Energy-gain spectroscopy studies of electron capture from helium by slow multiply charged neon ions

Energy spectra of the projectile ions have been measured following electron capture by slow ${\mathrm{Ne}}^{q+}$ ions on He for $3\le q\le 8$. Both single-capture and transfer ionization were observed. The reactions are all exoergic with positive energy defects between 3.6 and 31 eV, and with crossing radii between 8 and 2.1 Å. Capture is found to selectively populate states whose crossings lie at a radius which can be calculated on the basis of a simple prescription. The total transfer cross sections range up to 55% of the geometrical ones deduced from the measured crossing radii.