ABSTRACT
Bremsstrahlung and the excitation and ionization processes contribute to the energy loss of the projectile. Energy loss by excitation and ionization is referred to as collisional energy loss. The chapter presents order of magnitude estimates for the elastic scattering of an unpolarized electron from a neutral atom at any incident velocity and shows the compiled data. The theory of elastic and inelastic scattering of structureless charged particles from atoms has been presented in a number of studies. Shielding by atomic electrons, however, prevents the Coulomb divergence in the forward direction; for scattering on a neutral atom the total cross section and the differential cross section at all angles are finite. The inelastic scattering cross section is determined by the off-diagonal matrix elements of the interaction Hamiltonian. The term stopping power refers to the effect of the medium in slowing down the projectile.
