Determination of Photon Energy Absorption in Epoxy-Based Metallic Composite Samples

This study investigates the absorption of photon energy and the radiation-shielding efficacy of epoxy-based metallic composites that are reinforced with different weight fractions of bismuth oxide (Bi₂O₃) and barium sulfate (BaSO₄). Increasing the loading of Bi₂O₃ from 14.29% to 85.71% resulted in a corresponding increase in composite density, from 2.65 g/cm³ to 5.86 g/cm³. This enhancement in density, along with the higher atomic number of Bi₂O₃ relative to BaSO₄, contributed to improved ionizing-radiation absorption. Key attenuation parameters, such as mass attenuation coefficient (μm), effective atomic number (Zeff), effective electron density (Neff), and half-value layer (HVL), were assessed over photon energies ranging from 81 to 1332.5 keV. Experimental values closely aligned with theoretical XCOM data, validating significant photoelectric absorption at low energies, where the mass attenuation coefficient increased by up to 98% in high-Z-loaded samples. Composites containing increased Bi₂O₃ fractions exhibited enhanced photon attenuation, decreased half-value layer (HVL), and higher effective atomic number (Zeff) compared to BaSO₄-rich samples, indicating the shielding benefits of high-Z fillers. BaSO₄ enhanced structural uniformity and mechanical integrity, particularly complementing Bi₂O₃ in low-energy regimes. Neff diminished as photon energy increased, indicating a lower probability of photon–electron interactions at higher energies.