FLUCTUATIONS OF X_max AND PRIMARY PARTICLE MASS COMPOSITION IN THE RANGE OF ENERGY 5 × 10¹⁷ - 3 × 10¹⁹EV BY YAKUTSK DATA

Abstract

The experimental distributions of Xmax obtained with the Yakutsk EAS array at fixed energies of 5 × 10 17 , 1 × 10 18 and 5 × 10 18 eV are analysed. A recent version of the QGSJET model is used as a tool of our analysis. In the framework of this model, the most adequate mass composition of primary particles satisfying the experimental data on Xmax is selected.

Study of cosmic rays at the Yakutsk EAS array: energy spectrum and mass composition

“…It should be pointed out that according to Figure 9, the portion of heavy nuclei in CR flux energy above 2 × 10 18 eV is small and helium and CNO-group nuclei might play a significant role. We came to the same conclusion [33] where the shape of x max distribution was analyzed within the framework of QGSJet01 model at fixed energies 10 18 eV and ∼ 10 19 eV (see Fig. 10).…”

“…It is known fact that the depth of shower maximum (x max ) and fluctuations in EAS development are sensitive to atomic number of primary particle and for this reason they are used to estimate the CR mass composition [31][32][33]. It's especially important for ultra-high energy region where direct measurements of mass composition are impracticable.…”

The depth of maximum shower development and its fluctuations: cosmic ray mass composition at <i>E</i>₀≥10¹⁷ eV

“…It should be pointed out that according to Figure 3, the portion of heavy nuclei in the CR flux energy above 2 × 10 18 eV is small and helium and CNO-group nuclei might play a significant role. We came to the same conclusion [4] where the shape of the x max distribution was analyzed within the framework of the QGSJet01 model at fixed energies 10 18 eV and ∼ 10 19 eV (see Figure 4).…”

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

“…Joint analysis of showers allowed us to obtain quantitative estimates of the mass composition of primary CRs, using the distribution of X max at fixed energy [3]. To do this, we compared the experimental data and theoretical predictions according to QGSJET for different primary nuclei with applied criterion χ 2 .…”

“…In this review, we used the work of the Yakutsk group in which was introduced an estimation of the mass composition of cosmic rays at ultrahigh energies [1][2][3][4][5]. In these studies we analyzed the characteristics of longitudinal and lateral development of EAS, reconstructed according to observations at the Yakutsk array.…”