Electron-Impact Detachment ofD−: Near-Threshold Behavior and the Nonexistence ofD2−Resonances

${\mathrm{D}}^{-}$ has been stored in the heavy-ion storage ring ASTRID and merged with the electron beam from an electron cooler. The cross section for electron-impact detachment of ${\mathrm{D}}^{-}$ was measured for relative energies from 0 to 20 eV. No evidence is found for the earlier reported resonances that were ascribed to short-lived ${\mathrm{H}}^{2-}$ states. We present a simple classical "reaction-zone" model which essentially reproduces the data except in the region close to the threshold where the cross section is small.