Interpretation of the surface detector signal of 10^19 eV showers observed with the Pierre Auger Observatory based on QGSJET simulations

THE PIERRE AUGER COLLABORATION (AUTOR 434 DE 474); M. TUEROS (COAUTOR)

Beijing

Conferencia; 32nd International Cosmic Ray Conference 2011; 2011

Institute of High Energy Physics, Chinese Academy of Sciences

Muons in extensive air showers are messengers of the hadronic-shower core whose simulation is subject to large theoretical uncertainties due to our limited knowledge of multi-particle production in hadronic interactions. Different methods of deriving the fraction of the signal observed in the surface detectors coming from either the muonic or electromagnetic shower components are used to compare the data from the Pierre Auger Observatory with predictions of Monte Carlo simulations. The observations are quantified relative to the predictions obtained with QGSJET II and FLUKA as interaction models. The predicted number of muons at 1000 m from the shower axis is lower than that found in data, and the energy that would have to be assigned to the surface detector signal, based on shower simulations, is systematically higher than that derived from fluorescence observations.