Mass composition of cosmic rays with energy E0 ≥ 1017 eV, according to surface detectors of the Yakutsk EAS array
The lateral distribution of charged particles is investigated in extensive air showers (EASes) with energy E0 ≥ 1017 eV at the Yakutsk array using surface scintillation detectors over the period 1977–2013. Experimental values are compared to calculations made by different models of EAS development contained in the CORSICA software package. The best agreement between theory and experiment is observed with the QGSJET-01-d and QGSJET-II-04 models. A change in the mass composition of cosmic rays in the direction of purely proton is observed in the energy range of 1–20 × 1017 eV.