Fluctuations of the Maximum Depth of EASes with Energies Greater than 1017 eV, According to Measurements of Radio Emission at Frequencies of 30–35 MHz

Abstract

Results on the longitudinal development of extensive air showers (EAS) of ultrahigh energies are obtained from observations of radio emission at the Yakutsk array for the periods from 1986 to 1989 and from 2009 to 2014. The maximum depth of individual showers is determined and a statistical analysis of X_max is performed to estimate the fluctuations in the development of EAS σ(X_max) in the energy region of 10¹⁷–10¹⁸ eV. It is shown that σ(X_max) is 50–60 g cm² in the energy range of 10¹⁷–10¹⁸ eV, which does not contradict the mixed composition of cosmic rays (protons and helium nuclei). Data on the dependence of X_max on energy also indicate this.