RAYLEIGH AND COMPTON-SCATTERING CROSS-SECTIONS FOR LOW, MEDIUM AND HIGH Z-ELEMENTS IN THE ENERGY REGION -THAN-OR-EQUAL-TO-E-LESS-THAN-OR-EQUAL-TO-30.85KEV

Using nearly monoenergetic unpolarised K alpha X-ray photons coherent (Rayleigh) and incoherent (atomic Compton) scattering cross sections i n the atomic region 13 less than or equal to Z less than or equal to 8 2 have been measured at 23.18, 24.14 25.19, 26.27 and 30.85 keV. Exper imental scattering cross sections in the momentum transfer region 1.32 2h Angstrom(-1) less than or equal to q less than or equal to 1.759h A ngstrom(-1) [q=sin (theta/2)/lambda(Angstrom)] were obtained at an ang le of 90 degrees. Experimental coherent scattering cross sections are in good agreement with second order S-matrix calculations, compared to theoretical estimates based on form factor approximations. Experiment al incoherent scattering cross sections are higher than the theoretica l estimates calculated using non-relativistic incoherent scattering fu nctions for low and medium Z elements and lower for heavy elements. Th e latter is due to the binding effects at low photon energies.