  We have analyzed the cascade of secondary electrons in diamond and amorphous
carbon generated by the thermalisation of a single Auger electron. The elastic
electron mean free path was calculated as a function of impact energy in the
muffin-tin potential approximation. The inelastic scattering cross section and
the energy loss of the electron (expressed in terms of differential inverse
mean free path) were estimated from two "optical" models, that utilise the
measured dielectric constants of the materials. Using these data, a Monte-Carlo
model describing the time evolution of the cascade was constructed. The results
show that at most around 20-40 secondary cascade electrons are released by a
single Auger electron in a macroscopic sample of diamond or amorphous carbon.
Consideration of the real band structure of diamond reduces this number
further. The release of the cascade electrons happens within the first 100
femtoseconds after the emission of the primary Auger electron. The results have
implications to planned experiments with femtosecond X-ray sources.
