TY  - JOUR 
AU  - Pierre Auger Collaboration
AU  - Bueno Villar, Antonio
AU  - García Gámez, Diego
AU  - González, J. G.
AU  - Lozano Bahílo, Julio
AU  - Navarro, J. L.
AU  - Navas Concha, Sergio
PY  - 2009
SN  - 0927-6505
UR  - http://hdl.handle.net/10481/29084
AB  - 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,...
LA  - eng
PB  - Elsevier
KW  - Cosmic rays
KW  - Ultra high energy (UHE)
KW  - Photon
TI  - Upper limit on the cosmic-ray photon fraction at EeV energies from the Pierre Auger Observatory
ER  -