Study of muon disk structure at E0 ≥ 5 x 1016 eV using Yakutsk EAS array data

Results from the investigation of the temporal structure of the muon disk in extensive air showers (EAS) with primary energy E0 ≥ 5 x 1016 eV at distances 250 - 1500 m from the shower core are reported. The investigation is performed at the Yakutsk array using the large muon detector, which commenced operation in 1995, with the area 184 m2 and detection threshold Eμ ∼ 0.5 sec θ GeV. Two components with different muon disk thickness are found with the require the change in our opinion about the EAS development. A problem of existing of events with E0 ≥ 1020 eV is considered