Investigating the in-medium effects of strange particles with the FOPI detector

Strangeness production sub- or close-to-production threshold energies is believed to provide an insight into equilibration and the change of hadron properties in a hot and dense nuclear medium. K-mesons are predicted to exhibit a change of their effective in-medium mass and thus are an unique tool to study the partial restoration of the chiral symmetry of QCD. The FOPI detector at SIS 18 allows the identification of charged kaons and the reconstruction of neutral particles as K0S, Λ0 and φ-mesons by their charged decay products in a wide range of phase space. This presentation gives an overview of FOPI's recent results from a high statistic heavy-ion experiment (Ni+Ni rate at 1.93 AGeV) aiming at investigating the in-medium modifications in hot and compressed nuclear matter and from pion-induced reactions (π- rate at 1.7 GeV/c) offering a reference at normal nuclear matter density.