Elastic scattering of photons: perspectives and present status

Abstract

The importance of photon scattering data, including elastic scattering, is well known. The state-of-the-art precise method for estimating elastic scattering cross-sections of x- and γ-rays using the S-matrix is briefly discussed. Since the estimation of cross-sections using the S-matrix is very computer 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 photoeffect energies. For other energies it is suggested that one should use the recently interpolated tables of cross-sections (within an accuracy of better than 1% with S-matrix values) of all elements of the periodic table within the range 13 ≤ Z ≤ 104 and at photon energies at suitable intervals between 50 and 1500 keV for 55 different scattering angles θ between 0 and 180°. Future issues which require further investigation are also indicated.