Radiative electron capture into continuum in relativistic collisions of bare C ions with solid matter

Continuum X-rays emitted from Be- and C-targets bombarded with 75-290 MeV/u C6+ ions were observed with an HPGe detector placed at 90 deg. to the beam direction. In all spectra two components could be clearly distinguished: radiative electron capture into continuum (RECC) forming a characteristic edge, and secondary electron bremsstrahlung (SEB) which dominates at high photon energies. The shape of the spectra was compared to a theoretical description. A special emphasis was given to the details of the RECC edge. It has been found that at the highest projectile energy of 290 MeV/u, in opposite to the lower beam energies, the detailed structure of this edge cannot be reproduced satisfactory within the approach applied. (orig.)