INVESTIGADORES
BERTOU Xavier Pierre Louis
artículos
Título:
Upper limit on the cosmic-ray photon fraction at EeV energies from the Pierre Auger Observatory
Autor/es:
J. ABRAHAM,...; X. BERTOU
Revista:
ASTROPARTICLE PHYSICS
Editorial:
ELSEVIER SCIENCE BV
Referencias:
Año: 2009 vol. 31 p. 399 - 406
ISSN:
0927-6505
Resumen:
From direct observations of the longitudinal development of ultra-high energy air showers performed with the Pierre Auger Observatory, upper limits of 3.8%, 2.4%, 3.5% and 11.7% (at 95% c.l.) are obtained on the fraction of cosmic-ray photons above 2, 3, 5 and 10 EeV ð1 EeV 1018 eVÞ, respectively. These are the first experimental limits on ultra-high energy photons at energies below 10 EeV. The results com- plement previous constraints on topdown models from array data and they reduce systematic uncer- tainties in the interpretation of shower data in terms of primary flux, nuclear composition and proton- air cross-section.