Upper limit on the cosmic-ray photon fraction at EeV energies from the Pierre Auger Observatory

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 (1 EeV ≣ 10<sup>18</sup...

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Detalles Bibliográficos
Autores principales: Badagnani, Daniel Omar, Dova, María Teresa, Gómez Albarracín, Flavia Alejandra, Hansen, Patricia María, Mariazzi, Analisa Gabriela, Moreno, Juan Cruz, Tarutina, Tatiana, Tueros, Matías Jorge, Wahlberg, Hernán Pablo, The Pierre Auger Collaboration
Formato: Articulo
Lenguaje:Inglés
Publicado: 2009
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Acceso en línea:http://sedici.unlp.edu.ar/handle/10915/80633
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Sumario: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 (1 EeV ≣ 10<sup>18</sup> eV), respectively. These are the first experimental limits on ultra-high energy photons at energies below 10 EeV. The results complement previous constraints on top–down models from array data and they reduce systematic uncertainties in the interpretation of shower data in terms of primary flux, nuclear composition and protonair cross-section.