Systematics of pion emission in heavy ion collisions in the 1 A GeV regime

Abstract Using the large acceptance apparatus FOPI, we study pion emission in the reactions (energies in A GeV are given in parentheses): 40 Ca +  40 Ca (0.4, 0.6, 0.8, 1.0, 1.5, 1.93), 96 Ru +  96 Ru (0.4, 1.0, 1.5), 96 Zr +  96 Zr (0.4, 1.0, 1.5), 197 Au +  197 Au (0.4, 0.6, 0.8, 1.0, 1.2, 1.5). The observables include longitudinal and transverse rapidity distributions and stopping, polar anisotropies, pion multiplicities, transverse momentum spectra, ratios ( π + / π − ) of average transverse momenta and of yields, directed flow, elliptic flow. The data are compared to earlier data where possible and to transport model simulations.