EVALUATION OF GAMMA AND FAST NEUTRON SHIELDING PROPERTIES OF YEMENI BUILDING MATERIALS

This study evaluated the gamma radiation shielding properties of eight Yemeni rock samples (A0, A1, A2, B0, B1, R0, R1, and R2) across photon energies from 0.015 to 15 MeV. Key nuclear shielding parameters—including mass attenuation coefficient (MAC), half-value layer (HVL), mean free path (MFP), and effective atomic number (Zeff)—were calculated. Among the samples, A0 and R1 exhibited the best shielding performance, with MAC values reaching 21.0 and 21.4 cm²/g at 0.015 MeV, surpassing conventional materials such as ordinary concrete and commercial glasses Rs-360 and Rs-253 G18. Corresponding HVL values were as low as 0.045 cm for A0 and 0.042 cm for R1, indicating effective attenuation with minimal thickness. Low MFP values further confirm the high gamma photon interaction efficiency of these samples. Their Zeff values peaked near 20 at low energies, reflecting significant elemental contributions to photon absorption. Collectively, these results demonstrate that rock samples A0 and R1 offer superior gamma radiation shielding, requiring thinner layers to achieve comparable protection relative to traditional materials. Additionally, Macroscopic removal cross-section (ΣR) values ranged from 0.034 to 0.075 cm⁻¹, with sample A1 showing superior fast neutron shielding efficiency. Interestingly, ΣR decreased as sample density increased. This highlights their potential as cost-effective, naturally sourced shielding materials suitable for nuclear safety and construction applications.