an expanded study of the effects of irradiation on several additional candidate materials with high strength (AlBeMet, beryllium, Ti-V6-A14) or low CTE (a carbon-carbon composite, a new Toyota "gum" metal alloy [4], Super-Invar).

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  • The 2004 BESS-Polar scientific flight in Antarctica

    T. Yoshida, J. W. Mitchell, A. Yamamoto, K. Abe, H. Fuke, S. Haino, T. Hams, K. C. Kim, T. Kumazawa, M. H. Lee, Y. Makida, S. Matsuda, H. Matsumoto, K. Matsumoto, A. A. Moiseev, Z. D. Myers, J. Nishimura, M. Nozaki, A. Ogata, M. Oikawa, J. F. Ormes, M. Sasaki, E. S. Seo, Y. Shikaze, R. E. Streitmatter, J. Suzuki, K. Takeuchi, K. Tanaka, T. Taniguchi, T. Yamagami, K. Yoshimura

    Proceedings of the 29th International Cosmic Ray Conference, Vol 3: OG1   33 - 36   2005年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:TATA INST FUNDAMENTAL RESEARCH  

    The first scientific flight of the BESS-Polar experiment was carried out in December 2004, aiming at elementary particle phenomena in the early Universe through observation of low energy antiprotons and search for antimatter in the cosmic radiation. The BESS-Polar payload was launched on December 13 from Williams Field near the US McMurdo Station in Antarctica, and circulated around the South Pole for 8 days and 17 hours. During the flight, the superconducting spectrometer including the solar-cell power supply system worked well, and two terabytes scientific data were recorded on the onboard hard disk drives. The flight was terminated on December 21, and the payload landed on the Ross Ice Shelf. The recovery operation continued for a week, and the spectrometer was recovered safely.

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  • Cosmic ray H-1 and H-2 spectra from BESS 98

    ZD Myers, ES Seo, JZ Wang, RW Alford, K Abe, K Anraku, Y Asaoka, M Fujikawa, M Imori, T Maeno, Y Makida, H Matsumoto, H Matsunaga, J Mitchell, T Mitsui, A Moiseev, M Motoki, J Nishimura, M Nozaki, S Orito, J Ormes, T Saeki, T Sanuki, M Sasaki, Y Shikaze, T Sonoda, R Streitmatter, J Suzuki, K Tanaka, Ueda, I, N Yajima, T Yamagami, A Yamamoto, T Yoshida, K Yoshimura

    MARS INTERNATIONAL REFERENCE ATMOSPHERE, LIVING WITH A STAR AND FUNDAMENTAL PHYSICS   35 ( 1 )   151 - 155   2005年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD  

    The Balloon-borne Experiment with a Super-solenoidal Spectrometer (BESS) instrument has been flown annually from Lynn Lake Manitoba since 1993. The instrument has been upgraded several times to improve its performance. The instalment flown in 1998 was able to detect H-2 clearly between 0.13 and 1.78 GeV/n as a result of improvements made on the time-of-flight (TOF) system. The BESS 98 data were analyzed to obtain the ratio and absolute fluxes of H-1 and H-2 over this energy range. The results were compared with different cosmic ray propagation models and their implications regarding their propagation history are discussed in this paper. (c) 2004 COSPAR. Published by Elsevier Ltd. All rights reserved.

    DOI: 10.1016/j.asr.2003.10.050

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  • Measurement of cosmic-ray antiproton spectrum with BESS-2002

    S. Haino, K. Abe, H. Fuke, T. Maeno, Y. Makida, S. Matsuda, H. Matsumoto, J. W. Mitchell, A. A. Moiseev, J. Nishimura, M. Nozaki, O. Orito, U. Ormes, T. Sanuki, M. Sasaki, E. S. Seo, Y. Shikaze, R. E. Streitmatter, J. Suzuki, K. Tanaka, T. Yamagami, A. Yamamoto, T. Yoshida, K. Yoshimura

    PROCEEDINGS OF THE 29TH INTERNATIONAL COSMIC RAY CONFERENCE, VOL 3: OG1   13 - 16   2005年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:TATA INST FUNDAMENTAL RESEARCH  

    We report a cosmic-ray antiproton spectrum measured with the BESS balloon experiment performed in 2002, which was in an intermediate period between the solar maximum in 2000 and the coming solar minimum. The observed antiproton spectrum and the antiproton to proton ratio are crucial for further development of the drift model of the solar modulation effect which has been generally supported by the previous measurements.

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  • A high-power target experiment

    HG Kirk, SA Kahn, H Ludewig, RB Palmer, R Samulyak, N Simos, T Tsang, Efthymiopoulos, I, A Fabich, H Haseroth, F Haug, J Lettry, TA Gabriel, Graves, V, J Haines, P Spampinato, KT McDonald, JRJ Bennett, T Bradshaw, TR Edgecock, P Drumm, Y Ivanyushenkov, Y Hayato, K Yoshimura

    2005 IEEE PARTICLE ACCELERATOR CONFERENCE (PAC), VOLS 1-4   2433 - 2435   2005年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:IEEE  

    We describe an experiment designed as a proof-of-principle test for a target system capable of converting a 4-MW proton beam into a high-intensity muon beam suitable for incorporation into either a neutrino factory complex or a muon collider. The target system is based on exposing a free mercury jet to an intense proton beam in the presence of a high-strength solenoidal magnetic field.

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  • The BESS Program

    JW Mitchell, K Abe, K Anraku, H Fuke, S Haino, T Hams, M Imori, A Itazaki, K Izumi, T Kumazawa, MH Lee, T Maeno, Y Makida, S Matsuda, H Matsumoto, K Matsumoto, A Moiseev, ZD Myers, J Nishimura, M Nozaki, H Omiya, S Orito, JF Ormes, T Sanuki, M Sasaki, ES Seo, Y Shikaze, RE Streitmatter, J Suzuki, Y Takasugi, K Tanaka, K Tanizaki, T Yamagami, A Yamamoto, Y Yamamoto, K Yamato, T Yoshida, K Yoshimura

    NUCLEAR PHYSICS B-PROCEEDINGS SUPPLEMENTS   134   31 - 38   2004年9月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER  

    In nine flights between 1993 and 2002, the Balloon Borne Experiment with a Superconducting Spectrometer (BESS) has measured the energy spectrum of cosmic-ray antiprotons between 0.18 and 4.20 GeV, and the spectra of protons and helium to several hundred GeV. BESS has also placed stringent upper limits on the existence of antihelium and antiduterons. Above about 1 GeV, models in which antiprotons are secondary products of the interactions of primary cosmic rays with the ISM agree with the BESS spectrum. Below I GeV, BESS data suggest the presence of an additional source of antiprotons. The antiproton/proton ratios measured between 1993 and 1999, during the Sun's positive-polarity phase, are consistent with simple models of solar modulation. Results from the 2000 flight, following the solar magnetic field reversal, show a sudden increase in the antiproton/proton ratio and tend to favor a charge-sign-dependent drift model. To extend BESS measurements to lower energies, a new instrument, BESS-Polar, is under construction for a flight from Antarctica in 2004.

    DOI: 10.1016/j.nuclphysbps.2004.08.003

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  • Measurements of primary and atmospheric cosmic-ray spectra with the BESS-TeV spectrometer

    S Haino, T Sanuki, K Abe, K Anraku, Y Asaoka, H Fuke, M Imori, A Itasaki, T Maeno, Y Makida, S Matsuda, N Matsui, H Matsumoto, JW Mitchell, AA Moiseev, J Nishimura, M Nozaki, S Orito, JF Ormes, M Sasaki, ES Seo, Y Shikaze, RE Streitmatter, J Suzuki, Y Takasugi, K Tanaka, K Tanizaki, T Yamagami, A Yamamoto, Y Yamamoto, K Yamato, T Yoshida, K Yoshimura

    PHYSICS LETTERS B   594 ( 1-2 )   35 - 46   2004年7月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    Primary and atmospheric cosmic-ray spectra were precisely measured with the BESS-TeV spectrometer. The spectrometer was upgraded from BESS-98 to achieve seven times higher resolution in momentum measurement. We report absolute fluxes of primary protons and helium nuclei in the energy ranges, 1-540 GeV and 1-250 GeV/n, respectively, and absolute flux of atmospheric muons in the momentum range 0.6-400 GeV/c. (C) 2004 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.physletb.2004.05.019

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  • Measurements of atmospheric muon spectra at mountain altitude (vol 234, pg 541, 2002)

    T Sanuki, M Fujikawa, K Abe, K Anraku, Y Asaoka, H Fuke, S Haino, M Imori, K Izumi, T Maeno, Y Makida, N Matsui, H Matsumoto, H Matsunaga, M Motoki, J Nishimura, M Nozaki, S Orito, M Sasaki, Y Shikaze, T Sonoda, J Suzuki, K Tanaka, Y Toki, A Yamamoto, Y Yamamoto, K Yamato, T Yoshida, K Yoshimura

    PHYSICS LETTERS B   581 ( 3-4 )   272 - 273   2004年2月

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    記述言語:英語   出版者・発行元:ELSEVIER SCIENCE BV  

    DOI: 10.1016/j.physletb.2003.11.060

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  • Progress of the BESS Superconducting Spectrometer

    S Haino, K Abe, K Anraku, H Fuke, T Hams, N Ikeda, A Itasaki, K Izumi, T Kumazawa, MH Lee, T Maeno, Y Makida, S Matsuda, N Matsui, H Matsumoto, K Matsumoto, JW Mitchell, AA Moiseev, J Nishimura, M Nozaki, H Omiya, S Orito, JF Ormes, T Sanuki, M Sasaki, ES Seo, Y Shikaze, RE Streitmatter, J Suzuki, Y Takasugi, S Takeuchi, K Tanaka, T Taniguchi, K Tanizaki, T Yamagami, A Yamamoto, Y Yamamoto, K Yamato, T Yoshida, K Yoshimura

    NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT   518 ( 1-2 )   167 - 171   2004年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    Balloon-borne Experiment with a Superconducting Spectrometer (BESS) is a balloon-borne spectrometer to study elementary particle phenomena in the early Universe as well as the origin and the propagation of cosmic radiation. The instrument has a unique feature of a thin superconducting solenoid which enables a large acceptance with a cylindrical configuration. Nine balloon flights have been successfully carried out since 1993. In 2002, the detector was upgraded as the BESS-TeV spectrometer to extend primary cosmic-ray spectra up to 1 TeV. For further studies of low-energy antiprotons, a new spectrometer, BESS-Polar, with a ultra-thin superconducting solenoid is being developed for long duration balloon flights in Antarctica. (C) 2003 Elsevier B.V. All rights reserved.

    DOI: 10.1016/j.nima.2003.10.051

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  • BESS-polar experiment

    T Yoshida, A Yamamoto, J Mitchell, K Abe, H Fuke, S Haino, T Hams, N Ikeda, A Itazaki, K Izumi, MH Lee, T Maeno, Y Makida, S Matsuda, H Matsumoto, A Moiseev, J Nishimura, M Nozaki, H Omiya, JF Ormes, M Sasaki, ES Seo, Y Shikaze, A Stephens, R Streitmatter, J Suzuki, Y Takasugi, K Tanaka, K Tanizaki, T Yamagami, Y Yamamoto, K Yamato, K Yoshimura

    NEXT GENERATION IN SCIENTIFIC BALLOONING   33 ( 10 )   1755 - 1762   2004年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD  

    In order to investigate elementary particle phenomena in the early Universe, the BESS-polar experiment is proposed. It will study low-energy antiprotons and search for antinuclei in the galactic cosmic rays at the constant altitude maintained by a scientific balloon. A new superconducting spectrometer is being developed for long-duration balloon flights. In order to extend the detectable energy range of antiprotons down to 100 MeV, the thickness of materials along the trajectory of the incident particle is minimized. The spectrometer will be completed in 2003, and the first long-duration flight is planned in 2004. (C) 2004 COSPAR. Published by Elsevier Ltd. All rights reserved.

    DOI: 10.1016/j.asr.2003.05.017

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  • Targetry R&D for PRISM project

    K Yoshimura, H Ohnishi, T Nakamoto, A Yamamoto, Y Ajima, M Aoki, N Fukasawa, K Ishibashi, Y Kuno, T Miura, K Nakahara, N Nosaka, M Numajiri, T Ogitsu, A Sato, A Yamanoi, B Autin, P Sievers

    NEUTRINO FACTORIES AND SUPERBEAMS   721   325 - 328   2004年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:AMER INST PHYSICS  

    A conceptual design of the targetry for the high intensity slow muon source is presented. Based on simulation studies, critical issues are discussed and a baseline design is determined. We have started R&D works on superconducting solenoids as well as conducting targets, which is an alternative option.

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  • Measurement of cosmic-ray proton and antiproton spectra at mountain altitude

    T Sanuki, A Fujikawa, H Matsunaga, K Abe, K Anraku, H Fuke, S Haino, M Imori, K Izumi, T Maeno, Y Makida, N Matsui, H Matsumoto, J Nishimura, M Nozaki, S Orito, M Sasaki, Y Shikaze, J Suzuki, K Tanaka, A Yamamoto, Y Yamamoto, K Yamato, T Yoshida, K Yoshimura

    PHYSICS LETTERS B   577 ( 1-2 )   10 - 17   2003年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    Energy spectra of atmospheric secondary cosmic-ray protons and antiprotons were measured at mountain altitude, 2770 m above sea level. We observed more than 10(5) protons and 10(2) antiprotons. Our proton spectrum is generally consistent with other previous measurements. The observed antiproton spectrum suggests that the energy loss due to non-annihilation processes is less significant than that assumed in previous model calculations. (C) 2003 Published by Elsevier B.V.

    DOI: 10.1016/j.physletb.2003.10.021

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  • Current LH2-absorber R&D in MuCool

    MAC Cummings, D Allspach, L Bandura, EL Black, KW Cassel, A Dyshkant, D Errede, S Geer, J Greenwood, M Haney, D Hedin, S Ishimoto, CJ Johnstone, DM Kaplan, D Kubik, Y Kuno, W Lau, S Majewski, J Norem, B Norris, M Popovic, M Reep, D Summers, K Yoshimura

    JOURNAL OF PHYSICS G-NUCLEAR AND PARTICLE PHYSICS   29 ( 8 )   1689 - 1692   2003年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IOP PUBLISHING LTD  

    The MuCool hydrogen-absorber R&D program is summarized. Prototype absorbers featuring thin aluminum windows and 'flow-through' or 'convection' cooling are under development for eventual power-handling tests in a proton beam and a cooling demonstration in a muon beam. Testing these prototypes and their components involves application of novel techniques.

    DOI: 10.1088/0954-3899/29/8/331

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  • Non-neutrino physics working group summary

    JM Poutissou, K Yoshimura

    JOURNAL OF PHYSICS G-NUCLEAR AND PARTICLE PHYSICS   29 ( 8 )   2005 - 2011   2003年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IOP PUBLISHING LTD  

    This summary covers the physics topics that could benefit from the unprecedented flux of muons produced at the front end of the future neutrino factory. A selection of such opportunities was presented at NuFact02 and their demands on beam properties were evaluated. This summary will survey the rare muon decay experiments and the high precision measurements that could benefit from higher fluxes as well as some of the new programmes that could use very large mu(-) fluxes. A number of technological developments relevant to the neutrino factories were also discussed.

    DOI: 10.1088/0954-3899/29/8/391

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  • Measurements of proton, helium and muon spectra at small atmospheric depths with the BESS spectrometer

    K Abe, T Sanuki, K Anraku, Y Asaoka, H Fuke, S Haino, N Ikeda, M Imori, K Izumi, T Maeno, Y Makida, S Matsuda, N Matsui, T Matsukawa, H Matsumoto, JW Mitchell, AA Moiseev, J Nishimura, M Nozaki, S Orito, JF Ormes, M Sasaki, ES Seo, Y Shikaze, T Sonoda, RE Streitmatter, J Suzuki, K Tanaka, K Tanizaki, T Yamagami, A Yamamoto, Y Yamamoto, K Yamato, T Yoshida, K Yoshimura

    PHYSICS LETTERS B   564 ( 1-2 )   8 - 20   2003年7月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER  

    The cosmic-ray proton, helium, and muon spectra at small atmospheric depths of 4.5-28 g/cm(2) were precisely measured during the slow descending period of the BESS-2001 balloon flight. The variation of atmospheric secondary particle fluxes as a function of atmospheric depth provides fundamental information to study hadronic interactions of the primary cosmic rays with the atmosphere. (C) 2003 Published by Elsevier Science B.V.

    DOI: 10.1016/S0370-2693(03)00676-2

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  • Convection-type LH2 absorber R&D for muon ionization cooling

    S Ishimoto, L Bandura, EL Black, M Boghosian, KW Cassel, MA Cummings, C Darve, A Dyshkant, D Errede, S Geer, M Haney, D Hedin, R Johnson, CJ Johnstone, DM Kaplan, D Kubik, Y Kuno, S Majewski, M Popovic, M Reep, D Summers, S Suzuki, K Yoshimura

    NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT   503 ( 1-2 )   396 - 400   2003年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    A feasibility study on liquid hydrogen (LH2) absorbers for muon ionization cooling is reported. In muon ionization cooling, an LH2 absorber is required to have a high cooling power greater than 100 W to cool heat deposited by muons passing through. That heat in LH2 can be removed at either external or internal heat exchangers, which are cooled by cold helium gas. As one of the internal heat exchanger types, a convection-type absorber is proposed. In the convectiontype absorber, heat is taken away by the convection of LH2 in the absorber. The heat exchanger efficiency for the convection-type absorber is calculated. A possible design is presented. (C) 2003 Elsevier Science B.V. All rights reserved.

    DOI: 10.1016/S0168-9002(03)00724-1

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  • PRISM Overview

    K Yoshimura

    NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT   503 ( 1-2 )   254 - 257   2003年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    The PRISM project has been proposed to obtain a high-intensity slow muon beam. By employing two novel techniques, i.e., high-field pion capture and a longitudinal phase rotation, an intense (10(11)-10(12) mu/s), monochromatic (DeltaE/E similar or equal toa few %), and low-energy (20 MeV) muon beam can be produced. Muon beam with such features enable searches for lepton flavor violation at an unprecedented level as well as new field of muon application. (C) 2003 Elsevier Science B.V. All rights reserved.

    DOI: 10.1016/S0168-9002(03)00688-0

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  • Progress in absorber R&D for muon cooling

    DM Kaplan, EL Black, M Boghosian, KW Cassel, RP Johnson, S Geer, CJ Johnstone, M Popovic, S Ishimoto, K Yoshimura, L Bandura, MA Cummings, A Dyshkant, D Hedin, D Kubik, C Darve, Y Kuno, D Errede, M Haney, S Majewski, M Reep, D Summers

    NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT   503 ( 1-2 )   392 - 395   2003年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER  

    A stored-muon-beam neutrino factory may require transverse ionization cooling of the muon beam. We describe recent progress in research and development on energy absorbers for muon-beam cooling carried out by a collaboration of university and laboratory groups. (C) 2003 Elsevier Science B.V. All rights reserved.

    DOI: 10.1016/S0168-9002(03)00723-X

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  • Precise measurements of atmospheric muon fluxes with the BESS spectrometer

    M Motoki, T Sanuki, S Orito, K Abe, K Anraku, Y Asaoka, M Fujikawa, H Fuke, S Haino, M Imori, K Izumi, T Maeno, Y Makida, N Matsui, H Matsumoto, H Matsunaga, J Mitchell, T Mitsui, A Moiseev, J Nishimura, M Nozaki, J Ormes, T Saeki, M Sasaki, ES Seo, Y Shikaze, T Sonoda, R Streitmatter, J Suzuki, K Tanaka, Ueda, I, JZ Wang, N Yajima, T Yamagami, A Yamamoto, Y Yamamoto, K Yamato, T Yoshida, K Yoshimura

    ASTROPARTICLE PHYSICS   19 ( 1 )   113 - 126   2003年4月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    The vertical absolute fluxes of atmospheric muons and muon charge ratio have been measured precisely at different geomagnetic locations by using the BESS spectrometer. The observations had been performed at sea level (30 m above sea level) in Tsukuba, Japan, and at 360 m above sea level in Lynn Lake, Canada. The vertical cutoff rigidities in Tsukuba (36.2degreesN, 140.1degreesE) and in Lynn Lake (56.5degreesN, 101.0degreesW) are 11.4 and 0.4 GV, respectively. We have obtained vertical fluxes of positive and negative muons in a momentum range from 0.6 to 20 GeV/c with systematic errors <3% in both measurements. By comparing the data collected at two different geomagnetic latitudes, we have seen an effect of cutoff rigidity. The dependence on the atmospheric pressure and temperature, and the solar modulation effect have been also clearly observed. We also clearly observed the decrease of charge ratio of muons at low momentum side with at higher cutoff rigidity region. (C) 2002 Elsevier Science B.V. All rights reserved.

    DOI: 10.1016/S0927-6505(02)00195-0

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  • A new experiment to measure the muon electric dipole moment

    JP Miller, RM Carey, Logashenko, V, KR Lynch, BL Roberts, A Silenko, G Bennett, DM Lazarus, LB Leipuner, W Marciano, W Meng, WM Morse, R Prigl, YK Semertzidis, Balakin, V, A Bazhan, A Dunikov, B Khazin, IB Khriplovich, G Sylvestrov, Y Orlov, K Jungmann, PT Debevec, DW Hertzog, CJG Onderwater, CS Ozben, E Stephenson, M Auzinsh, P Cushman, R McNabb, N Shafer-Ray, K Yoshimura, A Aoki, Y Kuno, A Sato, M Iwasaki, FJM Farley

    INTERSECTIONS OF PARTICLE AND NUCLEAR PHYSICS   698   196 - 199   2003年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:AMER INST PHYSICS  

    A description is given of a new experiment to measure the muon electric dipole moment (EDM) to between sigma = 10(-24) e-cm and 10(-25) e-cm, which would be 5 to 6 orders of magnitude improvement over the current world average. Muons are stored in a magnetic ring. Precession due to Thomas precession and the magnetic moment are canceled with the proper combination of applied E and B fields. Only precession due to a non-vanishing EDM remains, resulting in a large amplification of the EDM signal. The method has general applicability to charged particles.

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  • A new method for a sensitive deuteron EDM experiment

    YK Semertzidis, M Aoki, M Auzinsh, Balakin, V, A Bazhan, GW Bennett, RM Carey, P Cushman, PT Debevec, A Dudnikov, FJM Farley, DW Hertzog, M Iwasaki, K Jungmann, D Kawall, B Khazin, IB Khriplovich, B Kirk, Y Kuno, DM Lazarus, LB Leipuner, Logashenko, V, KR Lynch, WJ Marciano, R Mcnabb, W Meng, JP Miller, WM Morse, CJG Onderwater, YF Orlov, CS Ozben, R Prigl, S Rescia, BL Roberts, N Shafer-Ray, A Silenko, EJ Stephenson, K Yoshimura

    INTERSECTIONS OF PARTICLE AND NUCLEAR PHYSICS   698   200 - 204   2003年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:AMER INST PHYSICS  

    In this paper a new method is presented for particles in storage rings which could reach a statistical sensitivity of 10(-27) e(.)cm for the deuteron EDM. This implies an improvement of two orders of magnitude over the present best limits on the T-odd nuclear forces xi parameter.

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  • BESS-Polar: Long duration flights at Antarctica to search for primordial antiparticles

    A Yamamoto, J Mitchell, K Abe, H Fuke, S Haino, N Ikeda, K Izumi, M Lee, T Maeno, Y Makida, S Matsuda, N Matsui, H Matsumoto, A Moiseev, J Nishimura, M Nozaki, H Omiya, JF Ormes, M Sasaki, ES Seo, Y Shikaze, J Suzuki, K Tanaka, K Tanizaki, T Yamagami, Y Yamamoto, K Yamato, T Yoshida, K Yoshimura

    NUCLEAR PHYSICS B-PROCEEDINGS SUPPLEMENTS   113   208 - 212   2002年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    The BESS-Polar experiment with long-duration balloon flights at Antarctica aims at extremely sensitive measurement of low energy antiprotons to search for novel primary origins in the early Universe, and to study cosmic-ray propagation and solar modulation. The search for cosmic antimatter is a fundamental objective to study baryon asymmetry in the Universe. The BESS experiment with high rigidity resolution and large geometrical acceptance will maximize advantages of long duration flights at Antarctica where the rigidity cut-off is lowest. A very compact and thin superconducting magnet spectrometer is being developed to maximize the detector performance in low energies. The BESS-Polar project and progress of the development are described.

    DOI: 10.1016/S0920-5632(02)01843-1

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  • Progress in search for antihelium with BESS

    M Sasaki, H Matsumoto, M Nozaki, T Saeki, K Abe, K Anraku, Y Asaoka, M Fujikawa, H Fuke, M Imori, S Haino, K Izumi, T Maeno, Y Makida, S Matsuda, N Matsui, T Matsukawa, H Matsunaga, JW Mitchell, T Mitsui, A Moiseev, M Motoki, J Nishimura, S Orito, JF Ormes, T Sanuki, Y Shikaze, ES Seo, T Sonoda, R Streitmatter, J Suzuki, K Tanaka, K Tanizaki, Ueda, I, JZ Wang, Y Yajima, Y Yamagami, A Yamamoto, Y Yamamoto, K Yamato, T Yoshida, K Yoshimura

    NUCLEAR PHYSICS B-PROCEEDINGS SUPPLEMENTS   113   202 - 207   2002年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    We have searched for antihelium nuclei in cosmic rays using the data obtained from balloon flights of the BESS magnetic spectrometer. The search was mainly based on track-quality selection, followed by rigidity analysis, and on the time-of-flight and dE/dx measurements by the scintillation counter hodoscope. We analysed all the data collected during 1993-2000 with a common analysis procedure. No antihelium nuclei events were found in the energy range from I to 14 GV. In order to determine a new upper limit, we have simulated the loss in the air and in the instrument of He (He) using the GEANT/GHEISHA code. Combined with the data collected in 1993 through 2000, a new 95 % confidence upper limit for the ratio of He/He at the top of the atmosphere of 6.8 x 10(-7) has been obtained to be after correcting for the interactions in the air and in the instruments.

    DOI: 10.1016/S0920-5632(02)01842-X

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  • Measurement of low-energy antiproton detection efficiency in BESS below 1 GeV

    Y Asaoka, K Yoshimura, T Yoshida, K Abe, K Anraku, M Fujikawa, H Fuke, S Haino, K Izumi, T Maeno, Y Makida, A Matsui, H Matsumoto, H Matsunaga, M Motoki, M Nozaki, S Orito, T Sanuki, M Sasaki, Y Shikaze, T Sonoda, J Suzuki, K Tanaka, Y Toki, A Yamamoto

    NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT   489 ( 1-3 )   170 - 177   2002年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    An accelerator experiment was performed using a low-energy antiproton beam to measure antiproton detection efficiency of BESS, a balloon-borne spectrometer with a superconducting solenoid. Measured efficiencies showed good agreement with calculated ones derived from the BESS Monte Carlo simulation based on GEANT/GHEISHA. With detailed verification of the BESS simulation, the relative systematic error of detection efficiency derived from the BESS simulation has been determined to be +/-5%, compared with the previous estimation of +/- 15% which was the dominant uncertainty for measurements of cosmic-ray antiproton flux. (C) 2002 Elsevier Science B.V. All rights reserved.

    DOI: 10.1016/S0168-9002(02)00804-5

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  • Measurements of atmospheric muon spectra at mountain altitude

    T Sanuki, M Fujikawa, K Abe, K Anraku, Y Asaoka, H Fuke, S Haino, M Imori, K Izumi, T Maeno, Y Makida, N Matsui, H Matsumoto, H Matsunaga, M Motoki, J Nishimura, M Nozaki, S Orito, M Sasaki, Y Shikaze, T Sonoda, J Suzuki, K Tanaka, Y Toki, A Yamamoto, Y Yamamoto, K Yamato, T Yoshida, K Yoshimura

    PHYSICS LETTERS B   541 ( 3-4 )   234 - 242   2002年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    We report new measurements of absolute fluxes of atmospheric unions at mountain altitude. The measurements were carried out with the BESS detector at the top of Mt. Norikura, 2770 m above sea level, in Japan. The overall errors were less than 10%. The measured results are discussed in comparison with theoretical calculations. (C) 2002 Elsevier Science B.V. All rights reserved.

    DOI: 10.1016/S0370-2693(02)02265-7

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  • Measurements of cosmic-ray low-energy antiproton and proton spectra in a transient period of solar field reversal

    Y Asaoka, Y Shikaze, K Abe, K Anraku, M Fujikawa, H Fuke, S Haino, M Imori, K Izumi, T Maeno, Y Makida, S Matsuda, N Matsui, T Matsukawa, H Matsumoto, H Matsunaga, J Mitchell, T Mitsui, A Moiseev, M Motoki, J Nishimura, M Nozaki, S Orito, JF Ormes, T Saeki, T Sanuki, M Sasaki, ES Seo, T Sonoda, R Streitmatter, J Suzuki, K Tanaka, K Tanizaki, Ueda, I, JZ Wang, Y Yajima, Y Yamagami, A Yamamoto, Y Yamamoto, K Yamato, T Yoshida, K Yoshimura

    PHYSICAL REVIEW LETTERS   88 ( 5 )   2002年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMER PHYSICAL SOC  

    The energy spectra of cosmic-ray low-energy antiprotons ((p) over bar 's) and protons (p's) have been measured by BESS in 1999 and 2000, during a period covering reversal at the solar magnetic field. Based an these measurements, a sudden increase of the (p) over bar /p flux ratio following the solar magnetic field reversal was observed, and it generally agrees with a drift model of the solar modulation.

    DOI: 10.1103/PhysRevLett.88.051101

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  • Measurement of cosmic-ray hydrogen and helium and their isotopic composition with the BESS experiment

    JZ Wang, ES Seo, K Anraku, M Fujikawa, M Imori, T Maeno, N Matsui, H Matsunaga, M Motoki, S Orito, T Saeki, T Sanuki, Ueda, I, K Yoshimura, Y Makida, J Suzuki, K Tanaka, A Yamamoto, T Yoshida, T Mitsui, H Matsumoto, M Nozaki, M Sasaki, J Mitchell, A Moiseev, J Ormes, R Streitmatter, J Nishimura, Y Yajima, T Yamagami

    ASTROPHYSICAL JOURNAL   564 ( 1 )   244 - 259   2002年1月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IOP PUBLISHING LTD  

    The cosmic-ray hydrogen and helium spectra have been measured by the Balloon Borne Experiment with a Superconducting Solenoid Spectrometer (BESS), which has been flown from Lynn Lake, Manitoba, Canada, annually since 1993. The BESS experiment provides excellent rigidity measurement and precise particle identification with a large geometric acceptance. We present here the hydrogen and helium nuclei energy spectra from 0.2 to 10 GeV nucleon(-1) and their isotopic composition from 0.2 to about 1 GeV nucleon(-1) for the first BESS flight. This provides the first simultaneous measurements of the cosmic-ray secondaries, deuterons, and He-3, with their primaries, protons, and He-4 over this energy range in a period of solar minimum. In this paper, we have achieved significant improvements in data analysis in the following aspects. First, the latest available cross-section data and their parameterizations were utilized in the simulation code developed for this study. Second, a complete simulation was performed for both protons and heavy ions : the delta-ray effect was properly simulated and showed a large influence on the measurement of heavy ions at high energies. Third, the secondary particle correction, which dominates the systematic uncertainty at low energies for singly charged particles, protons and deuterons, was calculated iteratively with the simultaneously measured primary cosmic-ray spectra. In general, the results of this experiment are consistent with other recent measurements using balloon-borne or satellite experiments, but with better precision. The measured spectra of protons, deuterons, 3He, and 4He and their corresponding ratios are compared with different interstellar/heliospheric propagation calculations, which were derived to fit observations of heavy nuclei. The overall good agreement indicates that the propagation history for light cosmic-ray elements, protons, deuterons, and helium nuclei is similar to that of the heavy nuclei. The H-2/H-1 ratio is sensitive to the propagation models, and our results show a tendency of better agreement with the reacceleration model than the standard leaky-box model.

    DOI: 10.1086/324140

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  • BESS and its future prospect for polar long duration flights

    A Yamamoto, K Abe, K Anraku, Y Asaoka, M Fujikawa, H Fuke, S Haino, M Imori, K Izumi, T Maeno, Y Makida, N Matsui, H Matsumoto, H Matsunaga, FB McDonald, J Mitchell, T Mitsui, A Moiseev, M Motoki, J Nishimura, M Nozaki, S Orito, JF Ormes, D Righter, T Saeki, T Sanuki, M Sasaki, ES Seo, Y Shikaze, T Sonoda, R Streitmatter, J Suzuki, K Tanaka, K Tanizaki, Ueda, I, JZ Wang, N Yajima, T Yamagami, Y Yamamoto, H Yamaoka, K Yamato, T Yoshida, K Yoshimura

    SCIENTIFIC BALLOONING IN THE NEXT CENTURY: GOALS AND CHALLENGES   30 ( 5 )   1253 - 1262   2002年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD  

    The Balloon-borne Experiment with a Superconducting Spectrometer, BESS, aims to study elementary particle/antiparticle phenomena in the early history of the Universe. The instrument has a unique feature of a thin superconducting solenoid magnet enabling a large geometrical acceptance with a horizontally cylindrical configuration. Seven balloon flights have been successfully carried out since 1993. More than 10(3) comic-ray antiproton have been unambiguously detected, and the energy spectrum has been measured with the characteristic peak at 2 GeV. The search for cosmic-ray antihelium brought the upper-limit of the antiheliuni/helium ratio down to < 10(-6). To extend the highly sensitive measurements, we are planning polar long duration flights in Antarctica focusing on the very low energy antiproton spectrum towards the solar-minimum in the next decade. (C) 2002 COSPAR. Published by Elsevier Science Ltd. All rights reserved.

    DOI: 10.1016/S0273-1177(02)00541-0

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  • Successive measurements of cosmic-ray antiproton spectrum in a positive phase of the solar cycle

    T Maeno, S Orito, H Matsunaga, K Abe, K Anraku, Y Asaoka, M Fujikawa, M Imori, Y Makida, N Matsui, H Matsumoto, J Mitchell, T Mitsui, A Moiseev, M Motoki, J Nishimura, M Nozaki, J Ormes, T Saeki, T Sanuki, M Sasaki, ES Seo, Y Shikaze, T Sonoda, R Streitmatter, J Suzuki, K Tanaka, Ueda, I, JZ Wang, N Yajima, T Yamagami, A Yamamoto, T Yoshida, K Yoshimura

    ASTROPARTICLE PHYSICS   16 ( 2 )   121 - 128   2001年11月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER  

    The energy spectrum of cosmic-ray antiprotons (p's) has been measured by BESS successively in 1993, 1995, 1997 and 1998. In total, 848 (p) over bar 's were clearly identified in energy range 0.18-4.20 GeV. From these successive measurements of the (p) over bar spectrum at various solar activity, we discuss about the effect of the solar modulation and the origin of cosmic-ray (p) over bar 's. The (p) over bar /p ratios showed no distinctive year-to-year variation during the positive Sun's polarity phase. (C) 2001 Elsevier Science B.V. All rights reserved.

    DOI: 10.1016/S0927-6505(01)00107-4

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  • Precise measurements of cosmic-ray antiproton spectrum in a positive phase of the solar cycle

    T Maeno, N Nozaki, S Orito, H Matsunaga, K Abe, K Anraku, Y Asaoka, M Fujikawa, M Imori, Y Makida, N Matsui, H Matsumoto, J Mitchell, T Mitsui, A Moiseev, M Motoki, J Nishimura, J Ormes, T Saeki, T Sanuki, M Sasaki, ES Seo, Y Shikaze, T Sonoda, R Streitmatter, J Suzuki, K Tanaka, Ueda, I, JZ Wang, N Yajima, T Yamagami, A Yamamoto, T Yoshida, K Yoshimura

    ORIGIN AND ACCELERATION OF COSMIC RAYS   27 ( 4 )   711 - 716   2001年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    The BESS spectrometer has measured the energy spectrum of cosmic-ray antiprotons successively in 1993, 1995, 1997 and 1998. In total, 848 antiprotons were clearly identified in energy range 0.18 to 4.20 GeV based on magnetic-rigidity, time-of-flight, energy loss, and Cherenkov radiation measurements. The measured antiproton spectra and antiproton/proton ratios were nearly identical at the upper end of the instrumental energy range, which is consistent with theoretical calculations. In the low energy region. our data show variations that are somewhat larger than expected. This might be due to statistical fluctuation, or might suggest a contribution of primary antiprotons from novel sources. (C) 2001 COSPAR. Published by Elsevier Science Ltd. All rights reserved.

    DOI: 10.1016/S0273-1177(01)00129-6

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  • Cosmic-ray antiprotons and antinuclei

    K Yoshimura

    ORIGIN AND ACCELERATION OF COSMIC RAYS   27 ( 4 )   693 - 703   2001年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    Recent progress in experimental observations and theoretical investigations of cosmic-ray antiprotons (P's) have brought new light on their origin. The (p) over bar energy spectrum measured by the recent BESS experiment shows the characteristic peak around 2 GeV, which was expected from "secondary" (p) over bar 's, i.e., produced in cosmic-ray interactions with the interstellar gas. The MASS and CAPRICE experiments have detected p's in the higher energy range and show that the flux decreases beyond the peak. These new data are well reproduced by theoretical calculations recently developed. Further sensitive observations with still higher statistics are required to investigate the propagation and solar modulation models in detail and to search for the primary (p) over bar component from novel sources, e.g. evaporating black holes or annihilating neutralino dark matter. In the case of antinuclei searches, an upper limit of a level of 10(-6) is obtained for the antihelium/helium ratio both from the BESS balloon flight and the AXIS space mission. In the future, BESS-polar and AMS on the ISS (International Space Station) may be expected to reach upper limits of 10(-7) and 10(-8), respectively. (C) 2001 COSPAR. Published by Elsevier Science Ltd. All rights reserved.

    DOI: 10.1016/S0273-1177(01)00111-9

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  • Precise measurements of cosmic-ray hydrogen and helium spectra with BESS

    T Sanuki, H Matsumoto, M Nozaki, K Abe, K Anraku, Y Asaoka, M Fujikawa, M Imori, T Maeno, Y Makida, N Matsui, H Matsunaga, J Mitchell, T Mitsui, A Moiseev, M Motoki, J Nishimura, S Orito, J Ormes, T Saeki, M Sasaki, ES Seo, Y Shikaze, T Sonoda, R Streitmatter, J Suzuki, K Tanaka, Ueda, I, JZ Wang, N Yajima, T Yamagami, A Yamamoto, T Yoshida, K Yoshimura

    ORIGIN AND ACCELERATION OF COSMIC RAYS   27 ( 4 )   761 - 766   2001年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    A series of Balloon-borne Experiments with a Superconducting Spectrometer, BESS, has been made since 1993. We report here the absolute cosmic-ray proton and helium spectra in energy ranges of 1 to 120 GeV and I to 54 GeV/nucleon, respectively, as measured by the 1998 balloon flight of the BESS spectrometer. Those spectra were determined within overall uncertainties of +/-5 % for protons and +/- 10 % for helium nuclei including statistical and systematic errors. The covered energy range is relevant to the atmospheric neutrinos observed as "fully contained events" in Super-Kamiokande. In order to extend the energy range up to around I TeV, we have started to design and develop new tracking detectors. Those energy spectra in a higher energy region will help to estimate the interstellar spectra of primary cosmic rays and the absolute fluxes of "up-going muons." (C) 2001 COSPAR. Published by Elsevier Science Ltd. All rights reserved.

    DOI: 10.1016/S0273-1177(01)00118-1

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  • Precision measurement of antiproton spectrum with BESS

    S Orito, T Maeno, H Matsunaga, K Abe, K Anraku, Y Asaoka, M Fujikawa, M Imori, M Ishino, Y Makida, N Matsui, H Matsumoto, J Mitchell, T Mitsui, A Moiseev, M Motoki, J Nishimura, M Nozaki, J Ormes, T Saeki, T Sanuki, M Sasaki, ES Seo, Y Shikaze, T Sonoda, R Streitmatter, J Suzuki, K Tanaka, Ueda, I, N Yajima, T Yamagami, A Yamamoto, T Yoshida, K Yoshimura

    SUN AND SIMILAR STARS/COSMIC RAY SPECTRA AND COMPOSITION   26 ( 11 )   1847 - 1850   2001年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    The absolute fluxes of the cosmic-ray antiproton are measured at solar minimum in the energy range 0.2 to 3.2 GeV, based on 460 antiprotons unambiguously detected by BESS spectrometer during its '95 and '97 balloon flights from Lynn Lake, Canada. In the resultant antiproton spectrum we have detected a clear peak around 2 GeV and measured its flux to 10% accuracy. The position and the absolute flux of the peak agree with the prediction of the Standard Leaky Box model for the "secondary" antiprotons. At low energies below I GeV, we observe an excess antiproton flux over the simple Standard Leaky Box prediction. This might indicate that the propagation mechanism needs to be modified, or might suggest a contribution of low-energy antiproton component from novel sources such as evaporating primordial black holes or the annihilating neutralino dark matter. Data from '98 and future Rights are expected to help us to clarify the situation. (C) 2001 COSPAR. Published by Elsevier Science Ltd. All rights reserved.

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  • Precise measurement of cosmic-ray proton and helium spectra with the BESS spectrometer

    T Sanuki, M Motoki, H Matsumoto, ES Seo, JZ Wang, K Abe, K Anraku, Y Asaoka, M Fujikawa, M Imori, T Maeno, Y Makida, N Matsui, H Matsunaga, J Mitchell, T Mitsui, A Moiseev, J Nishimura, M Nozaki, S Orito, J Ormes, T Saeki, M Sasaki, Y Shikaze, T Sonoda, R Streitmatter, J Suzuki, K Tanaka, Ueda, I, N Yajima, T Yamagami, A Yamamoto, T Yoshida, K Yoshimura

    ASTROPHYSICAL JOURNAL   545 ( 2 )   1135 - 1142   2000年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:UNIV CHICAGO PRESS  

    We report cosmic-ray proton and helium spectra in energy ranges of 1-120 GeV nucleon(-1) and 1-54 GeV nucleon(-1), respectively, measured by a flight of the Balloon-borne Experiment with Superconducting Spectrometer (BESS) in 1998. The magnetic rigidity of the cosmic ray was reliably determined by highly precise measurement of the circular track in a uniform solenoidal magnetic field of 1 T. Those spectra were determined within overall uncertainties of +/-5% for protons and +/- 10% for helium nuclei including statistical and systematic errors.

    DOI: 10.1086/317873

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  • Large-area scintillator hodoscope with 50 ps timing resolution onboard BESS

    Y Shikaze, S Orito, T Mitsui, K Yoshimura, H Matsumoto, H Matsunaga, M Nozaki, T Sonoda, Ueda, I, T Yoshida

    NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT   455 ( 3 )   596 - 606   2000年12月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    We describe the design and performance of a large-area scintillator hodoscope onboard the BESS rigidity spectrometer; an instrument with an acceptance of 0.3 m(2) sr. The hodoscope is configured such that 10 and 12 counters are, respectively, situated in upper and lower layers. Each counter is viewed from its ends by 2.5 in, fine-mesh photomultiplier tubes placed in a stray magnetic field of 0.2 T. Various beam-test data are presented. Use of cosmic-ray muons at ground-level confirmed 50 ps timing resolution for each layer, giving an overall time-of-fight resolution of 70 ps rms using a pure Gaussian-resolution function. Comparison with previous measurements on a similar scintillator hodoscope indicates good agreement with the scaling law that timing resolution is proportional to 1/rootN(pe), where N-pe is the effective number of photoelectrons. (C) 2000 Elsevier Science B.V. All rights reserved.

    DOI: 10.1016/S0168-9002(00)00571-4

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  • A superconducting solenoidal spectrometer for a balloon-borne experiment

    Y Ajima, K Anraku, T Haga, Y Higashi, H Honda, M Imori, S Inaba, N Kimura, M Kobayashi, Y Makida, N Matsui, H Matsumoto, H Matsunaga, M Motoki, M Nozaki, Y Nishihara, J Nishimura, S Orito, M Otoba, T Saeki, T Sanuki, M Sasaki, K Shimamura, J Suzuki, K Suzuki, N Takimi, K Tanaka, T Tsunoda, Ueda, I, T Yajima, T Yamagami, A Yamamoto, H Yamaoka, T Yoshida, K Yoshimura

    NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT   443 ( 1 )   71 - 100   2000年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    The BESS detector is a new type of balloon-borne spectrometer which utilizes various technologies recently developed for collider experiments. The principal scientific objectives include a measurement of cosmic-ray antiproton spectrum, search for anti-nuclei in cosmic radiation, and precise meaurements of cosmic-ray primaries. A thin superconducting solenoidal coil produces a uniform magnetic field of 1 T. Cylindrical drift chambers are located inside and outside the coil and perform continuous tracking. The momentum resolution is 0.5% at 1 GeV/c. i.e., the maximum detectable rigidity is 200 GV. Scintillation counter hodoscopes, placed above and below the solenoid, provide timing and dE/dx measurements and trigger generation. The timing resolution is 80 ps/counter. This cylindrical configuration achieves a large geometrical acceptance of 0.35 m(2) sr which is essential to detect rare cosmic-ray particles. In order to cope with high trigger rate and large data size, intelligent trigger circuits and a fast and parallel data acquision system are also developed. In 1993, the first scientific flight of the BESS apparatus was carried out and the first mass-measured antiprotons were detected at energies below 500 MeV (C) 2000 Elsevier Science B.V. All rights reserved.

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  • Precision measurement of cosmic-ray antiproton spectrum

    S Orito, T Maeno, H Matsunaga, K Abe, K Anraku, Y Asaoka, M Fujikawa, M Imori, M Ishino, Y Makida, N Matsui, H Matsumoto, J Mitchell, T Mitsui, A Moiseev, M Motoki, J Nishimura, M Nozaki, J Ormes, T Saeki, T Sanuki, M Sasaki, ES Seo, Y Shikaze, T Sonoda, R Streitmatter, J Suzuki, K Tanaka, Ueda, I, N Yajima, T Yamagami, A Yamamoto, T Yoshida, K Yoshimura

    PHYSICAL REVIEW LETTERS   84 ( 6 )   1078 - 1081   2000年2月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMERICAN PHYSICAL SOC  

    The energy spectrum of cosmic-ray antiprotons ((p) over bar's) has been measured in the range 0.18-3.56 GeV, based on 458 (p) over bar's collected by BESS in a recent solar-minimum period. We have detected for the first time a characteristic peak at 2 GeV of (p) over bar's originating from cosmic-ray interactions with the interstellar gas. The peak spectrum is reproduced by theoretical calculations, implying that the propagation models are basically correct and that different cosmic-ray species undergo a universal propagation. Future BESS data with still higher statistics will allow us to study the solar modulation and the propagation in detail and to search for primary (p) over bar components.

    DOI: 10.1103/PhysRevLett.84.1078

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  • Measurement of low-energy cosmic-ray antiprotons at solar minimum

    H Matsunaga, S Orito, H Matsumoto, K Yoshimura, A Moiseev, K Anraku, R Golden, M Imori, Y Makida, J Mitchell, M Motoki, J Nishimura, M Nozaki, J Ormes, T Saeki, T Sanuki, R Streitmatter, J Suzuki, K Tanaka, Ueda, I, N Yajima, T Yamagami, A Yamamoto, T Yoshida

    PHYSICAL REVIEW LETTERS   81 ( 19 )   4052 - 4055   1998年11月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMERICAN PHYSICAL SOC  

    The absolute fluxes of the cosmic-ray antiprotons at solar minimum are measured in the energy range 0.18 to 1.4 GeV, based on 43 events unambiguously detected in BESS 1995 data. The resultant energy spectrum appears to be flat below 1 GeV, compatible with a possible admixture of primary antiproton component with a soft energy spectrum, while the possibility of secondary antiprotons alone explaining the data cannot be excluded with the present accuracy. Further improvement of statistical accuracy and extension of the energy range are planned in future BESS flights. [S0031-9007(98)07573-5].

    DOI: 10.1103/PhysRevLett.81.4052

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  • Development of a large-area aerogel Cherenkov counter onboard BESS

    Y Asaoka, K Abe, K Yoshimura, M Ishino, M Fujikawa, S Orito

    NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT   416 ( 2-3 )   236 - 242   1998年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    This paper describes the development of a threshold-type aerogel Cherenkov counter with a large sensitive area of 0.6 m(2) to be carried onboard the BESS rigidity spectrometer to detect cosmic-my antiprotons. The design incorporates a large diffusion box containing 46 finemesh photomultipliers, with special attention being paid to achieving good performance under a magnetic field and providing sufficient endurance while minimizing material usage. The refractive index of the aerogel was chosen to be 1.03. By utilizing the muons and protons accumulated during the cosmic-ray measurements at sea level, a rejection factor of 10(4) was obtained against muons with beta approximate to 1, while keeping 97% efficiency for protons below the threshold. (C) 1998 Elsevier Science B.V. All rights reserved.

    DOI: 10.1016/S0168-9002(98)00772-4

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  • A new limit on the flux of cosmic antihelium

    T Saeki, K Anraku, S Orito, J Ormes, M Imori, B Kimbell, Y Makida, H Matsumoto, H Matsunaga, J Mitchell, M Motoki, J Nishimura, M Nozaki, M Otoba, T Sanuki, R Streitmatter, J Suzuki, K Tanaka, Ueda, I, N Yajima, T Yamagami, A Yamamoto, T Yoshida, K Yoshimura

    PHYSICS LETTERS B   422 ( 1-4 )   319 - 324   1998年3月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    A very sensitive search for cosmic-ray antihelium was performed using data obtained from three scientific flights of the BESS magnetic rigidity spectrometer. We have not observed any antihelium; this places a model-independent upper limit (95% C.L.) on the antihelium flux of 6 x 10(-4) m(-2)sr(-1)s(-1) at the top of the atmosphere in the rigidity region 1 to 16 GV, after correcting for the estimated interaction loss of antihelium in the air and in the instrument. The corresponding upper limit on the <(He)over bar>/He flux ratio is 3.1 x 10(-6), 30 times more stringent than the limits obtained in similar rigidity regions with magnetic spectrometers previous to BESS. (C) 1998 Published by Elsevier Science B.V.

    DOI: 10.1016/S0370-2693(98)00131-2

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  • Precision positioning of SuperKamiokande with GPS for a long-baseline neutrino oscillation experiment

    H Noumi, M Kurodai, M Ieiri, H Ishii, H Kasa, Y Katoh, M Minakawa, K Nakamura, K Nishikawa, Y Suzuki, M Takasaki, KH Tanaka, Y Yamanoi, K Yoshimura

    NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT   398 ( 2-3 )   399 - 408   1997年10月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    A positioning of the neutrino detector SuperKamiokande (SK) was made for a long-baseline neutrino oscillation experiment planned at KEK. For positioning, Global Positioning System (GPS) was employed. It has been demonstrated that GPS is of practical use for measuring the positions of SK and ECEK, being 250km distance from each other, to a better resolution. The geodetic coordinates at the SK center were obtained to be Lat. 36 degrees 25'32.5862 '' N., Long. 137 degrees 18'37.1241 '' E., H. 371.839 m in the global ellipsoidal coordinate system, WGS-84. The obtained coordinates are based on the coordinates given at a triangulation point at the KEK site. The present work will be fed back for constructing the neutrino beam line.

    DOI: 10.1016/S0168-9002(97)00899-1

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  • Antihelium in cosmic rays: A new upper limit and its significance

    JF Ormes, AA Moiseev, T Saeki, K Anraku, S Orito, RL Golden, M Imori, S Inaba, BL Kimbell, N Kimura, Y Makida, H Matsumoto, H Matsunaga, JW Mitchell, M Motoki, J Nishimura, M Nozaki, RE Streitmatter, J Suzuki, K Tanaka, Ueda, I, N Yajima, T Yamagami, A Yamamoto, T Yoshida, K Yoshimura

    ASTROPHYSICAL JOURNAL   482 ( 2 )   L187 - L190   1997年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:UNIV CHICAGO PRESS  

    We have searched for antihelium in the galactic cosmic rays using data obtained on the flight of the Balloon-borne Experiment with a Superconducting Spectrometer (BESS) launched from Lynn Lake, Manitoba, in northern Canada on 1995 July 25. The balloon reached an altitude of 36.5 km with a residual overburden of 5 g cm(-2). The total observation time was 12.2 kr with a live-time fraction of 0.61. No antihelium was observed after selections based on dE/dx and event quality cuts at rigidities between 1.6 and 16 GV/c; we infer that 536,420 helium nuclei survived the same cuts. This result leads to an upper limit to the <(He)over bar>/He abundance ratio of 8.1 x 10(-6) (95% confidence level), a factor of 2.7 over the lowest previous limit. Because this limit is for the first time at the level where predicted limits become astrophysically interesting (Ahlen et al.), we have reexamined the transport of cosmic rays in intergalactic space. We show that little can be learned about distant (> 10 Mpc) domains of antimatter from a null result.

    DOI: 10.1086/310700

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  • Cosmic-ray antiproton flux in the energy range form 200 to 600 MeV

    A Moiseev, K Yoshimura, Ueda, I, K Anraku, R Golden, M Imori, S Inaba, B Kimbell, N Kimura, Y Makida, H Matsumoto, H Matsunaga, J Mitchell, M Motoki, J Nishimura, M Nozaki, S Orito, J Ormes, T Saeki, ES Seo, S Stochaj, R Streitmatter, J Suzuki, K Tanaka, N Yajima, T Yamagami, A Yamamoto, T Yoshida

    ASTROPHYSICAL JOURNAL   474 ( 1 )   479 - 489   1997年1月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:UNIV CHICAGO PRESS  

    We have studied the low-energy antiprotons in the cosmic rays by utilizing data obtained by the Balloon-borne Experiment with a Superconducting magnetic rigidity Spectrometer (BESS) flown in 1993 July from Lynn Lake, Manitoba, Canada. A detailed description of the event selection criteria and back-ground corrections is given. Seven antiprotons are found that give an antiproton flux of 6.4(-3.5)(+5.5) x 10(-3)(m(2) sr s GeV)(-1) and an antiproton/proton ratio of 5.2(-2.8)(+4.4) x 10(-6) in the 200-600 MeV energy range. These results are consistent with a secondary origin of low-energy cosmic-ray antiprotons within our uncertainties, but they still require the precise measurement of the spectrum shape below 500 MeV to clarify exactly the model of particle propagation and possible contributions from exotic sources.

    DOI: 10.1086/303463

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  • Measurement of cosmic ray H and He isotopes in a Balloon Borne Experiment with a superconducting solenoid spectrometer

    ES Seo, H Matsunaga, K Anraku, M Imori, Y Makida, H Matsumoto, FB McDonald, J Mitchell, A Moiseev, M Motoki, J Nishimura, M Nozaki, S Orito, JF Ormes, M Otoba, T Saeki, T Sanuki, RE Streitmatter, J Suzuki, K Tanaka, Ueda, I, JZ Wang, N Yajima, T Yamagami, A Yamamoto, T Yoshida, K Yoshimura

    COSMIC RADIATION: SPECTRA AND COMPOSITION   19 ( 5 )   751 - 754   1997年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PERGAMON PRESS LTD  

    The Balloon Bome Experiment with a Superconducting Solenoid Spectrometer (BESS) was flown annually in 1993, 1994, and 1995. In this report we present the energy spectra and isotopic composition of cosmic ray H and He measured from the 1993 flight. The low energy fluxes of H and He agree with the IMP-8 satellite data for a 26 day period (7/14/93 - 8/9/93) that overlapped the BESS flight. Both H-2 and He-3 were well separated from H-1 and He-4. The measured spectra were corrected for the atmospheric overburden and compared with the interstellar/heliospheric propagation calculations. (C) 1997 COSPAR.

    DOI: 10.1016/S0273-1177(96)00140-8

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  • Cosmic ray antiproton spectrum measured by BESS in 1993-1995

    J Nishimura, H Matsunaga, M Motoki, A Moiseev, K Anraku, M Imori, Y Makida, H Matsumoto, J Mitchell, M Nozaki, S Orito, J Ormes, M Otoba, T Saeki, T Sanuki, R Streitmatter, J Suzuki, K Tanaka, Ueda, I, N Yajima, T Yamagami, A Yamamoto, T Yoshida, K Yoshimura

    COSMIC RADIATION: SPECTRA AND COMPOSITION   19 ( 5 )   771 - 774   1997年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PERGAMON PRESS LTD  

    Balloon-borne experiment using a superconducting spectrometer were carried out successfully in northern Canada, in summer 1993 to 1995. In `93 flight, seven antiprotons were detected in the kinetic range between cen 200 and 600 MeV. The corresponding cosmic ray antiproton flux at the top of the atmosphere is fond to be 6.4(-3.5)(+5.5) x 10(-3)(m(2) sr s GeV)(-1). In '95 flight. improvement on the TOF resolution resulted to the observation of the forty antiprotons in the kinetic energy region 175 MeV to 1.3 GeV. The analysis on '95 flight is under way. (C) 1997 COSPAR.

    DOI: 10.1016/S0273-1177(96)00145-7

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  • Measurements with photonic events in e(+)e(-) collisions at centre-of-mass energies of 130-140 GeV

    G Alexander, J Allison, N Altekamp, K Ametewee, KJ Anderson, S Anderson, S Arcelli, S Asai, D Axen, G Azuelos, AH Ball, E Barberio, RJ Barlow, R Bartoldus, Batley, JR, G Beaudoin, J Bechtluft, C Beeston, T Behnke, AN Bell, KW Bell, G Bella, S Bentvelsen, P Berlich, S Bethke, O Biebel, Blobel, V, IJ Bloodworth, JE Bloomer, P Bock, HM Bosch, M Boutemeur, BT Bouwens, S Braibant, RM Brown, HJ Burckhart, C Burgard, R Burgin, P Capiluppi, RK Carnegie, AA Carter, Carter, JR, CY Chang, C Charlesworth, DG Charlton, D Chrisman, SL Chu, PEL Clarke, Cohen, I, JE Conboy, OC Cooke, M Cuffiani, S Dado, C Dallapiccola, GM Dallavalle, C Darling, S DeJong, LA delPozo, MS Dixit, EDE Silva, M Doucet, E Duchovni, G Duckeck, IP Duerdoth, JEG Edwards, PG Estabrooks, HG Evans, M Evans, F Fabbri, P Fath, F Fiedler, M Fierro, HM Fischer, R Folman, DG Fong, M Foucher, H Fukui, A Furtjes, P Gagnon, A Gaidot, JW Gary, J Gascon, SM GasconShotkin, NI Geddes, C GeichGimbel, SW Gensler, FX Gentit, T Geralis, G Giacomelli, P Giacomelli, R Giacomelli, Gibson, V, WR Gibson, DM Gingrich, J Goldberg, MJ Goodrick, W Gorn, C Grandi, E Gross, M Gruwe, C Hajdu, GG Hanson, M Hansroul, M Hapke, CK Hargrove, PA Hart, C Hartmann, M Hauschild, CM Hawkes, R Hawkings, RJ Hemingway, G Herten, RD Heuer, MD Hildreth, JC Hill, SJ Hillier, T Hilse, PR Hobson, RJ Homer, AK Honma, D Horvath, R Howard, RE HughesJones, DE Hutchcroft, P IgoKemenes, DC Imrie, MR Ingram, A Jawahery, PW Jeffreys, H Jeremie, M Jimack, A Joly, G Jones, M Jones, RWL Jones, U Jost, P Jovanovic, J Kanzaki, D Karlen, T Kawamoto, RK Keeler, RG Kellogg, BW Kennedy, J King, J Kirk, S Kluth, T Kobayashi, M Kobel, DS Koetke, TP Kokott, S Komamiya, R Kowalewski, T Kress, P Krieger, J vonKrogh, P Kyberd, GD Lafferty, H Lafoux, R Lahmann, WP Lai, D Lanske, J Lauber, JG Layter, AM Lee, E Lefebvre, D Lellouch, J Letts, L Levinson, C Lewis, SL Lloyd, FK Loebinger, GD Long, B Lorazo, MJ Losty, J Ludwig, A Luig, A Malik, M Mannelli, S Marcellini, C Markus, AJ Martin, JP Martin, G Martinez, T Mashimo, W Matthews, P Mattig, WJ McDonald, J McKenna, EA Mckigney, TJ McMahon, AI McNab, F Meijers, S Menke, FS Merritt, H Mes, J Meyer, A Michelini, G Mikenberg, DJ Miller, R Mir, W Mohr, A Montanari, T Mori, M Morii, U Muller, B Nellen, B Nijjhar, R Nisius, SW ONeale, FG Oakham, F Odorici, OH Ogren, T Omori, MJ Oreglia, S Orito, M Palazzo, J Palinkas, JP Pansart, G Pasztor, Pater, JR, GN Patrick, MJ Pearce, S Petzold, JE Pilcher, J Pinfold, DE Plane, P Poffenberger, B Poli, A Posthaus, H Przysiezniak, DL Rees, D Rigby, MG Rison, SA Robins, N Rodning, JM Roney, A Rooke, E Ros, AM Rossi, M Rosvick, P Routenburg, Y Rozen, K Runge, O Runolfsson, DR Rust, R Rylko, EKG Sarkisyan, M Sasaki, C Sbarra, AD Schaile, O Schaile, F Scharf, P ScharffHansen, P Schenk, B Schmitt, M Schroder, HC SchultzCoulon, M Schulz, P Schutz, J Schwiening, WG Scott, TG Shears, BC Shen, CH ShepherdThemistocleous, P Sherwood, GP Siroli, A Sittler, A Skillman, A Skuja, AM Smith, TJ Smith, GA Snow, R Sobie, S SoldnerRembold, RW Springer, M Sproston, A Stahl, M Starks, K Stephens, J Steuerer, B Stockhausen, D Strom, F Strumia, P Szymanski, R Tafirout, H Takeda, P Taras, S Tarem, M Tecchio, N Tesch, M Thiergen, MA Thomson, E vonTorne, S Towers, M Tscheulin, E Tsur, AS Turcot, MF TurnerWatson, P Utzat, R vanKooten, G Vasseur, M Verzocchi, P Vikas, M Vincter, EH Vokurka, F Wackerle, A Wagner, CP Ward, DR Ward, JJ Ward, PM Watkins, AT Watson, NK Watson, P Weber, PS Wells, N Wermes, JS White, B Wilkens, GW Wilson, JA Wilson, T Wlodek, G Wolf, S Wotton, TR Wyatt, S Xella, S Yamashita, G Yekutieli, K Yoshimura, Zacek, V

    PHYSICS LETTERS B   377 ( 1-3 )   222 - 234   1996年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    Cross-sections and angular distributions for the production of events with single and multiple photons are measured from data recorded with the OPAL detector at the recently upgraded LEP collider. The measured cross-sections are generally consistent with Standard Model expectations for the e(+)e(-) --> <nu(nu)over bar gamma(gamma)> and e(+)e(-) --> gamma gamma(gamma) processes. Six events with an acoplanar photon pair and large missing mass are found. The observed number of events is larger than expected from e(+)e(-) --> <nu(nu)over bar gamma gamma>; however, the missing mass distribution is compatible with the Z(0) resonance. Deviations from QED are constrained by the data on e(+)e(-) --> gamma gamma(gamma). Lower limits are set at 95% confidence level on the QED cut-off parameters Lambda(+) and Lambda(-) of 152 GeV and 142 GeV, respectively, and also on the mass of an excited electron of 147 GeV.

    DOI: 10.1016/0370-2693(96)00488-1

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  • Topological search for the production of neutralinos and scalar

    G Alexander, J Allison, N Altekamp, K Ametewee, KJ Anderson, S Anderson, S Arcelli, S Asai, D Axen, G Azuelos, AH Ball, E Barberio, RJ Barlow, R Bartoldus, Batley, JR, G Beaudoin, J Bechtluft, C Beeston, T Behnke, AN Bell, KW Bell, G Bella, S Bentvelsen, P Berlich, S Bethke, O Biebel, Blobel, V, IJ Bloodworth, JE Bloomer, P Bock, HM Bosch, M Boutemeur, BT Bouwens, S Braibant, P BrightThomas, RM Brown, HJ Burckhart, C Burgard, R Burgin, P Capiluppi, RK Carnegie, AA Carter, Carter, JR, CY Chang, C Charlesworth, DG Charlton, D Chrisman, SL Chu, PEL Clarke, Cohen, I, JE Conboy, OC Cooke, M Cuffiani, S Dado, C Dallapiccola, GM Dallavalle, C Darling, S DeJong, LA delPozo, MS Dixit, EDE Silva, M Doucet, E Duchovni, G Duckeck, IP Duerdoth, JEG Edwards, PG Estabrooks, HG Evans, M Evans, F Fabbri, P Fath, F Fiedler, M Fierro, HM Fischer, R Folman, DG Fong, M Foucher, H Fukui, A Furtjes, P Gagnon, A Gaidot, JW Gary, J Gascon, SM GasconShotkin, NI Geddes, C GeichGimbel, SW Gensler, FX Gentit, T Geralis, G Giacomelli, P Giacomelli, R Giacomelli, Gibson, V, WR Gibson, DM Gingrich, J Goldberg, MJ Goodrick, W Gorn, C Grandi, E Gross, M Gruwe, C Hajdu, GG Hanson, M Hansroul, M Hapke, CK Hargrove, PA Hart, C Hartmann, M Hauschild, CM Hawkes, R Hawkings, RJ Hemingway, G Herten, RD Heuer, MD Hildreth, JC Hill, SJ Hillier, T Hilse, PR Hobson, RJ Homer, AK Honma, D Horvath, R Howard, RE HughesJones, DE Hutchcroft, P IgoKemenes, DC Imrie, MR Ingram, A Jawahery, PW Jeffreys, H Jeremie, M Jimack, A Joly, G Jones, M Jones, RWL Jones, U Jost, P Jovanovic, J Kanzaki, D Karlen, T Kawamoto, RK Keeler, RG Kellogg, BW Kennedy, J King, J Kirk, S Kluth, T Kobayashi, M Kobel, DS Koetke, TP Kokott, S Komamiya, R Kowalewski, T Kress, P Krieger, J vonKrogh, P Kyberd, GD Lafferty, H Lafoux, R Lahmann, WP Lai, D Lanske, J Lauber, JG Layter, AM Lee, E Lefebvre, D Lellouch, J Letts, L Levinson, C Lewis, SL Lloyd, FK Loebinger, GD Long, B Lorazo, MJ Losty, J Ludwig, A Luig, A Malik, M Mannelli, S Marcellini, C Markus, AJ Martin, JP Martin, G Martinez, T Mashimo, W Matthews, P Mattig, WJ McDonald, J McKenna, EA Mckigney, TJ McMahon, AI McNab, F Meijers, S Menke, FS Merritt, H Mes, J Meyer, A Michelini, G Mikenberg, DJ Miller, R Mir, W Mohr, A Montanari, T Mori, M Morii, U Muller, B Nellen, B Nijjhar, R Nisius, SW ONeale, FG Oakham, F Odorici, HO Ogren, T Omori, MJ Oreglia, S Orito, M Palazzo, J Palinkas, JP Pansart, G Pasztor, Pater, JR, GN Patrick, MJ Pearce, S Petzold, JE Pilcher, J Pinfold, DE Plane, P Poffenberger, B Poli, A Posthaus, H Przysiezniak, DL Rees, D Rigby, MG Rison, SA Robins, N Rodning, JM Roney, A Rooke, E Ros, AM Rossi, M Rosvick, P Routenburg, Y Rozen, K Runge, O Runolfsson, DR Rust, R Rylko, EKG Sarkisyan, M Sasaki, C Sbarra, AD Schaile, O Schaile, F Scharf, P ScharffHansen, P Schenk, B Schmitt, M Schroder, HC SchultzCoulon, M Schulz, P Schutz, J Schwiening, WG Scott, TG Shears, BC Shen, CH ShepherdThemistocleous, P Sherwood, GP Siroli, A Sittler, A Skillman, A Skuja, AM Smith, TJ Smith, GA Snow, R Sobie, S SoldnerRembold, RW Springer, M Sproston, A Stahl, M Starks, K Stephens, J Steuerer, B Stockhausen, D Strom, F Strumia, P Szymanski, R Tafirout, H Takeda, P Taras, S Tarem, M Tecchio, N Tesch, M Thiergen, MA Thomson, E vonTorne, S Towers, M Tscheulin, E Tsur, AS Turcot, MF TurnerWatson, P Utzat, R VanKooten, G Vasseur, M Verzocchi, P Vikas, M Vincter, EH Vokurka, F Wackerle, A Wagner, CP Ward, DR Ward, JJ Ward, PM Watkins, AT Watson, NK Watson, P Weber, PS Wells, N Wermes, JS White, B Wilkens, GW Wilson, JA Wilson, T Wlodek, G Wolf, S Wotton, TR Wyatt, S Xella, S Yamashita, G Yekutieli, K Yoshimura, Zacek, V

    PHYSICS LETTERS B   377 ( 4 )   273 - 288   1996年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    A search for scalar particles and neutralinos such as those predicted by supersymmetric models has been performed using a data sample of 4.4 million hadronic Z(0) decays recorded by the OPAL detector at the e(+)e(-) collider LEP. The production of such particles typically leads to event topologies consisting of an acoplanar pair of jets, or of a mono-jet, accompanied by sizeable missing energy owing to neutrinos and other undetectable neutral particles. Limits are obtained, at the 95% confidence level, on the masses and production rates of scalar particles produced in association with the Z(0). Limits are also placed on neutralino production, for which an additional possible signature is also studied, events containing a single observed photon. Within the Minimal Supersymmetric Standard Model, the mass of the lightest neutralino is found to be larger than 12.5 GeV/c(2) at 95% C.L., provided that tan beta is larger than 1.5.

    DOI: 10.1016/0370-2693(96)00502-3

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  • Search for chargino and neutralino production using the OPAL detector at root s=130-136GeV at LEP

    G Alexander, J Allison, N Altekamp, K Ametewee, KJ Anderson, S Anderson, S Arcelli, S Asai, D Axen, G Azuelos, AH Ball, E Barberio, RJ Barlow, R Bartoldus, Batley, JR, G Beaudoin, J Bechtluft, C Beeston, T Behnke, AN Bell, KW Bell, G Bella, S Bentvelsen, P Berlich, S Bethke, O Biebel, Blobel, V, IJ Bloodworth, JE Bloomer, P Bock, HM Bosch, M Boutemeur, BT Bouwens, S Braibant, RM Brown, HJ Burckhart, C Burgard, R Burgin, P Capiluppi, RK Carnegie, AA Carter, Carter, JR, CY Chang, C Charlesworth, DG Charlton, D Chrisman, SL Chu, PEL Clarke, Cohen, I, JE Conboy, OC Cooke, M Cuffiani, S Dado, C Dallapiccola, GM Dallavalle, C Darling, S DeJong, LA delPozo, MS Dixit, ED Silva, E Duchovni, G Duckeck, IP Duerdoth, JEG Edwards, PG Estabrooks, HG Evans, M Evans, F Fabbri, P Fath, F Fiedler, M Fierro, HM Fischer, R Folman, DG Fong, M Foucher, H Fukui, A Furtjes, P Gagnon, A Gaidot, JW Gary, J Gascon, SM GasconShotkin, NI Geddes, C GeichGimbel, SW Gensler, FX Gentit, T Geralis, G Giacomelli, P Giacomelli, R Giacomelli, Gibson, V, WR Gibson, DM Gingrich, J Goldberg, MJ Goodrick, W Gorn, C Grandi, E Gross, M Gruwe, C Hajdu, GG Hanson, M Hansroul, M Hapke, CK Hargrove, PA Hart, C Hartmann, M Hauschild, CM Hawkes, R Hawkings, RJ Hemingway, G Herten, RD Heuer, MD Hildreth, JC Hill, SJ Hillier, T Hilse, PR Hobson, RJ Homer, AK Honma, D Horvath, R Howard, RE HughesJones, DE Hutchcroft, P IgoKemenes, DC Imrie, MR Ingram, A Jawahery, PW Jeffreys, H Jeremie, M Jimack, A Joly, G Jones, M Jones, RWL Jones, U Jost, P Jovanovic, J Kanzaki, D Karlen, T Kawamoto, RK Keeler, RG Kellogg, BW Kennedy, J King, J Kirk, S Kluth, T Kobayashi, M Kobel, DS Koetke, TP Kokott, S Komamiya, R Kowalewski, T Kress, P Krieger, J vonKrogh, P Kyberd, GD Lafferty, H Lafoux, R Lahmann, WP Lai, D Lanske, J Lauber, JG Layter, AM Lee, E Lefebvre, D Lellouch, J Letts, L Levinson, C Lewis, SL Lloyd, FK Loebinger, GD Long, B Lorazo, MJ Losty, J Ludwig, A Luig, A Malik, M Mannelli, S Marcellini, C Markus, AJ Martin, JP Martin, G Martinez, T Mashimo, W Matthews, P Mattig, WJ McDonald, J McKenna, EA Mckigney, TJ McMahon, AI McNab, F Meijers, S Menke, FS Merritt, H Mes, J Meyer, A Michelini, G Mikenberg, B Miller, R Mir, W Mohr, A Montanari, T Mori, M Morii, U Muller, B Nellen, B Nijjhar, R Nisius, SW ONeale, FG Oakham, F Odorici, HO Ogren, T Omori, MJ Oreglia, S Orito, M Palazzo, J Palinkas, FM Palmonari, JP Pansart, G Pasztor, Pater, JR, GN Patrick, MJ Pearce, S Petzold, JE Pilcher, J Pinfold, DE Plane, P Poffenberger, B Poli, A Posthaus, H Przysiezniak, DL Rees, D Rigby, MG Rison, SA Robins, N Rodning, JM Roney, A Rooke, E Ros, AM Rossi, M Rosvick, P Routenburg, Y Rozen, K Runge, O Runolfsson, DR Rust, R Rylko, EKG Sarkisyan, M Sasaki, C Sbarra, AD Schaile, O Schaile, F Scharf, P ScharffHansen, P Schenk, B Schmitt, M Schroder, HC SchultzCoulon, M Schulz, P Schutz, J Schwiening, WG Scott, TG Shears, BC Shen, CH ShepherdThemistocleous, P Sherwood, GP Siroli, A Sittler, A Skillman, A Skuja, AM Smith, TJ Smith, GA Snow, R Sobie, S SoldnerRembold, RW Springer, M Sproston, A Stahl, M Starks, K Stephens, J Steuerer, B Stockhausen, D Strom, F Strumia, P Szymanski, R Tafirout, H Takeda, P Taras, S Tarem, M Tecchio, N Tesch, M Thiergen, MA Thomson, E vonTorne, S Towers, M Tscheulin, E Tsur, AS Turcot, MF TurnerWatson, P Utzat, R VanKooten, G Vasseur, M Verzocchi, P Vikas, M Vincter, EH Vokurka, F Wackerle, A Wagner, CP Ward, DR Ward, JJ Ward, PM Watkins, AT Watson, NK Watson, P Weber, PS Wells, N Wermes, JS White, B Wilkens, GW Wilson, JA Wilson, T Wlodek, G Wolf, S Wotton, TR Wyatt, S Xella, S Yamashita, G Yekutieli, K Yoshimura, Zacek, V

    PHYSICS LETTERS B   377 ( 1-3 )   181 - 194   1996年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    A search for charginos and neutralinos, predicted by supersymmetric theories, has been performed using a data sample of 2.6 pb(-1) at a centre-of-mass energy of root s = 130 GeV and 2.6 pb(-1) at 136 GeV collected with the OPAL detector at LEP during November 1995. No candidate events were observed. The 95% C.L. lower limit on the lightest chargino mass in the Minimal Supersymmetric Standard Model is 65.4 GeV if the universal scalar mass m(o) is greater than 1 TeV, and 58.7 GeV for the smallest m(o) compatible with slepton and sneutrino mass limits obtained at centre-of-mass energies near the Z peak. These limits were obtained under the conditions that the lightest chargino is heavier than the lightest neutralino by more than 10 GeV and tan beta is larger than 1.5. The results of a model independent search for charginos and neutralinos are also given.

    DOI: 10.1016/0370-2693(96)00301-2

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  • Improved measurement of the lifetime of the tau lepton

    G Alexander, J Allison, N Altekamp, K Ametewee, KJ Anderson, S Anderson, S Arcelli, S Asai, D Axen, G Azuelos, AH Ball, E Barberio, RJ Barlow, R Bartoldus, Batley, JR, G Beaudoin, J Bechtluft, C Beeston, T Behnke, AN Bell, KW Bell, G Bella, S Bentvelsen, P Berlich, S Bethke, O Biebel, Blobel, V, IJ Bloodworth, JE Bloomer, P Bock, HM Bosch, M Boutemeur, BT Bouwens, S Braibant, P BrightThomas, RM Brown, HJ Burckhart, C Burgard, R Burgin, P Capiluppi, RK Carnegie, AA Carter, Carter, JR, CY Chang, C Charlesworth, DG Charlton, D Chrisman, SL Chu, PEL Clarke, Cohen, I, JE Conboy, OC Cooke, M Cuffiani, S Dado, C Dallapiccola, GM Dallavalle, C Darling, S DeJong, LA delPozo, MS Dixit, EDE Silva, M Doucet, E Duchovni, G Duckeck, IP Duerdoth, JEG Edwards, PG Estabrooks, HG Evans, M Evans, F Fabbri, P Fath, F Fiedler, M Fierro, HM Fischer, R Folman, DG Fong, M Foucher, H Fukui, A Furtjes, P Gagnon, A Gaidot, JW Gary, J Gascon, SM GasconShotkin, NI Geddes, C GeichGimbel, SW Gensler, FX Gentit, T Geralis, G Giacomelli, P Giacomelli, R Giacomelli, Gibson, V, WR Gibson, DM Gingrich, J Goldberg, MJ Goodrick, W Gorn, C Grandi, E Gross, M Gruwe, C Hajdu, GG Hanson, M Hansroul, M Hapke, CK Hargrove, PA Hart, C Hartmann, M Hauschild, CM Hawkes, R Hawking, RJ Hemingway, G Herten, RD Heuer, MD Hildreth, JC Hill, SJ Hillier, T Hilse, PR Hobson, RJ Homer, AK Honma, D Horvath, R Howard, RE HughesJones, DE Hutchcroft, P IgoKemenes, DC Imrie, MR Ingram, A Jawahery, PW Jeffreys, H Jeremie, A Jimack, A Joly, G Jones, M Jones, RWL Jones, U Jost, P Jovanovic, J Kanzaki, D Karlen, T Kawamoto, RK Keeler, RG Kellogg, BW Kennedy, J King, J Kirk, S Kluth, T Kobayashi, M Kobel, DS Koetke, TP Kokott, S Komamiya, R Kowalewski, T Kress, P Krieger, J vonKrogh, P Kyberd, GD Lafferty, H Lafoux, R Lahmann, WP Lai, D Lanske, J Lauber, JG Layter, AM Lee, E Lefebvre, D Lellouch, J Letts, L Levinson, C Lewis, SL Lloyd, FK Loebinger, GD Long, B Lorazo, MJ Losty, J Ludwig, A Luig, A Malik, M Mannelli, S Marcellini, C Markus, AJ Martin, JP Martin, G Martinez, T Mashimo, W Matthews, P Mattig, WJ McDonald, J McKenna, EA Mckigney, TJ McMahon, AI McNab, F Meijers, S Menke, FS Merritt, H Mes, J Meyer, A Michelini, G Mikenberg, DJ Miller, R Mir, W Mohr, A Montanari, T Mori, M Morii, U Muller, B Nellen, B Nijjhar, R Nisius, SW ONeale, FG Oakham, F Odorici, HO Ogren, T Omori, MJ Oreglia, S Orito, M Palazzo, J Palinkas, JP Pansart, G Pasztor, Pater, JR, GN Patrick, MJ Pearce, S Petzold, JE Pilcher, J Pinfold, DE Plane, P Poffenberger, B Poli, A Posthaus, H Przysiezniak, DL Rees, D Rigby, MG Rison, SA Robins, N Rodning, JM Roney, A Rooke, E Ros, AM Rossi, M Rosvick, P Routenburg, Y Rozen, K Runge, O Runolfsson, DR Rust, R Rylko, EKG Sarkisyan, M Sasaki, C Sbarra, AD Schaile, O Schaile, F Scharf, P ScharffHansen, P Schenk, B Schmitt, M Schroder, HC SchultzCoulon, M Schulz, P Schutz, J Schwiening, WG Scott, TG Shears, BC Shen, CH ShepherdThemistocleous, P Sherwood, GP Siroli, A Sittler, A Skillman, A Skuja, AM Smith, TJ Smith, GA Snow, R Sobie, S SoldnerRembold, RW Springer, M Sproston, A Stahl, M Starks, K Stephens, J Steuerer, B Stockhausen, D Strom, F Strumia, P Szymanski, R Tafirout, H Takeda, P Taras, S Tarem, M Tecchio, N Tesch, M Thiergen, MA Thomson, E vonTorne, S Towers, M Tscheulin, E Tsur, AS Turcot, MF TurnerWatson, P Utzat, R VanKooten, G Vasseur, M Verzocchi, P Vikas, M Vincter, EH Vokurka, F Wackerle, A Wagner, CP Ward, DR Ward, JJ Ward, PM Watkins, AT Watson, NK Watson, P Weber, PS Wells, N Wermes, JS White, B Wilkens, GW Wilson, JA Wilson, T Wlodek, G Wolf, S Wotton, TR Wyatt, S Xella, S Yamashita, G Yekutieli, K Yoshimura, Zacek, V

    PHYSICS LETTERS B   374 ( 4 )   341 - 350   1996年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    A new measurement of the tau lifetime is presented. It uses data collected with the OPAL detector during 1994, which almost doubles the size of the OPAL tau sample. Two statistically independent techniques are used: an impact parameter analysis of one-prong decay tracks and a fit to the decay length distribution of three-prong decays. The lifetime obtained from the 1994 data by combining the results of these methods is tau(tau) = 289.7 +/- 2.5(stat) +/- 1.5(sys) fs. When combined with the previous OPAL tau lifetime measurement the improved tau lifetime is tau(tau) = 289.2 +/- 1.7(stat.) +/- 1.2(sys.) fs.

    DOI: 10.1016/0370-2693(96)00255-9

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  • A study of four-fermion final states with high multiplicity at LEP

    G Alexander, J Allison, N Altekamp, K Ametewee, KJ Anderson, S Anderson, S Arcelli, S Asai, D Axen, G Azuelos, AH Ball, E Barberio, RJ Barlow, R Bartoldus, Batley, JR, G Beaudoin, J Bechtluft, C Beeston, T Behnke, AN Bell, KW Bell, G Bella, S Bentvelsen, P Berlich, S Bethke, O Biebel, Blobel, V, IJ Bloodworth, JE Bloomer, P Bock, HM Bosch, M Boutemeur, BT Bouwens, S Braibant, RM Brown, HJ Burckhart, C Burgard, R Burgin, P Capiluppi, RK Carnegie, AA Carter, Carter, JR, CY Chang, C Charlesworth, DG Charlton, D Chrisman, SL Chu, PEL Clarke, Cohen, I, JE Conboy, OC Cooke, M Cuffiani, S Dado, C Dallapiccola, GM Dallavalle, C Darling, S DeJong, LA delPozo, MS Dixit, EDE Silva, M Doucet, E Duchovni, G Duckeck, IP Duerdoth, JEG Edwards, PG Estabrooks, HG Evans, M Evans, F Fabbri, P Fath, F Fiedler, M Fierro, HM Fischer, R Folman, DG Fong, M Foucher, H Fukui, A Furtjes, P Gagnon, A Gaidot, JW Gary, J Gascon, SM GasconShotkin, NI Geddes, C GeichGimbel, SW Gensler, FX Gentit, T Geralis, G Giacomelli, P Giacomelli, R Giacomelli, Gibson, V, WR Gibson, DM Gingrich, J Goldberg, MJ Goodrick, W Gorn, C Grandi, E Gross, M Gruwe, C Hajdu, GG Hanson, M Hansroul, M Hapke, CK Hargrove, PA Hart, C Hartmann, M Hauschild, CM Hawkes, R Hawkings, RJ Hemingway, G Herten, RD Heuer, MD Hildreth, JC Hill, SJ Hillier, T Hilse, PR Hobson, RJ Homer, AK Honma, D Horvath, R Howard, RE HughJones, DE Hutchcroft, P IgoKemenes, DC Imrie, MR Ingram, A Jawahery, PW Jeffreys, H Jeremie, M Jimack, A Joly, G Jones, M Jones, RWL Jones, U Jost, P Jovanovic, J Kanzaki, D Karlen, T Kawamoto, KR Keeler, RG Kellogg, BW Kennedy, J King, J Kirk, S Kluth, T Kobayashi, M Kobel, DS Koetke, TP Kokott, S Komamiya, R Kowalewski, T Kress, P Krieger, J vonKrogh, P Kyberd, GD Lafferty, H Lafoux, R Lahmann, WP Lai, D Lanske, J Lauber, JG Layter, AM Lee, E Lefebvre, D Lellouch, J Letts, L Levinson, C Lewis, SL Lloyd, FK Loebinger, GD Long, B Lorazo, MJ Losty, J Ludwig, A Luig, A Malik, N Mannelli, S Marcellini, C Markus, AJ Martin, JP Martin, G Martinez, T Mashimo, W Matthews, P Mattig, WJ McDonald, J McKenna, EA Mckigney, TJ McMahon, AI NcNab, F Meijers, S Menke, FS Merritt, H Mes, J Meyer, A Michelini, G Mikenberg, DJ Miller, R Mir, W Mohr, A Montanari, T Mori, M Morii, U Muller, B Nellen, B Nijjhar, R Nisius, SW ONeale, FG Oakham, F Odorici, HO Ogren, T Omori, MJ Oreglia, S Orito, M Palazzo, J Palinkas, JP Pansart, G Pasztor, Pater, JR, GN Patrick, MJ Pearce, S Petzold, JE Pilcher, J Pinfold, DE Plane, P Poffenberger, B Poli, A Posthaus, H Przysiezniak, DL Rees, D Rigby, MG Rison, SA Robins, N Rodning, JM Roney, A Rooke, E Ros, AM Rossi, M Rosvick, P Routenburg, Y Rozen, K Runge, O Runolfsson, DR Rust, R Rylko, EKG Sarkisyan, M Sasaki, C Sbarra, AD Schaile, O Schaile, F Scharf, P ScharffHansen, P Schenk, B Schmitt, M Schroder, HC SchultzCoulon, M Schulz, P Schutz, J Schwiening, WG Scott, TG Shears, BC Shen, CH ShepherdThemistocleous, P Sherwood, GP Siroli, A Sittler, A Skillman, A Skuja, AM Smith, TJ Smith, GA Snow, R Sobie, S SoldnerRembold, RW Springer, M Sproston, A Stahl, M Starks, K Stephens, J Steuerer, B Stockhausen, D Strom, F Strumia, P Szymanski, R Tafirout, H Takeda, P Taras, S Tarem, M Tecchio, N Tesch, M Thiergen, MA Thomson, E vonTorne, S Towers, M Tscheulin, E Tsur, AS Turcot, MF TurnerWatson, P Utzat, R VanKooten, G Vasseur, M Verzocchi, P Vikas, M Vincter, EH Vokurka, F Wackerle, A Wagner, CP Ward, DR Ward, JJ Ward, PM Watkins, AT Watson, NK Watson, P Weber, PS Wells, N Wermes, JS White, B Wilkens, GW Wilson, JA Wilson, T Wlodek, G Wolf, S Wotton, TR Wyatt, S Xella, S Yamashita, G Yekutieli, K Yoshimura, Zacek, V

    PHYSICS LETTERS B   376 ( 4 )   315 - 328   1996年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    A search for l(+)l(-) <q(q)over bar> (l = e, mu) four-fermion final states in high multiplicity events has been performed at root s approximate to m(z) and above the Z peak at root s = 130 GeV and root s = 136 GeV, The data taken with OPAL correspond to an integrated luminosity of 132.4 pb(-1) and 5.3 pb(-1) at root s approximate to m(z) and root s = 130-136 GeV, respectively. While at the Z resonance the data are in good agreement with the Standard Model predictions, we find more events than expected at root s = 130-136 GeV, especially in the mu(+)mu(-) <q(q)over bar> channel, where 5 events remain after all cuts, with only 0.6 predicted by the Monte Carlo simulation. For all center-of-mass energies the observed shapes of the differential distributions are consistent with the predictions.

    DOI: 10.1016/0370-2693(96)00397-8

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  • Measurement of cross-sections and asymmetries in e(+)e(-) collisions at 130-140 GeV centre-of-mass energy

    G Alexander, J Allison, N Altekamp, K Ametewee, KJ Anderson, S Anderson, S Arcelli, S Asai, D Axen, G Azuelos, AH Ball, E Barberio, RJ Barlow, R Bartoldus, Batley, JR, G Beaudoin, J Bechtluft, C Beeston, T Behnke, AN Bell, KW Bell, G Bella, S Bentvelsen, P Berlich, S Bethke, O Biebel, Blobel, V, IJ Bloodworth, JE Bloomer, P Bock, HM Bosch, M Boutemeur, BT Bouwens, S Braibant, RM Brown, HJ Burckhart, C Burgard, R Burgin, P Capiluppi, RK Carnegie, AA Carter, Carter, JR, CY Chang, C Charlesworth, DG Charlton, D Chrisman, SL Chu, PEL Clarke, Cohen, I, JE Conboy, OC Cooke, M Cuffiani, S Dado, C Dallapiccola, GM Dallavalle, C Darling, S DeJong, LA delPozo, MS Dixit, EDC Silva, M Doucet, E Duchovni, G Duckeck, IP Duerdorth, JEG Edwards, PG Estabrooks, HG Evans, M Evans, F Fabbri, P Fath, F Fiedler, M Fierro, HM Fischer, R Folman, DG Fong, M Foucher, H Fukui, A Furtjes, P Gagnon, A Gaidot, JW Gary, J Gascon, SM GasconShotkin, NI Geddes, C GeichGimbel, SW Gensler, FX Gentit, T Geralis, G Giacomelli, P Giacomelli, R Giacomelli, Gibson, V, WR Gibson, DM Gingrich, J Goldberg, MJ Goodrick, W Gorn, C Grandi, E Gross, M Gruwe, C Hajdu, GG Hanson, M Hansroul, M Hapke, CK Hargrove, PA Hart, C Hartmann, M Hauschild, CM Hawkes, R Hawkings, RJ Hemingway, G Herten, RD Heuer, MD Hildreth, JC Hill, SJ Hillier, T Hilse, PR Hobson, RH Homer, AK Honma, D Horvath, R Howard, RE HughesJones, DE Hutchcroft, P IgoKemenes, DC Imrie, MR Ingram, A Jawahery, PW Jeffreys, H Jeremie, M Jimack, A Joly, G Jones, M Jones, RWL Jones, U Jost, P Jovanovic, J Kanzaki, D Karlen, T Kawamoto, RK Keeler, RG Kellogg, BW Kennedy, J King, J Kirk, S Kluth, T Kobayashi, M Kobel, DS Koetke, TP Kokott, S Komamiya, R Kowalewski, T Kress, P Krieger, J vonKrogh, P Kyberd, GD Lafferty, H Lafoux, R Lahmann, WP Lai, D Lanske, J Lauber, JG Layter, AM Lee, E Lefebvre, D Lellouch, J Letts, L Levinson, C Lewis, SL Lloyd, FK Loebinger, GD Long, B Lorazo, MJ Losty, J Ludwig, A Luig, A Malik, M Mannelli, S Marcellini, C Markus, AJ Martin, JP Martin, G Martinez, T Mashimo, W Matthews, P Mattig, WJ McDonald, J McKenna, EA McKigney, TJ McMahon, AI McNab, F Meijers, S Menke, FS Merritt, H Mes, J Meyer, A Michelini, G Mikenberg, DJ Miller, R Mir, W Mohr, A Montanari, T Mori, M Morii, U Muller, B Nellen, B Nijjhar, R Nisius, SW ONeale, FG Oakham, F Odorici, HO Ogren, T Omori, MJ Oreglia, S Orito, M Palazzo, J Palinkas, JP Pansart, G Pasztor, Pater, JR, GN Patrick, MJ Pearce, S Petzold, JE Pilcher, J Pinfold, DE Plane, P Poffenberger, B Poli, A Posthaus, H Przysiezniak, DL Rees, D Rigby, MG Rison, SA Robins, N Rodning, JM Roney, A Rooke, E Ros, AM Rossi, M Rosvick, P Routenburg, Y Rozen, K Runge, O Runolfsson, DR Rust, R Rylko, EKG Sarkisyan, M Sasaki, C Sbarra, AD Schaile, O Schaile, F Scharf, P ScharffHansen, P Schenk, B Schmitt, M Schroder, HC SchultzCoulon, M Schulz, P Schutz, J Schwiening, WG Scott, TG Shears, BC Shen, CH ShepherdThemistocleous, P Sherwood, GP Siroli, A Sittler, SA Skillman, A Skuja, AM Smith, TJ Smith, GA Snow, R Sobie, S SoldnerRembold, RW Springer, M Sproston, A Stahl, M Starks, K Stephens, J Steuerer, B Stockhausen, D Strom, F Strumia, P Szymanski, R Tafirout, H Takeda, P Taras, S Tarem, M Tecchio, N Tesch, M Thiergen, MA Thomson, E vonTorne, S Towers, M Tscheulin, E Tsur, AS Turcot, MF TurnerWatson, P Utzat, R VanKooten, G Vasseur, M Verzocchi, P Vikas, M Vincter, EH Vokurka, F Wackerle, A Wagner, CP Ward, DR Ward, JJ Ward, PM Watkins, AT Watson, NK Watson, P Weber, PS Wells, N Wermes, JS White, B Wilkens, GW Wilson, JA Wilson, T Wlodek, G Wolf, S Wotton, TR Wyatt, S Xella, S Yamashita, G Yekutieli, K Yoshimura, Zacek, V

    PHYSICS LETTERS B   376 ( 1-3 )   232 - 244   1996年5月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:ELSEVIER SCIENCE BV  

    Production of events with multihadronic and leptonic final states has been measured in e(+)e(-) collisions at centre-of-mass mass energies significantly above the Z(0) mass, using the OPAL detector at LEP. A substantial production rate of radiative Z(0) gamma events was observed, as expected, together with events with less energetic initial-state photons, The cross-sections and leptonic forward-backward asymmetries were measured and compared with Standard Model expectations, In a model-independent fit to the Z(0) lineshape, the hadronic cross-section and lepton asymmetries presented here provide constraints on the size of the gamma Z(0)-interference term which are complementary to those afforded by LEP data accumulated at the Z(0) resonance.

    DOI: 10.1016/0370-2693(96)00394-2

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  • Searches for new physics

    GF Giudice, ML Mangano, G Ridolfi, R Ruckl, S Ambrosanio, S Asai, G Azuelos, H Baer, A Bartl, W Bernreuther, M Besancon, G Bhattacharyya, M Brhlik, LM Bryant, G Burkart, M Carena, R Casalbuoni, P Chankowski, D Choudhury, A Culatti, A Deandrea, W deBoer, G Carlino, S DeCurtis, G Degrassi, C Dionisi, A Djouadi, D Dominici, H Dreiner, H Eberl, L Favart, M Felcini, F Feruglio, H Fraas, F Franke, R Gatto, S Giagu, M Grazzini, JF Grivaz, JJ Hernandez, S Katsanevas, S Komamiya, S Kraml, P LeCoultre, S Lola, W Majerotto, A Masiero, T Medcalf, B Mele, G Montagna, R Munroe, S Navas, F NessiTebaldi, O Nicrosini, S Orito, F Piccinini, S Pokorski, W Porod, P Rebecchi, F Richard, S Rigolin, S RosierLees, S Shevchenko, Shoutko, V, A Shvorob, L Silvestrini, A Sopczak, R Tafirout, Tata, X, J Toth, A Trombini, C VanderVelde, R vanKooten, A Vicini, JH vonWimmerspergToeller, C Wagner, K Yoshimura

    PHYSICS AT LEP2, VOL. 1   96 ( 1 )   463 - 524   1996年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:C E R N  

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  • STATUS AND RESULT FROM BESS

    K ANRAKU, R GOLDEN, M IMORI, S INABA, B KIMBELL, N KIMURA, Y MAKIDA, H MATSUMOTO, H MATSUNAGA, J MITCHELL, M MOTOKI, J NISHIMURA, M NOZAKI, S ORITO, J ORMES, D RIGHTER, T SAEKI, R STREITMATTER, J SUZUKI, K TANAKA, UEDA, I, N YAJIMA, T YAMAGAMI, A YAMAMOTO, T YOSHIDA, K YOSHIMURA

    SCIENTIFIC BALLOONING   17 ( 9 )   101 - 110   1996年

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:PERGAMON PRESS LTD  

    A balloon-borne experiment using a superconducting solenoidal magnet spectrometer is being carried out with aims at making a precise measurement of low energy antiproton flux in cosmic rays and a highly sensitive search for primordial antimatter in the Universe. The spectrometer has a unique cylindrical configuration associated with a thin superconducting solenoidal magnet and is realizing a geometrical acceptance of 0.5 m(2)sr. The first scientific ballooning flight was successfully carried out in northern Canada, in summer, 1993, and the second flight is being prepared to he carried out in summer, 1994. Performance of the spectrometer in the first night and progress of the experiment are described.

    DOI: 10.1016/0273-1177(95)00684-7

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  • OBSERVATION OF COSMIC-RAY ANTIPROTONS AT ENERGIES BELOW 500 MEV

    K YOSHIMURA, S ORITO, UEDA, I, K ANRAKU, R GOLDEN, M IMORI, S INABA, B KIMBELL, N KIMURA, Y MAKIDA, H MATSUMOTO, H MATSUNAGA, J MITCHELL, M MOTOKI, J NISHIMURA, M NOZAKI, J ORMES, T SAEKI, R STREITMATTER, J SUZUKI, K TANAKA, N YAJIMA, T YAMAGAMI, A YAMAMOTO, T YOSHIDA

    PHYSICAL REVIEW LETTERS   75 ( 21 )   3792 - 3795   1995年11月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:AMERICAN PHYSICAL SOC  

    A search for cosmic-ray antiprotons was performed using a balloon-borne experiment with a superconducting magnetic rigidity spectrometer (BESS). We have detected four antiprotons in the kinetic energy range between 300 and 500 MeV, the first antiprotons to be identified by a direct mass measurement. The corresponding (p) over bar/p flux ratio at the top of the atmosphere is found to be 1.2(-0.65)(+1.0) X 10(-5). No antiprotons were observed in the range between 175 and 300 MeV, resulting in a 90% C.L. upper limit on the flux ratio of 2.9 X 10(-5).

    DOI: 10.1103/PhysRevLett.75.3792

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  • BALLOONING OF A THIN SUPERCONDUCTING SOLENOID FOR PARTICLE ASTROPHYSICS

    Y MAKIDA, K ANRAKU, J SUZUKI, A YAMAMOTO, M IMORI, T YOSHIDA, K YOSHIMURA, UEDA, I, T SAEKI, H MATSUNAGA, S ORITO, M MOTOKI, M NOZAKI, N YAJIMA, DL RIGHTER

    IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY   5 ( 2 )   658 - 661   1995年6月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC  

    A thin superconducting solenoid was launched by using a large balloon up to an altitude of 36.5 km in Northern Canada in the summer of 1993 as a core facility for the cosmic ray spectrometer, BESS. The magnet was excited up to 1.0 T in persistent current mode on the ground and was launched being attended with 2.7 G shocks. After 17 hours successful flight, it was discharged on the sky and made a mild descending and landing by using a parachute for recovery. The magnet was safely operated without problems during flight in 1993 and contributed to an second observation in the summer of 1994.

    DOI: 10.1109/77.402634

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  • Performance of BESS detector

    M Nozaki, R Streitmatter, A Yamamoto, T Yoshida, K Anraku, R Golden, M Imori, S Inaba, B Kimbell, M Kimura, Y Makida, H Matsumoto, H Matsunaga, J Mitchell, M Motoki, J Nishimura, S Orito, J Ormes, D Righter, T Saeki, J Suzuki, K Tanaka, N Yajima, T Yamagami, K Yoshimura

    24TH INTERNATIONAL COSMIC RAY CONFERENCE, VOL 3   579 - 582   1995年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:ARGALIA EDITORE DELLE ARTI GRAFICHE EDITORIALI SRL  

    BESS (balloon-borne Experiment with Superconducting Solenoid) is an omni-purpose spectrometer for cosmic ray measurements with a large geometrical acceptance of 0.3 m(2)sr and a high maximum detectable momentum of 200 GeV/c. The design principle and the performance of the detector will be presented based on the flight data in '93 and '94.

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  • Measurement of cosmic ray H and He spectra in a Balloon Borne Experiment with a Superconducting Solenoid Spectrometer

    ES Seo, K Yoshimura, T Yoshida, A Yamamoto, K Anraku, R Golden, M Imori, S Inaba, B Kimbell, N Kimura, Y Makida, H Matsumoto, H Matsunaga, J Mitchell, M Motoki, J Nishimura, M Nozaki, S Orito, J Ormes, T Saeki, R Streitmatter, J Suzuki, K Tanaka, Ueda, I, N Yajima, T Yamagami

    24TH INTERNATIONAL COSMIC RAY CONFERENCE, VOL 2   648 - 651   1995年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:ARGALIA EDITORE DELLE ARTI GRAFICHE EDITORIALI SRL  

    The cosmic ray H and He spectra have been measured from the 1993 balloon flight of the BESS spectrometer, which was launched from Lynn Lake, Manitoba, Canada on July 26, 1993 and spent 18 hrs at float altitude. The maximum detectable rigidity is estimated to be 200 GV. The measured spectra show an instrumental cutoff at similar to 170 MeV/n (0.6 GV for protons) which was apparently higher than the local geomagnetic cutoffs (0.38 - 0.56 GV) along the balloon trajectory. With the preliminary proton and helium spectra obtained from about 5% of the flight data, the solar modulation parameter for BESS-93 is estimated to be 700 +/- 100 MV.

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  • Observation of antiprotons at low energies by BESS detector

    S Orito, K Yoshimura, Ueda, I, K Anraku, R Golden, M Imori, S Inabe, B Kimbell, N Kimura, Y Makida, H Matsumoto, H Matsunaga, J Mitchell, M Motoki, J Nishimura, M Nozaki, J Ormes, T Saeki, R Streitmatter, J Suzuki, K Tanaka, N Yajima, T Yamagami, A Yamamoto, T Yoshida

    24TH INTERNATIONAL COSMIC RAY CONFERENCE, VOL 3   76 - 79   1995年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:ARGALIA EDITORE DELLE ARTI GRAFICHE EDITORIALI SRL  

    A search for cosmic-ray antiprotons was performed using a Balloon-borne Experiment with a Superconducting magnetic rigidity Spectrometer (BESS). We have detected four antiprotons in the kinetic energy range between 300 and 500 MeV, the lowest energy cosmic-ray antiprotons ever observed. The corresponding <(p)over bar /p> flux ratio at the top of the atmosphere is found to be 1.2 +/- 0.7 x 10(-5). No antiprotons were observed in the range between 175 and 300 MeV, resulting in a 90% C.L. upper limit on the flux ratio of 2.4 x 10(-5).

    Web of Science

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  • A REMOTE CONSOLE SYSTEM FOR BALLOON-BORNE EXPERIMENTS

    M IMORI, K YOSHIMURA, UEDA, I, T YOSHIDA, K ANRAKU, S INABA, T SAEKI, H HONDA, H MATSUNAGA, M MOTOKI, M NOZAKI, N TAKIMI, T YAMAGAMI

    IEEE TRANSACTIONS ON NUCLEAR SCIENCE   40 ( 4 )   913 - 916   1993年8月

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    記述言語:英語   掲載種別:研究論文(学術雑誌)   出版者・発行元:IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC  

    A remote console system is developed to improve remote control over experimental apparatus borne on the balloon. The remote console system, residing at a ground station for balloon borne experiments, sends commands to the apparatus and receives transmissions from it. The system communicates by radio with microcomputers incorporated in the experimental apparatus borne. on a balloon, where the microcomputers control the apparatus individually. The system includes plural personal computers and work stations which share the transmissions from the apparatus. The transmissions from the apparatus are formatted in a bit oriented protocol, which dispenses with a formatter and facilitate interface with the personal computers. The article describes the implementation of the system and the communication between the ground station and the balloon-borne apparatus.

    DOI: 10.1109/23.256683

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  • SEARCHING FOR PRIMORDIAL ANTIMATTER AT DISTANCES OF 30-MPC TO 300-MPC USING A BALLOON BORNE EXPERIMENT WITH A SUPERCONDUCTING SOLENOIDAL SPECTROMETER (BESS)

    K ANRAKU, RL GOLDEN, Y HIGASHI, M IMORI, S INABA, N KIMURA, Y MAKIDA, H MATSUMOTO, H MATSUNAGA, J MITCHELL, M MOTOKI, NISHIMURA, M NOZAKI, S ORITO, JF ORMES, D RIGHTER, T SAEKI, RE STREITMATTER, J SUZUKI, N TAKIMI, K TANAKA, T UEDA, N YAJIMA, T YAMAGAMI, A YAMAMOTO, T YOSHIDA, K YOSHIMURA

    23RD INTERNATIONAL COSMIC RAY CONFERENCE, VOL 2   156 - 159   1993年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:UNIV CALGARY PR  

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  • A REMOTE CONSOLE SYSTEM FOR BALLOON-BORNE EXPERIMENTS

    M IMORI, K YOSHIMURA, UEDA, I, T YOSHIDA, K ANRAKU, S INABA, T SAEKI, H HONDA, H MATSUNAGA, M MOTOKI, M NOZAKI, N TAKIMI, T YAMAGAMI

    CONFERENCE RECORD OF THE 1992 IEEE NUCLEAR SCIENCE SYMPOSIUM AND MEDICAL IMAGING CONFERENCE, VOLS 1 AND 2   508 - 510   1992年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:I E E E  

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  • REAL-TIME DATA PROCESSES IN A BALLOON-BORNE APPARATUS

    M IMORI, K ANRAKU, S INABA, UEDA, I, T SAEKI, T HAGA, T TSUNODA, M NOZAKI, T YAMAGAMI, T YOSHIDA, K YOSHIMURA

    CONFERENCE RECORD OF THE 1991 IEEE NUCLEAR SCIENCE SYMPOSIUM AND MEDICAL IMAGING CONFERENCE, VOLS 1-3   1178 - 1182   1991年

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    記述言語:英語   掲載種別:研究論文(国際会議プロシーディングス)   出版者・発行元:I E E E  

    DOI: 10.1109/NSSMIC.1991.259109

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▼全件表示

MISC

  • トリウム229アイソマー準位からの真空紫外光探索実験の現状

    平木貴宏, BEEKS Kjeld, 藤枝亮, 羽場宏光, 原秀明, 海野弘之, 笠松良崇, 北尾真司, 小無健司, 増田孝彦, 宮本祐樹, 岡井晃一, 笹尾登, SCHUMM Thorsten, 瀬戸誠, 重河優大, STELLMER Simon, 玉作賢治, 植竹智, 渡部信, 渡部司, 山口敦史, 安田勇輝, 依田芳卓, 吉見彰洋, 吉村浩司, 吉村太彦

    日本物理学会講演概要集(CD-ROM)   75 ( 2 )   2020年

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  • トリウム229アイソマー準位からの真空紫外光の探索

    海野弘行, 羽場宏光, 原秀明, 平木貴宏, 藤枝亮, 藤本弘之, 笠松良崇, 北尾真司, 小無健司, 増田孝彦, 宮本祐樹, 岡井晃一, 笹尾登, BEEKS Kjeld, SCHUMM Thorsten, 瀬戸誠, 重河優大, STELLMER Simon, 玉作賢治, 植竹智, 渡部信, 渡部司, 山口敦史, 安田勇輝, 依田芳卓, 吉見彰洋, 吉村浩司, 吉村太彦

    日本物理学会講演概要集(CD-ROM)   75 ( 1 )   2020年

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  • U-233のα-Y同時計数測定によるTh-229の原子核励起状態の半減期の決定

    重河優大, 山口敦史, 鈴木健太, 羽場宏光, 平木貴宏, 菊永英寿, 西村俊二, 笹尾登, 吉見彰洋, 吉村浩司

    日本放射化学会討論会(Web)   64th   2020年

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  • 核共鳴散乱を用いたトリウム229アイソマー準位への人工的遷移

    海野弘行, 羽場宏光, 原秀明, 平木貴宏, 藤枝亮, 藤本弘之, 鈴木健太, 笠松良崇, 北尾真司, 小無健司, 増田孝彦, 宮本祐樹, 岡井晃一, 笹尾登, 佐藤帯子, SCHUMM Thorsten, 瀬戸誠, 重河優大, STELLMER Simon, 玉作賢治, 植竹智, 渡部信, 渡部司, 山口敦史, 安田勇輝, 依田芳卓, 吉見彰洋, 吉村浩司, 吉村太彦

    日本物理学会講演概要集(CD-ROM)   74 ( 1 )   2019年

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  • トリウム229の原子核時計遷移分光

    鈴木健太, 羽場宏光, 原秀明, 平木貴宏, 藤枝亮, 藤本弘之, 海野弘行, 笠松良崇, 北尾真司, 小無健司, 増田孝彦, 宮本祐樹, 岡井晃一, 笹尾登, 佐藤帯子, SCHUMM Thorsten, 瀬戸誠, 重河優大, STELLMER Simon, 玉作賢治, 植竹智, 渡部信, 渡部司, 山口敦史, 安田勇輝, 依田芳卓, 吉見彰洋, 吉村浩司, 吉村太彦

    日本物理学会講演概要集(CD-ROM)   74 ( 1 )   2019年

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  • 19aSJ-7 コヒーレント二光子放出観測によるマクロコヒーレント増幅機構の実証(19aSJ ニュートリノの物理,素粒子実験領域)

    植竹 智, 原 秀明, 桂川 眞幸, 久間 晋, 増田 孝彦, 宮本 祐樹, 中野 逸夫, 大饗 千彰, 笹尾 登, 田中 実, 堤 康輔, 吉見 彰洋, 吉村 浩司, 吉村 太彦

    日本物理学会講演概要集   69 ( 2 )   22 - 22   2014年8月

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    記述言語:日本語   出版者・発行元:一般社団法人日本物理学会  

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  • 9pAW-11 水素分子振動準位間のコヒーレント2光子放出I(9pAW 量子エレクトロニクス(原子・分子の分光),領域1(原子分子・量子エレクトロニクス・放射線))

    宮本 祐樹, 原 秀明, 桂川 眞幸, 久間 晋, 増田 孝彦, 中野 逸夫, 大饗 千彰, 笹尾 登, 田中 実, 堤 康輔, 植竹 智, 吉見 彰洋, 吉村 浩司, 吉村 太彦

    日本物理学会講演概要集   69 ( 2 )   92 - 92   2014年8月

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    記述言語:日本語   出版者・発行元:一般社団法人日本物理学会  

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  • 9pAW-12 水素分子振動準位間のコヒーレント2光子放出II(9pAW 量子エレクトロニクス(原子・分子の分光),領域1(原子分子・量子エレクトロニクス・放射線))

    原 秀明, 桂川 眞幸, 久間 晋, 増田 孝彦, 宮本 祐樹, 中野 逸夫, 大饗 千彰, 笹尾 登, 田中 実, 堤 康輔, 植竹 智, 吉見 彰洋, 吉村 浩司, 吉村 太彦

    日本物理学会講演概要集   69 ( 2 )   93 - 93   2014年8月

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    記述言語:日本語   出版者・発行元:一般社団法人日本物理学会  

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  • 20pSD-1 マクロコヒーレンス生成に向けたXe準安定状態に関する分光実験(ニュートリノの物理,素粒子実験領域)

    吉見 彰洋, 笹尾 登, 植竹 智, 久間 晋, 中嶋 享, 大饗 千彰, 宮本 祐樹, 川口 建太郎, 堤 康輔, 唐 健, 福見 敦, 田中 実, 中野 逸夫, 若林 知成, 吉村 浩司, 吉村 太彦

    日本物理学会講演概要集   68 ( 2 )   16 - 16   2013年8月

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    記述言語:日本語   出版者・発行元:一般社団法人日本物理学会  

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  • J-PARCでのミューオン電子転換探索実験(COMET実験)における電磁カロリメータの開発研究

    大石航, 五十嵐洋一, 上野一樹, 川越清以, 佐藤朗, 齊藤直人, 東城順治, 豊田晃久, 西口創, 深尾祥紀, 松本侑樹, 三原智, 三部勉, 吉岡瑞樹, 吉村浩司, GRIGORIEV Dmitry, KUZMENKO Anastasiya, VELICHEVA Elena, VLADIMIR Kalinnikov

    日本物理学会講演概要集   68 ( 1 )   2013年

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  • J-PARCでのミューオン電子転換探索実験(COMET実験)における電磁カロリメータの開発研究

    大石航, 五十嵐洋一, 上野一樹, 川越清以, 佐藤朗, 齊藤直人, 東城順治, 豊田晃久, 中居勇樹, 西口創, 深尾祥紀, 松本侑樹, 三原智, 三部勉, 吉岡瑞樹, 吉村浩司, GRIGORIEV Dmitry, KUZMENKO Anastasiya, VELICHEVA Elena, VLADIMIR Kalinnikov

    日本物理学会講演概要集   68 ( 2 )   2013年

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  • 第2回南極周回飛翔宇宙線観測実験-BESS-Polar II報告

    吉村浩司, 安部航, 折戸玲子, 坂井賢一, 篠田遼子, 鈴木純一, 田中賢一, 谷口敬, 西村純, 野崎光昭, 灰野禎一, 長谷川雅也, 福家英之, 堀越篤, 槙田康博, 松川陽介, 松田晋弥, 山上隆正, 山本明, 吉田哲也, MITCHELL John W., HAMS Thomas, KIM Ki-Chun, LEE Moohyung, ORMES Jonathan F., SEBASTIAN Frank San, SASAKI Makoto, SEO Eun-Suk, STREITMATTER Robert E., THAKUR Neeharika

    宇宙航空研究開発機構研究開発報告 JAXA-RR-   ( 09-007 )   2010年

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  • 南極大陸における2007年BESS-極の科学飛行

    HASEGAWA Masaya, HORIKOSHI Atsushi, MATSUDA Shinya, MAKIDA Yasuhiro, SUZUKI Junichi, TANAKA Kenichi, YAMAMOTO Akira, YOSHIMURA Koji, NISHIMURA Jun, SAKAI Kenichi, SHINODA Ryoko, ORITO Reiko, MATSUKAWA Yosuke, KUSUMOTO Akira, FUKE Hideyuki, YAMAGAMI Takamasa, YOSHIDA Tetsuya, HAMS Thomas, MITCHELL John W., SASAKI Makoto, STREITMATTER Robert E., KIM Ki-chun, LEE Moo-hyon, SEO Eun-suk, ORMES Jonathan F., THAKUR Neeharika

    Transactions of the Japan Society for Aeronautical and Space Sciences, Space Technology Japan (Web)   7 ( ists26 )   2009年

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  • BESS-Polar:南極周回飛翔・超伝導スペクトロメータによる宇宙起源反粒子の精密探査

    山本明, 安部航, 泉康介, 板崎輝, 大宮英紀, 折戸玲子, 熊沢輝之, 坂井賢一, 志風義明, 篠田遼子, 鈴木純一, 高杉佳幸, 竹内一真, 谷崎圭裕, 田中賢一, 谷口敬, 西村純, 野崎光昭, 灰野禎一, 長谷川雅也, 福家英之, 堀越篤, 槙田康博, 松川陽介, 松田晋弥, 松本賢治, 山上隆正, 大和一洋, 吉田哲也, 吉村浩司, MITCHELL John W., HAMS Thomas, KIM Ki-Chun, LEE Moohyung, MOISEEV Alexander A., MYERS Zachary D., ORMES Jonathan F., SASAKI Makoto, SEO Eun-Suk, STREITMATTER Robert E.

    宇宙航空研究開発機構研究開発報告 JAXA-RR-   ( 07-009 )   2008年

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  • BESS-Polar用太陽電池システムの三陸検証実験

    福家英之, 野崎光昭, 安部航, 池田伸穂, 大宮英紀, 斎藤芳隆, 並木道義, 松本賢治, 吉村浩司

    宇宙科学研究所報告 特集   ( 45 )   2003年

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▼全件表示

受賞

  • Group Achievement 賞

    2012年4月   NASA  

    吉村浩司, BESS-Polarチーム

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  • Group Achievement 賞

    2009年4月   NASA  

    吉村浩司・BESS-Polarチーム

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共同研究・競争的資金等の研究

  • 冷却極性分子の量子操作による電子の永久電気双極子モーメント探索

    研究課題/領域番号:20KK0068  2020年10月 - 2026年03月

    日本学術振興会  科学研究費助成事業 国際共同研究加速基金(国際共同研究強化(B))  国際共同研究加速基金(国際共同研究強化(B))

    増田 孝彦, 吉村 浩司, 植竹 智

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    配分額:18720000円 ( 直接経費:14400000円 、 間接経費:4320000円 )

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  • 王陵級巨大古墳の構造分析に関する文理融合型総合研究

    研究課題/領域番号:20H05634  2020年08月 - 2025年03月

    日本学術振興会  科学研究費助成事業 基盤研究(S)  基盤研究(S)

    清家 章, 鈴木 茂之, 山口 雄治, 居島 薫, 白木 一郎, 光本 順, 野崎 貴博, 永嶺 謙忠, 福永 伸哉, 吉村 浩司, 南 健太郎, 三宅 康博, 野坂 俊夫, 鳥養 映子

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    配分額:195650000円 ( 直接経費:150500000円 、 間接経費:45150000円 )

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  • ミュオンラジオグラフィを用いた巨大古墳調査法の開発にかかる研究

    研究課題/領域番号:20H00027  2020年04月 - 2025年03月

    日本学術振興会  科学研究費助成事業 基盤研究(A)  基盤研究(A)

    清家 章, 鈴木 茂之, 居島 薫, 白木 一郎, 光本 順, 永嶺 謙忠, 福永 伸哉, 吉村 浩司, 南 健太郎, 三宅 康博

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    配分額:45370000円 ( 直接経費:34900000円 、 間接経費:10470000円 )

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  • トリウム229極低エネルギーアイソマーの解明と基礎物理への応用

    研究課題/領域番号:18H01230  2018年04月 - 2021年03月

    日本学術振興会  科学研究費助成事業 基盤研究(B)  基盤研究(B)

    吉村 浩司, 笠松 良崇

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    配分額:17290000円 ( 直接経費:13300000円 、 間接経費:3990000円 )

    高性能標的と改良したX線計測システムを用いて,高輝度放射光施設SPring-8において実験を遂行し,第二励起準位の核共鳴散乱を観測し,トリウム229を基底状態から能動的に励起することに成功した。これにより,第一励起状態(アイソマー状態)への遷移を能動的に制御することが可能になり,アイソマーからの真空脱励起光観測への大きなステップが達成された。
    【X線エネルギーモニタ】シリコン標準結晶を用いてX線のエネルギーを精密にモニタする装置(ボンド法)を産業総合研究所,理化学研究所と共同で開発し,共鳴エネルギー探索の際のエネルギースキャンにおけるX線エネルギーの不定性を0.07 eV以下に減らすことに成功した。
    【トリウム229の能動的な核励起に成功】9個のAPD(アバランシュフォトダイオード)をアレイ状に配置したセンサを用いて,優れた高速応答性を確保しつつ立体角を増加させたシステム,および大阪大,理研と共同で開発したトリウム標的,および高精度エネルギーモニターを用いてSPring-8で実験を行い,第二励起準位の核共鳴散乱を観測し,その寿命を求めることに成功した。トリウム229を基底状態からX線により能動的に励起したのは世界でも初である。
    【真空紫外光の観測の予備テスト】共鳴エネルギーに合わせたX線を照射することで,能動的に生成されたアイソマー状態(第一励起状態)から放出する真空紫外光の観測を開始した。標的としは真空紫外光に対して透過性のある光学結晶(トリウムをドープしたCaF2)を用いて,微小な光を集光する光学系を構築して,予備テストを行い十分な性能を発揮していることを確認した。

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  • トリウム229アイソマー極低エネルギー準位の決定とその特異性の究明

    研究課題/領域番号:15H03661  2015年04月 - 2018年03月

    日本学術振興会  科学研究費助成事業 基盤研究(B)  基盤研究(B)

    吉村 浩司, 吉見 彰洋, 笹尾 登, 山口 敦史, 瀬戸 誠

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    配分額:17030000円 ( 直接経費:13100000円 、 間接経費:3930000円 )

    原子核としては異常に小さい eV オーダーのトリウム-229アイソマー準位を,高輝度放射光 X 線および高速検出器系による核共鳴散乱を用いた新しい手法で探索した。そのための高時間分解能高速応答X線計測システム,高性能標的システム,X線集光システムを開発し,従来では困難であった1 ns以下の短い寿命の高精度な核共鳴データを取得することに成功した。

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  • 原子を用いたニュートリノ質量分光の基礎研究

    研究課題/領域番号:15H02093  2015年04月 - 2018年03月

    日本学術振興会  科学研究費助成事業 基盤研究(A)  基盤研究(A)

    笹尾 登, 吉村 浩司, 吉村 太彦, 田中 実

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    配分額:42510000円 ( 直接経費:32700000円 、 間接経費:9810000円 )

    本研究の最終目標は原子を用いるという世界に先駆けた方法により、ニュートリノの未確定重要パラメータを包括的に決定することにある。そのため原子や分子の励起準位からの光を伴うニュートリノ対放出過程に注目する。実験で鍵を握るポイントは量子干渉効果によるレートの増幅である。本研究では水素分子振動励起準位からの二光子対超放射過程を用いて、当該増幅機構の詳細を実験的に研究した。その結果、通常のラマン型励起による対超放射過程に加え、対向型励起等によっても当該過程を観測することに成功した。これらの結果は理論予想と概ね一致する。また理論面では背景過程除去法や初期位相印加により実験感度が向上することを発見した。

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  • 大強度ビームの2次元プロファイルとビームハローの超高感度同時計測装置の開発

    研究課題/領域番号:24310079  2012年04月 - 2016年03月

    日本学術振興会  科学研究費助成事業 基盤研究(B)  基盤研究(B)

    橋本 義徳, 外山 毅, 堀 洋一郎, 吉村 浩司, 武藤 豪

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    配分額:17810000円 ( 直接経費:13700000円 、 間接経費:4110000円 )

    J-PARCメインリングの大強度ビームのための測定装置の具体的設計と部分的製作を行った.内容は次の5点に要約される.(1) ビーム条件の検討及びバックグラウンドの測定から,十分な信号対ノイズ比を確認した.(2) 真空内で使うアルミ製主光学系を開発した.(3) リングの真空環境を悪化させない真空機器とインターロックの設計を行った.(4)ビームから見た装置のインピーダンスの計算を行い,ビームへ悪影響を及ぼす因子のないことを確認した.(5) 測定系を他のプロファイルモニターに使用しその有効性を実証した.真空容器の製作をH28年度中に行い,大強度ビームの測定を開始する予定である.

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  • 地上ガンマ線望遠鏡のための次世代PPDカメラの開発

    研究課題/領域番号:22340061  2010年04月 - 2013年03月

    日本学術振興会  科学研究費助成事業 基盤研究(B)  基盤研究(B)

    西嶋 恭司, 櫛田 淳子, 吉村 浩司, 梶野 文義, 佐々木 修, 中家 剛

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    配分額:17810000円 ( 直接経費:13700000円 、 間接経費:4110000円 )

    3mm×3mm(50μm)MPPCの基礎特性を調べた結果、温度特性として-3.1×10^4/℃,が得られた。また、ダークノイズを主とするノイズレートは,超過電圧,温度に依存していること,クロストーク発生確率の超過電圧特性は指数関数と一次直線の和で表せること,クロストークとアフターパルスの和の発生確率の超過電圧特性は温度に依存しないことなどが確かめられた。3mm×3 mm(50μm)MPPCを4×4並べたディスクリートアレイ4個でプロトタイプカメラを作成し、小型の大気チェレンコフ望遠鏡で観測を試みたが、チェレンコフ光を検出することに成功しなかった。理由として、MPPC信号のパルス幅に比べてトリガーレートが高過ぎたことが上げられる。

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  • 長時間気球観測データを用いた宇宙線反重陽子・反ヘリウムの精密探索

    研究課題/領域番号:22540322  2010年04月 - 2013年03月

    日本学術振興会  科学研究費助成事業 基盤研究(C)  基盤研究(C)

    吉村 浩司, 長谷川 雅也, 山本 明, 坂井 賢一, 佐々木 誠

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    配分額:4290000円 ( 直接経費:3300000円 、 間接経費:990000円 )

    本研究では、BESS-Polar IIの観測データを用いて反重陽子および反ヘリウムの探索を行った。南極から回収した測定器を用いた検証を行うことにより、実験中に生じた様々な問題について知見を得て、新たな較正により測定器性能を向上させることができた。従来に比べ1桁上の感度での探索を行った結果、観測データ中には反重陽子、反ヘリウムは観測されなかった。反ヘリウムに関しては、過去のBESS実験のデータと合わせる事により、BESS以前の結果にくらべ、1000倍の精度での探査結果となり、我々の周りに反物質優勢の世界がないことの最も直接的な証拠をあたえることとなった。

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  • 大強度パルス化ミューオンビームの開発によるレプトンフレーバー物理の新展開

    研究課題/領域番号:22340065  2010年 - 2012年

    日本学術振興会  科学研究費助成事業 基盤研究(B)  基盤研究(B)

    三原 智, 西口 創, 青木 正治, 吉村 浩司

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    配分額:7410000円 ( 直接経費:5700000円 、 間接経費:1710000円 )

    2008 年度より供用運転が開始された大強度陽子加速器施設(J-PARC)において、高純度大強度パルス化ミューオン源の開発を推進し、素粒子物理学の新たな領域を開拓するための基礎研究を推進した。本研究で行ったパルス化ミューオン源の開発にあたっては、隣り合う2つのパルス間にビーム粒子の漏れ出しがないことが重要である。このため、本研究では独創的な方法によるパルス形成方法の開拓とビーム診断方法の開発を行った。

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  • マクロコヒーラント増幅機構を用いたニュートリノ対生成の検出

    研究課題/領域番号:21104002  2009年04月 - 2015年03月

    日本学術振興会  科学研究費助成事業 新学術領域研究(研究領域提案型)  新学術領域研究(研究領域提案型)

    笹尾 登, 中野 逸夫, 吉村 太彦, 福見 敦, 若林 知成, 田中 実, 桂川 眞幸, 南條 創, 川口 建太郎, 唐 健, 久保園 芳博, 谷垣 勝己, 中嶋 亨, 吉村 浩司, 吉見 彰洋, 植竹 智, 久間 晋, 谷口 敬, 南條 創

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    配分額:411840000円 ( 直接経費:316800000円 、 間接経費:95040000円 )

    「マクロコヒーランス増幅」は原子を用いたニュートリノ質量分光計画にと極めて重要な増幅機構である。本研究の最大の成果は、水素分子振動励起状態(v=1)からの二光子放射過程を用いて原理検証実験を行い、期待通りの結果を得たことにある。具体的には、断熱ラマン過程を用いて振動励起準位に励起し、二光子コヒーラント放射が観測された。この結果自然放射過程に比較し、15桁以上の巨大な増幅効果が確認された。これにより原子を用いたニュートリノ質量分光の道を大きく切り開くことが出来た。この他、多様な原子分子を用い超放射過程の詳細研究や位相緩和の研究などニュートリノ質量分光に対する基礎研究を行った。

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  • 長時間飛翔観測による一次宇宙線スペクトルの短期過渡変動の研究

    研究課題/領域番号:19340070  2007年 - 2009年

    日本学術振興会  科学研究費助成事業 基盤研究(B)  基盤研究(B)

    吉村 浩司, 長谷川 雅也, 山本 明, 槇田 康博

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    配分額:18590000円 ( 直接経費:14300000円 、 間接経費:4290000円 )

    BESS-PolarII測定器の中で飛跡検出器のガス制御システム、圧力センサーについて改良を施し、2007年12月~2008年1月にかけて、南極周回飛翔実験を実施した。24.5日間の気球飛翔観測により、約47億事象の宇宙線を観測することに成功した。測定器全般の較正を行って宇宙線事象の選別を行い、較正された温度、圧力センサ等のデータを用いて補正を行った後、一次宇宙線(陽子)のスペクトルを求め、短期的な日々のスペクトルの強度変化と太陽風との相関を精度よく求めることができた。

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  • 南極周回飛翔超伝導スペクトロメータによる太陽活動極小期の宇宙起源反粒子探査

    研究課題/領域番号:18104006  2006年 - 2009年

    日本学術振興会  科学研究費助成事業 基盤研究(S)  基盤研究(S)

    山本 明, 吉村 浩司, 槙田 康博, 野崎 光昭, 長谷川 雅也, 吉田 哲也

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    配分額:104260000円 ( 直接経費:80200000円 、 間接経費:24060000円 )

    南極周回飛翔超伝導スペクトロメータを用いた太陽活動極小期(2007-2008年)の宇宙線観測の成功により、宇宙線反粒子、反物質に関する研究が飛躍的に発展した。(1)宇宙線反陽子(<1GeV)二次粒子として整合性を持ち、(2)S.Hawkingによって予言された原始ブラックホール(PBH)及びその蒸発を起源とする宇宙線反陽子を示唆する観測はされず、偏差、7シグマ以上の分離レベルで、その存在上限を下げ、(3)宇宙における物質・反物質存在比の非対称性の検証を進め、反ヘリウム/ヘリウム存在上限比として、<7x10E-8を得た。BESS実験を通して、二桁以上探索感度を高める成果を得た。

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  • 円形加速器を用いたミューオンイオン化冷却の基礎研究

    研究課題/領域番号:18340065  2006年 - 2008年

    日本学術振興会  科学研究費助成事業 基盤研究(B)  基盤研究(B)

    佐藤 朗, 石元 茂, 鈴木 祥二, 久野 良孝, 森 義治, 吉村 浩司, 板橋 隆久, 吉田 誠, 大木 俊征

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    配分額:17790000円 ( 直接経費:15000000円 、 間接経費:2790000円 )

    次世代の大型加速器計画であるニュートリノ・ファクトリーやミューオン・コライダーを実現するためには、ミューオン・ビームのイオン化冷却技術確立が重要である。本研究では、円形加速器を用いた効率の良いビーム冷却を目指し、現実的なビーム冷却リングの設計を検討した。このなかで、ビーム冷却やビームの入出射に必要な長いストレートセクションを持つレーストラック型FFAGを新しく提案し、それをビーム冷却リングへ応用することを検討し、また、くさび型超流動ヘリウム減速材の開発を進めた。

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  • ミューオン物理学の新展開を狙うスーパー・ミューオン・ビームの研究

    研究課題/領域番号:15GS0211  2003年 - 2007年

    日本学術振興会  科学研究費助成事業 学術創成研究費  学術創成研究費

    久野 良孝, 青木 正治, 佐藤 朗, 吉村 浩司, 大森 千広, 中野 貴志, 能町 正治, 菅谷 頼仁, 大木 俊征, 二宮 史郎

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    配分額:513500000円 ( 直接経費:395000000円 、 間接経費:118500000円 )

    現在利用できるミューオン・ビームでは、その強度や性質はともに不十分であり、実験条件に厳しい制約を課している。そこで、我々は、ミューオン科学を飛躍的に発展させるために、ミューオン・ビームの強度を従来の約1万倍程度に増加し、かつ位相空間回転法という高輝度化の手法を施すことで、元々広いエネルギー分布を持つミューオン・ビームをエネルギーの揃った、いわゆる「スーパー・ミューオン・ビーム」という夢のミューオン・ビームを実現することを目指している。特に、大阪大学グループは、ミューオンを用いた素粒子物理学の研究を推進しており、本研究で開発されるスーパー・ミューオン・ビームを使って、荷電レプトンのレプトンフレーバー保存の破れを現在の実験精度を10^6倍ほど上回る精度で探索するPRISM/PRIME実験などを計画している。
    本学術創成研究では、位相空間回転法という新しい高輝度化手法に必要な要素技術開発と同手法の原理検証を目的とした。まず、本手法に不可欠である超高電場勾配高周波加速システム、及び大口径固定磁場強収束型ミューオン蓄積リングの開発に成功した。さらに、これらを組み合わせた位相空間回転試験用リングを建設し、位相空間回転の原理実証実験を行った。これにより位相空間回転法に必要な基礎技術の開発が完了し、このリングでの試験により設計通りに荷電粒子が高輝度化されることを実証された。
    これにより、次世代ミューオン科学の計画が大きく推進した。また、新しく考案したα線によるビーム光学評価手法も、加速器性能を簡便に正確に調べる新しい手法として高い評価を得た。これらの研究開発は、ミューオン科学の発展のみならず、将来の加速器計画(たとえば、ニュートリノ・ファクトリ計画やミューオン・コライダ計画など)への波及効果も大きく、多大な技術的貢献をなすものであり、本研究計画の成功は広く賞賛されている。

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  • 大強度高輝度ミューオン源のための電流収束型標的の開発

    研究課題/領域番号:14204028  2002年 - 2004年

    日本学術振興会  科学研究費助成事業 基盤研究(A)  基盤研究(A)

    吉村 浩司, 小林 隆, 五十嵐 洋一, 西川 公一郎, 岩下 芳久, 西川 公一郎

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    配分額:55510000円 ( 直接経費:42700000円 、 間接経費:12810000円 )

    本研究では、パイオン生成標的にパルス電流を流すことにより、生成した二次粒子を標的内部に収束し、エミッタンスの小さいビームを得るという「電流収束型標的」の実現を目指して以下のような技術開発を行った。
    1,PRISM実験での要求を満たすパラメータを設定し、水銀を標的材料に用いた場合の基本設計を行った。原理実証を行うために必要な仕様を決定し、水銀循環装置、大電流パルス電源、大容量パルストランス等の装置を開発した。
    2.大強度の陽子ビーム標的をデザインする際には、ビームによる標的への入熱量が重要なパラメータとなる。新たに開発したCryogenicカロリーメータを用いて,実際に標的にビームを当てた状況で入熱量を直接測定して、計算コードの有効性・精度を確かめた。
    3.大強度ビーム、大パルス電流に耐えうる材料の選定は、標的開発におけるもっとも重要な課題の一つである。標的および標的容器の材料として有望な性質を持つ候補について、材料物性の測定と陽子ビームを照射することによる変化を測定した。
    4.収束作用を確認するための手段として、二次粒子の位置・運動量をシンチレーティングファイバー測定器と超伝導磁石によって測定し、様々な運動量の粒子が混在するビームのエミッタンスを測定する方法を確立した。
    以上のように、「電流収束型標的」の実現のために必要な技術的課題に取り組んだ。それぞれにおいて、シミュレーション/計算に頼るのではなく、可能なかぎり実験を行って直接検証を行った。これにより、「電流収束型標的」のみならず、一般的な標的技術、ビーム技術に対しても、知見を得ることができた。残念ながら、当初の目的であったビーム実験による収束作用の確認については、時間的な制約および加速器のシャットダウンもあり、3年間のスコープからは実現することができなかったが、ここで得られた成果をもとに早期実現を目指したい。

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  • BESS測定器による宇宙線μ粒子絶対流束高度変化の精密測定

    研究課題/領域番号:12047206  2000年 - 2003年

    日本学術振興会  科学研究費助成事業 特定領域研究  特定領域研究

    佐貫 智行, 吉村 浩司, 笠原 克昌, 吉村 浩司, 野崎 光昭, 上田 郁夫, 佐貫 智行, 森下 伊三男

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    配分額:98700000円 ( 直接経費:98700000円 )

    気球上昇中に超伝導スペクトロメータ(BESS)を用いて観測した宇宙線のデータを解析し、残留大気圧にして5〜800g/cm2に於ける大気μ粒子のスペクトルを精密に求め、μ粒子の強度が高度と共に変化する様子(いわゆる発達曲線)を得た。この発達曲線から、大気の上層ではμ粒子が生成され、高度が低くなるに従って崩壊していく様子を克明に捉えることができた。他の実験で得られた同種のデータと比較して、本研究で得たデータは、統計誤差が小さく、また、系統誤差も小さく押さえ込むことに成功した。また、地上で観測した様々のμ粒子スペクトルを解析し、μ粒子の強度は季節や緯度等、様々な環境の影響を受けることを示した。
    また、大気μ粒子・大気ニュートリノのモンテカルロ計算に最適化したクラスタ計算機のハードとソフトの調整を進め、計算速度を向上させた。計算コードの最適化を進め、観測データとの詳細な比較を行った。モンテカルロ計算に組み込む相互作用モデルとして様々なモデルを用い、任意の高度に於いてそれぞれのモデルが予言する大気μ粒子のスペクトルを得た。気球高度(残留大気圧にして5〜30g/cm2)に於ける大気μ粒子のスペクトルと、モンテカルロ計算の詳細な比較から、宇宙線と大気分子の相互作用モデルとしてはDPMJET-IIIモデルが最適であると分かった。次に、入力データとしてBESSが測定した一次宇宙線のエネルギースペクトルを、また、相互作用モデルとしてDPMJET-IIIモデルを組み込んだ上で、詳細な大気構造を再現したモンテカルロ計算を行った。この結果、1GeV/c以下と数十GeV以上の領域ではBESSが測定した結果と、計算結果に有意な食い違いが見られ、相互作用モデルに修正が必要であると分かった。

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  • 一次宇宙線(陽子・ヘリウム)の精密測定による大気ニュートリノ絶対強度の決定

    研究課題/領域番号:12047227  2000年 - 2003年

    日本学術振興会  科学研究費助成事業 特定領域研究  特定領域研究

    吉田 哲也, 槇田 康博, 吉村 浩司, 三井 清美, 笠原 克昌, 山本 明

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    配分額:166800000円 ( 直接経費:166800000円 )

    平成14年度に実施したBESS気球搭載型超伝導スペクトロメータを用いた宇宙粒子線観測気球実験のデータ解析を進め、1〜540GeVの広いエネルギー領域にわたる一次宇宙線(陽子・ヘリウム)エネルギースペクトルを10%以下の精度で決定した。
    平成14年8月に実施された気球実験では気球運用のトラブルから観測時間が予定より短く、また平成15年度の気球実験はNASAの科学観測用大型気球のトラブルの頻発による使用許可取り消しのため実施できなかった。そこで測定器性能の理解を徹底的に深めて平成14年に得られたデータを最大限生かし、初期の目標をほぼ達成するエネルギー領域と精度でエネルギースペクトルを決定できた。
    データ解析にあたっては、PCコンプレックスとSANEデータストレージシステムを組み合わせた新しいデータ解析用計算機システムを構築し、フライトデータから信頼できる測定器較正パラメタを導出し、またシミュレーションデータの生成に利用した。
    BESS測定器についても地上での観測における高エネルギー領域での粒子識別性能を向上させるため、シリカエアロジェルカウンタの改良を進めた。飛跡検出器読出し用電子回路も10ビット精度のフラッシュADCシステムを構築し、運動量分解能の一層の改善を図った。また超伝導マグネットの運用に必要な機器を更新し、地上観測において効率的に超伝導ソレノイドを運用できるように改善した。
    これらの成果は平成15年8月に開催された国際宇宙線会議(ICRC2003)や「第5回ニュートリノ振動とその起源ワークショップ(NOON2004)」、日本物理学会等で報告された。

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  • 超伝導スペクトロメータによる宇宙起源反物質の精密探査

    研究課題/領域番号:11440085  1999年 - 2001年

    日本学術振興会  科学研究費助成事業 基盤研究(B)  基盤研究(B)

    吉田 哲也, 吉村 浩司, 槇田 康博, 山本 明

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    配分額:11900000円 ( 直接経費:11900000円 )

    BESS超伝導スペクトロメータを用いた宇宙粒子線観測気球実験を実施し、1次宇宙線中の宇宙起源反物質の探索を行った。平成11年度から13年度まで各々1回の気球実験をカナダ・マニトバ州リンレークもしくは米国ニューメキシコ州フォートサムナーで行った。収集したデータから1次宇宙線中の反ヘリウム核の探索を行ったが、反ヘリウム核事象は見つからなかった。この結果をこれまでのBESS実験で得られた結果と合わせて1次宇宙線中の反ヘリウム核のヘリウム核に対する存在比の上限値として6.8×10^<-7>を与えた。この値は飛翔体を用いたこれまで世界で行われた宇宙起源反物質探索の中で最も厳しい上限値であり、我々の銀河の近傍が物質で形作られている直接的な証拠である。
    またこれまでのBESS実験に比べて10倍以上高感度で宇宙起源反物質を探索することを目指した長時間宇宙線観測気球実験のための測定器R&Dと搭載器の製作を進めた。長時間気球実験の実施に不可欠な(1)着水時や緊急着地時に備えた超伝導マグネットの安全対策、(2)測定器の健全性を確保するための多点・分散型環境モニタシステムの開発、(3)長時間気球実験用軽量・低物質量飛跡検出器(ドリフトチェンバ)の製作が本研究で進められ、一部は実際に気球実験に搭載され所定の性能を得られたことが確かめられた。
    これらの成果をもとに第7回BESSワークショップなどを通じて南極周回科学観測気球による10〜20日間程度の宇宙粒子線観測実験の検討を進め、この「BESS-Polar」実験に用いる新しい超伝導スペクトロメータの開発を進め、平成15年12月から16年1月にかけて第1回南極周回・長時間宇宙粒子線観測実験を実施できるよう準備を進めている。

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  • BESS超伝導スペクトロメータによる宇宙線反陽子の起源の探索

    研究課題/領域番号:11694104  1999年 - 2000年

    日本学術振興会  科学研究費助成事業 基盤研究(A)  基盤研究(A)

    吉田 哲也, 槇田 康博, 吉村 浩司, 山本 明, 野崎 光昭, 佐貫 智行, 折戸 周治

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    配分額:13400000円 ( 直接経費:13400000円 )

    気球搭載型超伝導スペクトロメータ(BESS)を用いて地磁気限界硬度の小さなカナダ北部において宇宙粒子線観測気球実験を実施し、太陽活動が極大に達する時期での各種一次粒子宇宙線のエネルギースペクトラムを観測した。宇宙線観測気球実験は平成11年8月11日及び平成12年8月10日の2回カナダ・マニトバ州リンレークにて実施された。気球高度約37kmでの高空でそれぞれ34時間、35時間のデータ収集が行われた。これらの観測時間は平成10年度までの実験の1.5倍以上であり高精度観測を実施でき、特にこの2年間だけで1000例を超える宇宙線反陽子事象を捉えた。
    この太陽活動極大期における観測によって、今後宇宙起源反陽子の存否を探索していくにあたって、その観測の規準となる二次起源反陽子のエネルギースペクトラムを正確に知るのに不可欠な宇宙線に対する太陽活動影響の電荷依存性を明確に観測した。また一次宇宙線中の反ヘリウム核の探索を進め、世界で最も厳しいヘリウム核に対する存在比の上限値7×10^<-7>を得た。同時に一次宇宙線陽子・ヘリウム成分の精密なエネルギースペクトラムを測定し、特に1GeV以下の低エネルギー領域での統計量を測定器の改良によって改善し、気球上昇中のデータを用いて宇宙線の大気発展モデルの検証を行った。また同じく気球上昇中のデータから二次宇宙線μ粒子成分のエネルギースペクトラムの残留大気圧依存性を観測した。
    さらにこれまでのBESS実験で得られた成果を吟味し、将来の方向性を議論するために第7回BESSワークショップを開催し、これまでのBESS実験に比べて一桁以上高感度の宇宙起源反陽子探索を目的とした、極地における長時間気球実験の実施を目指していくことが国内外の研究分担者・協力者により検討された。

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  • 超伝導スペクトロメーターによる宇宙線反粒子の精密探査

    研究課題/領域番号:08044102  1996年 - 1997年

    日本学術振興会  科学研究費助成事業 国際学術研究  国際学術研究

    山本 明, ORMES Jonath, 吉村 浩司, 折戸 周治, 槙田 康博, 吉田 哲也, KIMBELL Barb

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    配分額:6500000円 ( 直接経費:6500000円 )

    超伝導スペクトロメーターによる宇宙線反粒子の精密探査は、日米間の国際共同気球実験として平成5年度に第一期の計画がスタートして以来、平成8年度まで1.2GeV以下の運動エネルギー領域において40イベントを越す質量同定を含む宇宙線反陽子のスペクトルの観測に成功した。今年度は一層の測定器の性能向上を図り、さらに高エネルギー領域までカバーした宇宙線反陽子スペクトルの精密決定を目指し、実験を推進した。これによって、その宇宙線反陽子の起源として標準的な宇宙線伝播モデルによる二次粒子によるものであるか、または暗黒物質の候補とされている超対称粒子の対消滅または原始ブラックホールの蒸発等により生成される可能性を示唆するものであるかを見極める事を目標とした。
    気球飛翔実験はこれまでと同様、カナダ・マニトバ州北部・リンレークにて行なわれ、1ケ月余りの現地での準備期間を経て、7月27日にスペクトロメーターの打ち上げに成功した。機器はすべて順調に作動し、目標を上回る観測に成功した。また実験機器データも無事回収され、解析が精力的に進められている。予備的な結果として、すでに300イベントを超える反陽子が検出されている。これまでの観測精度を1ケタ上回る宇宙線反陽子スペクトルの精密観測結果となり、宇宙線反陽子の起源についてより一層の解明が期待される。この結果は、今夏予定されている宇宙線国際会議で公表される予定である。

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  • 電子陽電子衝突装置LEP及びLEP-IIでのOPAL測定器による素粒子の研究

    研究課題/領域番号:06044046  1994年 - 1996年

    日本学術振興会  科学研究費助成事業 国際学術研究  国際学術研究

    小林 富雄, HEUER Ralf D, 大森 恒彦, 神前 純一, 吉村 浩司, 森井 政宏, 森 俊則, 真下 哲郎, 川本 辰男, 駒宮 幸男, 折戸 周治, ROLF DieterH, HEUER Rolf D, 萩原 薫, 佐々木 真人, ALDO Micheli, ROLF Dieter, 塚本 俊夫, 川越 清以, 竹下 徹, 武田 廣

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    配分額:31300000円 ( 直接経費:31300000円 )

    CERN(欧州素粒子研究機構,在ジュネ-ブ)は、21世紀初頭まで素粒子物理学のエネルギーフロンティアをになう加速器として、世界最大かつ最高エネルギーの電子陽電子衝突装置LEPを建設した。東京大学素粒子物理国際研究センターを中心とするグループは、このLEPを用いた国際共同実験OPALにおいて、常に主導的な役割を果たしてきている。OPAL実験の提案および、その設計に重要な貢献をし、測定器の最重要構成要素の一つである電磁カロリメタの開発、建設をおこない、その運転、保守、改良を続けている。また、実験開始以来、大型計算機やワークステーションを用いて多量のデータを精力的に解析し、物理研究の最前線において活躍を続けている。
    LEPは平成元年の運転開始から平成7年までは、電子陽電子の衝突エネルギーをZ^O粒子(弱い相互作用を媒介する質量約910億電子ボルトの中性粒子)の質量付近に合わせてZ^O粒子を大量に生成し、その生成、崩壊を詳細に観測することにより、素粒子相互作用の標準理論をLEP以前に比べて圧倒的な精度で検証し、また、素粒子の世代数が3であることを初めて決定するなど、この数年間の素粒子物理の進歩に重要な貢献をしてきた。平成7年後半からはLEPのエネルギー増強計画LEP2が開始され、平成8年には、W粒子(弱い相互作用を媒介する質量約800億電子ボルトの荷電粒子)を対生成できるエネルギーに到達し、歴史上初めて電子陽電子衝突実験でW粒子を直接詳細に観測できるようになった。これにより、標準理論を新しい角度から検証し、また、今までの約2倍の衝突エネルギーで実験を行なうことにより新しい粒子や現象が見えてくる可能性が開けた。
    本科学研究費補助金(国際学術)の当該年度のうち、平成6年度と7年度にOPALは約270万のZ^O崩壊事象を記録した。実験開始から積算すると約500万のZ^O崩壊事象を記録したことになる。この大量のデータから得られた最近の主な成果を以下に示す。
    (1)Z^Oの諸性質(質量、全崩壊幅、レプトン対およびクォーク対への部分崩壊幅、前後方非対称度、タウ-レプトンの偏極度など)のより精密な測定を行ない、電弱標準理論の精密な検証をおこなった。また、その結果から標準理論を使って、トップクォークの質量を正確に推定した。トップクォークは最近、米国テバトロン加速器により発見され予言どおりの質量であることが確認された。同様にW粒子の質量も正確に算出することができる。これをLEP2での精密な直接測定と比較することは理論の厳しい検証となる。
    (2)Z^Oの崩壊から得られる大量のタウ粒子を使って、新しい手法により、実験的にあまり良く知られてなかったタウ-ニュートリノの質量に新しい制限を得た。
    (3)ボトムクォークを含む中間子やバリオンの寿命や中性ボトム中間子の粒子-反粒子振動などを、様々な手法で画期的な精度で測定した。
    (4)物質の質量の起源を与えるヒッダス粒子や新粒子の探索を幅広い角度から行なったが、このエネルギーでは発見されなかった。このような新粒子探索は、より高いエネルギーのLEP2に引き継がれた。
    平成7年度11月にLEPはZ^Oから離れ、まず衝突エネルギーを約1.5倍に上げて実験を行なった。LEPは、必要な新技術開発を克服し予定通りの強度で電子と陽電子を衝突させることに成功した。東京大学の建設した電磁カロリメタも全カウンタ9440本が高性能を維持しており、OPALのほとんど全ての物理解析に重要な貢献をしている。平成8年度にはLEPは更にエネルギーを上げ、W粒子を対生成できるエネルギーに達した。LEP2でのこれまでの主な成果は以下のとおり。
    (1)Wの質量は生成断面積から算出する方法と、検出器で一事象ごとにWの質量を再構成するという2つの独立な方法で測られた。今のところLEP全体でわずか数百のW対生成事象しかないが、他の加速器の実験による今までの結果と同じ程度の測定精度が既に得られた。
    (2)標準理論から期待されるさまざまな反応を幅広く測定し、LEP2のエネルギーでも実験結果と理論の予言が良く一致していることを確かめた。標準理論を越える新物理から予想される僅かなずれと比較することでこれらに対する新しい知見が得られた。
    (3)これまでの探索の結果、ヒッグス粒子はその質量が688億電子ボルトより重い事がわかった。また、超対称性粒子の探索も引つづきおこなわれ、超対称性理論のパラメーターに更に厳しい制限を与えた。また、これらの結果をもちいてグルイ-ノの質量にたいしても他の実験で得られたものより厳しい制限を与えることができた。
    以上をはじめとする数多くの成果は逐次国際会議等で報告され、既に学術専門誌に発表されたか、または発表が決定している。現時点では、今までに収集したデータの解析及び来年度からの更に高いエネルギーでの実験準備を精力的に行なっている。Wの質量の精度を約5倍上げる等、測定精度を格段に上げることのみならず、いよいよヒッグス粒子や超対称性粒子が発見される可能性の高い領域であり、数多くの研究成果が期待されている

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  • 素粒子原子核物理学B (2021年度) 第1学期  - 月1,月2

  • 量子光学基礎論 (2021年度) 後期  - 火5,火6

  • 宇宙天体物理学1 (2020年度) 第4学期  - 月1,月2

  • 宇宙天体物理学A (2020年度) 第4学期  - 月1,月2

  • 実験量子物理学 (2020年度) 前期  - その他

  • 数理物理科学ゼミナール(物理学系) (2020年度) 通年  - その他

  • 極限量子物理学演習 (2020年度) その他  - その他

  • 極限量子物理学演習 (2020年度) 通年  - その他

  • 素粒子と宇宙 (2020年度) 第1学期  - 金5,金6

  • 素粒子原子核物理学1 (2020年度) 第3学期  - 月1,月2

  • 素粒子原子核物理学1 (2020年度) 3・4学期  - 月1,月2

  • 素粒子原子核物理学2 (2020年度) 第1学期  - 火1,火2

  • 素粒子原子核物理学2 (2020年度) 1・2学期  - 火1,火2

  • 素粒子原子核物理学A (2020年度) 第3学期  - 月1,月2

  • 量子光学基礎論 (2020年度) 後期  - 火5,火6

▼全件表示

 

メディア報道

  • トリウム229アイソマー状態生成 新聞・雑誌

    科学新聞社  科学新聞  2019年9月20日

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  • 原子核時計実現に前進、岡山大学などが世界初の成果 テレビ・ラジオ番組

    KSB瀬戸内海放送  KSBスーパーJチャンネル  2019年9月13日

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  • 「3000億年に1秒のずれ」原子核時計実現へ一歩 岡山大チームが基礎技術開発 新聞・雑誌

    毎日新聞社  毎日新聞  2019年9月12日

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  • 岡山大・理研など、自然界で最小の励起エネルギーをもつ原子核状態の人工的生成に成功 新聞・雑誌

    日本経済新聞社  日本経済新聞  2019年9月12日

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  • 岡山大など、原子核状態の人工生成に初成功 大量かつ自在に 新聞・雑誌

    日刊工業新聞社  日刊工業新聞  2019年9月12日

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  • 超精密時計開発へ前進 誤差3千億年に1秒 新聞・雑誌

    山陽新聞社  山陽新聞  2019年9月12日

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  • 3千億年に1秒しかずれない「原子核時計」実現への道 岡山大などの研究

    財経新聞社  財経新聞  2019年9月12日

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  • 原子核時計実用化に向け前進 テレビ・ラジオ番組

    NHK岡山放送局  おはよう岡山  2019年9月11日

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