L3-SUBSHELL ALIGNMENT OF MAGNESIUM AFTER ELECTRON-CAPTURE BY PROTONS

We have measured the alignment of Mg+ (L3) ions after electron capture by H+ in the energy range E(H+) = 40-240 keV (range of relative velocity v(H+)/v(L3) = 0.6-1.5) via the coincidences between the non-isotropically emitted L3-M1M1 Auger electrons and the neutral H atoms. Our experimental results show a strong resonance-like behaviour of the alignment values A20c as function of relative velocity with a maximum at about v(H+)/v(L3) = 0.8. This is in qualitative agreement with the theoretical values obtained with the Oppenheimer-Brinkmann-Kramers (OBK) approximation. The tendency of the experimental alignment results towards large negative values at high collision velocities is in accordance with the high-velocity behaviour of the OBK approximation and the semiclassical impulse approximation.