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

An universal description of the polarization bremsstrahlung of a fast charg ed particle on a multielectron atom (Z much greater than 1, Z is the nuclea r charge) is obtained using the local electron density method and the Thoma s-Fermi statistical model. It is shown that the cross section of the proces s can be represented in the form d sigma(PB)(omega) = Z(2)d<(sigma)over til de>(PB)(nu), where the function d<(sigma)over tilde>(PB)(nu) exhibits appro ximate scaling with respect to the parameter omega/Z = nu, and the correspo nding R factor (ratio of the cross sections in the polarization and ordinar y channels) is greater than 1 in a wide range of frequencies and reaches it s maximum value at frequencies omega approximate to Z Ry. It is demonstrate d that in the frequency range p(a)c < (h) over bar omega < gamma(2)p(a)c (g amma is the relativistic factor, p(a) 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 undergo es narrowing due to the compensation, by the momentum of the emitted photon , of the momentum transfer from the incident particle to the atomic core. ( C) 2000 MAIK "Nauka/Interperiodica".