  The results of a theoretical investigation of prompt many-body ionization are
reported. Our calculations address an experiment that reported ionization in
Rydberg gases for densities two orders of magnitude less than expected from
ionization between pairs of atoms. The authors argued that the results were due
to the simultaneous interaction between many atoms. We performed classical
calculations for many interacting Rydberg atoms with the ions fixed in space
and have found that the many atom interaction does allow ionization at lower
densities than estimates from two atom interactions. However, we found that the
density fluctuations in a gas play a larger role. These two effects are an
order of magnitude too small to account for the experimental results suggesting
at least one other mechanism strongly affects ionization.
