The stopping power of Ag and Au, with regard to higher-order Z1-effects

Abstract

We have measured the absolute stopping cross section ϵ of Ag and Au with a precision of 3%, using backscattering geometry. The velocity of the projectiles (p, [d], He, Li, and C) ranges from about 1.5υ0 to 4υ0. These measurements are compared to calculations of ϵ including the Barkas and Bloch terms. We use a local density approximation employing the harmonic-oscillator calculations by Sigmund and Haagerup, by Mikkelsen and Sigmund, and the calculations by Bloch, introducing a simple shell correction. Within the energy range where our approximations apply, good agreement with the measured proton stopping cross section is found. Furthermore, we find from our calculations that the ratio of the stopping cross sections of Ag and Au does not depend on the type of projectile (in all orders of Z1), in agreement with our measurements.