Strangeness production and propagation at sub-threshold energies, Y. Leifels for the FOPI Collaboration, GSI Damrstadt, Planckstr. 1, 64291 Darmstadt, Germany − In the energy range of the Heavy Ion Synchrotron at GSI nuclear matter densities of 2 - 3ρ0 at relative moderate temperatures are created in relativistic heavy ion collisions.  A multitude of phenomenons have been observed, i.e. collective flow, stopping and particle production, which have been confronted to the predictions of theoretical models to investigate the constraints on the bulk characteristics of nuclear matter.


In trying to describe in addition the strangeness degree of freedom evidence was found that strange particle observables might be influenced by the KN potentials in the dense baryonic medium.  We review the strangeness production in Heavy Ion collisions at energies around the NN production threshold and discuss recent measurements of the FOPI collaboration on charged kaon flow over a wide impact parameter range.  The data is compared to comprehensive state-of-the-art transport models.


The dense nuclear matter environment produced in those collisions may provide unique opportunities to form strange few body systems. The FOPI detector is especially suited to reconstruct such states by their charged particle decays. Apart from strongly decaying states special emphasis will be put on the search for long living weakly decaying states, i.e. Hyper-Nuclei.  Light Hyper-Nuclei are reconstructed by their two body decay channels and the production of Hyper-Tritons is studied with respect to λ and t(3He).