ExperimentalK-vacancy production probabilities of nearly symmetric heavy-ion collision systems in comparison with the2pπ−2pσrotational-coupling model

Measurements are reported for the impact parameter ($b$) dependence of $K$-vacancy production probabilities [$P_K\mathrm{}\left(b\right)\mathrm{}$] in collisions of 54.4- and 90-MeV Ni with targets of Ni, Ge, and Rb. The shape of $P_K\mathrm{}\left(b\right)\mathrm{}$ is found to be qualitatively similar to that expected for the $2p\pi -2p\sigma$ rotational-coupling mechanism, but the maximum found at large $b$ is shifted to smaller $b$ in comparison with the predicted adiabatic maximum. This behavior is investigated systematically by applying a simple scaling law within the $2p\pi -2p\sigma$ rotational-coupling model on these and all published $P_K\mathrm{}\left(b\right)\mathrm{}$ data of nearly symmetric collision systems.