P. Abreu, LIP - Lisboa
M. Aglietta, Università degli Studi di Torino
M. Ahlers, University of Wisconsin-Madison
E. J. Ahn, Fermi National Accelerator Laboratory
I. F.M. Albuquerque, Universidade de São Paulo
D. Allard, APC - AstroParticule et Cosmologie
I. Allekotte, Instituto Balseiro
J. Allen, New York University
P. Allison, The Ohio State University
A. Almela, Universidad Tecnologica Nacional
J. Alvarez Castillo, Universidad Nacional Autónoma de México
J. Alvarez-Muñiz, Universidad de Santiago de Compostela
R. Alves Batista, Universidade Estadual de Campinas
M. Ambrosio, Università degli Studi di Napoli Federico II
A. Aminaei, Radboud Universiteit
L. Anchordoqui, University of Wisconsin-Milwaukee
S. Andringa, LIP - Lisboa
T. Antiči'C, Rudjer Boškovi'c Institute
C. Aramo, Università degli Studi di Napoli Federico II
E. Arganda, Universidad Nacional de La Plata
F. Arqueros, Universidad Complutense de Madrid
H. Asorey, Instituto Balseiro
P. Assis, LIP - Lisboa
J. Aublin, Laboratoire de Physique Nucléaire et de Hautes Energies
M. Ave, Karlsruher Institut für Technologie
M. Avenier, Laboratoire de Physique Subatomique et de Cosmologie de Grenoble
G. Avila, Pierre Auger Observatory
A. M. Badescu, University Politehnica of Bucharest
M. Balzer, Karlsruher Institut für Technologie
K. B. Barber, The University of Adelaide
A. F. Barbosa, Centro Brasileiro de Pesquisas Físicas
R. Bardenet, Laboratoire de l'Accélérateur Linéaire
S. L.C. Barroso, Universidade Estadual do Sudoeste da Bahia

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A thorough search of the sky exposed at the Pierre Auger Cosmic Ray Observatory reveals no statistically significant excess of events in any small solid angle that would be indicative of a flux of neutral particles from a discrete source. The search covers from -90° to +15° in declination using four different energy ranges above 1 EeV (1018 eV). The method used in this search is more sensitive to neutrons than to photons. The upper limit on a neutron flux is derived for a dense grid of directions for each of the four energy ranges. These results constrain scenarios for the production of ultrahigh energy cosmic rays in the Galaxy. © 2012. The American Astronomical Society. All rights reserved..

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Astrophysical Journal