Studies on the response of a water-Cherenkov detector of the Pierre Auger Observatory to atmospheric muons using an RPC hodoscope

Abstract

Extensive air showers, originating from ultra-high energy cosmic rays, have been successfully measured through the use of arrays of water-Cherenkov detectors (WCDs). Sophisticated analyses exploiting WCD data have made it possible to demonstrate that shower simulations, based on different hadronic-interaction models, cannot reproduce the observed number of muons at the ground. The accurate knowledge of the WCD response to muons is paramount in establishing the exact level of this discrepancy. In this work, we report on a study of the response of a WCD of the Pierre Auger Observatory to atmospheric muons performed with a hodoscope made of resistive plate chambers (RPCs), enabling us to select and reconstruct nearly 600 thousand single muon trajectories with zenith angles ranging from 0${}^{\circ }$ to 55${}^{\circ }$. Comparison of distributions of key observables between the hodoscope data and the predictions of dedicated simulations allows us to demonstrate the accuracy of the latter at a level of 2%. As the WCD calibration is based on its response to atmospheric muons, the hodoscope data are also exploited to show the long-term stability of the procedure.

arXiv commentPublished version, 25 pages, 9 figures

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• The Pierre Auger Cosmic Ray Observatory
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• Simulation of large photomultipliers for experiments in astroparticle physics
• Analytical calculation of the charge spectrum generated by ionizing particles in Resistive Plate Chambers at low gas gain

Cited by in corpus (3)

• Reconstruction of Events Recorded with the Surface Detector of the Pierre Auger Observatory
• Calculation of the High-Energy Neutron Flux for Anticipating Errors and Recovery Techniques in Exascale Supercomputer Centres
• The gamma/hadron discriminator $LCm$ in realistic air shower array experiments