Polarization bremsstrahlung of a fast charged particle on a Thomas-Fermi atom

Abstract

An universal description of the polarization bremsstrahlung of a fast charged particle on a multi-electron atom (Z ≫ 1, Z is the nuclear charge) is obtained using the local electron density method and the Thomas-Fermi statistical model. It is shown that the cross section of the process can be represented in the form \(d\sigma ^{PB} (\omega ) = Z^2 d\tilde \sigma ^{PB} (\nu )\), where the function \(d\tilde \sigma ^{PB} (\nu )\) exhibits approximate scaling with respect to the parameter ω/Z = v, and the corresponding R factor (ratio of the cross sections in the polarization and ordinary channels) is greater than 1 in a wide range of frequencies and reaches its maximum value at frequencies ω ≈ ZRy. It is demonstrated that in the frequency range pac < ħω < γ2pac (γ is the relativistic factor, pa is the characteristic momentum of the atomic electrons, and c is the speed of light) the angular distribution of the polarization bremsstrahlung of a relativistic charged particle undergoes narrowing due to the compensation, by the momentum of the emitted photon, of the momentum transfer from the incident particle to the atomic core.