Abstract
We present the measurement of the density of GeV muons in near-vertical air showers by the IceTop array at the South Pole. The muon density is measured at 600 m and 800 m lateral distance from the shower axis in air showers between 1 PeV and 100 PeV. This result can be used to constrain hadronic interaction models by comparing it with the outcome of Monte Carlo simulations. We show that some models do not produce muon densities in agreement with this result unless an unphysical composition of the primary cosmic ray flux is assumed.
Highlights
One of the challenges in understanding cosmic-ray induced extended air showers is the accurate description of hadronic interactions over several decades in the centerof-mass energy, from a few tens of GeV to more than 106 GeV
Note that the muon density for iron air showers in relation to proton showers is different for each model
We show the expected muon density according to three cosmic ray flux models
Summary
One of the challenges in understanding cosmic-ray induced extended air showers is the accurate description of hadronic interactions over several decades in the centerof-mass energy, from a few tens of GeV to more than 106 GeV. The remainder of the energy is carried by hadrons, mostly charged pions, that go on to further interact as part of a hadronic cascade This process is repeated until the energy per particle is less than a critical energy, at which point the mesons decay, producing muons that can reach the ground. Measurements of muons in air showers, made by the Pierre Auger collaboration, have provided evidence for a discrepancy between data and simulations for primary energies above 1 EeV [7, 8]. Hybrid measurements, which used both detector components, have been used to infer mass composition of the primary cosmic ray flux [18] The latter measurements were based on the fact that TeV muons, as opposed to the electromagnetic (EM) component of the air showers, are able to penetrate the ice shield above the deep part of IceCube
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