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176 results on '"Takehisa Hasegawa"'

3. Heavy carrier doping by hydrogen in the spin-orbit coupled Mott insulator Sr2IrO4

Author

Markus Wilde, Mitsuhiko Maesato, Takahiro Maruyama, T. Ozawa, Katsuyuki Fukutani, Hiraku Ogino, Takahito Terashima, Hiroshi Kitagawa, Y. Yamashita, Takehisa Hasegawa, Masayuki Ochi, Akira Chikamatsu, G.C. Lim, and Kazuhiko Kuroki

Subjects
Materials science, Hydrogen, Condensed matter physics, Mott insulator, Doping, Lattice (group), chemistry.chemical_element, Electron, Crystal, Condensed Matter::Materials Science, chemistry, Hall effect, Condensed Matter::Superconductivity, Condensed Matter::Strongly Correlated Electrons, Energy (signal processing)
Abstract

Highly efficient carrier doping into the spin-orbit coupled Mott insulator ${\mathrm{Sr}}_{2}{\mathrm{IrO}}_{4}$ is achieved by low-energy hydrogen ion beam irradiation at low temperature. We demonstrate that heavy doping of hydrogen into a ${\mathrm{Sr}}_{2}{\mathrm{IrO}}_{4}$ epitaxial thin film induces a large increase in conductivity by band-filling control via electron doping, which is confirmed by Hall effect measurements. The introduction of a large amount of hydrogen and its distribution along the depth direction are clarified by nuclear reaction analysis. The doped interstitial and substitutional hydrogens act as electron donors with minimum perturbation to the lattice, as evidenced by crystal structural analysis and first-principles calculations of the defect formation energy for doped hydrogen. The hydrogen-doping method offers a strategy toward realization of novel quantum phases in strongly correlated spin-orbit entangled systems.

Published
2021

4. Synergistic epidemic spreading in correlated networks

Author

Shogo Mizutaka, Kizashi Mori, and Takehisa Hasegawa

Subjects
Physics - Physics and Society, FOS: Biological sciences, Populations and Evolution (q-bio.PE), Quantitative Biology::Populations and Evolution, FOS: Physical sciences, Physics and Society (physics.soc-ph), Quantitative Biology - Populations and Evolution
Abstract

We investigate the effect of degree correlation on a susceptible-infected-susceptible (SIS) model with a nonlinear cooperative effect (synergy) in infectious transmissions. In a mean-field treatment of the synergistic SIS model on a bimodal network with tunable degree correlation, we identify a discontinuous transition that is independent of the degree correlation strength unless the synergy is absent or extremely weak. Regardless of synergy (absent or present), a positive and negative degree correlation in the model reduces and raises the epidemic threshold, respectively. For networks with a strongly positive degree correlation, the mean-field treatment predicts the emergence of two discontinuous jumps in the steady-state infected density. To test the mean-field treatment, we provide approximate master equations of the present model. We quantitatively confirm that the approximate master equations agree with not only all qualitative predictions of the mean-field treatment but also corresponding Monte-Carlo simulations., Comment: 11 pages, 9 figures

Published
2021

5. Search for coherent charged pion production in neutrino-carbon interactions

Author

J. H. Choi, M. M. Khabibullin, Stephane T'Jampens, R. Gran, L. Whitehead, R. L. Helmer, T. Ishida, Katsuki Hiraide, S. Andringa, E. Fernandez, Takaaki Kajita, J. Y. Kim, J. Zalipska, A. Blondel, Shoei Nakayama, R. Terri, A. Ikeda, Y. Totsuka, Y. Takubo, Minoru Yoshida, S. Nawang, O. V. Mineev, C. Mariani, Y. Takeuchi, T. Nakadaira, Federico Sanchez, H. I. Jang, G. Jover, Shinya Yamada, G. Sitjes, T. Hara, Takehisa Hasegawa, K. Ishihara, K. K. Joo, K. McConnel, K. Nishikawa, Jordi Burguet-Castell, P. Novella, J. Hill, N. Tamura, Silvia Borghi, R. Schroeter, H. Yokoyama, F. Pierre, Michael B. Smy, M. Sekiguchi, J.J. Gómez-Cadenas, Y. Takenaga, Masaya Hasegawa, M. Miura, Yuichi Oyama, K. Kaneyuki, J. L. Stone, T. Inagaki, U. Dore, S. B. Kim, Makoto Sakuda, H. C. Bhang, Yu. Kudenko, J. Bouchez, M. Y. Pac, L. Ludovici, W. Wang, Koji Nakamura, Tomoyuki Maruyama, I. S. Jeong, C. Cavata, Itsuo Nakano, J. Argyriades, Toshio Namba, A. N. Khotjantsev, S. Matsuno, Masayuki Nakahata, Taichi Morita, Yasunari Suzuki, T. Kobayashi, T. Kutter, A. K. Ichikawa, H. Maesaka, Yoshitaka Itow, Masaaki Tanaka, A. Sarrat, K. Taki, Ko Okumura, F. Nova, E. J. Jeon, Hiroshi Sato, K. Asakura, P. Kitching, C. W. Walter, A. Konaka, Shigeki Aoki, S P Mikheyev, A. Cervera, C. Mauger, Kate Scholberg, J. Kameda, C. McGrew, Atsumu Suzuki, A. Okada, Y. Hayato, A. Minamino, H. G. Berns, Shoji Yamamoto, K. Hayashi, J. Mallet, Henry W. Sobel, K. Nitta, Tadayuki Takahashi, John G. Learned, Shaomin Chen, A. Tornero-Lopez, A. Rodriguez, D. Kerr, S. Likhoded, E. Sharkey, Y. Kuno, E. Kearns, C. O. Kim, Katsuhiro Kobayashi, Shigetaka Moriyama, Y. Fukuda, C. Saji, C. Yanagisawa, R. Ashie, K. O. Cho, T. Ishii, R. Nambu, X. Espinal, Y. Moriguchi, R. J. Wilkes, I. T. Lim, Masashi Yokoyama, Tsuyoshi Nakaya, J. Kubota, Masataka Iinuma, J. Yoo, Masato Shiozawa, T. Iwashita, C. K. Jung, D. Kielczewska, I. Kato, Y. Obayashi, S. Mine, M. Fechner, S. Ueda, E. Aliu, Mark R. Vagins, N. Yershov, W. R. Kropp, Yusuke Koshio, S. M. Oser, M. Ishitsuka, David William Casper, C. Mitsuda, J. Hosaka, K. K. Shiraishi, P. F. Loverre, T. Sasaki, L. R. Sulak, V. A. Matveev, Blondel, Alain, Borghi, Silvia, Cervera Villanueva, Anselmo, and Schroeter, Raphaël

Subjects
Particle physics, Meson, Physics::Instrumentation and Detectors, Neutrino-nucleus reactions, FOS: Physical sciences, General Physics and Astronomy, ddc:500.2, 01 natural sciences, 7. Clean energy, High Energy Physics - Experiment, Nuclear physics, High Energy Physics - Experiment (hep-ex), Pion, Experiment-HEP, 0103 physical sciences, Nuclear Experiment (nucl-ex), 010306 general physics, Neutrino oscillation, Nuclear Experiment, Charged current, Physics, Muon, Tamura, Norio, 010308 nuclear & particles physics, Neutrino oscillations, Física, 田村, 詔生, Production (computer science), High Energy Physics::Experiment, Neutrino, Lepton
Abstract

We report the result from a search for charged-current coherent pion production induced by muon neutrinos with a mean energy of 1.3 GeV. The data are collected with a fully active scintillator detector in the K2K long-baseline neutrino oscillation experiment. No evidence for coherent pion production is observed and an upper limit of $0.60 \times 10^{-2}$ is set on the cross section ratio of coherent pion production to the total charged-current interaction at 90% confidence level. This is the first experimental limit for coherent charged pion production in the energy region of a few GeV., 5 pages, 4 figures

Published
2021

8. Search for proton decay via p→e+π0 and p→μ+π0 with an enlarged fiducial volume in Super-Kamiokande I-IV

Author

J. S. Jang, B. Bodur, Yuji Kishimoto, L. H. V. Anthony, Rongkun Wang, J. L. Raaf, L. Labarga, K. Nakamura, T. Niwa, T. Kobayashi, F. d. M. Blaszczyk, M. Jakkapu, M. Hartz, Y. Nishimura, P. Weatherly, S. Moriyama, Y. Isobe, T. Boschi, Hiroshi Ito, B. Richards, G. Santucci, Masayuki Nakahata, N. Ospina, Y. Uchida, V. Takhistov, C. K. Jung, M. Mori, M. Taani, Y. Sonoda, M. Ikeda, M. Koshiba, P. de Perio, T. Yano, A. T. Suzuki, K. Okamoto, J. F. Martin, Masato Shiozawa, Y. Choi, Yoshitaka Itow, H. Okazawa, G. Pintaudi, E. Radicioni, L. Ludovici, W. R. Kropp, K. Sakashita, Yutaka Nakajima, C. Xu, Hiroaki Menjo, P. Paganini, M. Miura, T. Nakadaira, G. Pronost, F. Iacob, R. G. Park, B. D. Xu, N. F. Calabria, O. Drapier, Makoto Sakuda, Ke. Nakamura, M. Jiang, A. Coffani, M. Posiadala-Zezula, T. Horai, Ko Okumura, H. W. Sobel, S. Matsuno, A. Giampaolo, S. Molina Sedgwick, Yuuki Nakano, T. Mochizuki, T. Tashiro, T. Towstego, S. Imaizumi, K. Hagiwara, H.A. Tanaka, S. Cao, S. Sakai, B. W. Pointon, F. Nova, R. Sasaki, R. Matsumoto, Intae Yu, P. Mehta, Y. Kataoka, D. Fukuda, C. Bronner, M. G. Catanesi, S. Han, Pablo Fernandez, H. Miyabe, M. J. Wilking, Yuichi Oyama, R. P. Litchfield, C. M. Nantais, D. Bravo-Berguño, B. Quilain, J. G. Learned, K. Yasutome, S. Zsoldos, Y. Kuno, Ke. Abe, K. Nishijima, S. Locke, Atsushi Takeda, J. C. Hill, K. Ohta, T. Wester, E. Kearns, Vincenzo Berardi, N. Piplani, G. De Rosa, Masashi Yokoyama, J. L. Stone, David A. Wark, J. Y. Yang, M. Tsukada, Y. Takahira, Masaki Ishitsuka, M. Thiesse, K. Iwamoto, G.D. Barr, A. Konaka, S. J. Jenkins, M. R. Vagins, J. Walker, N. J. Griskevich, A. Ali, Yusuke Koshio, Y. Takemoto, A. Pritchard, W. Y. Ma, D. Barrow, L. F. Thompson, T. Ishizuka, Makoto Hasegawa, Y. Nagao, J. McElwee, A. Minamino, Tsuyoshi Nakaya, B. Jamieson, M. Shinoki, K. Frankiewicz, N. McCauley, S. B. Kim, I. T. Lim, S. Yamamoto, T. Matsubara, J. Y. Kim, A. Orii, S. El Hedri, J. Feng, L. Cook, Y. Takeuchi, T. Kajita, J. Bian, H. K. Tanaka, Seiko Hirota, T. Kikawa, M. Gonin, J. Xia, M. Friend, Masaaki Tanaka, N. W. Prouse, C. W. Walter, T. Sugimoto, Hiroyuki Sekiya, Y. Fukuda, L. Wan, R. Akutsu, Y. Hayato, T. Sekiguchi, Yasunari Suzuki, T. Shiozawa, C. Vilela, Ll. Marti, T. Yoshida, Song Chen, K. S. Ganezer, Yuto Ashida, T. Tsukamoto, T. Okada, T. Nakamura, N. Ogawa, T. Ishida, C. Yanagisawa, A. Goldsack, S. Nakayama, R. A. Wendell, A. Takenaka, K. Sato, A. K. Ichikawa, J. Kameda, Th. A. Mueller, Shintaro Ito, P. Mijakowski, Kalen Martens, Kate Scholberg, S. Mine, K. M. Tsui, Takehisa Hasegawa, M. Lamoureux, Hirokazu Ishino, Chris Simpson, G. Collazuol, F. Di Lodovico, M. Kuze, M. Inomoto, A. A. Sztuc, M. B. Smy, B. Zaldivar, Yuta Kato, L. N. Machado, and M. Harada

Subjects
Physics, 010308 nuclear & particles physics, Proton decay, Detector, 01 natural sciences, Lower limit, Nuclear physics, Volume (thermodynamics), 0103 physical sciences, Pi, Atmospheric neutrino, 010306 general physics, Fiducial marker, Super-Kamiokande
Abstract

We have searched for proton decay via p→e+π0 and p→μ+π0 modes with the enlarged fiducial volume data of Super-Kamiokande from April 1996 to May 2018, which corresponds to 450 kton·years exposure. We have accumulated about 25% more livetime and enlarged the fiducial volume of the Super-Kamiokande detector from 22.5 kton to 27.2 kton for this analysis, so that 144 kton·years of data, including 78 kton·years of additional fiducial volume data, has been newly analyzed. No candidates have been found for p→e+π0 and one candidate remains for p→μ+π0 in the conventional 22.5 kton fiducial volume and it is consistent with the atmospheric neutrino background prediction. We set lower limits on the partial lifetime for each of these modes: τ/B(p→e+π0)>2.4×1034 years and τ/B(p→μ+π0)>1.6×1034 years at 90% confidence level.

Published
2020

11. Emergence of Long-Range Correlations in Random Networks

Author

Shogo Mizutaka and Takehisa Hasegawa

Subjects
Physics, Random graph, Physics - Physics and Society, Characteristic length, Computer Networks and Communications, FOS: Physical sciences, Function (mathematics), Physics and Society (physics.soc-ph), Disordered Systems and Neural Networks (cond-mat.dis-nn), Condensed Matter - Disordered Systems and Neural Networks, Giant component, Computer Science Applications, Exponential function, Correlation function, Artificial Intelligence, Critical point (thermodynamics), Cutoff, Statistical physics, Information Systems
Abstract

We perform an analytical analysis of the long-range degree correlation of the giant component in an uncorrelated random network by employing generating functions. By introducing a characteristic length, we find that a pair of nodes in the giant component is negatively degree-correlated within the characteristic length and uncorrelated otherwise. At the critical point, where the giant component becomes fractal, the characteristic length diverges and the negative long-range degree correlation emerges. We further propose a correlation function for degrees of the $l$-distant node pairs, which behaves as an exponentially decreasing function of distance in the off-critical region. The correlation function obeys a power-law with an exponential cutoff near the critical point. The Erd\H{o}s-R\'{e}nyi random graph is employed to confirm this critical behavior., Comment: 9 pages, 2 figures

Published
2020

12. Structure of percolating clusters in random clustered networks

Author

Shogo Mizutaka and Takehisa Hasegawa

Subjects
Physics, Physics::Physics and Society, Physics - Physics and Society, Assortativity, Node (networking), FOS: Physical sciences, Percolation threshold, Physics and Society (physics.soc-ph), Computer Science::Social and Information Networks, Poisson distribution, 01 natural sciences, 010305 fluids & plasmas, symbols.namesake, Fractal, Percolation, 0103 physical sciences, symbols, Cluster (physics), Statistical physics, 010306 general physics, Clustering coefficient
Abstract

We examine the structure of the percolating cluster (PC) formed by site percolation on a random clustered network (RCN) model. Using the generating functions, we formulate the clustering coefficient and assortative coefficient of the PC. We analytically and numerically show that the PC in the highly clustered networks is clustered even at the percolation threshold. The assortativity of the PC depends on the details of the RCN. The PC at the percolation threshold is disassortative when the numbers of edges and triangles of each node are assigned by Poisson distributions, but assortative when each node in an RCN has the same small number of edges, most of which form triangles. This result seemingly contradicts the disassortativity of fractal networks, although the renormalization scheme unveils the disassortative nature of a fractal PC., 15 pages, 10 figures

Published
2019

13. Percolation on a maximally disassortative network

Author

Shogo Mizutaka and Takehisa Hasegawa

Subjects
Physics, Physics - Physics and Society, Statistical Mechanics (cond-mat.stat-mech), Generating function, FOS: Physical sciences, General Physics and Astronomy, Percolation threshold, Physics and Society (physics.soc-ph), Degree distribution, 01 natural sciences, 010305 fluids & plasmas, Percolation, 0103 physical sciences, Exponent, Bipartite graph, Statistical physics, 010306 general physics, Critical exponent, Scaling, Condensed Matter - Statistical Mechanics
Abstract

We propose a maximally disassortative (MD) network model which realizes a maximally negative degree-degree correlation, and study its percolation transition to discuss the effect of a strong degree-degree correlation on the percolation critical behaviors. Using the generating function method for bipartite networks, we analytically derive the percolation threshold and the order parameter critical exponent, $\beta$. For the MD scale-free networks, whose degree distribution is $P(k) \sim k^{-\gamma}$, we show that the exponent, $\beta$, for the MD networks and corresponding uncorrelated networks are same for $\gamma>3$ but are different for $2, Comment: 7 pages, 3 figures

Published
2019

14. Real-time supernova neutrino burst monitor at Super-Kamiokande

Author

A. T. Suzuki, J. F. Martin, T. Nakadaira, G. Carminati, Makoto Sakuda, K. Iyogi, J. L. Raaf, K. Sakashita, K. Kaneyuki, Takaaki Kajita, T. Sekiguchi, E. Kearns, R. A. Wendell, Masashi Yokoyama, Yasunari Suzuki, Y. Hayato, M. Ikeda, John Hill, S. B. Kim, J. Y. Kim, M. Goldhaber, S. N. Smith, Seiko Hirota, T. Kikawa, C. Yanagisawa, Yejin Zhang, T. Ishizuka, L. Marti, K. Tateishi, Tsuyoshi Nakaya, J. S. Jang, A. Himmel, Song Chen, K. Nishijima, W. R. Kropp, S. Tobayama, Takaaki Mori, Kate Scholberg, W. E. Keig, V. Takhistov, Atsushi Takeda, Shigeki Tasaka, E. Richard, J. L. Stone, L. R. Sulak, K. Ieki, Yusuke Suda, Hirokazu Ishino, K. S. Ganezer, R. J. Wilkes, S. Moriyama, R. Tacik, Masayuki Nakahata, I. Kametani, M. Miura, L. Labarga, T. Kobayashi, K. P. Lee, C. K. Jung, Yoshitaka Itow, J. Imber, Masato Shiozawa, Y. Choi, Koh Ueno, H.A. Tanaka, M. J. Wilking, Yasuhiro Kishimoto, A. Konaka, M. B. Smy, Kimihiro Okumura, T. Tomura, H. Okazawa, Y. Kuno, S. Nakayama, T. Yokozawa, T. Tsukamoto, C. Bronner, T. Akiri, B. L. Hartfiel, S. Mine, S. Berkman, J. G. Learned, J. Gustafson, S. Matsuno, T. McLachlan, Takehisa Hasegawa, J. Kameda, P. Fernandez, K. Connolly, P. Mijakowski, K. Choi, K. Huang, Kazuhiro Suzuki, A. Kibayashi, Y. Koshio, T. Ishida, M. Koshiba, H. K. Tanaka, M. R. Vagins, A. Murakami, A. Minamino, G. Mitsuka, I. T. Lim, P. de Perio, T. Yano, A. L. Renshaw, Kenzo Nakamura, Yuichi Oyama, R. Yamaguchi, K. Abe, Y. Totsuka, Susumu Takahashi, T. Wongjirad, Y. Takeuchi, T. Ishii, K. Martens, Y. Nishimura, C. W. Walter, N. Hong, Joshua Hignight, Hiroyuki Sekiya, Y. Fukuda, Yuuki Nakano, T. J. Irvine, Y. Haga, P. Weatherly, and H. W. Sobel

Subjects
High Energy Astrophysical Phenomena (astro-ph.HE), Physics, 010308 nuclear & particles physics, Astrophysics::High Energy Astrophysical Phenomena, Solar neutrino, High Energy Physics::Phenomenology, FOS: Physical sciences, Astronomy, Astronomy and Astrophysics, Astrophysics, Solar neutrino problem, 01 natural sciences, Cosmic neutrino background, Astrophysics - Solar and Stellar Astrophysics, Neutrino detector, 0103 physical sciences, Measurements of neutrino speed, High Energy Physics::Experiment, Neutrino astronomy, Neutrino, Astrophysics - High Energy Astrophysical Phenomena, Super-Kamiokande, 010303 astronomy & astrophysics, Solar and Stellar Astrophysics (astro-ph.SR)
Abstract

We present a real-time supernova neutrino burst monitor at Super-Kamiokande (SK). Detecting supernova explosions by neutrinos in real time is crucial for giving a clear picture of the explosion mechanism. Since the neutrinos are expected to come earlier than light, a fast broadcasting of the detection may give astronomers a chance to make electromagnetic radiation observations of the explosions right at the onset. The role of the monitor includes a fast announcement of the neutrino burst detection to the world and a determination of the supernova direction. We present the online neutrino burst detection system and studies of the direction determination accuracy based on simulations at SK., 15 pages, 8 figures, accepted for publication in Astroparticle Physics

Published
2016

16. Observability transitions in clustered networks

Author

Yuta Iwase and Takehisa Hasegawa

Subjects
Social and Information Networks (cs.SI), FOS: Computer and information sciences, Statistics and Probability, Physics - Physics and Society, Degree (graph theory), Node (networking), Monte Carlo method, FOS: Physical sciences, Statistical and Nonlinear Physics, Observable, Computer Science - Social and Information Networks, Physics and Society (physics.soc-ph), Poisson distribution, 01 natural sciences, Unobservable, 010305 fluids & plasmas, symbols.namesake, 0103 physical sciences, symbols, Statistical physics, Observability, 010306 general physics, Cluster analysis, Mathematics
Abstract

We investigate the effect of clustering on network observability transitions. In the observability model introduced by Yang, Wang, and Motter [Phys. Rev. Lett. 109, 258701 (2012)], a given fraction of nodes are chosen randomly, and they and those neighbors are considered to be observable, while the other nodes are unobservable. For the observability model on random clustered networks, we derive the normalized sizes of the largest observable component (LOC) and largest unobservable component (LUC). Considering the case where the numbers of edges and triangles of each node are given by the Poisson distribution, we find that both LOC and LUC are affected by the network's clustering: more highly-clustered networks have lower critical node fractions for forming macroscopic LOC and LUC, but this effect is small, becoming almost negligible unless the average degree is small. We also evaluate bounds for these critical points to confirm clustering's weak or negligible effect on the network observability transition. The accuracy of our analytical treatment is confirmed by Monte Carlo simulations., 12 pages, 6 figures

Published
2018

17. Search For A Ξ Bound State In The 12C(K-,K+)X Reaction At 1.8 Gev/c

Author

W. S. Jung, T. Takahashi, Hirokazu Tamura, S. Marcello, K. Shirotori, Megumi Naruki, Kenichi Imai, A. Feliciello, Koji Miwa, Shoichi Hasegawa, Mifuyu Ukai, Kiyoshi Tanida, Manami Fujita, Ryotaro Honda, Kanae Aoki, Tomofumi Nagae, Manami Nakagawa, Y. Nakada, Kenji Hosomi, Hiroyuki Sako, Shunsuke Kanatsuki, Yudai Ichikawa, Kensuke Kobayashi, S. Kimbara, Jihwa Lee, Takeshi O. Yamamoto, Petr Evtoukhovitch, Z. Tsamalaidze, Elena Botta, Takehisa Hasegawa, Susumu Sato, Aya Sakaguchi, Toshiyuki Gogami, S. H. Hayakawa, Yuya Akazawa, T. J. Moon, S. H. Kim, J. K. Ahn, Hitoshi Sugimura, T. Hayakawa, Hiroyuki Ekawa, T. Nanamura, and Y. Sasaki

Subjects
Physics, Nuclear physics, Full width at half maximum, Spectrometer, Resolution (electron density), Bound state, Hadron, Intensity (heat transfer), Energy (signal processing), Beam (structure)
Abstract

We have carried out a pilot data taking of the J-PARC E05 experiment to search for the bound state peaks of $^{12}_\Xi$Be in the $^{12}$C$(K^-, K^+)X$ reaction at 1.8 GeV/$c$. The measurement was performed at the K1.8 beam line of the J-PARC hadron experimental hall with a typical $K^-$ beam intensity of $6\times 10^{5}$ every six seconds. So far the best energy resolution of about 6 MeV$_{FWHM}$ was achieved with the existing SKS spectrometer. With a reasonable statistics, we have succeeded to observe peak structures in the bound region, which seems to suggest that the potential depth of $\Xi$ would be deeper than 14 MeV estimated in the previous measurements.

Published
2017

18. Search for proton decay via p→e+π0 and p→μ+π0 in 0.31 megaton·years exposure of the Super-Kamiokande water Cherenkov detector

Author

M. J. Wilking, H. W. Sobel, Y. Takeuchi, Y. Totsuka, T. Wongjirad, T. Kajita, Tomohiko Nakajima, Yuichi Oyama, Seiko Hirota, T. Kikawa, T. Ishii, A. T. Suzuki, J. C. Hill, J. F. Martin, T. Nakadaira, M. Friend, Makoto Sakuda, Y. Nishimura, N. Hong, C. W. Walter, Joshua Hignight, Kate Scholberg, T. Sekiguchi, Erin O'Sullivan, S. N. Smith, W. R. Kropp, S. Tobayama, C. Kachulis, Atsushi Takeda, T. Tsukamoto, Shigeki Tasaka, J. Kameda, Yasunari Suzuki, J. S. Jang, J. L. Palomino, M. Koshiba, Hiroyuki Sekiya, P. Mijakowski, Kalen Martens, Y. Fukuda, Hiromasa Tanaka, R. G. Park, M. R. Vagins, Ko Okumura, K. Iyogi, Y. M. Zhang, T. Yano, V. Takhistov, S. Mine, T. J. Irvine, T. Ishida, Kazuhiro Suzuki, J. Gustafson, Takaaki Mori, Ke. Abe, P. Weatherly, Song Chen, J. L. Stone, Takehisa Hasegawa, S. Berkman, J. L. Raaf, Z. Li, K. Sakashita, A. Minamino, Y. Hayato, T. Suzuki, S. Nakayama, R. A. Wendell, Hirokazu Ishino, Yuji Kishimoto, I. T. Lim, K. Choi, K. Nakamura, Pablo Fernandez, Y. Kuno, M. Goldhaber, C. M. Nantais, R. Tacik, D. Fukuda, K. Kaneyuki, S. Moriyama, Yoshitaka Itow, T. Tomura, M. Miura, K. Huang, A. Kibayashi, Masayuki Nakahata, L. Labarga, H. Okazawa, H.A. Tanaka, T. Kobayashi, K. S. Ganezer, S. Cao, C. Bronner, J. G. Learned, S. Matsuno, C. Yanagisawa, E. Richard, Y. Haga, Yuuki Nakano, M. Hartz, R. J. Wilkes, K. Nishijima, Brandon L. Hartfiel, K. Frankiewicz, S. B. Kim, J. Y. Kim, A. Orii, C. Xu, A. Himmel, E. Kearns, A. Konaka, Masashi Yokoyama, Yusuke Koshio, T. Ishizuka, Tsuyoshi Nakaya, C. K. Jung, M. Ikeda, Masato Shiozawa, Y. Choi, Takahiro Hiraki, T. Kayano, Yusuke Suda, J. Imber, L. R. Sulak, Xiao-yan Li, Ll. Marti, M. B. Smy, and R. Akutsu

Subjects
Physics, Particle physics, Proton, 010308 nuclear & particles physics, Cherenkov detector, Proton decay, Hydrogen atom, Expected value, 7. Clean energy, 01 natural sciences, law.invention, Nuclear physics, 13. Climate action, law, 0103 physical sciences, Neutron, Neutrino, 010306 general physics, Super-Kamiokande
Abstract

We have searched for proton decay via p→e+π0 and p→μ+π0 using Super-Kamiokande data from April 1996 to March 2015, 0.306 megaton·years exposure in total. The atmospheric neutrino background rate in Super-Kamiokande IV is reduced to almost half that of phase I-III by tagging neutrons associated with neutrino interactions. The reach of the proton lifetime is further enhanced by introducing new signal criteria that select the decay of a proton in a hydrogen atom. No candidates were seen in the p→e+π0 search. Two candidates that passed all of the selection criteria for p→μ+π0 have been observed, but these are consistent with the expected number of background events of 0.87. Lower limits on the proton lifetime are set at τ/B(p→e+π0)>1.6×1034 years and τ/B(p→μ+π0)>7.7×1033 years at 90% confidence level.

Published
2017

20. Search for Neutrinos in Super-Kamiokande associated with Gravitational Wave Events GW150914 and GW151226

Author

Takahiro Hiraki, Y. Totsuka, S. Cao, Hirokazu Ishino, C. Bronner, T. Kayano, C. W. Walter, K. Sakashita, J. G. Learned, Seiko Hirota, J. S. Jang, A. T. Suzuki, T. Tsukamoto, Yoshitaka Itow, C. Xu, H. K. Tanaka, R. J. Wilkes, Takaaki Kajita, T. Ishida, J. F. Martin, J. L. Raaf, M. Goldhaber, Hiroyuki Sekiya, T. Nakadaira, A. Himmel, Yejin Zhang, T. Ishii, Y. Fukuda, L. Wan, Y. Kuno, Makoto Sakuda, R. G. Calland, T. Suzuki, Z. Li, Shigeki Tasaka, Y. Takeuchi, C. Kachulis, V. Takhistov, K. Huang, K. Haga, Atsushi Takeda, S. Mine, A. Kibayashi, C. Yanagisawa, J. L. Palomino, Y. Hayato, B. L. Hartfiel, John Hill, K. Martens, M. Miura, J. Gustafson, L. Labarga, Y. Nishimura, K. Nishijima, T. Kobayashi, A. Konaka, Takehisa Hasegawa, K. Kaneyuki, N. Hong, Tomohiko Nakajima, T. Sekiguchi, Erin O'Sullivan, M. Friend, M. R. Vagins, Kimihiro Okumura, Joshua Hignight, Yusuke Koshio, H. A. Tanaka, T. Tomura, Yasunari Suzuki, K. Iyogi, C. K. Jung, S. Moriyama, R. A. Wendell, Kate Scholberg, G. Santucci, Masayuki Nakahata, H. Okazawa, Takaaki Mori, E. Richard, M. Hartz, Song Chen, I. T. Lim, W. R. Kropp, Masato Shiozawa, Y. Choi, S. Tobayama, M. Jiang, J. L. Stone, Yasuhiro Kishimoto, M. Ikeda, S. Nakayama, L. R. Sulak, T. Yano, K. Nakamura, R. Tacik, D. Fukuda, S. Matsuno, C. Nantais, S. B. Kim, J. Y. Kim, J. Kameda, A. Orii, E. Kearns, Masashi Yokoyama, K. Choi, Pablo Fernandez, P. Mijakowski, N. D. Patel, T. Ishizuka, Tsuyoshi Nakaya, Kazuhiro Suzuki, S. N. Smith, Yusuke Suda, K. S. Ganezer, M. J. Wilking, K. Frankiewicz, T. Nakamura, J. Imber, M. B. Smy, Xiao-yan Li, Ll. Marti, S. Berkman, Yuichi Oyama, A. Minamino, K. Abe, M. Koshiba, R. G. Park, F. d. M. Blaszczyk, P. Weatherly, R. Akutsu, Yuuki Nakano, H. W. Sobel, and UAM. Departamento de Física Teórica

Subjects
Physics::Instrumentation and Detectors, Astrophysics::High Energy Astrophysical Phenomena, FOS: Physical sciences, 7. Clean energy, 01 natural sciences, Gravitational waves, High Energy Physics - Experiment, Nuclear physics, High Energy Physics - Experiment (hep-ex), Coincident, 0103 physical sciences, GW151226, Neutrinos, 010303 astronomy & astrophysics, Zenith, Physics, High Energy Astrophysical Phenomena (astro-ph.HE), Muon, 010308 nuclear & particles physics, Gravitational wave, High Energy Physics::Phenomenology, Física, Astronomy and Astrophysics, 13. Climate action, Space and Planetary Science, High Energy Physics::Experiment, Neutrino, Astroparticle physics, Super-Kamiokande, Astrophysics - High Energy Astrophysical Phenomena, Event (particle physics)
Abstract

Astrophysical Journal Letters 830.1 (2016): L11 reproduced by permission of the AAS, We report the results from a search in Super-Kamiokande for neutrino signals coincident with the first detected gravitational-wave events, GW150914 and GW151226, as well as LVT151012, using a neutrino energy range from 3.5 MeV to 100 PeV. We searched for coincident neutrino events within a time window of ±500 s around the gravitational-wave detection time. Four neutrino candidates are found for GW150914, and no candidates are found for GW151226. The remaining neutrino candidates are consistent with the expected background events. We calculated the 90% confidence level upper limits on the combined neutrino fluence for both gravitational-wave events, which depends on event energy and topologies. Considering the upward-going muon data set (1.6 GeV-100 PeV), the neutrino fluence limit for each gravitational-wave event is 14-37 (19-50) cm-2 for muon neutrinos (muon antineutrinos), depending on the zenith angle of the event. In the other data sets, the combined fluence limits for both gravitational-wave events range from 2.4 ×104 to 7.0 ×109 cm-2, The Super-Kamiokande experiment has been built and operated from funding by the Japanese Ministry of Education, Culture, Sports, Science and Technology, the U.S. Department of Energy, and the U.S. National Science Foundation. Some of us have been supported by funds from the Korean Research Foundation (BK21 and KNRC), the National Research Foundation of Korea (NRF-20110024009), the European Union (H2020 RISE-GA641540-SKPLUS), the Japan Society for the Promotion of Science, the National Natural Science Foundation of China under grant No. 11235006, and the Scinet and Westgrid consortia of Compute Canada

Published
2016

21. First measurement of radioactive isotope production through cosmic-ray muon spallation in Super-Kamiokande IV

Author

H.A. Tanaka, K. Martens, M. Koshiba, Yuuki Nakano, C. Bronner, W. R. Kropp, S. Tobayama, K. Huang, J. G. Learned, K. Nakamura, Y. Nishimura, P. de Perio, A. Kibayashi, J. S. Jang, A. Himmel, A. L. Renshaw, Y. M. Zhang, A. T. Suzuki, J. F. Martin, C. W. Walter, H. W. Sobel, Y. Hayato, C. K. Jung, Masato Shiozawa, Y. Choi, N. Hong, T. Nakadaira, J. Kameda, Makoto Sakuda, C. Yanagisawa, P. Weatherly, E. Kearns, Masashi Yokoyama, T. Tsukamoto, K. Frankiewicz, J. L. Raaf, Joshua Hignight, T. Ishizuka, Tsuyoshi Nakaya, C. Kachulis, K. Kaneyuki, John Hill, Hiroyuki Sekiya, L. Labarga, A. Minamino, T. Kobayashi, P. Mijakowski, T. Sekiguchi, K. Nishijima, G. Carminati, C. Nantais, S. B. Kim, J. Y. Kim, A. Orii, Y. Fukuda, I. Kametani, K. Choi, Pablo Fernandez, J. L. Palomino, S. Berkman, Kazuhiro Suzuki, Y. Takeuchi, Y. Totsuka, Susumu Takahashi, T. Wongjirad, T. J. Irvine, Shaomin Chen, Yasunari Suzuki, Takaaki Kajita, H. K. Tanaka, Takaaki Mori, M. Miura, B. L. Hartfiel, Atsushi Takeda, Yuichi Oyama, K. Iyogi, S. Nakayama, T. Yano, K. Ieki, Y. Haga, M. Ikeda, Z. Li, M. R. Vagins, T. Ishii, M. J. Wilking, Shigeki Tasaka, R. J. Wilkes, A. Konaka, T. Ishida, M. Friend, J. L. Stone, N. J. Griskevich, E. Richard, R. A. Wendell, K. Abe, Yusuke Koshio, Yoshitaka Itow, R. Tacik, T. Tomura, Kimihiro Okumura, Yusuke Suda, K. Sakashita, I. T. Lim, T. Suzuki, H. Okazawa, S. Moriyama, Masayuki Nakahata, J. Imber, Yasuhiro Kishimoto, M. Goldhaber, K. S. Ganezer, M. B. Smy, Xiao-yan Li, Ll. Marti, Seiko Hirota, T. Kikawa, S. Matsuno, V. Takhistov, T. Kayano, S. N. Smith, Y. Kuno, L. R. Sulak, S. Mine, J. Gustafson, Takehisa Hasegawa, Tomohiko Nakajima, Kate Scholberg, M. Hartz, and Hirokazu Ishino

Subjects
Physics, Particle physics, Physics - Instrumentation and Detectors, Muon, 010308 nuclear & particles physics, Chlorine-36, Order (ring theory), 01 natural sciences, High Energy Physics - Experiment, Nuclear physics, High Energy Physics - Phenomenology, 13. Climate action, 0103 physical sciences, Neutron, Production (computer science), Neutrino, Astrophysics - High Energy Astrophysical Phenomena, 010306 general physics, Super-Kamiokande, Energy (signal processing)
Abstract

Cosmic-ray-muon spallation-induced radioactive isotopes with $\beta$ decays are one of the major backgrounds for solar, reactor, and supernova relic neutrino experiments. Unlike in scintillator, production yields for cosmogenic backgrounds in water have not been exclusively measured before, yet they are becoming more and more important in next generation neutrino experiments designed to search for rare signals. We have analyzed the low-energy trigger data collected at Super-Kamiokande-IV in order to determine the production rates of $^{12}$B, $^{12}$N, $^{16}$N, $^{11}$Be, $^9$Li, $^8$He, $^9$C, $^8$Li, $^8$B and $^{15}$C. These rates were extracted from fits to time differences between parent muons and subsequent daughter $\beta$'s by fixing the known isotope lifetimes. Since $^9$Li can fake an inverse-beta-decay reaction chain via a $\beta + n$ cascade decay, producing an irreducible background with detected energy up to a dozen MeV, a dedicated study is needed for evaluating its impact on future measurements; the application of a neutron tagging technique using correlated triggers was found to improve this $^9$Li measurement. The measured yields were generally found to be comparable with theoretical calculations, except the cases of the isotopes $^8$Li/$^8$B and $^9$Li., Comment: 12 pages, 6 figures, accepted by PRD for publication

Published
2016

22. An Introduction to Complex Networks

Author

Takehisa Hasegawa

Subjects
Combinatorics, Stochastic geometry models of wireless networks, Interdependent networks, Continuum percolation theory, Statistical physics, Complex network, Hierarchical network model, Degree distribution, Average path length, Clustering coefficient, Mathematics
Abstract

We review some studies on complex networks. The complex networks often have structural characteristics: the power-law degree distribution; the logarithmic size dependence of the average path length; and the high clustering coefficient. Several network models with such properties are introduced. We also consider the percolation models on the scale-free networks to show how the critical probability and critical behavior change with network topology.

Published
2011

23. Susceptibility of the Ising model on the scale-free network with a Cayley tree-like structure

Author

Koji Nemoto and Takehisa Hasegawa

Subjects
Statistics and Probability, Surface (mathematics), Condensed matter physics, Transition temperature, Structure (category theory), Ising model, Tree (set theory), Condensed Matter Physics, Degree distribution, Magnetic susceptibility, Mathematics, Spin-½
Abstract

We derive the exact expression for the zero-field susceptibility of each spin of the Ising model on the scale-free (SF) network having the degree distribution P ( k ) ∝ k − γ with the Cayley tree-like structure. The system shows that: (i) the zero-field susceptibility of a spin in the interior part diverges below the transition temperature of the SF network with the Bethe lattice-like structure T c for γ > 3 , while it diverges at any finite temperature for γ ≤ 3 , and (ii) the surface part diverges below the divergence temperature of the SF network with the Cayley tree-like structure T s for γ > 3 , while it diverges at any finite temperature for γ ≤ 3 .

Published
2008

24. Test of Lorentz invariance with atmospheric neutrinos

Author

Susumu Takahashi, T. Wongjirad, H. Okazawa, C. K. Jung, Yuichi Oyama, K. Ieki, T. Ishii, K. Sakashita, Masato Shiozawa, Y. Choi, R. J. Wilkes, R. Yamaguchi, K. Abe, Hirokazu Ishino, M. Ikeda, T. J. Irvine, J. Kameda, P. Fernandez, P. Mijakowski, Kazuhiro Suzuki, K. Martens, Y. Nishimura, M. Goldhaber, Yejin Zhang, S. Matsuno, K. Iyogi, J. S. Jang, S. Moriyama, S. B. Kim, J. Y. Kim, M. Koshiba, Y. Takeuchi, C. Yanagisawa, N. Hong, A. Himmel, Masayuki Nakahata, K. P. Lee, Lawrence Sulak, Atsushi Takeda, Joshua Hignight, Yoshihiro Suzuki, Takaaki Mori, J. L. Stone, A. T. Suzuki, K. Kaneyuki, T. Sekiguchi, K. Nishijima, Kate Scholberg, J. F. Martin, T. Nakadaira, Shigeki Tasaka, A. Konaka, B. L. Hartfiel, John Hill, S. Mine, Makoto Sakuda, J. Gustafson, E. Kearns, Yusuke Suda, Masashi Yokoyama, P. de Perio, T. Yano, A. L. Renshaw, Takehisa Hasegawa, Yusuke Koshio, Kimihiro Okumura, C. W. Walter, S. N. Smith, T. Ishizuka, J. Imber, M. Miura, Tsuyoshi Nakaya, W. E. Keig, M. B. Smy, T. Akiri, G. Carminati, K. Tateishi, Y. Haga, Hiroyuki Sekiya, K. Choi, Ll. Marti, L. Labarga, T. Kobayashi, Yoshitaka Itow, Seiko Hirota, T. Kikawa, Y. Fukuda, Y. Kuno, S. Berkman, J. G. Learned, T. McLachlan, E. Richard, P. Weatherly, Takaaki Kajita, K. Connolly, A. Minamino, Yasuhiro Kishimoto, Y. Hayato, R. A. Wendell, Song Chen, H. K. Tanaka, Yuuki Nakano, H.A. Tanaka, V. Takhistov, H. W. Sobel, C. Bronner, M. R. Vagins, I. Kametani, R. Tacik, A. Murakami, G. Mitsuka, I. T. Lim, K. Huang, S. Nakayama, K. S. Ganezer, A. Kibayashi, T. Tsukamoto, T. Ishida, T. Yokozawa, W. R. Kropp, S. Tobayama, K. Nakamura, J. L. Raaf, M. J. Wilking, Koh Ueno, Y. Totsuka, T. Tomura, and UAM. Departamento de Física Teórica

Subjects
Physics, Nuclear and High Energy Physics, Particle physics, 010308 nuclear & particles physics, Lorentz transformation, High Energy Physics::Phenomenology, Isotropy, FOS: Physical sciences, Física, Lorentz covariance, 7. Clean energy, 01 natural sciences, High Energy Physics - Experiment, High Energy Physics - Experiment (hep-ex), symbols.namesake, Orders of magnitude (time), Standard-Model Extension, 0103 physical sciences, Range (statistics), symbols, High Energy Physics::Experiment, Neutrino, 010306 general physics, Neutrino oscillation
Abstract

Artículo escrito por un elevado número de autores, solo se referencian el que aparece en primer lugar, el nombre del grupo de colaboración, si le hubiere, y los autores pertenecientes a la UAM, A search for neutrino oscillations induced by Lorentz violation has been performed using 4,438 live-days of Super-Kamiokande atmospheric neutrino data. The Lorentz violation is included in addition to standard three-flavor oscillations using the nonperturbative standard model extension (SME), allowing the use of the full range of neutrino path lengths, ranging from 15 to 12,800 km, and energies ranging from 100 MeV to more than 100 TeV in the search. No evidence of Lorentz violation was observed, so limits are set on the renormalizable isotropic SME coefficients in the eμ, μτ, and eτ sectors, improving the existing limits by up to 7 orders of magnitude and setting limits for the first time in the neutrino μτ sector of the SME, We would like to thank A. Kostelecky for his advice and support and we are grateful to J. S. Diaz for working closely with us to calculate and implement the Lorentz-violating oscillation probabilities. The authors gratefully acknowledge the cooperation of the Kamioka Mining and Smelting Company. Super-K has been built and operated from funds provided by the Japanese Ministry of Education, Culture, Sports, Science and Technology, the U.S. Department of Energy, and the U.S. National Science Foundation. This work was partially supported by the Research Foundation of Korea (BK21 and KNRC), the Korean Ministry of Science and Technology, the National Science Foundation of China, the European Union FP7 (DS laguna-lbno PN- 284518 and ITN invisibles GA-2011-289442), the National Science and Engineering Research Council (NSERC) of Canada, and the Scinet and Westgrid consortia of Compute Canada

Published
2015

25. Measurement of neutrino oscillation by the K2K experiment

Author

S. Andringa, T. Nakadaira, R. Gran, Tadayuki Takahashi, Yoshitaka Itow, Makoto Sakuda, F. Nakata, K. Fujii, A. Rodriguez, D. Kerr, M. H. Ahn, U. Dore, S. Likhoded, S P Mikheyev, K. Martens, Y. Totsuka, Y. Takubo, Kate Scholberg, Y. Takeuchi, Yu. Kudenko, Shinya Yamada, H. I. Jang, S. C. Boyd, M. Okumura, A. Blondel, A. Ikeda, K. Tashiro, Itsuo Nakano, C. K. Jung, M. Sekiguchi, H. Yokoyama, F. Pierre, Minoru Yoshida, M. Kitamura, L. Whitehead, K. Taki, S. Nawang, N. Yershov, Shogo Nishiyama, O. V. Mineev, E. Sharkey, K. Kaneyuki, Hirokazu Ishino, D. Kielczewska, Shoei Nakayama, Taichi Morita, Y. Kurimoto, Hiroyuki Noumi, T. Otaki, R. Schroeter, L. Ludovici, E. J. Jeon, Takashi Kobayashi, J. Kameda, M. Onchi, Y. Yamanoi, C. Cavata, M. Sorel, Katsuki Hiraide, H. C. Bhang, P. F. Loverre, J. Bouchez, M. Y. Pac, G. Sitjes, S. Mine, C. O. Kim, I. Kato, E. Seo, A. Shima, T. Kutter, K. Hayashi, H. So, S. M. Oser, T. Ishida, J. Hill, J. Catala, A. K. Ichikawa, Tomoyuki Maruyama, T. Hara, K. K. Joo, Lawrence Sulak, P. Novella, Susumu Noda, S. Fukuda, K. Takenaka, Yoshitaka Kuno, T. Ishii, Masaaki Tanaka, F. Nova, John G. Learned, Y. Yamada, B. H. Kang, Y. Obayashi, M. Takasaki, A. Minamino, A. Tornero-Lopez, J.J. Gómez-Cadenas, Takanori Sasaki, M. Fechner, S. Echigo, C. Yanagisawa, J. Zalipska, C. McGrew, G. Jover, J.H. Kim, K. Nakamura, K. B. McConnel Mahn, S. B. Kim, V. A. Matveev, M. Minakawa, A. Cervera, C. W. Walter, Y. Takenaga, Y. Hayato, Yuichi Oyama, Masaya Hasegawa, M. Miura, G. Kume, M. Tada, David William Casper, Takehisa Hasegawa, C. Mitsuda, K. Sato, J. Hosaka, A. Suzuki, R. L. Helmer, Hyosun Kim, Katsuhiro Kobayashi, A. Sakai, Nobuyuki Sakurai, Yusuke Koshio, S. Ueda, Shoji Yamamoto, J. Mallet, S. Matsuno, H. Takeuchi, T. Ooyabu, Masayuki Nakahata, Y. Aoyama, R. Terri, R. Ashie, H. Ishii, Y. Suga, Masashi Yokoyama, J. S. Jang, G. Mitsuka, E. Aliu, H. Tanaka, A. Sarrat, Mark R. Vagins, K. K. Shiraishi, Takaaki Kajita, Masaki Ishitsuka, Kenichi Tanaka, Yoshihiro Suzuki, H. Park, Masaharu Ieiri, X. Espinal, Y. Moriguchi, Beom Jun Kim, Michael B. Smy, Y. Fukuda, T. Iwashita, R. J. Wilkes, I. Higuchi, I. T. Lim, Y. Kato, W. R. Kropp, Federico Sanchez, Toshio Namba, C. Mariani, H. Maesaka, Ko Okumura, E. Kearns, Shigeki Aoki, T. Toshito, Hiroshi Sato, K. Asakura, P. Kitching, C. Mauger, J. Argyriades, H. Nishino, S. H. Lim, A. Okada, M. Kohama, M. Takatsuki, F. Berghaus, Tsuyoshi Nakaya, C. Saji, J. Kubota, Jordi Burguet-Castell, H. G. Berns, W. Wang, Masataka Iinuma, E. Hirose, J. Yoo, K. Nishikawa, J. Y. Kim, Henry W. Sobel, K. Nitta, Y. Tanaka, Masato Shiozawa, Shaomin Chen, A. Konaka, Shigetaka Moriyama, K. O. Cho, R. Nambu, N. Tamura, Silvia Borghi, J. L. Stone, T. Inagaki, A. N. Khotjantsev, Y. Fujii, J. H. Choi, M. M. Khabibullin, Stephane T'Jampens, E. Fernandez, I. S. Jeong, and K. Ishihara

Subjects
Physics, Nuclear and High Energy Physics, Particle physics, Tamura, Norio, 010308 nuclear & particles physics, Oscillation, T2K experiment, FOS: Physical sciences, Física, Elementary particle, 7. Clean energy, 01 natural sciences, High Energy Physics - Experiment, Nuclear physics, Massless particle, High Energy Physics - Experiment (hep-ex), K2K experiment, 0103 physical sciences, 田村, 詔生, Neutrino, 010306 general physics, Neutrino oscillation, Lepton
Abstract

We present measurements of nu_mu disappearance in K2K, the KEK to Kamioka long-baseline neutrino oscillation experiment. One hundred and twelve beam-originated neutrino events are observed in the fiducial volume of Super-Kamiokande with an expectation of 158.1^{+9.2}_{-8.6} events without oscillation. A distortion of the energy spectrum is also seen in 58 single-ring muon-like events with reconstructed energies. The probability that the observations are explained by the expectation for no neutrino oscillation is 0.0015% (4.3sigma). In a two flavor oscillation scenario, the allowed Delta m^2 region at sin^2(2theta) is between 1.9 and 3.5 x 10^{-3} eV^2 at the 90% C.L. with a best-fit value of 2.8 x 10^{-3} eV^2., Comment: 40 pages, 48 figures

Published
2006

26. Search for proton decay viap→νK+using260 kiloton·yeardata of Super-Kamiokande

Author

Shigeki Tasaka, E. Kearns, Y. Takeuchi, Masashi Yokoyama, K. Martens, S. Moriyama, M. Miyake, Yuichi Oyama, Masayuki Nakahata, T. Ishizuka, Tsuyoshi Nakaya, C. W. Walter, Takaaki Mori, Takaaki Kajita, K. Abe, A. T. Suzuki, K. P. Lee, K. S. Ganezer, J. L. Stone, L. Labarga, T. Kobayashi, T. Nakadaira, Makoto Sakuda, K. Sakashita, M. Dziomba, K. Choi, K. Ieki, T. Tsukamoto, Joshua Hignight, Yoshihiro Suzuki, Hiroyuki Sekiya, R. J. Wilkes, K. Iyogi, H. Kaji, H. W. Sobel, Y. Totsuka, J. Takeuchi, T. Wongjirad, I. Taylor, Y. Fukuda, H. Okazawa, T. Ishida, M. Goldhaber, C. Yanagisawa, S. B. Kim, J. Y. Kim, Song Chen, H. Sui, A. L. Renshaw, C. K. Jung, M. Ikeda, Masato Shiozawa, Y. Choi, Yoshitaka Itow, K. Nishijima, J. Kameda, J. Imber, T. Ishii, K. Connolly, Y. Hayato, Atsushi Takeda, P. Mijakowski, S. N. Smith, H. Zhang, S. Matsuno, R. A. Wendell, T. McLachlan, A. Kibayashi, Ll. Marti, John Hill, Yusuke Koshio, S. Nakayama, W. E. Keig, K. Kaneyuki, T. Sekiguchi, K. Bays, Justin Albert, Y. Kuno, J. S. Jang, T. Yokozawa, Y. Takenaga, M. Miura, J. L. Raaf, J. G. Learned, L. R. Sulak, M. B. Smy, Koh Ueno, Y. Obayashi, M. R. Vagins, W. R. Kropp, K. Nakamura, A. Murakami, G. Mitsuka, I. T. Lim, A. Minamino, K. Nishikawa, M. Koshiba, Ko Okumura, S. Mine, Takehisa Hasegawa, Hidetoshi Kubo, Hirokazu Ishino, Zishuo Yang, Kate Scholberg, and G. Carminati

Subjects
Physics, Nuclear physics, Nuclear and High Energy Physics, Particle physics, Proton, Proton decay, Super-Kamiokande, Lower limit
Abstract

We have searched for proton decay via p→νK+ using Super-Kamiokande data from April 1996 to February 2013, 260 kiloton•year exposure in total. No evidence for this proton decay mode is found. A lower limit of the proton lifetime is set to τ/B(p→νK+)>5.9×1033 years at 90% confidence level.

Published
2014

27. GPS survey in long baseline neutrino-oscillation measurement

Author

Kenzo Nakamura, K. Nishikawa, T. Inagaki, E. Kusano, Michifumi Minakawa, M. Kohama, Yutaka Yamanoi, M. Kurodai, Makoto Sakuda, Masaharu Ieiri, Kazuhiro Tanaka, Hiroyuki Noumi, Minoru Takasaki, Yoshihiro Suzuki, Takehisa Hasegawa, Y. Katoh, and Tomoyuki Maruyama

Subjects
Physics, Nuclear and High Energy Physics, Beam diameter, Muon, Physics::Instrumentation and Detectors, law.invention, Nuclear physics, Magnetic horn, Nuclear Energy and Engineering, Neutrino detector, law, Physics::Accelerator Physics, Focal length, High Energy Physics::Experiment, Electrical and Electronic Engineering, Neutrino, Neutrino oscillation, Beam (structure)
Abstract

We made a series of surveys to obtain neutrino beam line direction toward SuperKamiokande (SK) at a distance of 250 km for the long-baseline neutrino oscillation experiment at KEK. We found that the beam line is directed to SK within 0.03 mr and 0.09 mr (in sigma) in the horizontal and vertical directions, respectively. During beam operation, we monitored the muon distribution from secondary pions produced at the target and collected by a magnetic horn system. We found that the horn system functions like a lens of a point-to-parallel optics with magnification of approximately -100 and the focal length of 2.3 m. Namely, a small displacement of the primary beam position at the target is magnified about a factor -100 at the muon centroid, while the centroid position is almost stable against a change of the incident angle of the primary beam. Therefore, the muon centroid can be a useful monitor of the neutrino beam direction. We could determine the muon centroid within 6 mm and 12 mm in horizontal and vertical directions, respectively. This means that the neutrino beam direction could be controlled within 0.03 mr and 0.06 mr (in sigma) in the horizontal and vertical directions, respectively. We confirmed the beam direction with the neutrino distribution reconstructed at the near detector in KEK.

Published
2004

28. Polarization measurement in the COMPASS polarized target

Author

Takehisa Hasegawa, J.H. Koivuniemi, St. Goertz, S. Ishimoto, T. Matsuda, J. Ball, Takahiro Iwata, G. Reicherz, A. Magnon, Yu. Kisselev, Fabrice Gautheron, K. Kondo, Norihiro Doshita, Günter Baum, JM LeGoff, P. Berglund, W. Meyer, and N Horikawa

Subjects
Physics, Nuclear and High Energy Physics, business.industry, polarized target, NA58, polarization measurement, Polarization (waves), Atomic packing factor, COMPASS, NMR, Polarized target, Optics, Compass, COMPASS experiment, Continuous wave, business, Instrumentation
Abstract

Continuous wave nuclear magnetic resonance (NMR) is used to determine the target polarization in the COMPASS experiment. The system is made of the so-called Liverpool Q-meters, Yale-cards, and VME modules for data taking and system controlling. In 2001 the NMR coils were embedded in the target material, while in 2002 and 2003 the coils were mounted on the outer surface of the target cells to increase the packing factor of the material. Though the error of the measurement became larger with the outer coils than with the inner coils, we have performed stable measurements throughout the COMPASS run time for 3 years. The maximum polarization was þ57% and � 53% as the average in the target cells. r 2004 Elsevier B.V. All rights reserved. PACS: 29.25.Pj; 82.56.� b

Published
2004

29. Development of a scintillating-fibre detector with position-sensitive photomultipliers for high-rate experiments

Author

A. Sidorov, A. Riazantsev, S. Horikawa, Takahiro Iwata, Naoaki Horikawa, Y. Miyachi, T. Matsuda, I. Daito, K. Kuroda, N. Takabayashi, I. Manuilov, T. Toeda, A. Gorin, and Takehisa Hasegawa

Subjects
Physics, Nuclear and High Energy Physics, Photomultiplier, Large Hadron Collider, Physics::Instrumentation and Detectors, business.industry, Detector, Particle detector, Optics, Scintillation counter, Measuring instrument, High Energy Physics::Experiment, business, Instrumentation, Image resolution, Beam (structure)
Abstract

An extensive study was performed on the development of fast and precise scintillating-fibre detectors with position-sensitive photomultipliers (PSPM) for application in high-rate experiments. Several detector prototypes with Kuraray multi-cladding fibres of 0.5 mm diameter and Hamamatsu 16-channel H6568 PSPMs were constructed and tested under different beam conditions at the CERN PS and SPS beam lines. High time resolution of the order of 300 ps (r.m.s.) was obtained with spatial resolution of about 125 μm (r.m.s.) and with detection efficiency in excess of 98%. The detector prototype equipped with a 3-m-long light guide was also tested and showed a time resolution of about 540 ps (r.m.s.). Results of tests using a high-intensity muon beam show excellent stability of the detector performances in time and spatial resolutions as well as in detection efficiency under beam fluxes of up to 1.4×108 muons per 2.4-second spill.

Published
2004

30. First results of the large COMPASS polarized target

Author

I. Daito, J. M. Le Goff, Y. Kisselev, P. Berglund, T. Iwata, A. Magnon, J. Heckmann, A. Meier, J. Ball, G. Reicherz, St. Goertz, E. Radtke, N. Horikawa, Fabrice Gautheron, J.H. Koivuniemi, N. Takabayashi, W. Meyer, Norihiro Doshita, K. Kondo, Takehisa Hasegawa, J. Harmsen, and Günter Baum

Subjects
Nuclear physics, Physics, Nuclear and High Energy Physics, Large Hadron Collider, Deuterium, Compass, Dilution refrigerator, Spin structure, Polarization (waves), Nucleon, Instrumentation, Magnetic field
Abstract

The COMPASS (NA58) experiment at CERN operates with a large solid polarized target (PT) to study the spin structure of the nucleon. The COMPASS PT system started its operation with the target material 6 LiD in 2001. Deuteron polarizations of +54.2% and −47.1% were achieved in a 3 He / 4 He dilution refrigerator at a magnetic field of 2.5 T . The equal spin temperature (EST) concept was found to hold among the deuteron, the 6 Li and the 7 Li nuclei during the dynamic nuclear polarization (DNP) process. The agreement with the EST concept allows the permanent monitoring of only one nuclear species by the nuclear magnetic resonance (NMR) method.

Published
2003

31. Indications of Neutrino Oscillation in a 250 km Long-Baseline Experiment

Author

David William Casper, C. W. Walter, Makoto Sakuda, C. Yanagisawa, Toshio Namba, M. H. Ahn, K. Martens, W. R. Kropp, Nobuyuki Sakurai, H. W. Sobel, S. Fukuda, Atsumu Suzuki, H. Maesaka, Takehisa Hasegawa, T. Iwashita, Minoru Yoshida, Y. Fukuda, S. H. Lim, S. B. Boyd, K. Nishikawa, S. Mine, J. L. Stone, Y. Takeuchi, K. Kaneyuki, Yuichi Oyama, E. Kearns, T. Inagaki, Shinya Yamada, Y. Totsuka, E. J. Jeon, M. Kohama, Shoei Nakayama, Koji Nakamura, S. Matsuno, H. I. Jang, Kazumasa Miyano, J. Hill, C. K. Jung, Masaya Hasegawa, M. Miura, S. B. Kim, Tomoyuki Maruyama, J. H. Choi, D. Kielczewska, Hwangseo Park, I. Kato, John G. Learned, Itsuo Nakano, L. R. Sulak, T. Ishida, A. Obayashi, E. Sharkey, Susumu Noda, H. C. Bhang, T. Ishii, N. Tamura, M. Y. Pac, Yasunari Suzuki, C. O. Kim, N. Sasao, J. S. Jang, H. Yokoyama, W. Gajewski, Kate Scholberg, Ken-ichiro Kobayashi, A. K. Ichikawa, T. Toshito, R. J. Wilkes, Shigetaka Moriyama, A. Kibayashi, J. Y. Kim, I. T. Lim, T. Hara, Shogo Nishiyama, J. Kameda, C. McGrew, M. Ishitsuka, H. So, Shigeki Aoki, J. Yoo, J. Zalipska, Takashi Kobayashi, A. Ikeda, Y. Hayato, A. L. Stachyra, Mark R. Vagins, Masato Shiozawa, Shoji Yamamoto, Tsuyoshi Nakaya, Y. Suga, F. Nakata, Beom Jun Kim, Yoshitaka Itow, Yusuke Koshio, T. Ooyabu, Masayuki Nakahata, Takaaki Kajita, C. Mauger, and A. Okada

Subjects
Physics, Tamura, Norio, Physics::Instrumentation and Detectors, Oscillation, Astrophysics::High Energy Astrophysical Phenomena, Solar neutrino, High Energy Physics::Phenomenology, FOS: Physical sciences, General Physics and Astronomy, Solar neutrino problem, High Energy Physics - Experiment, Nuclear physics, High Energy Physics - Experiment (hep-ex), K2K experiment, Measurements of neutrino speed, High Energy Physics::Experiment, 田村, 詔生, Neutrino, Neutrino oscillation, Charged current
Abstract

The K2K experiment observes indications of neutrino oscillation: a reduction of $\nu_\mu$ flux together with a distortion of the energy spectrum. Fifty-six beam neutrino events are observed in Super-Kamiokande (SK), 250 km from the neutrino production point, with an expectation of $80.1^{+6.2}_{-5.4}$. Twenty-nine one ring $\mu$-like events are used to reconstruct the neutrino energy spectrum, which is better matched to the expected spectrum with neutrino oscillation than without. The probability that the observed flux at SK is explained by statistical fluctuation without neutrino oscillation is less than 1%., Comment: 5 pages, 3 figures embedded, LaTeX with RevTeX style, accepted for publication in PRL on December 13, 2002

Published
2003

32. Determination of solar neutrino oscillation parameters using 1496 days of Super-Kamiokande-I data

Author

Masatoshi Koshiba, Takashi Kobayashi, M. Ishitsuka, Shoichi Yamada, Takaaki Kajita, A. Kibayashi, L. R. Sulak, Shantanu Desai, Y. Ichikawa, K. Kobayashi, M. D. Messier, Y. Totsuka, T. Shibata, K. Kaneyuki, M. Takita, J. Shirai, S. Tasaka, W. E. Keig, Atsumu Suzuki, M. Earl, D. W. Liu, John G. Learned, M. Etoh, R. Nishimura, Makoto Sakuda, G. W. Sullivan, A. L. Stachyra, K. Miyano, C. W. Walter, Y. Nagashima, S. Matsuno, E. Sharkey, S. Dazeley, Hyosun Kim, D. Takemori, R. Svoboda, G. Guillian, R. W. Ellsworth, C. McGrew, A. M. Gago, K. Martens, S. Moriyama, C. Saji, J. Kameda, J. L. Stone, David William Casper, S. Nakayama, Yoshihiro Suzuki, T. Ishii, Kunio Inoue, Yoshitaka Itow, M. L. Chen, D. Turč, Y. Obayashi, J. A. Goodman, C. Mitsuda, K. S. Ganezer, T. Inagaki, Y. Kajiyama, S. Hatakeyama, R. J. Wilkes, M. Goldhaber, Y. Gando, M. Koike, Toshio Namba, Henry W. Sobel, K. Nitta, M. Ackermann, Y. Fukuda, E. Kearns, B. Viren, Koji Nakamura, S. Mine, Kyoshi Nishijima, Masayuki Nakahata, K. Nishikawa, M. Miura, Y. Takeuchi, Todd Haines, M. B. Smy, S. C. Boyd, T. Ishizuka, S. Fukuda, A. K. Ichikawa, Minoru Yoshida, C. Yanagisawa, H. Okazawa, K. Ishihara, A. Suzuki, M. Kohama, T. Iwashita, J. Hill, A. Okada, N. Sakurai, H. G. Berns, Alec Habig, Y. Watanabe, Mikio Morii, E. Blaufuss, Tsuyoshi Nakaya, C. K. Jung, C. Mauger, T. Toshito, J. Yoo, D. Kielczewska, Magdalena Malek, T. Maruyama, Masato Shiozawa, I. Kato, T. Barszczak, H. Takeuchi, Y. Hatakeyama, S. B. Kim, W. R. Kropp, Y. Oyama, Y. Hayato, Yusuke Koshio, Takehisa Hasegawa, Hirokazu Ishino, M. R. Vagins, W. Gajewski, and Kate Scholberg

Subjects
Physics, Nuclear and High Energy Physics, Particle physics, Standard solar model, Solar neutrino, High Energy Physics::Phenomenology, Solar neutrino problem, High Energy Physics - Experiment, Nuclear physics, Neutrino detector, High Energy Physics::Experiment, Neutrino, GALLEX, Super-Kamiokande, Neutrino oscillation
Abstract

A number of different fits to solar neutrino mixing and mass square difference were performed using 1496 days of Super-Kamiokande-I's solar neutrino data. These data select two allowed areas at large neutrino mixing when combined with either the solar $^8$B flux prediction of the standard solar model or the SNO interaction rate measurements. A global fit combining SK data with the solar neutrino interaction rates measured by Homestake, SNO, Gallex/GNO and SAGE prefers a single allowed area, the Large Mixing Angle solution, at the 98.9% confidence level. The mass square difference $\Delta m^2$ between the two mass eigenstates ranges from about 3 to $19\times10^{-5}$eV$^2$, while the mixing angle $\theta$ is in the range of $\tan^2\theta\approx$0.25--0.65., Comment: 10 Pages, 4 figures, submitted to Physics Letters B

Published
2002

33. Efficiency of prompt quarantine measures on a susceptible-infected-removed model in networks

Author

Koji Nemoto and Takehisa Hasegawa

Subjects
Random graph, Physics - Physics and Society, Computer science, FOS: Physical sciences, Articles, Physics and Society (physics.soc-ph), 01 natural sciences, Measure (mathematics), Preventive vaccination, Uncorrelated, 010305 fluids & plasmas, law.invention, Networks and Complex Systems, law, 0103 physical sciences, Statistics, Quarantine, 010306 general physics, Epidemic model
Abstract

This study focuses on investigating the manner in which a prompt quarantine measure suppresses epidemics in networks. A simple and ideal quarantine measure is considered in which an individual is detected with a probability immediately after it becomes infected and the detected one and its neighbors are promptly isolated. The efficiency of this quarantine in suppressing a susceptible-infected-removed (SIR) model is tested in random graphs and uncorrelated scale-free networks. Monte Carlo simulations are used to show that the prompt quarantine measure outperforms random and acquaintance preventive vaccination schemes in terms of reducing the number of infected individuals. The epidemic threshold for the SIR model is analytically derived under the quarantine measure, and the theoretical findings indicate that prompt executions of quarantines are highly effective in containing epidemics. Even if infected individuals are detected with a very low probability, the SIR model under a prompt quarantine measure has finite epidemic thresholds in fat-tailed scale-free networks in which an infected individual can always cause an outbreak of a finite relative size without any measure. The numerical simulations also demonstrate that the present quarantine measure is effective in suppressing epidemics in real networks., Comment: 10 pages, 7 figures

Published
2017

34. Transition-type change between an inverted Berezinskii-Kosterlitz-Thouless transition and an abrupt transition in bond percolation on a random hierarchical small-world network

Author

Tomoaki Nogawa and Takehisa Hasegawa

Subjects
Small-world network, Statistical Mechanics (cond-mat.stat-mech), FOS: Physical sciences, Disordered Systems and Neural Networks (cond-mat.dis-nn), Condensed Matter - Disordered Systems and Neural Networks, Fixed point, Renormalization group, Network topology, Combinatorics, Kosterlitz–Thouless transition, Pitchfork bifurcation, Fractal, Exponent, Statistical physics, Condensed Matter - Statistical Mechanics, Mathematics
Abstract

We study bond percolation on a one-parameter family of hierarchical small-world network, and find a meta-transition between the inverted BKT transition and the abrupt transition driven by changing the network topology. It is found that the order parameter is continuous and fractal exponent is discontinuous in the inverted BKT transition, and oppositely, the former is discontinuous and the latter is continuous in the abrupt transition. The gaps of the order parameter and fractal exponent in each transition go to vanish as approaching the meta-transition point. This point corresponds to a marginal power-law transition. In the renormalization group formalism, this meta-transition corresponds to the transition between transcritical and saddle-node bifurcations of the fixed point via a pitchfork bifurcation., 5 pages, 5 figures

Published
2014

35. Critical Phase in Complex Networks: a Numerical Study

Author

Koji Nemoto, Tomoaki Nogawa, and Takehisa Hasegawa

Subjects
Physics, Phase transition, Physics - Physics and Society, Control and Optimization, Critical phenomena, Computational Mechanics, FOS: Physical sciences, Statistical and Nonlinear Physics, Disordered Systems and Neural Networks (cond-mat.dis-nn), Physics and Society (physics.soc-ph), Complex network, Condensed Matter - Disordered Systems and Neural Networks, Fractal, Critical point (thermodynamics), Percolation, Phase (matter), Exponent, Discrete Mathematics and Combinatorics, Statistical physics
Abstract

We compare phase transition and critical phenomena of bond percolation on Euclidean lattices, nonamenable graphs, and complex networks. On a Euclidean lattice, percolation shows a phase transition between the nonpercolating phase and percolating phase at the critical point. The critical point is stretched to a finite region, called the critical phase, on nonamenable graphs. To investigate the critical phase, we introduce a fractal exponent, which characterizes a subextensive order of the system. We perform the Monte Carlo simulations for percolation on two nonamenable graphs - the binary tree and the enhanced binary tree. The former shows the nonpercolating phase and the critical phase, whereas the latter shows all three phases. We also examine the possibility of critical phase in complex networks. Our conjecture is that networks with a growth mechanism have only the critical phase and the percolating phase. We study percolation on a stochastically growing network with and without a preferential attachment mechanism, and a deterministically growing network, called the decorated flower, to show that the critical phase appears in those models. We provide a finite-size scaling by using the fractal exponent, which would be a powerful method for numerical analysis of the phase transition involving the critical phase., Comment: 24 pages, 26 figures, to be published in Discontinuity, Nonlinearity, and Complexity

Published
2014
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36. Limits on sterile neutrino mixing using atmospheric neutrinos in Super-Kamiokande

Author

E. Richard, Atsushi Takeda, T. Tomura, J. S. Jang, H. Okazawa, A. Minamino, A. Himmel, John Hill, S. Moriyama, Yasuhiro Kishimoto, Masayuki Nakahata, A. T. Suzuki, M. Koshiba, J. F. Martin, K. Martens, Y. Takeuchi, T. Nakadaira, W. E. Keig, Y. Nishimura, S. Matsuno, Makoto Sakuda, Yuichi Oyama, K. Sakashita, C. Yanagisawa, Song Chen, K. P. Lee, J. L. Raaf, N. Hong, Yoshitaka Itow, E. Kearns, H. W. Sobel, Yuuki Nakano, T. Tsukamoto, M. Miura, R. Yamaguchi, K. Abe, Masashi Yokoyama, Joshua Hignight, T. McLachlan, K. Nishijima, Yoshihiro Suzuki, K. Choi, Pablo Fernandez, Takaaki Mori, M. Goldhaber, Yejin Zhang, T. Ishida, T. Ishizuka, C. W. Walter, I. Kametani, P. de Perio, T. Yano, Tsuyoshi Nakaya, Y. Totsuka, Susumu Takahashi, C. K. Jung, B. L. Hartfiel, S. Berkman, T. Akiri, J. L. Stone, Hiroyuki Sekiya, A. L. Renshaw, K. Connolly, Y. Fukuda, T. Wongjirad, Kimihiro Okumura, Masato Shiozawa, Y. Choi, Takaaki Kajita, K. Kaneyuki, Shigeki Tasaka, K. Ieki, M. Ikeda, M. J. Wilking, Y. Haga, R. J. Wilkes, P. Weatherly, T. Sekiguchi, S. B. Kim, J. Y. Kim, H.A. Tanaka, T. Ishii, R. Tacik, C. Bronner, J. G. Learned, S. N. Smith, W. R. Kropp, S. Tobayama, K. Nakamura, T. J. Irvine, K. Tateishi, Yusuke Suda, H. K. Tanaka, J. Imber, M. B. Smy, Ll. Marti, A. Konaka, K. Huang, A. Kibayashi, Yusuke Koshio, M. R. Vagins, A. Murakami, Seiko Hirota, T. Kikawa, G. Mitsuka, I. T. Lim, Y. Hayato, Y. Kuno, R. A. Wendell, L. Labarga, T. Kobayashi, G. Carminati, K. Iyogi, S. Mine, J. Gustafson, Takehisa Hasegawa, Kate Scholberg, Hirokazu Ishino, K. S. Ganezer, S. Nakayama, J. Kameda, P. Mijakowski, Kazuhiro Suzuki, V. Takhistov, L. R. Sulak, Koh Ueno, T. Yokozawa, and UAM. Departamento de Física Teórica

Subjects
Nuclear and High Energy Physics, Particle physics, Sterile neutrino, Physics::Instrumentation and Detectors, Astrophysics::High Energy Astrophysical Phenomena, Solar neutrino, FOS: Physical sciences, 01 natural sciences, High Energy Physics - Experiment, Nuclear physics, High Energy Physics - Experiment (hep-ex), High Energy Physics - Phenomenology (hep-ph), 0103 physical sciences, 010306 general physics, Neutrino oscillation, Mixing (physics), Physics, 010308 nuclear & particles physics, High Energy Physics::Phenomenology, Física, Solar neutrino problem, High Energy Physics - Phenomenology, High Energy Physics::Experiment, Neutrino, Atmospheric neutrino, Super-Kamiokande
Abstract

Artículo escrito por un elevado número de autores, solo se referencian el que aparece en primer lugar, el nombre del grupo de colaboración, si le hubiere, y los autores pertenecientes a la UAM, We present limits on sterile neutrino mixing using 4,438 live-days of atmospheric neutrino data from the Super-Kamiokande experiment. We search for fast oscillations driven by an eV2-scale mass splitting and for oscillations into sterile neutrinos instead of tau neutrinos at the atmospheric mass splitting. When performing both of these searches we assume that the sterile mass splitting is large, allowing sin2(Δm2L/4E) to be approximated as 0.5, and we assume that there is no mixing between electron neutrinos and sterile neutrinos (|Ue4|2=0). No evidence of sterile oscillations is seen and we limit |Uμ4|2 to less than 0.041 and |Uτ4|2 to less than 0.18 for Δm2>0.1eV2 at the 90% C.L. in a 3+1 framework. The approximations that can be made with atmospheric neutrinos allow these limits to be easily applied to 3+N models, and we provide our results in a generic format to allow comparisons with other sterile neutrino models, The authors gratefully acknowledge the cooperation of the Kamioka Mining and Smelting Company. Super-K has been built and operated from funds provided by the Japanese Ministry of Education, Culture, Sports, Science and Technology, the U.S. Department of Energy, and the U.S. National Science Foundation. This work was partially supported by the Research Foundation of Korea (BK21 and KNRC), the Korean Ministry of Science and Technology, the National Science Foundation of China, the European Union FP7 (DS laguna-lbno PN- 284518 and ITN invisibles GA-2011-289442) the National Science and Engineering Research Council (NSERC) of Canada, and the Scinet and Westgrid consortia of Compute Canada

Published
2014
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37. Overview of Λ-hypernuclear weak decay results with the SKS

Author

Haruhiko Outa, T.-A. Shibata, Hiroyuki Noumi, M. Sekimoto, Tadamitsu Kishimoto, S. Ajimura, L. I. Tang, Takehisa Hasegawa, R. Sawafta, H. C. Bhang, T. Takahashi, Osamu Hashimoto, K. Omata, M. Youn, T. Tanida, Yongsun Kim, Yoichi Sato, Y. Ohta, Tsuneo Fukuda, Tomofumi Nagae, H. Hotchi, Kazushige Maeda, T. Tamura, Hwangseo Park, J. H. Kim, and Kanae Aoki

Subjects
Physics, Nuclear physics, Nuclear and High Energy Physics, chemistry, Silicon, chemistry.chemical_element, Yttrium, Carbon
Published
2001

38. The π− mesonic decay rates on 12ΛC, 28ΛSi and ΛFe

Author

Y. Sato, Kanae Aoki, Tadamitsu Kishimoto, S. Ajimura, H. C. Bhang, T. Takahashi, Osamu Hashimoto, K. Omata, M. Youn, Kazushige Maeda, M. Sekimoto, H. Hotchi, Hwangseo Park, Takehisa Hasegawa, Haruhiko Outa, Y. Ohta, Yongsun Kim, Hiroyuki Noumi, and T.-A. Shibata

Subjects
Physics, Nuclear physics, Nuclear and High Energy Physics
Published
2001

39. SolarB8and hep Neutrino Measurements from 1258 Days of Super-Kamiokande Data

Author

Y. Watanabe, J. Hill, M. Morii, T. Toshito, Minoru Yoshida, Y. Nagashima, J. A. Goodman, Y. Oyama, S. Tasaka, W. E. Keig, Y. Hayato, C. W. Walter, Atsumu Suzuki, Yusuke Koshio, B. Lee, K. Kaneyuki, Magdalena Malek, Soo-Bong Kim, M. B. Smy, Y. Fukuda, E. Kearns, Yoshitaka Itow, K. Nishikawa, M. Takita, L. R. Price, J. Shirai, M. Koike, H. Takeuchi, A. Suzuki, B. Viren, C. Saji, E. Sharkey, S. Dazeley, G. Guillian, S. Moriyama, M. Kohama, K. Ishihara, C. Mitsuda, C. McGrew, S. Matsuno, C. K. Jung, Tsuyoshi Nakaya, Heekyong Kim, H. Okazawa, D. Kielczewska, Yoshihiro Suzuki, C. Mauger, J. Yoo, Y. Totsuka, T. Ishii, M. Goldhaber, Kunio Inoue, Masato Shiozawa, Y. Takeuchi, R. J. Wilkes, T. Barszczak, U. Golebiewska, Alec Habig, M. Earl, D. W. Liu, R. Svoboda, J. Kameda, G. W. Sullivan, Takehisa Hasegawa, Masayuki Nakahata, Y. Gando, M. Ishitsuka, Hirokazu Ishino, Y. Hatakeyama, S. Mine, Shantanu Desai, Y. Ichikawa, A. L. Stachyra, K. Miyano, Takashi Kobayashi, W. R. Kropp, Tomoyuki Maruyama, R. W. Ellsworth, J. L. Stone, Henry W. Sobel, K. Nitta, H. Fujiyasu, E. Blaufuss, Kyoshi Nishijima, T. Inagaki, M. R. Vagins, Koji Nakamura, Masatoshi Koshiba, M. Miura, W. Gajewski, Kate Scholberg, A. Kibayashi, L. R. Sulak, T. Shibata, M. D. Messier, Makoto Sakuda, S. C. Boyd, T. Ishizuka, Y. Obayashi, K. Martens, John G. Learned, K. Kobayashi, Y. Kajiyama, Shoichi Yamada, Takaaki Kajita, M. Etoh, K. S. Ganezer, Todd Haines, D. Turcan, C. Yanagisawa, A. Okada, N. Sakurai, S. Nakayama, David William Casper, A. Sakai, and D. Takemori

Subjects
Physics, Sudbury Neutrino Observatory, Particle physics, Recoil, Solar neutrino, General Physics and Astronomy, Flux, Electron, Neutrino, Super-Kamiokande, Energy (signal processing)
Abstract

Solar neutrino measurements from 1258days of data from the Super-Kamiokande detector are presented. The measurements are based on recoil electrons in the energy range 5.0{endash}20.0MeV. The measured solar neutrino flux is 2.32{+-}0.03(stat){sup +0.08}{sub {minus}0.07}(syst){times}10{sup 6} cm{sup {minus}2}s{sup {minus}1} , which is 45.1{+-}0.5(stat ){sup +1.6}{sub {minus}1.4}(syst) % of that predicted by the BP2000 SSM. The day vs night flux asymmetry ({Phi}{sub n}{minus}{Phi}{sub d})/ {Phi}{sub average} is 0.033{+-}0.022(stat){sup +0.013}{sub {minus}0.012}(syst) . The recoil electron energy spectrum is consistent with no spectral distortion. For the hep neutrino flux, we set a 90% C.L.upper limit of 40{times}10{sup 3} cm{sup {minus}2}s{sup {minus}1} , which is 4.3times the BP2000 SSM prediction.

Published
2001

40. Constraints on Neutrino Oscillations Using 1258 Days of Super-Kamiokande Solar Neutrino Data

Author

Hirokazu Ishino, H. Takeuchi, K. Kaneyuki, Makoto Sakuda, M. Ishitsuka, K. Martens, K. Kobayashi, S. Matsuno, T. Shibata, Minoru Yoshida, David William Casper, Shantanu Desai, Y. Ichikawa, A. Sakai, Y. Takeuchi, J. L. Stone, E. Blaufuss, S. Nakayama, John G. Learned, Henry W. Sobel, K. Nitta, D. Turcan, R. W. Ellsworth, Kyoshi Nishijima, A. L. Stachyra, K. Miyano, Y. Watanabe, D. Takemori, M. Etoh, G. Guillian, S. Moriyama, T. Ishii, Kunio Inoue, Tomoyuki Maruyama, C. W. Walter, T. Inagaki, Y. Hatakeyama, M. Goldhaber, B. Viren, J. Hill, M. Morii, S. Tasaka, W. E. Keig, Shoichi Yamada, Takaaki Kajita, Koji Nakamura, T. Toshito, Soo-Bong Kim, M. Takita, L. R. Price, J. Shirai, C. Yanagisawa, D. W. Liu, Yoshitaka Itow, C. K. Jung, Y. Fukuda, E. Kearns, Todd Haines, Atsumu Suzuki, D. Kielczewska, M. Miura, Takehisa Hasegawa, E. Sharkey, G. W. Sullivan, S. Fukuda, M. Koike, S. Dazeley, Masayuki Nakahata, K. Nishikawa, C. McGrew, Magdalena Malek, M. R. Vagins, N. Sakurai, A. Okada, H. Okazawa, K. Ishihara, W. Gajewski, Kate Scholberg, Yoshihiro Suzuki, H. Fujiyasu, Y. Nagashima, Y. Kajiyama, J. Kameda, K. S. Ganezer, K. B. Lee, Alec Habig, Y. Totsuka, C. Saji, J. A. Goodman, M. Earl, Takashi Kobayashi, S. C. Boyd, T. Ishizuka, Masatoshi Koshiba, Y. Obayashi, A. Kibayashi, L. R. Sulak, C. Mitsuda, R. Svoboda, R. J. Wilkes, U. Golebiewska, K. K. Young, S. Mine, M. B. Smy, M. D. Messier, M. Kohama, Heekyong Kim, C. Mauger, J. Yoo, Masato Shiozawa, T. Barszczak, Y. Gando, W. R. Kropp, A. Suzuki, Tsuyoshi Nakaya, Y. Oyama, Y. Hayato, and Yusuke Koshio

Subjects
Physics, Particle physics, Astrophysics::High Energy Astrophysical Phenomena, Solar neutrino, High Energy Physics::Phenomenology, General Physics and Astronomy, Flux, Solar neutrino problem, High Energy Physics - Experiment, Nuclear physics, Measurements of neutrino speed, High Energy Physics::Experiment, Neutrino, Super-Kamiokande, Neutrino oscillation, Zenith
Abstract

We report the result of a search for neutrino oscillations using precise measurements of the recoil electron energy spectrum and zenith angle variations of the solar neutrino flux from 1258 days of neutrino-electron scattering data in Super-Kamiokande. The absence of significant zenith angle variation and spectrum distortion places strong constraints on neutrino mixing and mass difference in a flux-independent way. Using the Super-Kamiokande flux measurement in addition, two allowed regions at large mixing are found., Comment: 6 pages, 4 figures, submitted to PRL

Published
2001

41. Electronic states in the spin-density wave phase of organic conductors: roles of the coexisting 2kF and 4kF charge–density waves

Author

Y. Saso, Tomohiro Yamaguchi, Mitsuhiko Maesato, Takehisa Hasegawa, Ryusuke Kondo, V.A. Bondarenko, and Seiichi Kagoshima

Subjects
Condensed matter physics, Chemistry, Mechanical Engineering, Metals and Alloys, Charge density, Condensed Matter Physics, Magnetic susceptibility, Electronic, Optical and Magnetic Materials, Amplitude, Mechanics of Materials, Seebeck coefficient, Phase (matter), Materials Chemistry, Spin density wave, Wave vector, Charge density wave
Abstract

Many kinds of experiments have suggested the presence of a subphase structure in the SDW state of (TMTSF)2PF6 and its family. However, its origin is unclear. We studied electronic properties of the SDW state by diffuse X-ray, thermopower and magnetic measurements. It was found that the amplitude of the 2kF and 4kF CDWs coexisting with the SDW decreases with decreasing temperature. The thermopower and the magnetic susceptibility measurements show anomalies in their temperature dependence in the SDW state. It is conjectured that a possible change in the SDW wave vector causes the subphase structure leading to these anomalies in the electronic and structural properties.

Published
2001

42. Suppressing epidemics on networks by exploiting observer nodes

Author

Takehisa Hasegawa, Yuichi Yoshida, and Taro Takaguchi

Subjects
Connected component, Social and Information Networks (cs.SI), FOS: Computer and information sciences, Mathematical optimization, Stochastic Processes, Physics - Physics and Society, Epidemic dynamics, FOS: Physical sciences, Computer Science - Social and Information Networks, Observer (special relativity), Physics and Society (physics.soc-ph), Models, Theoretical, Topology, Communicable Diseases, Humans, Cluster analysis, Epidemics, Mathematics
Abstract

To control infection spreading on networks, we investigate the effect of observer nodes that recognize infection in a neighboring node and make the rest of the neighbor nodes immune. We numerically show that random placement of observer nodes works better on networks with clustering than on locally treelike networks, implying that our model is promising for realistic social networks. The efficiency of several heuristic schemes for observer placement is also examined for synthetic and empirical networks. In parallel with numerical simulations of epidemic dynamics, we also show that the effect of observer placement can be assessed by the size of the largest connected component of networks remaining after removing observer nodes and links between their neighboring nodes., 14 pages, 6 figures

Published
2013

43. Observability transitions in correlated networks

Author

Taro Takaguchi, Naoki Masuda, and Takehisa Hasegawa

Subjects
Social and Information Networks (cs.SI), FOS: Computer and information sciences, Connected component, Discrete mathematics, Physics - Physics and Society, Statistical Mechanics (cond-mat.stat-mech), Structure (category theory), FOS: Physical sciences, Contrast (statistics), Computer Science - Social and Information Networks, Observable, Physics and Society (physics.soc-ph), Topology, Degree distribution, Node (circuits), Observability, Condensed Matter - Statistical Mechanics, Heterogeneous network, Mathematics
Abstract

Yang, Wang, and Motter [Phys. Rev. Lett. 109, 258701 (2012)] analyzed a model for network observability transitions in which a sensor placed on a node makes the node and the adjacent nodes observable. The size of the connected components comprising the observable nodes is a major concern of the model. We analyze this model in random heterogeneous networks with degree correlation. With numerical simulations and analytical arguments based on generating functions, we find that negative degree correlation makes networks more observable. This result holds true both when the sensors are placed on nodes one by one in a random order and when hubs preferentially receive the sensors. Finally, we numerically optimize networks with a fixed degree sequence with respect to the size of the largest observable component. Optimized networks have negative degree correlation induced by the resulting hub-repulsive structure; the largest hubs are rarely connected to each other, in contrast to the rich-club phenomenon of networks., Comment: 14 pages, 5 figures

Published
2013

44. Tau Neutrinos Favored over Sterile Neutrinos in Atmospheric Muon Neutrino Oscillations

Author

C. Yanagisawa, Y. Takeuchi, S. Nakayama, H. Fujiyasu, Minoru Yoshida, S. Inaba, N. Sakurai, Y. Totsuka, K. S. Ganezer, M. Etoh, H. Takeuchi, C. Mitsuda, K. Kaneyuki, Y. Gando, C. W. Walter, R. J. Wilkes, U. Golebiewska, B. K. Kim, R. W. Ellsworth, Hirokazu Ishino, H. Okazawa, K. Kobayashi, K. K. Young, S. Fukuda, M. L. Chen, R. Svoboda, S. Mine, Todd Haines, M. Earl, T. Maruyama, T. Inagaki, J. Hill, Atsumu Suzuki, Koji Nakamura, Soo-Bong Kim, M. Takita, L. R. Price, J. Shirai, E. Blaufuss, A. Suzuki, M. Miura, Y. Fukuda, E. Kearns, Y. Obayashi, John G. Learned, Masatoshi Koshiba, A. Kibayashi, E. Sharkey, A. Okada, L. R. Sulak, J. L. Stone, G. W. Sullivan, Shoichi Yamada, Takaaki Kajita, C. Mauger, Masato Shiozawa, C. Saji, Henry W. Sobel, K. Nitta, T. Barszczak, J. Kameda, Y. Nagashima, Kyoshi Nishijima, K. Nishikawa, S. C. Boyd, T. Ishizuka, C. McGrew, Y. Watanabe, R. Sanford, M. D. Messier, J. A. Goodman, Yoshihiro Suzuki, M. Morii, K. Ishihara, T. Toshito, M. B. Smy, S. Matsuno, Osamu Sasaki, M. Kohama, Magdalena Malek, Ko Okumura, Takehisa Hasegawa, T. Ishii, Kunio Inoue, Alec Habig, Takashi Kobayashi, M. R. Vagins, W. Gajewski, Kate Scholberg, Masayuki Nakahata, G. Guillian, S. Moriyama, M. Takahashi, M. Goldhaber, M. Ishitsuka, Y. Ichikawa, A. L. Stachyra, K. Miyano, Y. Oyama, Y. Hayato, B. Viren, Yusuke Koshio, C. K. Jung, M. Takahata, D. Kielczewska, W. R. Kropp, Makoto Sakuda, K. Martens, David William Casper, A. Sakai, Yoshitaka Itow, M. Kirisawa, M. Koike, D. Takemori, S. Tasaka, W. E. Keig, and Y. Hatakeyama

Subjects
Physics, Sterile neutrino, Particle physics, Physics::Instrumentation and Detectors, Astrophysics::High Energy Astrophysical Phenomena, Solar neutrino, High Energy Physics::Phenomenology, General Physics and Astronomy, Solar neutrino problem, High Energy Physics - Experiment, Cosmic neutrino background, Neutrino detector, Measurements of neutrino speed, High Energy Physics::Experiment, Neutrino, Neutrino astronomy
Abstract

The previously published atmospheric neutrino data did not distinguish whether muon neutrinos were oscillating into tau neutrinos or sterile neutrinos, as both hypotheses fit the data. Using data recorded in 1100 live-days of the Super-Kamiokande detector, we use three complementary data samples to study the difference in zenith angle distribution due to neutral currents and matter effects. We find no evidence favoring sterile neutrinos, and reject the hypothesis at the 99% confidence level. On the other hand, we find that oscillation between muon and tau neutrinos suffices to explain all the results in hand., Comment: 9 pages with 2 figures, submitted to PRL

Published
2000

45. Asymmetric weak decay of polarized hypernuclei

Author

T.-A. Shibata, A. Okusu, H. C. Bhang, Kiyomi Ikeda, T. Kishimoto, Takashi Nakano, Hiroyuki Noumi, S. Ajimura, M. Youn, Kazushige Maeda, Yongsun Kim, M. Sekimoto, Toshiyuki Takahashi, Osamu Hashimoto, Tomofumi Nagae, Yukichi Tanaka, N. Shinkai, Takehisa Hasegawa, Hwangseo Park, Hiroyasu Ejiri, M. Ishikawa, and K. Manabe

Subjects
Physics, Nuclear and High Energy Physics, Particle physics, Meson, media_common.quotation_subject, Nuclear Theory, Weak interaction, Polarization (waves), Asymmetry, Nuclear physics, Pion, High Energy Physics::Experiment, Nuclear Experiment, Exchange model, media_common
Abstract

We measured the asymmetric weak decay of the polarized Λ5He hypernuclei. The polarization was derived by the observed asymmetry of the mesonic decay pions for the first time. The asymmetry parameter of the nonmesonic decay has been evaluated using the obtained polarization and the asymmetry of the decay protons. The positive asymmetry parameter contradicts theoretical prediction based on meson exchange model. The present data indicates the limitation of the model in ΛN weak interaction, in particular short range phenomena such the nonmesonic decay of hypernuclei.

Published
2000

46. Asymmetry in nonmesonic decay of polarized Λ5He hypernucleus

Author

T.-A. Shibata, H. C. Bhang, Kiyomi Ikeda, Yukichi Tanaka, H. Park, Toshiyuki Takahashi, M. Youn, Tomofumi Nagae, N. Shinkai, Yongsun Kim, A. Okusu, Osamu Hashimoto, Tadafumi Kishimoto, Hiroyasu Ejiri, M. Ishikawa, Hiroyuki Noumi, M. Sekimoto, Takehisa Hasegawa, K. Manabe, S. Ajimura, Takashi Nakano, and Kazushige Maeda

Subjects
Physics, Nuclear and High Energy Physics, Particle physics, media_common.quotation_subject, Hypernucleus, Asymmetry, media_common
Published
2000

47. Search for Proton Decay throughp→ν¯K+in a Large Water Cherenkov Detector

Author

C. W. Walter, C. Mauger, M. Koshiba, A. Okada, T. Kobayashi, Y. Hatakeyama, K. Nakamura, John G. Learned, T. Futagami, M. R. Vagins, Ko Okumura, J. Hill, V. J. Stenger, S. Kasuga, Y. Fukuda, Yuichi Oyama, G. W. Sullivan, T. Hayakawa, Ken-ichiro Kobayashi, A. T. Suzuki, Masayuki Nakahata, F. Tsushima, Akira Hasegawa, Y. Takeuchi, K. Ishihara, David William Casper, Makoto Sakuda, Kunio Inoue, S. Mine, A. Sakai, Nobuyuki Sakurai, L. R. Price, J. Shirai, Yoshitaka Itow, K. Martens, M. Kirisawa, Hiroshi Ogawa, J. S. George, Y. Kanaya, K. Nishikawa, M. Koike, H. W. Sobel, Yasunari Suzuki, M. Nemoto, J. L. Stone, K. Higuchi, Shigeki Tasaka, E. Sharkey, J. Kameda, S. Hatakeyama, Osamu Sasaki, Takehisa Hasegawa, Y. Watanabe, L. R. Sulak, R. Sanford, S. Inaba, M. B. Smy, Takaaki Kajita, H. Ishino, J. A. Goodman, Kazumasa Miyano, D. Takemori, M. Takahata, Y. Kobayashi, E. Blaufuss, S. Nakayama, K. Kaneyuki, C. Saji, M. Etoh, W. Doki, H. Okazawa, K. S. Ganezer, W. Gajewski, Kate Scholberg, D. Kielczewska, Y. Totsuka, C. McGrew, M. Earl, T. Ishii, Alec Habig, H. Fujiyasu, S. Matsuno, M. Koga, Minoru Yoshida, L. Wai, Tomoyuki Maruyama, T. J. Haines, Y. Obayashi, M. Takita, M. Miura, Takashi Yamaguchi, B. Viren, M. Takahashi, W. R. Kropp, S. Yamada, M. D. Messier, S. Echigo, R. J. Wilkes, K. K. Young, C. Yanagisawa, K. Nishijima, R. W. Ellsworth, A. Kibayashi, Y. Nagashima, H. Takeuchi, B. K. Kim, W. E. Keig, M. L. Chen, M. Goldhaber, Y. Hayato, T. Iwamoto, Yusuke Koshio, S. B. Kim, A. L. Stachyra, M. Kohama, C. K. Jung, Masato Shiozawa, T. Barszczak, E. Kearns, A. Suzuki, R. Svoboda, and Junichi Kanzaki

Subjects
Nuclear physics, Physics, Particle physics, Proton, Proton decay, Cherenkov detector, law, High Energy Physics::Phenomenology, General Physics and Astronomy, High Energy Physics::Experiment, Neutrino, Lower limit, law.invention
Abstract

We present results of a search for proton decays, $p\ensuremath{\rightarrow}\overline{\ensuremath{\nu}}{K}^{+}$, using data from a $33\mathrm{kt}\ifmmode \dot{}\else \.{}\fi{}\mathrm{yr}$ exposure of the Super-Kamiokande detector. Two decay modes of the kaon, ${K}^{+}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\nu}}_{\ensuremath{\mu}}$ and ${K}^{+}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{0}$, were studied. The data were consistent with the background expected from atmospheric neutrinos; therefore a lower limit on the partial lifetime of the proton $\ensuremath{\tau}/B(p\ensuremath{\rightarrow}\overline{\ensuremath{\nu}}{K}^{+})$ was found to be $6.7\ifmmode\times\else\texttimes\fi{}{10}^{32}\mathrm{years}$ at $90%$ confidence level.

Published
1999

48. Low-temperature diffuse X-ray studies of charge-density waves coexisting with spin-density waves in the organic conductors (TMTSF)2PF6 and (TMTSF)2AsF6

Author

Seiichi Kagoshima, Y. Saso, Takehisa Hasegawa, Ryusuke Kondo, and M. Maesato

Subjects
Condensed matter physics, Scattering, X-ray, Charge density, General Chemistry, Atmospheric temperature range, Condensed Matter Physics, chemistry.chemical_compound, Amplitude, chemistry, Hexafluorophosphate, Materials Chemistry, Spin density, Electrical conductor
Abstract

The behaviors of 2 k F and 4 k F charge-density waves (CDWs) coexisting with spin-density waves (SDWs) in the title compounds were studied by diffuse X-ray scattering down to 1.6 K. It was found in the PF 6 compound that CDWs disappear below 3–4 K while they are present in the temperature range between 4 and 12 K, the SDW onset temperature. This behavior is possibly related to the subphase structure of SDW. In the AsF 6 compound, the amplitude of CDW is very small, which is related to the difference between the heat capacities of these two compounds observed previously.

Published
1999

49. Measurement of the Flux and Zenith-Angle Distribution of Upward Throughgoing Muons by Super-Kamiokande

Author

L. R. Price, J. Shirai, E. Sharkey, C. K. Jung, S. Mine, M. Takahata, D. Kielczewska, J. W. Flanagan, Y. Kanaya, Hiroshi Ogawa, Takehisa Hasegawa, Y. Hayato, Y. Watanabe, R. Sanford, J. A. Goodman, Kazumasa Miyano, Minoru Yoshida, H. Okazawa, T. Iwamoto, Ken-ichiro Kobayashi, David William Casper, E. Ichihara, C. W. Walter, Yuichi Oyama, F. Tsushima, Todd Haines, W. Doki, S. Hatakeyama, Takaaki Kajita, H. Ishino, A. Sakai, Yusuke Koshio, L. Wai, Michael B. Smy, Nobuyuki Sakurai, W. E. Keig, Mark R. Vagins, Tomoyuki Maruyama, T. Kobayashi, C. Mauger, Makoto Sakuda, Junichi Kanzaki, K. Nakamura, J. Kameda, B. Viren, M. Miura, Frederick Reines, Ko Okumura, Masatoshi Koshiba, T. Hayakawa, S. Matsuno, T. Ishii, M. D. Messier, Soo-Bong Kim, S. Kasuga, Y. Fukuda, M. Goldhaber, S. Echigo, Yasunari Suzuki, K. Martens, V. J. Stenger, A. Suzuki, R. Svoboda, A. Okada, S. Tasaka, W. R. Kropp, Atsumu Suzuki, A. Kibayashi, Masayuki Nakahata, Y. Totsuka, J. L. Stone, C. Yanagisawa, K. Fujita, E. Kearns, M. L. Chen, W. Gajewski, Kate Scholberg, Kunio Inoue, C. McGrew, K. Ishihara, M. Takita, Y. Takeuchi, K. Kaneyuki, C. Saji, M. Earl, E. Blaufuss, Shinya Yamada, M. Etoh, Masato Shiozawa, K. S. Ganezer, A. L. Stachyra, John G. Learned, Yoshitaka Itow, T. Barszczak, Kyoshi Nishijima, Takashi Yamaguchi, R. W. Ellsworth, R. A. Doyle, T. Futagami, R. J. Wilkes, K. K. Young, Y. Kobayashi, G. W. Sullivan, M. Kohama, Alec Habig, J. S. George, M. Nemoto, L. R. Sulak, M. Koga, H. W. Sobel, Osamu Sasaki, D. Takemori, Shoei Nakayama, K. Nishikawa, J. Hill, Y. Nagashima, B. K. Kim, and Akira Hasegawa

Subjects
Physics, Muon, Astrophysics::High Energy Astrophysical Phenomena, General Physics and Astronomy, Flux, High Energy Physics - Experiment, Nuclear physics, Distribution (mathematics), Angular distribution, Muon flux, High Energy Physics::Experiment, Atomic physics, Super-Kamiokande, Zenith, Energy (signal processing)
Abstract

A total of 614 upward through-going muons of minimum energy 1.6 GeV are observed by Super-Kamiokande during 537 detector live days. The measured muon flux is 1.74+/-0.07(stat.)+/-0.02(sys.)x10^{-13}cm^{-2}s^{-1}sr^{-1} compared to an expected flux of 1.97+/-0.44(theo.)x10^{-13}cm^{-2}s^{-1}sr^{-1}. The absolute measured flux is in agreement with the prediction within the errors. However, the zenith angle dependence of the observed upward through-going muon flux does not agree with no-oscillation predictions. The observed distortion in shape is consistent with the \nu_\mu \nu_\tau oscillation hypothesis with \sin^22\theta > 0.4 and 1x10^{-3} < \Delta m^2 < 1x10^{-1} eV^{2} at 90% confidence level., Comment: 8 pages w/ 3 figures new version contains minor fixes, as it appears in PRL

Published
1999

50. Measurement of the Solar Neutrino Energy Spectrum Using Neutrino-Electron Scattering

Author

L. R. Price, J. Shirai, D. Takemori, J. Hill, Yuichi Oyama, C. Yanagisawa, C. K. Jung, M. Takahata, M. Takita, D. Kielczewska, Y. Totsuka, E. Sharkey, Y. Nagashima, Takaaki Kajita, H. Ishino, W. E. Keig, Mark R. Vagins, C. W. Walter, R. W. Ellsworth, E. Blaufuss, Masatoshi Koshiba, F. Tsushima, M. Earl, Takashi Yamaguchi, A. Kibayashi, T. Ishii, M. D. Messier, B. K. Kim, M. Goldhaber, B. Viren, Yohei Kobayashi, M. Etoh, J. Hsu, S. Echigo, P. G. Halverson, W. R. Kropp, K. S. Ganezer, Makoto Sakuda, K. Nakamura, David William Casper, A. T. Suzuki, R. J. Wilkes, Y. Kanaya, E. Ichihara, Soo-Bong Kim, Y. Hayato, K. Fujita, C. McGrew, E. Kearns, K. K. Young, S. Kasuga, K. Martens, Y. Watanabe, A. Sakai, R. Sanford, Y. Fukuda, Masayuki Nakahata, T. Iwamoto, Y. Takeuchi, Yusuke Koshio, M. Nemoto, H. Okazawa, S. Hatakeyama, Shinya Yamada, Z. Conner, S. Nakayama, K. Kaneyuki, C. Saji, Michael B. Smy, L. R. Sulak, S. Matsuno, Junichi Kanzaki, R. A. Doyle, Yasunari Suzuki, Todd Haines, S. Mine, N. Sakurai, A. L. Stachyra, C. Mauger, Alec Habig, K. Nishikawa, M. Koga, A. Okada, J. W. Flanagan, Masato Shiozawa, M. Kohama, Hiroshi Ogawa, J. L. Stone, T. Barszczak, J. S. George, J. A. Goodman, V. J. Stenger, Takehisa Hasegawa, A. Suzuki, R. Svoboda, Ko Okumura, Kunio Inoue, T. Kobayashi, W. Gajewski, Kate Scholberg, Frederick Reines, K. Ishihara, L. Wai, Tomoyuki Maruyama, H. W. Sobel, Osamu Sasaki, Kyoshi Nishijima, T. Hayakawa, Minoru Yoshida, G. W. Sullivan, John G. Learned, M. Miura, T. Futagami, Ken-ichiro Kobayashi, Yoshitaka Itow, J. Kameda, M. L. Chen, Kazumasa Miyano, W. Doki, S. Tasaka, and Akira Hasegawa

Subjects
Physics, Particle physics, Scattering, Physics::Instrumentation and Detectors, Solar neutrino, General Physics and Astronomy, Solar neutrino problem, High Energy Physics - Experiment, Nuclear physics, Recoil, Neutrino detector, Measurements of neutrino speed, High Energy Physics::Experiment, Neutrino, Neutrino oscillation
Abstract

A measurement of the energy spectrum of recoil electrons from solar neutrino scattering in the Super--Kamiokande detector is presented. The results shown here are obtained from 504 days of data taken between the 31st of May, 1996 and the 25th of March, 1998. The shape of the measured spectrum is compared with the expectation for solar B8 neutrinos. The comparison takes into account both kinematic and detector related effects in the measurement process. The spectral shape comparison between the observation and the expectation gives a chi-square of 25.3 with 15 degrees of freedom, corresponding to a 4.6% confidence level., Comment: 12 pages, 3 figures

Published
1999

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