On the theory of bremsstrahlung of fast electrons

The cross section for the bremsstrahlung of fast electrons has been calculated for a general-type field on the basis of application of the quasiclassical wave functions for the electron in an external field and expansion in descending powers of the momentum. The computational error can be traced in each stage. The expressions for the quasiclassical wave functions obtained previously are presented. A general expression for the differential bremsstrahlung cross section has been derived in the variables of the momentum transferred. The bremsstrahlung cross section has been calculated for both large and small momenta transferred. It has been shown that for the large momentum transfer the bremsstrahlung cross section is approximately factorized, i.e., can be represented as the product of the elastic scattering cross section by the emission probability, the accuracy of the factorization being dependent upon the frequency. The method is illustrated by considering the bremsstrahlung in the Coulomb field. Corrections (approximately p-1) for the well-known Bethe-Maximont formula have been found. It has been shown that, when one considers the bremsstrahlung of a fast particle passina through an atomic row, the correction increases proportionally to the squared number of atoms in the row. The applicability of the method developed is restricted merely to the channeling effects