Recent Extensions to the Air Shower Simulation Program Corsika

CORSIKA is a Monte Carlo program simulating the evolution of extensive air showers in the atmosphere initiated by photons, nucleons, or nuclei. The new version 5.20 was released in March 1997. The major modiications with respect to version 4.5 concern: Treatment of high energy hadronic interactions by 5 diierent models, corresponding inelastic hadronic cross-sections for mean free path calculation, extension to highest energies (10 20 eV) including a thinning algorithm, improved muon tracking comprising muon bremsstrahlung and direct e + e ? pair production processes, and a version running on PCs under LINUX. INTRODUCTION The simulation program CORSIKA (COsmic Ray SImulation for KASCADE) has been developed (Capdevielle et al., 1992, Knapp and Heck, 1993) to analyze extensive air shower (EAS) measurements performed with the KASCADE experiment (Klages et al., 1997). Since the rst version from 1990 many improvements and extensions have been added (Knapp et al., 1995), to meet requirements of the KASCADE experiment and of a widespread user community involved in EAS and neutrino experiments. HADRONIC INTERACTION MODELS One of the major uncertainties in Monte Carlo simulation of EAS is the dependence upon the hadronic interaction models. Usually these models are tuned to t collider data, but unfortunately none of the collider experiments registers particles emitted into the extreme forward direction, as they disappear in the beam pipe. These particles carry most of the hadronic energy and are of highest importance in the development of EAS, since they transport a high energy fraction deep into the atmosphere. Moreover, when extrapolating to energies exceeding those accessible by accelerators, one has to rely on theoretical guidelines. In the past several phenomenological event generators have been built, based on simple models or on more elaborate theoretical foundations. Most of them reproduce the collider data but their predictions diier when applied to typical EAS energies and small angles. To estimate the systematic errors due to the hadronic interaction model, we have implemented in CORSIKA ve hadronic interaction models for energies > 80 GeV per nucleon. This enables a systematic comparison of all ve models within the environment of the CORSIKA program (Knapp et al., 1996). VENUS, QGSJET, and DPMJET model hadronic interactions of nucleons and nuclei on the basis of the Gribov-Regge theory, which successfully describes elastic scattering and the total hadronic cross-section as a function of energy. The rise of the cross-sections is accounted for by the multiple exchange of supercritical pomerons. …