Core structure of extensive air showers at primary energies around the knee by a multifractal moments analysis

Abstract

Patterns of particle distributions in the core of extensive air showers, measured by multiwire proportional chambers installed below the central detector of the KASCADE experiment are analysed in terms of multi-fractal moments. Correlating the obtained mass sensitive parameters with the shower size and the number of reconstructed muons in the core region, an artificial neural net analysis leads to probability distributions for associating single showers to particular primary masses. The resulting chemical composition in the energy region of the knee tends to a heavier composition after the knee. The knee position seems to be shifted to higher energies in case of heavy primary cosmic rays.