Applications of muon signal to electromagnetic signal showers universality for mass composition and hadronic interactions studies

TL;DR

This paper introduces a method leveraging the universality of muon to electromagnetic signal ratios in air showers to estimate muon content and primary mass composition with reduced model dependence, aiding hadronic interaction studies.

Contribution

It demonstrates a novel approach to estimate muon signals and primary cosmic ray composition using universality properties, minimizing dependence on interaction models.

Findings

Muons and electromagnetic signals show universal behavior above 45° zenith angles.

The method allows model-independent estimation of muon content in air showers.

Application to simulated data enables accurate primary mass determination.

Abstract

We present the first results of the application of the recently found universality of behavior of muon signal to electromagnetic (EM) signal ratio with respect to the vertical depth of showers maximum for mass composition and hadronic interaction studies. Making use of the fact that for zenith angles above 45 degrees the dependence of the ratio on the vertical depth of shower maximum is very similar for QGSJET II and EPOS 1.99 we show that this provides the possibility to estimate muon shower content in almost interaction model independent way. To evaluate the excess of signal in the data in respect to Monte-Carlo predictions we propose to use mass independence of the electromagnetic signal. Using the simulations with EPOS 1.99 as a fake data we show that one can determine the absolute scaling factor between these fake data and the interaction model under test (QGSJET II in our case). Applying this scaling factor to the total and muon signals of QGSJET II one can make accurate conclusions on the primary mass of samples prepared with EPOS 1.99.