2004/01/31 by Markus Risse, M. Risse, P. Homola +4 · 6 citations
Physics and Astronomy · #Astrophysics and Cosmic Phenomena #Dark Matter and Cosmic Phenomena #Particle physics theoretical and experimental studies #astro-ph #hep-ph
paper · pdf · doi:10.1016/j.astropartphys.2004.04.003
published as Astropart.Phys. 21 (2004) 479-490 · 20 pages, 8 figures; v2 matches version accepted by Astroparticle Physics
arxiv created 2004/04/05 · openalex publication_date 2004/05/29 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The longitudinal profile of the most energetic cosmic-ray air shower measured so far, the event recorded by the Fly's Eye detector with a reconstructed primary energy of about 320 EeV, is compared to simulated shower profiles. The calculations are performed with the CORSIKA code and include primary photons and different hadron primaries. For primary photons, preshower formation in the geomagnetic field is additionally treated in detail. For primary hadrons, the hadronic interaction models QGSJET01 and SIBYLL2.1 have been employed. The predicted longitudinal profiles are compared to the observation. A method for testing the hypothesis of a specific primary particle type against the measured profile is described which naturally takes shower fluctuations into account. The Fly's Eye event is compatible with any assumption of a hadron primary between proton and iron nuclei in both interaction models, although differences between QGSJET01 and SIBYLL2.1 in the predicted profiles of lighter nuclei exist. The primary photon profiles differ from the data on a level of ~1.5 sigma. Although not favoured by the observation, the primary photon hypothesis can not be rejected for this particular event.