Systematics of pion emission in heavy ion collisions in the regime

Using the large acceptance apparatus FOPI, we study pion emission in the reactions (energies in A GeV are given in parentheses): 40Ca + 40Ca (0.4, 0.6, 0.8, 1.0, 1.5, 1.93), 96Ru + 96Ru (0.4, 1.0, 1.5), 96Zr + 96Zr (0.4, 1.0, 1.5), 197Au + 197Au (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.