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EUSO: A space observatory for ultra high energy cosmic rays

Abstract : One of the most challenging issues in Astroparticle Physics is the observation of a small sample of Cosmic Rays with energy around 10+20 eV. by both AGASA and and Hires experiments. Fundamental questions are raised in connection with their origin and propagation in the interstellar and intergalactic space. Their existence may imply extremely efficient yet unknown acceleration mechanism from most active and energetic astrophysical sources or disintegrations of super heavy particles, relics of the first instant of the universe. At such energies, the cosmological photon background could have presented a real obstacle for most of known particles. Their presence beyond expected distance limits could be an indication of the failure of Lorenz invariance or a singular role played by neutrinos. EUSO, acronym for Extreme Universe Space Observatory is a pioneer study from space of ultra high energy cosmic rays, observable when they interact with the earth atmosphere. During an ESA (European Space Agency) phase A study by an international collaboration including Europe, Japan and USA, a telescope has been designed to be installed in the International Station. EUSO will use an imaging system based on a couple of large Fresnel lenses of 5m2, and a focal surface segmented into 200000 pixels, to measure both fluorescence and Cerenkov UV light emitted when the cosmic ray interacted with the earth atmosphere. The light signals will be collected and treated using multianode photodetectors associated with integrated circuits of submicronic technology. At an altitude of 430 km from the ground and pointing at nadir, the EUSO telescope will be able to observe with a total angle of view of 60 degrees a surface on ground of 180000 km2 or 2 1012 tons of sensitive mass. EUSO will be able to collect an order of magnitude more events than any scheduled experiment on ground ( i.e. AUGER), or few thousands events above an energy threshold of 5.10+19 eV within three years of operation. EUSO will allow a precise determination of the global cosmic ray spectrum at its extreme energy, the distribution of their arrival direction, and also the localization and the counting of compact sources if they exist. A description of the instrument and its performances will be presented.
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Submitted on : Tuesday, January 10, 2006 - 5:37:52 PM
Last modification on : Monday, July 20, 2020 - 9:18:27 AM


  • HAL Id : in2p3-00025347, version 1




D.H. Koang. EUSO: A space observatory for ultra high energy cosmic rays. 2005. ⟨in2p3-00025347⟩



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