# Itarare Group Sandstone as a Sustainable Alternative Material for Photon Radiation Shielding
## 5 Conclusions  
Our results indicate that even minor variations in the composition of sandstone oxides, particularly those with higher atomic numbers, such as Fe\({}_{2}\)O\({}_{3}\), significantly affect the shielding properties of these rocks. Generally, samples containing larger quantities of heavier elements exhibited higher mass and linear attenuation coefficients. The density of the samples also influenced the latter. As a result, these samples required reduced material thicknesses (mean free path, half-value layer, and tenth-value layer) to effectively attenuate photons across various energy levels. At the lowest analyzed photon energy, the main differences between samples were primarily explained by photoelectric absorption, for which the chemical composition of the sandstones had an impact on the shielding parameters. In intermediate energy regions, such as 1 MeV, incoherent scattering explained the differences between samples, with less impact of the chemical composition on the results. For the highest energy (10 MeV), although incoherent scattering remained the dominant process, pair production influenced the shielding parameters, with differences in the chemical composition of the samples affecting these parameters.  
Parameters related to photon scattering, such as EBF and EABF, exhibited effective shielding characteristics, particularly in samples with higher concentrations of heavier elements. Our findings indicate that the studied sandstone samples demonstrate satisfactory shielding capabilities, especially when compared to materials like cement. The results were simulated based on the chemical composition and density of bulk samples, while also considering their porosity. If we had chosen to analyze solely the powder form--suitable for producing compacted bricks--the performance of the evaluated sandstones could have potentially improved. Although various samples from different rock layers showed some variability in shielding effectiveness, all layers yielded close results in terms of shielding. Therefore, this study suggests that sandstone samples can be employed in their natural state or that material can be extracted from the rocks to produce blocks or be blended with other substances, such as concrete, to create more efficient photon attenuation materials.  
It is essential to note that this study was conducted theoretically based on the chemical composition and density of the sandstone samples and without the use of experimental measurements. Factors like sample volume and mechanical properties--important for practical applications--were also not taken into account. Therefore, future research should include experimental studies and mechanical characterization to fully assess the suitability of the sandstone studied for radiation shielding in close-field conditions. We also need to mention that our results were obtained for a sandstone type common in Brazil; however, for other types of sandstones from other regions with different chemical compositions and structures, new simulations or measurements are necessary.  
Conceptualization, L.F.P. and I.S.M.; methodology, G.W.P. and I.S.M.; formal analysis, G.W.P.; investigation, G.W.P.; resources, L.F.P. and I.S.M.; writing--original draft, G.W.P. and L.F.P., writing--review and editing, G.W.P. and L.F.P., project administration, I.S.M. and L.F.P.; funding acquisition, L.F.P. All authors have read and agreed to the published version of the manuscript.  
This research was partially funded by \"Conselho Nacional de Desenvolvimento Cientifico e Tecnologico\" (CNPQ) (Grant 303950/2023-4) and \"Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior\" (Capes) (Grant Code 001).  
Not applicable.  
The raw data supporting the conclusions of this article will be made available by the authors on request.  
**Acknowledgments: We thank FASCA (Laboratory of Physics Applied to Soils and Environmental Sciences) for the infrastructure for the XRF analyses.**