EVALUATING MULTI-LAYERED SHIELDS FOR LOW ENERGY PHOTONS USING MCNP5 CODE AND XCOM PROGRAM

MCNP5 was used to evaluate the shielding properties of different composite shields made of combinations of four elements; Tungsten (W), Bismuth (Bi), Tin (Sn), and Zinc (Zn), at different weight ratios. Attenuation coefficients calculated by MCNP5 were compared with XCOM theoretical data for 11 different photon energies ranging from (15 -150 keV). Mass attenuation coefficient (μ/ρ), half-value layer (HVL), and mean free path (MFP) were also calculated. MCNP5 calculations were in good agreement with the XCOM data. Attenuation coefficients were sensitive to changes in photon energy. Two of the studied composite shields were found better alternatives to lead shields over the medical diagnostic photon energies up to 150 keV.