Density Effect in the Ionization Energy Loss of Fast Charged Particles in Matter

Recent experimental work and its theoretical interpretation concerned with the density effect on the energy loss of charged particles in matter is reviewed with particular reference to electrons and muons. Recent proposals that radiative corrections should result in a significant reduction in the ionization loss at very high energies are analyzed in some detail. It is concluded that such an effect has not been substantiated experimentally, and that the predicted radiative corrections are likely to be small (∼1%).