Atomic-field bremsstrahlung has been studied with a longitudinally polarized electron beam. The correlation between the initial orientation of the electron spin and the angle of photon polarization has been measured at the photon high energy tip region. In the time reversal this corresponds to a so-far unobserved phenomenon of production of longitudinally polarized electrons by photoionization of unpolarized atoms with linearly polarized photons. The results confirm the fully relativistic calculations for radiative recombination and suggest a new method for electron beam polarimetry.

We report on a study of the polarization transfer between transversely polarized incident electrons and the emitted x rays for electron-atom bremsstrahlung. By means of Compton polarimetry we performed for the first time an energy-differential measurement of the complete properties of bremsstrahlung emission related to linear polarization, i.e., the degree of linear polarization as well as the orientation of the polarization axis. For the high-energy end of the bremsstrahlung continuum the experimental results for both observables show a high sensitivity on the initial electron spin polarization and prove that the polarization orientation is virtually independent of the photon energy.

The Sherman function, which is a measure of the spin asymmetry in the elastic scattering of transversely polarized electrons from heavy targets, is calculated within the relativistic partial-wave representation. For collision energies above 40 MeV, oscillations of the Sherman function develop at the backward scattering angles which mirror the influence of the nuclear potential and which scale inversely with the nuclear size. We give predictions for 20-200 MeV electrons colliding with 64 Zn, 208 Pb and 238 U. We propose the measurement of the diffraction structures in the angular distribution of the Sherman function for a 208 Pb target at a beam energy near 80 MeV. The feasibility of such an experiment is addressed.

SynopsisThe correlation between electron spin and photon linear polarization in atomic-field bremsstrahlung was measured with a polarized electron beam. The angle of photon polarization and the photon emission intensity were found to be correlated with the spin orientation. These effects are interpreted in terms of spin-orbit interaction. They lead to a new technique of electron beam polarimetry.

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