INVESTIGADORES
HANSEN Patricia Maria
artículos
Título:
Upper limit on the cosmic-ray photon fraction at EeV energies from the Pierre Auger Observatory
Autor/es:
THE PIERRE AUGER COLLABORATION (P HANSEN PERTENECE A LA COLABORACIÓN AUGER)
Revista:
ASTROPARTICLE PHYSICS
Editorial:
ELSEVIER SCIENCE BV
Referencias:
Lugar: Amsterdam; Año: 2009 vol. 31 p. 399 - 406
ISSN:
0927-6505
Resumen:
From direct observations of the longitudinal development of ultra-high energy air showers performedwith the Pierre Auger Observatory, upper limits of 3.8%, 2.4%, 3.5% and 11.7% (at 95% c.l.) are obtainedon the fraction of cosmic-ray photons above 2, 3, 5 and 10 EeV ð1 EeV 1018 eVÞ, respectively. Theseare the first experimental limits on ultra-high energy photons at energies below 10 EeV. The results complementprevious constraints on top?down models from array data and they reduce systematic uncertaintiesin the interpretation of shower data in terms of primary flux, nuclear composition and protonaircross-section.