Stopping Power of a Medium for Charged Particles

The classical cross section for charged-particle interactions is used to estimate the ratio of hard to soft collisions. For fast charged particles, the cross section obtained from a straight trajectory approximation is used to derive an expression for the non-relativistic collision stopping power. This is extended to a discussion of stopping power for relativistic particles and radiative stopping power for light particles. The behavior of stopping power with particle energy and depth in a medium is also discussed.