Measurement of the mean number of muons with energies above 500 GeV in air showers detected with the IceCube Neutrino Observatory

TL;DR

This study measures the average number of high-energy muons in cosmic ray air showers using IceCube, comparing results with simulations and revealing discrepancies in muon predictions at different energies.

Contribution

First measurement of high-energy muons in air showers with IceCube, comparing multiple hadronic models and highlighting inconsistencies in muon predictions.

Findings

Measured muon counts agree with simulations for high-energy muons.

Discrepancies found between low- and high-energy muon predictions in models.

Results suggest need for improved hadronic interaction models.

Abstract

We present a measurement of the mean number of muons with energies larger than 500 GeV in near-vertical extensive air showers initiated by cosmic rays with primary energies between 2.5 PeV and 100 PeV. The measurement is based on events detected in coincidence between the surface and in-ice detectors of the IceCube Neutrino Observatory. Air showers are recorded on the surface by IceTop, while a bundle of high-energy muons ("TeV muons") from the shower can subsequently produce a track-like event in the IceCube in-ice array. Results are obtained assuming the hadronic interaction models Sibyll 2.1, QGSJet-II.04, and EPOS-LHC. The measured number of TeV muons is found to be in agreement with predictions from air-shower simulations. The results have also been compared to a measurement of low-energy muons by IceTop, indicating an inconsistency between the predictions for low- and high-energy muons in simulations based on the EPOS-LHC model.