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, INCLUYE S MOLLERACH

EUROPEAN JOURNAL OF PHYSICS

IOP PUBLISHING LTD

Lugar: Londres; Año: 2020

0143-0807

The hybrid design of the Pierre Auger Observa-tory allows for the measurement of the properties of exten-sive air showers initiated by ultra-high energy cosmic rayswith unprecedented precision. By using an array of proto-type underground muon detectors, we have performed thefirst direct measurement, by the Auger Collaboration, of themuon content of air showers between 2 × 10 17 and 2 × 10 18eV. We have studied the energy evolution of the attenuation-corrected muon 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 at10 17.5 eV and 10 18 eV. We find that, for the models to explainthe data, an increase in the muon density of 38% ±4%(12%)23%± 21%18% for EPOS- LHC, and of 50%(53%) ±4%(13%) ± 20%for QGSJetII- 04, is respectively needed.