Direct measurement of the muonic content of extensive air showers between 2×10**17 and 2×10**18 eV at the Pierre Auger Observatory

THE PIERRE AUGER COLLABORATION; DIEGO G. MELO

The European Physical Journal C volume

Springer Nature

Año: 2020

1434-6052

The hybrid design of the Pierre Auger Observatory allows for the measurement of the properties of extensive air showers initiated by ultra-high energy cosmic rays with unprecedented precision. By using an array of prototype underground muon detectors, we have performed the first direct measurement, by the Auger Collaboration, of the muon content of air showers between 2x10**17 and 2x10**18 eV. We have studied the energy evolution of the attenuation-corrected muon density, and compared it to predictions from air shower simulations. The observed densities are found to be larger than those predicted by models. We quantify this discrepancy by combining the measurements from the muon detector with those from the Auger fluorescence detector at 10**17.5eV and 10**18eV. We find that, for the models to explain the data, an increase in the muon density of 8% +/- 4% (12%) for EPOS-LHC, and of 50%  (53%) +/- 4%(13%) for QGSJETII-04, is respectively needed.