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arXiv · 1010.1185

The depth of maximum shower development and its fluctuations: cosmic ray mass composition at E_0 >= 10^17 eV

S. P. Knurenko·A. Sabourov
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Abstract

We present new data on Cherenkov light observations obtained during the period 1994-2009, after a modernization of the Yakutsk EAS array. A complex analysis of $\xmax$ and its fluctuations $\sigma(\xmax)$ was performed over a wide energy range. With the new data, according to QGSJet II model, an estimation was made of the cosmic ray mass composition for $\E \sim 10^{17} - 3 \times 10^{19}$ eV. The result points towards a mixed composition with a large portion of heavy nuclei at $\E \sim 10^{17}$ eV and the dominance of light nuclei at $\E \sim 10^{19}$ eV. The analysis of $\sigma(\xmax)$ energy dependence for the same energies qualitatively confirms this result. The shape of the $\xmax$ distribution at fixed energy $10^{18}$ eV is analysed to make more precise conclusions on cosmic ray mass composition.

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S. P. Knurenko, A. Sabourov. 2010-10-06. The depth of maximum shower development and its fluctuations: cosmic ray mass composition at E_0 >= 10^17 eV. https://doi.org/10.5194/astra-7-251-2011

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