Pion-Production in Heavy-Ion Collisions at SIS energies

Abstract

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 $\Delta (1232)$ we also take into account nucleon resonances up to masses of $1.9GeV/c^2$ as well as $\pi$-, $\eta$- and $\rho$-mesons. We study in detail the influence of the higher baryonic resonances and the $2\pi$-production channels ($NN\to NN\pi \pi$) on the pion spectra in comparison to ${\pi }^{-}$ data from $Ar+KCl$ collisions at $1.8$ GeV/A and ${\pi }^0$-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.

Comments: 31 pages, 18 figures (inlcuded), to appear in Z. Phys. A