  We study mutual ionization in collisions between atomic hydrogen and helium
at impact velocities near the electronic threshold for this process (determined
by the condition that kinetic energy of an equivelocity free electron is
approximately equal to the sum of binding energies of active electrons in the
projectile and target). We show that this process is substantially influenced
by the Coulomb repulsion between the emitted electrons and that the atomic
nuclei are very strongly involved in the momentum balance along the collision
velocity.
