An upper limit to the photon fraction in cosmic rays above 1019 eV from the Pierre Auger Observatory
Document Type
Article
Publication Date
1-1-2007
Abstract
An upper limit of 16% (at 95% c.l.) is derived for the photon fraction in cosmic rays with energies greater than 1019 eV, based on observations of the depth of shower maximum performed with the hybrid detector of the Pierre Auger Observatory. This is the first such limit on photons obtained by observing the fluorescence light profile of air showers. This upper limit confirms and improves on previous results from the Haverah Park and AGASA surface arrays. Additional data recorded with the Auger surface detectors for a subset of the event sample support the conclusion that a photon origin of the observed events is not favored. © 2006 Elsevier B.V. All rights reserved.
Publication Source (Journal or Book title)
Astroparticle Physics
First Page
155
Last Page
168
Recommended Citation
Abraham, J., Aglietta, M., Aguirre, C., Allard, D., Allekotte, I., Allison, P., Alvarez, C., Alvarez-Muñiz, J., Ambrosio, M., Anchordoqui, L., Anjos, J., Aramo, C., Arisaka, K., Armengaud, E., Arneodo, F., Arqueros, F., Asch, T., Asorey, H., Atulugama, B., Aublin, J., Ave, M., Avila, G., Bacelar, J., Bäcker, T., Badagnani, D., Barbosa, A., Barbosa, H., Barkhausen, M., Barnhill, D., Barroso, S., Bauleo, P., Beatty, J., & Beau, T. (2007). An upper limit to the photon fraction in cosmic rays above 1019 eV from the Pierre Auger Observatory. Astroparticle Physics, 27 (2-3), 155-168. https://doi.org/10.1016/j.astropartphys.2006.10.004