# Itarare Group Sandstone as a Sustainable Alternative Material for Photon Radiation Shielding
## 4 Discussion
However, as photon energy increases (from 1 MeV to 10 MeV), both MAC and LAC show a decrease in photon attenuation, which is consistent with findings from several other studies involving rocks [6; 34; 35]. Another observation is the slight differences between MAC and LAC as photon energy increases. This can be explained by the fact that as photon energy rises, the likelihood ofphotons interacting with the samples decreases, making variations in chemical composition less significant. It is well known that when photon energy increases, denser materials are required to attenuate them. When the differences in density and chemical composition of the materials are minor, the variations in attenuation between samples become negligible [1; 3; 6; 7]. The parameters of MFP (Figure 5), HVL (Figure 6), and TVL (Figure 7) exhibited the lowest values for the RMPS and RMPI samples at the lowest photon energies (0.015 MeV and 0.1 MeV). This finding aligns with the higher LAC values observed for these samples at lower energies, as MFP, HVL, and TVL are inversely related to LAC (see Equations (5)-(7)). In other words, a higher LAC in a sample results in a shorter distance that photons can travel, along with the necessary thicknesses to attenuate 50% and 90% of the radiation [36]. As the photon energy increases from 1 to 10 MeV, the differences between these parameters become less pronounced, with the lowest values generally observed for the RMPS samples. [PERSON] and [PERSON] [37] reported similar HVL, LAC, and MAC values for sandstones at photon energies around 0.1 MeV and 1 MeV. Their sandstone samples contained higher amounts of SiO\({}_{2}\) and Fe\({}_{2}\)O\({}_{3}\) compared to our samples. The LAC and TVL values found in our study are comparable to those reported by [PERSON] et al. [38] for concrete samples at energies near 1 MeV, as concrete is commonly used for radiation shielding. Additionally, at approximately the same photon energy of 1 MeV, [PERSON] et al. [39], who studied rocks from the Jabal Elham mountain, found LAC, MFP, HVL, and TVL values similar to those observed in our research. This suggests that the sandstones we investigated exhibit attenuation characteristics comparable to those of other rock types. The greater sensitivity of the shielding parameters (LAC, MAC, MFP, HVL, and TVL) to the chemical composition and density of the samples at lower photon energies (0.015 MeV and 0.1 MeV) is associated with the process responsible for attenuating the photons. At lower energies, the most important process is photoelectric absorption, which is dependent on \(Z^{4-5}\)[40; 41; 42]. For this reason, slight variations in the chemical composition of the samples, particularly in the heavier elements, have a greater impact on the shielding parameters [43]. For energies where incoherent scattering becomes the primary interaction mechanism (E > 0.1 MeV), the rock's chemical composition becomes less significant [44]. This effect has only a linear dependence on \(Z\)[38; 45; 46]. At 10 MeV, the shielding parameters again exhibit greater differences between samples, but these differences are still less pronounced than those observed at the smallest photon energies. This result is mainly associated with the production of pairs that begins to occur for photons greater than 1.02 MeV [44]. This effect is dependent on \(Z^{2}\)[37; 38], which explains why the shielding parameters become more sensitive to the chemical composition of the samples again [47]. Heavier elements have a higher probability of undergoing the pair production effect, which accounts for almost 30% of the contribution of this effect to photon attenuation (Figure 10). Both EBF and EABF (Figures 8 and 9) demonstrate a clear dependence on the energy of the incident photons. In both low- and high-energy regions, the accumulation factors are at their lowest. This trend is linked to the predominant interaction mechanisms, such as photoelectric absorption and pair production [48].