RADIATIVE ELECTRON-CAPTURE BY RELATIVISTIC HEAVY-IONS

We present a direct method for calculation of radiative electron captu re (REC) X-ray emission in relativistic ion-atom collisions. Results o btained within the distorted-wave impulse approximation (DWIA) are com pared with recent experimental data for the collisions of heavy ions w ith light atoms. Simple closed analytic formulae are derived for small alpha Z describing the polarization and the angular distribution of r adiation. Good agreement with recent experiments is found for photoemi ssion rates and angular distributions. Our results for helium and bery llium targets indicate that the photon spectrum is rather insensitive to target structure, but strongly dependent on multiple-scattering cor rections, and this contradicts other recent theoretical predictions. I n asymmetric collisions our results are in broad agreement with experi ment and relativistic impulse approximation (RIA) calculations. Throug h detailed analysis of magnetic transitions in terms of the electron a nd photon polarization correlation parameters, important new features are introduced and discussed.