One- and two-step double-electron capture in slow Ar6+-He collisions.

Double-electron capture by slow (15--30 eV/u) Ar{sup 6+} ions from He has been studied by simultaneous measurements of postcollisional projectile energy-gain and angular distributions. The recorded spectra are interpreted with the aid of a semiclassical collision model. We find evidence for distinguishable one- and two-step double-electron capture in the energy region investigated.