Measurements of the muon content of air showers at the Pierre Auger Observatory

I. VALIÑO; THE PIERRE AUGER COLLABORATION.; S. J. SCIUTTO

Kiel

Simposio; 24th Cosmic Ray Symposium; 2014

The Pierre Auger Observatory offers a unique window to study cosmic raysand particle physics at energies above 3EeV (corresponding to a centre-of-mass energy of75TeV in proton-proton collisions) inaccessible to accelerator experiments. We discuss thedifferent methods of estimating the number of muons in showers recorded at the Pierre AugerObservatory, which is an observable sensitive to primary mass composition and to propertiesof the hadronic interactions in the shower. The muon content, derived from data with thesemethods, is presented and compared to predictions from the post-LHC hadronic interactionmodels for different primary composition. We find that models do not reproduce well the Augerobservations, displaying a deficit of muons at the ground. In the light of these results, a betterunderstanding of ultra-high energy extensive air showers and hadronic interactions is crucial todetermine the composition of ultra-high energy cosmic rays. We report on the upgrade plans ofthe Pierre Auger Observatory to achieve this science goal.