How Does the Soil Chemical Composition Affect the Mass Attenuation Coefficient? A Study Using Computer Simulation to Understand the Radiation-Soil Interaction Processes

Abstract

In the last few decades, a lot of research has focused on the radiation interaction with complex materials such as soil. The mass attenuation coefficient ($\mu$) is important to analyze the different physical properties of porous media. For this reason, it is important to understand how $\mu$ varies as a function of the chemical composition of porous materials. This study analyzes the influence of the chemical composition on $\mu$, from $1$ to $1500 \mathrm{keV}$, using the XCOM computer simulation code. Five types of soil, containing variable proportions of ${\mathrm{SiO}}_{2}$, ${\mathrm{Al}}_{2}{\mathrm{O}}_{3}$, ${\mathrm{Fe}}_{2}{\mathrm{O}}_{3}$, and ${\mathrm{TiO}}_{2}$, were evaluated. The results showed that the influence of each of the partial effects (photoelectric, coherent, and incoherent scattering), in $\mu$ values, occurred from their dependence on the atomic number ($Z$), with greater $Z$ influence in low energies. A detailed analysis of the influence of the chemical composition considering the oxides individually is also presented. In addition, this paper brings a comprehensive description of the methodology employed for the measurements of the radiation interaction main effects and it can also be used to teach physics applied courses in areas such as modern physics, dosimetry, and radiation protection, among others.