Elastic scattering of ${}_{}{}^{152}{}_{}{}^{}\mathrm{Eu}$ and ${}_{}{}^{154}{}_{}{}^{}$Eu γ rays by atoms

Differential cross sections are reported for the elastic scattering of 344-, 411-, 444-, 723-, 779-, 868-, 964-, 1005-, 1086-, 1112-, 1275-, and 1408-keV γ rays through scattering angles from 2° to 45° by targets of Cu, Mo, Sn, Ta, Pb, and U. The results have been compared with two sets of theoretical cross sections for Rayleigh plus nuclear-Thomson plus Delbruck scattering. The first set was interpolated from the tables of P. P. Kane et al. [Phys. Rep. 140, 75 (1986)], which are based upon exact S-matrix amplitudes for inner-shell Rayleigh scattering and use of modified form factors and photoelectric cross sections for outer-shell Rayleigh scattering; the second set was based upon modified-form-factor Rayleigh amplitudes for all electron shells. The measured cross sections agree to closer than 10% with the Kane et al. calculations and indicate that for larger scattering angles, higher photon energies, and heavier target elements the modified form factor overestimates Rayleigh scattering. At small scattering angles there is no evidence for any systematic discrepancy between experiment and the cross sections of Kane et al.