Theory of Effective Charge and Stopping Power of Heavy Ions

Abstract

The Knipp-Teller theory of stopping power for heavy ions is reviewed and revised. The basic idea of using the Thomas-Fermi theory to describe the electron charge around the moving ion is retained. The major alteration which is introduced is in relating the degree of ionization to the velocity of the ion. The zero-order term of the resulting theory comes within 10% or so of predicting observed mean electronic stopping powers for ions with $z>\mathrm{}6\mathrm{}$ and $\frac{\epsilon }{z^{\frac{4}{3}}}>0.002\mathrm{}$, where $z$ is the atomic number of the ion and $\epsilon$ its kinetic energy in million electron volts per atomic mass unit.