Anomalous population of deep capture states of fast ions emerging from solid foils

The first comparison of core-state populations of initially bare ${\mathrm{Kr}}^{36+}$ ions emerging from gaseous and solid targets is presented. Another new important feature of this experiment lies in the fact that for such fast heavy ions, the single-collision condition is fulfilled even in solid targets. Our results can be explained by a wake-field–induced Stark mixing of the substates in a solid. Further coherence angles and field strength measurement are discussed.