Estimation of the Composition of Ultra-High Energy Cosmic Rays Using the Muon Correlation Method Based on Yakutsk EAS Array Data

In this article a new method is proposed for estimating the mass composition of cosmic rays in individual events with energies above \(1.25 \times {{10}^{{19}}}\) eV. It is based on a joint analysis of experimental data and simulation results obtained using the QGSjet-II.04 model for muons with threshold energy \({{E}_{\mu }} = 1.0 \times \cos \theta \) GeV in air showers with zenith angles up to 60°. The data from ground-based and underground scintillation detectors of the Yakutsk EAS array were used. Separate groups of nuclei and other primary particles were found.