Y Takahashi

Publications (3)0 Total impact

• Source

  Available from: Toshikazu Ebisuzaki

  Article: JEM-EUSO Science Objectives

  Gustavo Medina-Tanco, K Asano, D. Cline, T. Ebisuzaki, S Inoue, P. Lipari, E. Parizot, A. Santangelo, G. Sigl, Y Takahashi, H Takami, M. Teshima, T. J. Weiler, for the JEM-EUSO Collaboration
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  ABSTRACT: JEM-EUSO, on board of the Japanese Exploration Module of the International Space Station, is being proposed as the first space observatory devoted to UHECR. Its privileged position at 430 km above the Earth surface, combined with a large field of view, innovative optics and a high efficiency focal surface, results in an unprecedented exposure which significantly surpasses that of the largest ground observatories. The large number of events expected above the GZK threshold for photo-pion production by protons will allow the directional identification of individual sources and the determination of their spectra, i.e., doing astronomy and astrophysics through the particle channel. Similar goals can be achieved in the case of light UHECR nuclei. Furthermore, the atmospheric target volume ($\sim 10^{12}$ ton) makes the possibility of neutrino observation a highlight of the mission. Other exploratory objectives include the detection of extreme energy gammas and the study of Galactic magnetic fields as well as global observations of the earth's atmosphere, including clouds, night-glows, plasma discharges, and meteors. In this contribution we will describe the scientific objectives of JEM-EUSO. Comment: Proc. of the 31st Intl. Cosmic Ray Conference, Lodz, Poland, 2009
  09/2009;
• Source

  Available from: Toshikazu Ebisuzaki

  Article: Development of neutrino initiated cascades at mid and high altitudes in the atmosphere

  A. D. Supanitsky, G. Medina-Tanco, K Asano, D. Cline, T. Ebisuzaki, S Inoue, P. Lipari, A. Santangelo, K Shinozaki, G. Sigl, Y Takahashi, M. Teshima, for the JEM-EUSO Collaboration
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  ABSTRACT: Neutrinos are a very promising messenger at tens of EeV and above. They can be produced by several channels, namely as by products of hadronic interactions at the sources, as the main products of the decay of super massive particles and, in a guaranteed way, as the result of the propagation of UHECR through the bath of microwave relic photons. A new era of very large exposure space observatories, of which the JEM-EUSO mission is a prime example, is on the horizon and, with it, it is even larger the possibility of astrophysical neutrino detection at the highest energies. In the present work we use a combination of the PYTHIA interaction code with the CONEX shower simulation package in order to produce fast one-dimensional simulations of neutrino initiated showers in air. We make a detail study of the structure of the corresponding longitudinal profiles, but focus our physical analysis mainly on the development of showers at mid and high altitudes, where they can be an interesting target for space fluorescence observatories. Comment: Proceedings of the 31st ICRC, Lodz, Poland, July 2009
  09/2009;
• Source

  Available from: Toshikazu Ebisuzaki

  Article: Hadron-gamma discrimination from an orbital UHECR observatory

  A. D. Supanitsky, G. Medina-Tanco, K Asano, D. Cline, T. Ebisuzaki, S Inoue, P. Lipari, N Sakaki, A. Santangelo, K Shinozaki, G. Sigl, Y Takahashi, M. Teshima, for the JEM-EUSO Collaboration
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  ABSTRACT: The identification of very high energy photons is of great importance for the understanding of the origin of extreme energy cosmic rays (EECR). Several can be the sources of high energy photons at Earth. A guaranteed component is the flux of high energy photons expected as a consequence of the interaction of cosmic rays with the cosmic photon background. Another contribution may be expected as by-product at the acceleration sites of protons and nuclei, although such flux should be strongly suppressed for distant sources. On the other hand, top-down scenarios involving the decay of super heavy relic particles or topological defects, even if not currently favored, have as a characteristic signature an increasingly dominant flux of photons at the highest energies. In this work we study the statistical separation between hadron and photon showers at energies where both, LPM effect and magnetospheric interactions are important for the development of the cascades. We consider a detector with the same orbital characteristics as JEM-EUSO, but disregard trigger and reconstruction efficiencies, in order to define the maximum ideal discrimination power attainable. Comment: Proceedings of the 31st ICRC, Lodz, Poland, July 2009
  09/2009;