POLARIZATION EFFECTS ON MULTIPLE-SCATTERING GAMMA TRANSPORT

The scattering of X-rays and gamma-rays are events that have strong dependencies on the polarization of the incident and scattered photons. Because of this, scattering problems that can be solved without explicit reference to the state of polarization of the incident and scattered radiation are exceptional. This article reviews available information on polarization effects arising when photons in the X-ray and gamma-ray regime undergo photoelectric effect, coherent (Rayleigh) scattering and incoherent (Compton) scattering by atomic electrons. In addition to descriptions and discussion of these effects, we study the backscattering of gamma-rays from an infinite thickness target excited with a plane slant monodirectional and monochromatic source, using the Boltzmann transport theory and the mathematical representation of polarization introduced by Stokes. Results from this model, for both unpolarized and polarized gamma-ray sources, are compared with computations performed neglecting or averaging polarization effects, showing the limitations of such approximations.