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

Elastic-scattering differential cross-sections for 88.03-keV photons have been measured at an angle of 125 degrees for 17 elements in the atomic region 30 less than or equal to Z less than or equal to 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 (similar to 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 (similar to5 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 (similar to 28 times) smaller and higher by 31%. respectively. (C) 2001 Elsevier Science B.V. All rights reserved.