Production Of K+ And Of K- Mesons In Heavy-Ion Collisions From 0.6a To 2.0a Gev Incident Energy

This paper summarizes the yields and the emission patterns of K+ and of K- mesons measured in inclusive C+C, Ni+Ni, and Au+Au collisions at incident energies from 0.6A to 2.0A GeV using the Kaon Spectrometer KaoS at GSI. For Ni+Ni collisions at 1.5A and at 1.93A GeV as well as for Au+Au at 1.5A GeV, detailed results are presented of the multiplicities, of the inverse slope parameters, and of the anisotropies in the angular emission patterns as a function of the collision centrality. When comparing transport-model calculations to the measured K+ production yields, an agreement is only obtained for a soft nuclear equation of state (compression modulus K-N approximate to 200 MeV). The production of K- mesons at energies around 1A to 2A GeV is dominated by the strangeness-exchange reaction K-N -><-pi Y (Y=Lambda,Sigma) which leads to a coupling between the K- and K+ yields. However, both particle species show distinct differences in their emission patterns suggesting different freeze-out conditions for K+ and K- mesons.