Sensitivity of the correlation between the depth of shower maximum and the muon shower size to the cosmic ray composition

Abstract

The composition of ultra-high energy cosmic rays is an important issue in astroparticle physics research, and additional experimental results are required for further progress. Here we investigate what can be learned from the statistical correlation factor r between the depth of shower maximum and the muon shower size, when these observables are measured simultaneously for a set of air showers. The correlation factor r contains the lowest-order moment of a two-dimensional distribution taking both observables into account, and it is independent of systematic uncertainties of the absolute scales of the two observables. We find that, assuming realistic measurement uncertainties, the value of r can provide a measure of the spread of masses in the primary beam. Particularly, one can differentiate between a well-mixed composition (i.e., a beam that contains large fractions of both light and heavy primaries) and a relatively pure composition (i.e., a beam that contains species all of a similar mass). The number of events required for a statistically significant differentiation is ~ 200. This differentiation, though diluted, is maintained to a significant extent in the presence of uncertainties in the phenomenology of high energy hadronic interactions. Testing whether the beam is pure or well-mixed is well motivated by recent measurements of the depth of shower maximum.

arXiv commentAccepted for publication in Astroparticle Physics, LA-UR-12-20084

References in corpus (15)

• Measurement of the energy spectrum of cosmic rays above 10^18 eV using the Pierre Auger Observatory
• QGSJET-II: towards reliable description of very high energy hadronic interactions
• Parton Ladder Splitting and the Rapidity Dependence of Transverse Momentum Spectra in Deuteron-Gold Collisions at RHIC
• One-dimensional Hybrid Approach to Extensive Air Shower Simulation
• Indications of Proton-Dominated Cosmic Ray Composition above 1.6 EeV
• Non-linear screening effects in high energy hadronic interactions
• Constraints from the first LHC data on hadronic event generators for ultra-high energy cosmic-ray physics
• New facts about muon production in Extended Air Shower simulations
• Extensive Air Shower Simulations at the Highest Energies
• Implications of the cosmic ray spectrum for the mass composition at the highest energies
• First Results of Fast One-dimensional Hybrid Simulation of EAS Using CONEX
• Constraints on the flux of primary cosmic-ray photons at energies E > 10^18 eV from Yakutsk muon data
• Underground Muon Counters as a Tool for Composition Analyses
• A comprehensive study of shower to shower fluctuations
• Hybrid Simulation of Cosmic Ray Air Showers

Cited by in corpus (8)

• Evidence for a mixed mass composition at the `ankle' in the cosmic-ray spectrum
• Ultra-High-Energy Cosmic Rays: The Intersection of the Cosmic and Energy Frontiers
• Acceleration and propagation of ultra high energy cosmic rays
• Identification of the primary mass of inclined cosmic ray showers from depth of maximum and number of muons parameters
• Composition determination of cosmic rays from the muon content of the showers
• Towards solving the mass-composition problem in ultra high energy cosmic rays
• Maximum entropy analysis of cosmic ray composition
• Study of Dispersion of Mass Distribution of Ultra-High Energy Cosmic Rays using a Surface Array of Muon and Electromagnetic Detectors