  Swarm techniques have largely been used to investigate electron transport in
very dilute gases in order to shed light on the electron-atom (molecule)
scattering cross section and, hence, on the interaction potential. The
theoretical basis for the analysis of these experiments is classical Kinetic
Theory. However, electron transport in dense media, either in gaseous- or
condensed phase, is a physical phenomenon of fundamental and practical
interest. Dense rare gases are model systems for disordered media. They are
particularly well suited to investigate how the dynamics and energetics of
quasifree electrons change as the environment density is gradually increased. A
review on the electron swarm experiments in dense rare gases is presented here.
