Attenuation of a non-parallel beam of gamma radiation by thick shielding-application to the determination of the 235U enrichment with NaI detectors

This paper is dedicated to the calculation by numerical integration of the geometrical correction factor (Kwtc) which describes the effective mean path length of the radiation through the absorbing layer. This factor was calculated as a function of various measurement parameters (types and dimensions of the detector, of the collimator and of the shielding) for the most commonly used collimator shapes and detectors. Both coherent scattering (Rayleigh) and incoherent scattering (Compton) are taken into account for the calculation of the radiation interaction within the detector.