EXPERIMENTAL-STUDY ON COHERENT SCATTERING OF 145.4 AND 279.2 KEV GAMMA-RAYS BY MEDIUM AND HEAVY-ELEMENTS

Differential cross sections for coherent scattering of 145.4 and 279.2 keV gamma rays were measured for Cu, Mo, Ag, Cd, Sn, Pr, Sm, Gd, Dy, Ho, Yb, Ta, W, Pb, Th and U employing a reflection geometry set-up wit h a graded shielding arrangement. A 133 cm(3) HPGe detector was used t o detect the scattered gamma rays. The measured cross sections were co mpared with the experimental values in literature and with the numeric ally calculated results using S-matrix theory for available cases. Fro m the measured cross sections the form factors corresponding to 8.295 and 15.923 Angstrom(-1) photon momentum transfer were extracted. The r esults are discussed in the light of the predictions of form factor fo rmalisms.