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Michael Prouza Center for Particle Physics Institute of Physics Academy of Sciences of the Czech Republic Prague Studies of the ultra-high energy cosmic ray composition at the Pierre Auger Observatory Michael Prouza Center for Particle Physics Institute of Physics Academy of Sciences of the Czech Republic Prague
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The Pierre Auger Observatory Participating countries: Argentina, Australia, Bolivia *, Brazil, Czech Republic, France, Germany, Italy, Mexico, Netherlands, Poland, Portugal, Slovenia, Spain, United Kingdom, USA and Vietnam * * - associated countries More than 250 PhD scientists from more than 60 institutions from 15 (+2) countries. Participating countries are in cyan. 2/21
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Pierre Auger Observatory Southern hemisphere: Malargüe, Mendoza province, Argentina Northern hemisphere (planned): Lamar, Colorado, USA The construction of the southern site in Argentina is (almost) completed. See www.augernorth.org for details Lifetime of the observatory: 15 - 20 yrs 3/21
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The Pierre Auger Observatory = hybrid detector of cosmic rays The array of surface Cherenkovov detectors is accompanied with system of fluorescence telescopes, which observes faint UV/visible light during clear nights. This fluorescence light origins as by-product during the interactions of shower particles with the atmosphere. Scheme of hybrid detector function 4/21
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Ground detectors of the Pierre Auger Observatory Ground detectors: Covered surface: 3000 km 2 Number of detectors: 1600 Type of detector: Detector of Cherenkov radiation, each consisting of 12 000 litres of ultrapure water and equipped with 3 photomultipliers. Spacing between detectors: 1.5 km. 5/21
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11 square meter segmented mirror Aperture stop and optical filter 440 pixel camera Fluorescence detectors of the Pierre Auger Observatory Fluorescence telescopes: Number of telescopes: 24 Mirrors: 3.6 m x 3.6 m with field of view 30º x 30º, each telescope is equipped with 440 photomultipliers. 6/21
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Evolution of the hybrid detector Production of scientific data since late 2003. 7/21
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Outlook Comparison of integrated aperture Integrated exposure (1 Jan 2004 – 31 Dec 2008): 12,790 km 2 sr yr 8/21
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Auger Energy Spectrum For more details see arXiv:0906.2189 9/21
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Auger Energy Spectrum 10/21
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Mass Composition For more details see arXiv:0906.2319 Or talk by Michael Unger: http://web.phys.ntnu.no/~mika/unger2.pdfhttp://web.phys.ntnu.no/~mika/unger2.pdf 11/21
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Shower Profile 12/21
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FD mass-sensitive parameters Average Shower Maximum, Shower-to-shower fluctuations, RMS(X max ) 13/21
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FD mass composition results 14/21
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SD mass-sensitive parameters Signal risetime, t 1/2 15/21
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SD mass-sensitive parameters Deviation to average risetime, Δ (θ - zenith angle) For more details see arXiv:0906.2319 Or Hernan Wahlberg’s talk at ICRC’09, Lodz 16/21
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SD mass-sensitive parameters Risetime asymmetry, b/a (t 1/2 /r = a + b cos ζ; ζ - shower plane azimuth) XAsymMax, sec θ position, where b/a is maximal 17/21
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Mass composition summary Elongation rate flattens at high energy Fluctuations decrease with energy Two options (both can be simultaneously true): 1.) Cosmic rays heavier at high energy 2.) Hadronic models at UHE energy need modification 18/21
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3.8% 2.4% 3.5% 2.0% 5.1% 31 % Photon limit Piotr Homola (Pierre Auger Coll.), ICRC’09, Lodz; arXiv 0906.2347 19/21
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COSMOGENIC s Neutrino limit J. Tiffenberg (Pierre Auger Coll.), ICRC’09, Lodz; arXiv 0906.2347 20/21
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Anisotropy D. Hague (Pierre Auger Coll.) & J. De Mello Neto (Pierre Auger Coll.), ICRC’09, Lodz; arXiv 0906.2347 AGN correlation Search for intrinsic anisotropy 21/21
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