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 $\delta$, i. e., the reduction in the ionization loss of fast charged particles due to the dielectric polarization of the medium. The general expression for $\delta$ thus obtained is applicable to both condensed materials and gases. Its accuracy is such that the resulting values of the ionization loss $\frac{\mathrm{dE}}{\mathrm{dx}}$ are expected to have a maximum error of less than 2% throughout the range of momenta where the density effect is important.