Muons in air showers at the Pierre Auger Observatory: Measurement of atmospheric production depth

TL;DR

This paper demonstrates how the Pierre Auger Observatory's surface detectors can reconstruct muon production depth distributions in air showers, providing insights into cosmic ray composition and hadronic interactions.

Contribution

It introduces a method to measure muon production depth using surface detector timing data, aiding in cosmic ray composition analysis.

Findings

Reconstructed muon production depth distributions for air showers.

Defined X(mu)max as the depth of maximum muon production.

Assessed X(mu)max's potential to determine cosmic ray mass composition.

Abstract

The surface detector array of the Pierre Auger Observatory provides information about the longitudinal development of the muonic component of extensive air showers. Using the timing information from the flash analog-to-digital converter traces of surface detectors far from the shower core, it is possible to reconstruct a muon production depth distribution. We characterize the goodness of this reconstruction for zenith angles around 60 deg. and different energies of the primary particle. From these distributions we define X(mu)max as the depth along the shower axis where the production of muons reaches maximum. We explore the potentiality of X(mu)max as a useful observable to infer the mass composition of ultrahigh-energy cosmic rays. Likewise, we assess its ability to constrain hadronic interaction models.