1210.1360 (R. A. Antonov et al.)

Results on the primary CR spectrum and composition reconstructed with the SPHERE-2 detector    [PDF]

R. A. Antonov, S. P. Beschapov, E. A. Bonvech, D. V. Chernov, T. A. Dzhatdoev, Mir. Finger, Mix. Finger, V. I. Galkin, N. V. Kabanova, A. S. Petkun, D. A. Podgrudkov, T. M. Roganova, S. B. Shaulov, T. I. Sysoeva

First preliminary results of the balloon-borne experiment SPHERE-2 on the all-nuclei primary cosmic rays (PCR) spectrum and primary composition are presented. The primary spectrum in the energy range $10^{16}$--$5\cdot10^{17}$ eV was reconstructed using characteristics of Vavilov-Cherenkov radiation of extensive air showers (EAS), reflected from a snow surface. Several sources of systematic uncertainties of the spectrum were analysed. A method for separation of the primary nuclei' groups based on the lateral distribution function' (LDF) steepness parameter is presented. Preliminary estimate of the mean light nuclei' fraction $f_{30-150}$ at energies $3\cdot10^{16}$--$1.5\cdot10^{17}$ eV was performed and yielded $f_{30-150}$= (21$\pm$11)%.

View original: http://arxiv.org/abs/1210.1360