  The coefficient of self-diffusion for a homogeneously cooling granular gas
changes significantly if the impact-velocity dependence of the restitution
coefficient $\epsilon$ is taken into account. For the case of a constant
$\epsilon$ the particles spread logarithmically slow with time, whereas the
velocity dependent coefficient yields a power law time-dependence. The impact
of the difference in these time dependences on the properties of a freely
cooling granular gas is discussed.
