SOLID-STATE EFFECTS ON RAYLEIGH-SCATTERING EXPERIMENTS - LIMITS FOR THE FREE-ATOM APPROXIMATION

Elastic scattering of photons from solid samples of Pb, Pt, and W was measured in order to investigate the limits within which scattering ex periments can be described as being due to free atoms. The experiments were performed with photons of 22.1 keV from an x-ray tube and from a n Am-241 (59.54 keV) gamma source, providing a momentum transfer rangi ng from x = 0.1 to 2.0 angstrom-1. It is shown that the low-momentum-t ransfer limit for the free-atom approximation will depend on the scatt erer, temperature, geometrical resolution, and on the accuracy of the experiment.