Influence of anisotropy of Compton scattering on low energy x-ray reflection

Abstract

The reflection of x-rays from a semi-infinite water target, for energies ranging from 10 to 60 keV, often used in x-ray diagnostics, is investigated by Monte Carlo simulation. The same process was also treated analytically as the classical albedo problem for isotropic scattering without energy loss. Good agreement of results for the angular distribution of reflected photons of the two approaches is obtained for higher photon energies from the energy range considered. Multiple collision scattering dominates at higher energies, leading to isotropization of the photon distribution. Discrepancies between the isotropic scattering model and Monte Carlo results appear at the lower part of the energy range. Monte Carlo results show that at these energies photon reflection is governed mainly by single collisions and that these discrepancies are caused by anisotropy of the distribution of single backscattered photons. It is shown that the inclusion of the anisotropy of single Compton backscattering in the analytical model greatly improves the agreement with Monte Carlo results.