Separation of the light and heavy mass groups of 1016-10 18 eV cosmic rays by studying the ratio muon size to shower size of KASCADE-Grande data

Abstract

KASCADE-Grande is an air-shower observatory devoted to the study of cosmic rays with energies in the range 1016-1018 eV. In KASCADE-Grande, different detector systems allow independent measurements of the number of muons (Nμ) and charged particles (Nch) of air showers, which are the basis for several energy and composition studies of cosmic rays. In this contribution, a composition analysis using the shower size ratio lgNμ/lgNch, corrected for attenuation in the atmosphere, is described. Using QGSJET II-based simulations of different primaries, it is shown that an energy independent cut on the shower ratio can be chosen in order to separate the cosmic ray events into light and heavy mass groups. The analysis is applied to the KASCADE-Grande data. The energy spectra derived from the analysis are presented.