Correction for multiple scattering of unpolareed photons in attenuation coefficient measurements

Abstract

Calculations of the diffusion of unpolarized photons in thin thickness targets have been performed with recourse to a vector transport model taking rigorously into account the polarization introduced by the scattering interactions. An order-ofinteractions solution of the Boltmann transport equation for photons was used to describe the multiple scattering terms due to the prevailing effects in the X-ray regime. An analytical expression for the correction factor to the attenuation coefficient is given in terms of the solid angle subtended by the detector and the energy interval characterizing the detection response. Although the main corrections are due to the influence of the pure Rayleigh effect, first-and second-order chains involving the Rayleigh and Compton effects have been considered as possible sources of overlapping contributions to the transmitted intensity. The extent of the corrections is estimated and some examples are given for pure elements targets.