Measurement of the muon content in air showers at the Pierre Auger Observatory

¹ Institute of Nuclear Physics, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
² Observatorio Pierre Auger, Av. San Martín Norte 304, 5613 Malargüe, Argentina

^a e-mail: darko.veberic@kit.edu
^b Full author list: http://www.auger.org/archive/authors_2015_10.html

Published online: 4 July 2016

Abstract

The muon content of extensive air showers produced by ultra-high energy cosmic rays is an observable sensitive to the composition of primary particles and to the properties of hadronic interactions governing the evolution of air-shower cascades. We present different methods for estimation of the number of muons at the ground and the muon production depth. These methods use measurements of the longitudinal, lateral, and temporal distribution of particles in air showers recorded by the detectors of the Pierre Auger Observatory. The results, obtained at about 140 TeV center-of-mass energy for proton primaries, are compared to the predictions of LHC-tuned hadronic-interaction models used in simulations with different primary masses. The models exhibit a deficitin the predicted muon content. The combination of these results with other independent mass composition analyses, such as those involving the depth of shower maximum observable_max, provide additional constraints on hadronic-interaction models for energies beyond the reach of the LHC.