Abstract
The non-Thomson contribution to the quasi-elastic X-ray cross-section in non-magnetic metallic Beryllium has been investigated by synchrotron radiation. Such a term is brought about by scattered photons with polarization perpendicular to that of the incoming beam. A properly designed polarization analysis device has been employed for the measurement. The present results show that a non-Thomson contribution is actually present in beryllium. The possible link of this term to dynamic magnetic scattering is investigated by means of a simple theoretical model.