Study of polycarbonate-bismuth nitrate composite for shielding against gamma radiation

Polycarbonate (PC) loaded with different filler levels equal to 0.1, 0.2, 0.3, 0.5, 0.75, 1.0, 2.5, 3.5 and 5.0 wt% (weight percent) of bismuth nitrate pentahydrate (Bi(NO₃)₃·5H₂O or BNP) were prepared by dispersion of filler in PC solution, followed by casting. The values of mass attenuation coefficient (μ_m), effective atomic number (Z_eff), effective electron density (N_el), half value layer (HVL) thickness, tenth value layer (TVL) thickness and photon mean free path (MFP or λ) were determined for specific gamma photon energies ranging from 303 up to 1332 keV, both computationally and experimentally. Considerable variation in the radiation attenuation parameters was observed, which is mainly dependent on the energy of incident gamma ray photon and the concentration of BNP incorporated as filler within the PC matrix. Values of the experimentally determined parameters like μ_m, Z_eff and N_el were compared with the computationally estimated values, and they are found to be in good agreement. The results are discussed, taking into consideration our understanding of the interaction of gamma radiation with matter. (author)