Z oscillation of mean charges of energetic ions emerging from a carbon foil: Correlation with the shell structure of ions

Equilibrium mean charges q-bar of ions passing through a carbon foil were observed to oscillate vs projectile atomic number Z at ion energies 0.55, 1, and 2 MeV/u. The maxima of the oscillation take place for closed-shell ions having the electrons in mean number Z-q-bar = 10 and 28.