A Direct Comparison of Muon Measurements at the Yakutsk Array and the Pierre Auger Observatory

TL;DR

This paper compares muon measurements from the Yakutsk Array and Pierre Auger Observatory, revealing discrepancies with theoretical models and identifying calibration issues affecting muon density and energy estimates.

Contribution

It provides a direct comparison of muon data from two major observatories and analyzes the sources of measurement discrepancies with models and calibration.

Findings

Muon densities differ by a factor of 1.53 from predictions.

Auger overestimates muon densities by 1.22 times.

Primary energy is underestimated by 1.25 times in Auger.

Abstract

Here we consider the results of direct measurements of muons in extensive air showers with zenith angles $\theta \le 45^{\circ}$ and energy above $10^{17}$ eV, obtained at the Pierre Auger Observatory and Yakutsk array. In both experiments muons were registered with underground scintillation detectors with $\approx 1.0 \times \sec\theta$ GeV energy threshold. Measured density values were compared to theoretical predictions calculated within the framework of the QGSJet-II.04 hadron interaction model. They differ by factor $1.53 \pm 0.13$(stat). We demonstrate that this difference is due to overestimation of muon densities by 1.22 times and underestimation of primary energy by 1.25 times in the Auger experiment.