Large-angle elastic scattering of 88.03-keV photons by elements with 30⩽ Z⩽92

Abstract

Elastic-scattering differential cross-sections for 88.03-keV photons have been measured at an angle of 125° for 17 elements in the atomic region 30⩽ Z⩽92. The measured elastic-scattering cross-sections have been compared with those obtained in the independent-particle approximation through calculations of the modified-relativistic form factors (MFs), a combination of the MFs and angle-independent `anomalous' scattering factors (ASFs), and the relativistic second-order S-matrix. The S-matrix cross-sections, in general, represent the trend of the measured data over the whole atomic region under investigation. However, these values are, on an average, lower by 10% than the measured ones. The MF cross-sections, in general, exhibit considerable deviations (∼30%) from the measured values. In the case of Bi with K-shell binding energy, E K(Bi)=90.526 keV, just above the incident photon energy ( E inc) of 88.03 keV, the MF cross-section is found to be enormously (∼5 times) higher than the measured value. The MF cross-sections in combination with ASFs are in good agreement with the measured values for all the elements except for Pb ( E K(Pb)=88.004 keV) and Bi, where these values are enormously (∼28 times) smaller and higher by 31%, respectively.