Quantitative predictions for the doubly differential detachment collisions, 0.5-MeV ${\mathrm{H}}^{-}+\mathrm{He}\to \mathrm{H}\mathrm{}(n=2\mathrm{})+{\mathrm{He}}^{*}+e^{-}$, are provided by use of hyperspherical wave functions for the H-$e^{-}$ system. Individual H-$e^{-}$ hyperspherical channels are identified as producing distinct "cusp," "shape resonance," and/or "shoulder" features in the laboratory-frame cross sections. Moreover, the first quantitative predictions of the expected Gailitis-Damburg dipole-field-induced oscillations in the cross sections above the $\mathrm{H}\mathrm{}(n=2\mathrm{})\mathrm{}$ threshold are presented and distinguished from ${}_{}{}^1{}_{}{}^{}P_{}^{\circ }{}_{}{}^{}$ shape resonance effects.

• Received 11 August 1988

DOI:https://doi.org/10.1103/PhysRevLett.62.407