Rayleigh scattering of 145- and 279-keV gamma rays in Al, Cu, Sn, and Pb at forward angles.

Abstract

The integral Rayleigh scattering (RS) cross sections of \ensuremath{\gamma} rays for Al, Cu, and Sn at 145 keV energy and for Al, Cu, Sn, and Pb at 279 keV energy have been determined at angles below 7\ifmmode^\circ\else\textdegree\fi{} by a new method, and are compared with the theoretical integral RS cross sections computed using the non- relativistic form factors (NRFF) of Hubbell et al., the relativistic form factors (RFF) of Hubbell and Overbo, and the modified form factors (MFF) of Schaupp et al. The present experimental results are in fairly good agreement with each of these NRFF, RFF, and MFF theoretical values below 6\ifmmode^\circ\else\textdegree\fi{} within the uncertainties quoted. However, the experimental integral RS cross sections for medium- and high-Z elements appear to be consistently closer to the MFF theoretical values as the scattering angle increases.