Elastic scattering of photons: Perspectives and present status

The importance of photon scattering data, including elastic scattering, is web known, The state-of-the-art precise method for estimating elastic scatt ering cross-sections of x- and gamma-rays using the S-matrix is briefly dis cussed. Since the estimation of cross-sections using the S-matrix is very c omputer intensive, other alternatives to obtaining cross-sections with the same precision as that of the S-matrix are discussed. It is concluded that the modified form factor with angle-independent anomalous scattering factor could be used for photon energies below and near the K-threshold photoeffe ct energies, For other energies it is suggested that one should use the rec ently interpolated tables of cross-sections (within an accuracy of better t han 1% with S-matrix values) of all elements of the periodic table within t he range 13 less than or equal to Z less than or equal to 104 and at photon energies at suitable intervals between 50 and 1500 keV for 55 different sc attering angles theta between 0 and 180 degrees, Future issues which requir e further investigation are also indicated. Copyright (C) 1999 John Wiley & Sons, Ltd.