The production of K+ mesons in proton-nucleus collisions from 1.0 to 2.5
GeV is analyzed with respect to one-step nucleon-nucleon (NNāNYK+) and
two-step Ī-nucleon (ĪNāK+YN) or pion-nucleon (ĻNāK+Y) production channels on the basis of a coupled-channel transport
approach (CBUU) including the kaon final state interactions. The influence of
momentum-dependent potentials for the nucleon, hyperon and kaon in the final
state are studied as well as the importance of K+ elastic rescattering in
the target nucleus. The transport calculations are compared to the experimental
K+ spectra taken at LBL Berkeley, SATURNE, CELSIUS, GSI and COSY-J\"ulich.
It is found that the momentum-dependent baryon potentials effect the excitation
function of the K+ cross section; at low bombarding energies of ā¼ 1.0
GeV the attractive baryon potentials in the final state lead to a relative
enhancement of the kaon yield whereas the net repulsive potential at bombarding
energies ā¼ 2 GeV causes a decrease of the K+ cross section. Furthermore
it is pointed out, that especially the K+ spectra at low momenta (or kinetic
energy TKā) allow to determine the in-medium K+ potential almost model
independently due to a relative shift of the K+ spectra in kinetic energy
that arises from the acceleration of the kaons when propagating out of the
nuclear medium to free space, i.e. converting potential energy to kinetic
energy of the free kaon.Comment: 11 pages, LaTeX, including 10 postscript figures, submitted to Eur.
Phys. J.