POLARIZATION EFFECTS ON MULTIPLE-SCATTERING GAMMA TRANSPORT

The scattering of X-rays and gamma-rays are events that have strong de pendencies on the polarization of the incident and scattered photons. Because of this, scattering problems that can be solved without explic it reference to the state of polarization of the incident and scattere d radiation are exceptional. This article reviews available informatio n on polarization effects arising when photons in the X-ray and gamma- ray regime undergo photoelectric effect, coherent (Rayleigh) scatterin g and incoherent (Compton) scattering by atomic electrons. In addition to descriptions and discussion of these effects, we study the backsca ttering of gamma-rays from an infinite thickness target excited with a plane slant monodirectional and monochromatic source, using the Boltz mann transport theory and the mathematical representation of polarizat ion introduced by Stokes. Results from this model, for both unpolarize d and polarized gamma-ray sources, are compared with computations perf ormed neglecting or averaging polarization effects, showing the limita tions of such approximations.