COULOMB CORRECTIONS TO BREMSSTRAHLUNG IN ELECTRIC FIELD OF HEAVY ATOM AT HIGH ENERGIES
Lee R.N., Milstein A.I., Strakhovenko V.M., Schwarz O.Ya.

Received: April 29, 2004

PACS: 12.20.Ds, 95.30.Cq

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We consider the differential and partially integrated cross sections for bremsstrahlung from high-energy electrons in the atomic field, with this field taken into account exactly. We use the semiclassical electron Green's function and wave functions in an external electric field. It is shown that the Coulomb corrections to the differential cross section are very susceptible to screening. Nevertheless, the Coulomb corrections to the cross section summed over the final-electron states are independent of screening in the leading approximation in the small parameter 1/mr_scr (r_scr is the screening radius and m is the electron mass, ). We also consider bremsstrahlung from a finite-size electron beam on a heavy nucleus. The Coulomb corrections to the differential probability are also very susceptible to the beam shape, while the corrections to the probability integrated over momentum transfer are independent of it, apart from the trivial factor, which is the electron-beam density at zero impact parameter. For the Coulomb corrections to the bremsstrahlung spectrum, the next-to-leading terms with respect to the parameters ( is the electron energy) and 1/mr_scr are obtained.