Study of Dispersion of Mass Distribution of Ultra-High Energy Cosmic Rays using a Surface Array of Muon and Electromagnetic Detectors

TL;DR

This paper proposes a method to analyze the mass distribution of ultra-high energy cosmic rays using surface detectors measuring muon and electromagnetic signals, introducing a parameter sensitive to mass dispersion.

Contribution

It introduces a new parameter based on the zenith angle dependence to study mass dispersion, tested with two post-LHC hadronic interaction models.

Findings

Weak dependence on hadronic interaction models

Consistent results across different models

Parameter effectively indicates mass distribution dispersion

Abstract

We consider a hypothetical observatory of ultra-high energy cosmic rays consisting of two surface detector arrays that measure independently electromagnetic and muon signals induced by air showers. Using the constant intensity cut method, sets of events ordered according to each of both signal sizes are compared giving the number of matched events. Based on its dependence on the zenith angle, a parameter sensitive to the dispersion of the distribution of the logarithmic mass of cosmic rays is introduced. The results obtained using two post-LHC models of hadronic interactions are very similar and indicate a weak dependence on details of these interactions.