Review of SIS experimental results on strangeness

A review of meson emission in heavy-ion collisions at incident energies around 1-2 A GeV is presented. It is shown how the shape of the spectra and the various particle yields vary with system size, with centrality and with incident energy. A statistical model assuming thermal and chemical equilibrium and exact strangeness conservation (i.e. strangeness conservation per collision) explains most of the observed features. Emphasis is put on the study of K + and K - emission. Within the framework of this statistical model it is shown that the experimentally observed equality of K + and K - rates at threshold corrected energies is due to a crossing of two excitation functions. Furthermore, the independence of the K + to K - ratio of the number of participating nucleons observed between 1 and 10 A GeV is consistent with this model. The observed flow effects are beyond the scope of this model.