Density effect for the ionization loss of charged particles in various substances

The density-effect correction δ(β) for the ionization energy loss of charged particles has been evaluated as a function of the particle velocity for a total of 278 substances, including 98 cases of elements of the periodic table (12 gases and 86 condensed materials, including liquid hydrogen and graphite of three different densities) and 180 chemical compounds and substances of biological interest (13 gases and 167 liquid or solid substances). In the calculations, up-to-date values of the mean excitation potential I and of the atomic absorption edges hvi were employed as input data for the general equations for δ(β) previously derived by Sternheimer.