KASCADE-Grande observation of features in the cosmic ray spectrum between knee and ankle

The detection of high-energy cosmic rays above a few hundred TeV is realized by the observation of extensive air-showers. By using the multi-detector setup of KASCADE-Grande, and here in particular the detectors of the large Grande array, the energy spectrum and the elemental composition of high-energy cosmic rays in the energy range from 10 PeV to 1 EeV are investigated. The estimation of energy and mass of the high-energy primary particles is based on the combined analysis of the total number of charged particles and the total number of muons measured by the detector arrays of Grande and KASCADE, respectively. The latest analysis results have shown that in the all-particle spectrum two features are present: a hardening of the spectrum at energies around 20 PeV and a steepening, i.e. a knee-like structure, at 80-90 PeV. The latter one was found to be due to a decrease of flux of the heavy mass component.