Characteristics of air showers with energy more than 10

The paper presents results on the longitudinal development of air showers of ultra-high energies obtained from radio emission measurements at the Yakutsk array. The energy, the depth of maximum development of individual showers are determined and a statistical analysis of Xmax in order to estimate the fluctuation of air shower development σ(Xmax) in the energy region 1017-1018 eV is performed. It is shown that σ(Xmax) in the energy region 1017-1018 eV is equal to 50-60 g·cm-2, which doesn’t contradict with a mixed composition of cosmic rays - protons and helium nuclei. This is also indicated by data of the Xmax value dependence on energy

Search for ultra-high energy photons by complex data of the Yakutsk array

Complex analysis of the Yakutsk array data in order to find air showers produced by photons with energy ≥1018 eV is carried out. On the basis of simulations and experimental data, selection criteria are formed and air showers with characteristics close to those criteria are selected. Using the data an upper limit of the integral photon flux in cosmic radiation of ultra-high energies is obtained

Characteristics of air showers with energy more than 1017 eV reconstructed by the Yakutsk array radio emission measurements

The paper presents results on the longitudinal development of air showers of ultra-high energies obtained from radio emission measurements at the Yakutsk array. The energy, the depth of maximum development of individual showers are determined and a statistical analysis of Xmax in order to estimate the fluctuation of air shower development σ(Xmax) in the energy region 1017-1018 eV is performed. It is shown that σ(Xmax) in the energy region 1017-1018 eV is equal to 50-60 g·cm-2, which doesn’t contradict with a mixed composition of cosmic rays - protons and helium nuclei. This is also indicated by data of the Xmax value dependence on energy

Search for ultra-high energy photons by complex data of the Yakutsk array

Complex analysis of the Yakutsk array data in order to find air showers produced by photons with energy ≥1018 eV is carried out. On the basis of simulations and experimental data, selection criteria are formed and air showers with characteristics close to those criteria are selected. Using the data an upper limit of the integral photon flux in cosmic radiation of ultra-high energies is obtained

Ultra-high energy cosmic rays: 40 years retrospective of continuous observations at the Yakutsk array: Part 2. Mass composition of cosmic rays at ultra high energies

In the paper, we describe methods for the analysis and present results for the mass composition of cosmic rays, obtained by using these techniques over a large time span. The data were obtained at the Small Cherenkov array over a 20 – year period of continuous observation and 40 – years of observations at the main Yakutsk array. Our experimental data indicate a change in the mass composition in the energy range 1016–1018 eV and is confirmed by independent results obtained by other EAS arrays