Pion-Production in Heavy-Ion Collisions at SIS energies ∗†

We investigate the production of pions in heavy-ion collisions in the energy range of 1- 2 GeV/A. The dynamics of the nucleus-nucleus collisions is described by a set of coupled transport equations of the Boltzmann-Uehling-Uhlenbeck type for baryons and mesons. Besides the N(938) and the ∆(1232) we also take into account nucleon resonances up to masses of 1.9 GeV/c 2 as well as π-, η- and ρ-mesons. We study in detail the influence of the higher baryonic resonances and the 2π-production channels (NN → NNππ) on the pion spectra in comparison to π − data from Ar + KCl collisions at 1.8 GeV/A and π 0-data for Au+Au at 1.0 GeV/A. We, furthermore, present a detailed comparison of differential pion angular distributions with the BEVALAC data for Ar + KCl at 1.8 GeV/A. The general agreement obtained indicates that the overall reactions dynamics is well described by our novel transport approach. 1

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