The KASCADE-Grande energy spectrum of cosmic rays and the role of hadronic interaction models

Previous results obtained by KASCADE-Grande using the QGSjetII-02 hadronic interaction model have shown that the energy spectrum of cosmic rays between 1016eV and 1018eV exhibits a significant hardening at approximately 2×1016eV and a slight but statistically significant steepening close to 1017eV. Moreover, the analysis with QGSjetII-02 suggests that the break observed around 1017eV is caused by the heavy component of primary cosmic rays. In this paper, we report on the results of similar analyses performed using the SIBYLL 2.1 and EPOS 1.99 hadronic interaction models to interpret the data. The present results confirm qualitatively the previous findings. However, the intensity of the all-particle spectrum, the positions of the hardening and steepening of the spectrum, as well as the relative abundance of the heavy and light mass groups depend on the hadronic interaction model used to interpret the data.