Abraham, J., M. Aglietta, C. Aguirre, D. Allard, I. Allekotte, P. Allison, C. Alvarez, J. Alvarez-Muniz, M. Ambrosio, L. Anchordoqui et al. "Anisotropy studies around the galactic centre at EeV energies with the Auger Observatory." ASTROPARTICLE PHYSICS 27, no. 4 (2007): 244–253.
Abstract: Data from the Pierre Auger Observatory are analyzed to search for anisotropies near the direction of the Galactic Centre at EeV energies. The exposure of the surface array in this part of the sky is already significantly larger than that of the fore-runner experiments. Our results do not support previous findings of localized excesses in the AGASA and SUGAR data. We set an upper bound on a point-like flux of cosmic rays arriving from the Galactic Centre which excludes several scenarios predicting sources of EeV neutrons from Sagittarius A. Also the events detected simultaneously by the surface and fluorescence detectors (the 'hybrid' data set), which have better pointing accuracy but are less numerous than those of the surface array alone, do not show any significant localized excess from this direction. (c) 2006 Elsevier B.V. All rights reserved.
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Abraham, J., M. Aglietta, C. Aguirre, D. Allard, I. Allekotte, P. Allison, C. Alvarez, J. Alvarez-Muniz, M. Ambrosio, L. Anchordoqui et al. "An upper limit to the photon fraction in cosmic rays above 10(19) eV from the Pierre Auger Observatory." ASTROPARTICLE PHYSICS 27, no. 2-3 (2007): 155–168.
Abstract: An upper limit of 16% (at 95% c.l.) is derived for the photon fraction in cosmic rays with energies greater than 10(19) eV, based on observations of the depth of shower maximum performed with the hybrid detector of the Pierre Auger Observatory. This is the first such limit on photons obtained by observing the fluorescence light profile of air showers. This upper limit confirms and improves on previous results from the Haverah Park and AGASA surface arrays. Additional data recorded with the Auger surface detectors for a subset of the event sample support the conclusion that a photon origin of the observed events is not favored. (c) 2006 Elsevier B.V. All rights reserved.
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Abraham, J., M. Aglietta, I. C. Aguirre, M. Albrow, D. Allard, I. Allekotte, P. Allison, J. A. Muniz, M. G. do Amaral, M. Ambrosio et al. "Properties and performance of the prototype instrument for the Pierre Auger Observatory." NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT 523, no. 1-2 (2004): 50–95.
Abstract: Construction of the first stage of the Pierre Auger Observatory has begun. The aim of the Observatory is to collect unprecedented information about cosmic rays above 10(18) eV. The first phase of the project, the construction and operation of a prototype system, known as the engineering array, has now been completed. It has allowed all of the sub-systems that will be used in the full instrument to be tested under field conditions. In this paper, the properties and performance of these sub-systems are described and their success illustrated with descriptions of some of the events recorded thus far. (C) 2003 Elsevier B.V. All rights reserved.
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