Radiation shielding and mechanical performance of lead-free novel glasses: Insights from Geant4 Monte Carlo simulations

The ionizing radiation shielding performance of a novel glass system, prepared using the traditional melt-quenching technique, was experimentally investigated at different photon energies using three gamma-emitting radioisotopes: ²²Na, ⁶⁰Co, and ¹³⁷Cs. These sources provided discrete photon energies of 511 keV, 662 keV, 1173 keV, 1275 keV, and 1332 keV. The results are then benchmarked with the data simulated using the Geant4 Monte Carlo toolkit and with results obtained from Phy-X software. The mass density increased from 6.567 g/cm³ to 7.213 g/cm³ as the Bi₂O₃ and ZnO content increased. The linear attenuation coefficient ($\mu$) hits 643.1 cm⁻¹ for the BZ4 sample at 0.015 MeV, outperforming conventional shielding materials such as steel-magnetite. The Kolmogorov-Smirnov test confirmed excellent agreement between Geant4 and Phy-X (D_max = 0.14 %, p = 1.00). Different ionizing radiation shielding properties were also derived and calculated from $\mu \text{,}$ such as half-value layer, mean-free path, and effective atomic number. Mechanical properties showed reductions in Young's modulus from 72.487 GPa to 63.689 GPa and the shear modulus from 30.068 GPa to 26.597 GPa, indicating reduced glass stability. At the same time, Poisson's ratio remained below 0.3, confirming high cross-linking density. These results demonstrate the suitability of Bi₂O₃-rich borate glasses for advanced radiation-shielding applications with optimized mechanical properties.