Backward peak in the electron spectrum from collisions of 70-keV protons with a target from a hydrogen-atom source

A large, broad peak has been found in the electron energy spectrum from 30 to 100-keV H{sup +}+H collisions. The peak, which is centered at 31 eV, appears only in the backward directions. It is suggested that while the peak is unlikely to come from collisions with atoms in the ground or metastable states, it could arise from collisions with atoms in highly excited states or from autoionizing states of the residual H{sub 2} in the target.