General expression for the density effect for the ionization loss of charged particles

This paper presents a simple reformulation of the expression for the density effect correction δ, i. e., the reduction in the ionization loss of fast charged particles due to the dielectric polarization of the medium. The general expression for δ thus obtained is applicable to both condensed materials and gases. Its accuracy is such that the resulting values of the ionization loss dE/dx are expected to have a maximum error of less than 2% throughout the range of momenta where the density effect is important.