Inherent role of density on the gamma ray attenuation characteristics of red mud based shield

High-energy radiation shielding materials are vital for protecting against radiation hazards. Both the atomic number and density of the shield plays a prominent role in attenuating high-energy photons. This study reports the inherent role of density on the gamma ray attenuation characteristics of the shields. The radiation shields with various densities between 2.12 to 5.23 g/cm³ were fabricated by varying their porosity through hot compaction rather than altering their compositions or materials as reported in literatures. Red mud (100 %) (Alumina industry waste) (RM) and red mud:Bi₂O₃ (50:50 wt%) mixtures (RMBi) were used to fabricate the shields. For example, the RMBi samples with density varying between 2.63 to 5.23 g/cm³ were prepared by applying 0–39.02 MPa pressure at 1000 °C. Eventually, the porosity of RMBi sample has decreased from 50 % to 2 % while increasing the pressure. The compressive strength of RMBi samples are 6.8, 101.8, 243.2 and 283.3 MPa. The gamma ray attenuation characteristics of the shields were studied using ²²Na source (0.511 and 1.274 MeV) in a narrow beam geometry. The linear attenuation coefficient (μ) of RMBi sample was found to increase from 0.0176 to 0.0272 mm^-1 while increasing the density from 2.63 to 5.23 g/cm³. The attenuation characteristics such as μ, half value layer and mean free path are well in agreement with the theoretical values obtained through Phy-X/PSD software except the effective atomic number (Z_eff). The Compton backscattering experiment was performed using ¹³⁷Cs point source (0.662 MeV) to determine Z_eff. The Z_eff of RMBi sample was noticed to increase from 20.99 to 40.92 while increasing the density of the shield whereas the Z_eff stays constant (19.90) when calculated using Phy-X/PSD software.