Coherent scattering of 59.5-keV γ rays by some medium and heavy elements

Whole-atom differential coherent scattering cross sections were measured for 59.5-keV γ rays scattered at 90° by Cu, Mo, Ag, Cd, Sn, Pr, Sm, Gd, Dy, Ho, Yb, Ta, W, Pb, Th, and U employing a reflection-geometry setup and an effective graded shielding arrangement. A 2-${\mathrm{cm}}^3$ hyperpure Ge detector was used for detecting coherently scattered γ rays. The measured cross sections are compared with the theoretical values based on the numerical partial-wave calculations for the available cases. Form factors corresponding to 3.395-Å ${}_{}{}^{\mathrm{-}1}{}_{}{}^{}$ photon-momentum transfer were extracted from the measured cross sections. The results were compared with the different formalisms of form-factor theory and their relative appropriateness is discussed.