Single ionization of the HD molecule by fast ion impact is used to populate
the vibrational continuum of the HD+ electronic ground state (1s sigma). T
he resulting dissociation leads to two final states, the lower 1s sigma sta
te or the first excited 2p sigma state, which is 3.7 meV higher at the sepa
rated atom limit due to the finite nuclear mass correction to the Born-Oppe
nheimer approximation. We find dissociation to the lower H+ + D(1s) state t
o be about 7% more likely than to the upper H(1s) + D+ final state. The maj
or experimental difficulty in this measurement is the determination of the
H-2 contamination in the HD target. Two different methods of determining th
is contamination are presented, and the details of the measurement of the r
elative yields of the final two ground-state dissociation channels are disc
ussed. The experimental results are compared to our coupled channels calcul
ation and to a model based on Meyerhof's approximate formulation.