The coherent excitation of overlapping atomic states by ion projectiles has a strong effect on the angular distribution of Auger electrons. Therefore, the measurement of the angular anisotropy of outgoing Auger electrons is suitable for the quantitative studies of the influence of the coherence. In our experiment the Ne target was bombarded with $700–2000\text{keV}$ ${\mathrm{H}}^{+}$ and $2000\text{keV}$ ${\mathrm{He}}^{+}$ projectiles. The angular distributions of ${KL}_{2,3}{\text{−}LLL}_{2,3}$ Auger electrons emitted from the decay of the coherently excited $1s2p$ doubly vacancy states of Ne were measured. The anisotropy parameter of the Auger decay was deduced from the measurements and compared with theoretical results calculated using the multiconfiguration Dirac-Fock method. The results indicate that one should go beyond the $LS$ coupling scheme even at this relatively low atomic number element, but also suggest that only partially overlapping states need to be taken into account.

• Received 9 January 2004

DOI:https://doi.org/10.1103/PhysRevA.69.062708