ar X iv : a st ro - p h / 06 12 15 7 v 1 6 D ec 2 00 6 New p + C data in fixed target experiments and the muon component in extensive air showers

The interpretation of extensive air shower (EAS) measurements is strongly dependent on the hadronic interaction models used for simulating reference showers. We study the importance of low-energy hadronic interactions in simulated air showers, generated with the simulation package CORSIKA, for the observed characteristics of extensive air showers. In particular we investigate in detail the energy and the phase space regions of secondary particle production which are most important for muon production. This phase space region is covered by fixed target experiments at CERN. In the second part of this work we present preliminary momentum spectra of secondary π + and π − in p+C collisions at 12 GeV/c measured with the HARP spectrometer at the PS accelerator at CERN. In addition we use the new p+C NA49 data at 158 GeV/c to check the reliability of hadronic interaction models for muon production in EAS. Finally, possibilities to measure relevant quantities of hadron production in existing and planned accelerator experiments are discussed. 1. Relation of muons in EAS to hadronic interactions In order to extract information (energy and particle type) on the primary particle from ground based air shower measurements, simulation of air showers using electromagnetic and hadronic interaction models are necessary. These simulations show uncertainties which come mainly from hadronic interaction models. Muons measured at ground level are one of the main ingredients to infer energy and mass of the primary particle of an air shower. Furthermore muons are sensitive to the characteristics of hadronic interactions. One aim of this work is to specify the low-energy hadronic interactions which are important for the muon production in EAS. We simulate extensive air showers with a modified version of the simulation package CORSIKA [1]. This special version stores the information of the last hadronic interaction where mesons are produced which decay into muons. The initiator hadron of the last hadronic interaction is called the grandmother particle and the meson which decays into a muon is named mother particle. For the following analysis vertical proton showers with a primary energy of 10 15 eV are used. In this CORSIKA simulation, the hadronic interaction model GHEISHA * See author list of [13] [2] is applied for energies up to 80 GeV and QGSJET-01 [3] for higher energies. Simulations with other models are in preparation. In Fig. 1 the energy spectra of grandmother particles of different particle types are shown. Most of the grandmother particles …