Münster 2002 – scientific programme

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HK: Physik der Hadronen und Kerne

HK 4: Nuclear and Particle Astrophysics I

HK 4.1: Group Report

Monday, March 11, 2002, 16:15–16:45, C

The Physics of the Knee in the Cosmic-Ray Spectrum – Recent Results from KASCADE – — •Karl-Heinz Kampert — Institut für Experimentelle Kernphysik, University of Karlsruhe and Forschungzzentrum Karlsruhe

An update on measurements of cosmic rays in the energy range around 10¹⁵ eV is presented. Emphasis is placed on recent KASCADE data and on progress in air shower simulations using the CORSIKA package. High energy hadrons observed in the KASCADE calorimeter exhibit a distinct sensitivity to details in the modelling of high-energy hadronic interactions, particularly to the inelastic p-Air cross section and to diffractive dissociation. Thus, the experimental data can be used to constrain models employed in EAS simulations. Electron and muon shower sizes, on the other hand, are well suited to extract the energy and mass of the primary particles. Applying unfolding methods to their size spectra and adopting a model of high energy hadronic interactions, energy distributions of 4 mass groups are reconstructed in the energy range between 10¹⁵ and 10¹⁷ eV. The preliminary energy spectra show a knee-like structure in each of these distributions. Their position suggests a scaling according to the rigidity of the primary particle. Astrophysical implications of this important finding will be discussed.