Direct measurement of the muonic content of extensive air showers between 2 × 1017 and 2 × 1018 eV at the Pierre Auger Observatory

THE PIERRE AUGER COLLABORATION.; S. J. SCIUTTO

EUROPEAN PHYSICAL JOURNAL C - PARTICLES AND FIELDS

SPRINGER

Lugar: Berlin; Año: 2020 vol. 80 p. 751 - 769

1434-6044

The hybrid design of the Pierre Auger Observatoryallows for the measurement of the properties of extensiveair showers initiated by ultra-high energy cosmic rayswith unprecedented precision. By using an array of prototypeunderground muon detectors, we have performed thefirst direct measurement, by the Auger Collaboration, of themuon content of air showers between 2×1017 and 2×1018eV.We have studied the energy evolution of the attenuationcorrectedmuon density, and compared it to predictions fromair shower simulations. The observed densities are found tobe larger than those predicted by models. We quantify thisdiscrepancy by combining the measurements from the muondetector with those from the Auger fluorescence detector at1017.5 eV and 1018 eV.We find that, for themodels to explainthe data, an increase in the muon density of 38% ±4%(12%)±21%18% for EPOS- LHC, and of 50%(53%) ±4%(13%) ±23%20%for QGSJetII- 04, is respectively needed.