Evidence for Residual K -Shell Excitation in Chlorine Ions Penetrating Carbon

Chlorine ions at 70 and 140 MeV energy impinge upon {~}1-{μ}g/cm² Cu targets, in one case after emerging from a carbon prefoil and in the second striking Cu on the back side of a carbon foil. The latter approach leads to an appreciable increase in the Cu K x-ray yield, an effect which is explained in terms of residual Cl K-shell excitation and which is in accord with a simple model of competing rearrangement processes.