Importance of vacancy cascades in argon recoil-ion charge-state distributions accompanied by coincident projectile-electron capture and loss

Argon recoil-ion charge-state distributions produced by beams of 0.7-MeV/u ${\mathrm{Cl}}^{5+,8+,10+}$ have been measured by time-of-flight techniques in coincidence with single- and double-charge-changed projectiles. In an essential improvement to the usual multinomial description of ionization in the independent-electron-ejection model, we find the inclusion of one (two) Auger vacancy cascades significantly alters the description of the recoil-ion spectra corresponding to single (double) capture. The single- and double-projectile-electron loss and capture spectra strongly resemble each other, suggesting that loss of one or two projectile electrons is closely associated with loss of one or two target $L$ electrons, respectively. These conclusions are consistent with impact parameters inferred from determinations of mean recoil energy.