Monte Carlo simulation of reflection effects of multi-element materials on gamma rays

To study the effects of the gamma reflection of multi-element materials, gamma ray transport models of single-element materials, such as iron and lead, and multi-element materials, such as polyethylene and ordinary concrete, were established in this study. Relationships among the albedo factors of the gamma photons and energies and average energy of the reflected gamma rays by material type, material thickness, incident gamma energy, and incidence angle of gamma rays were obtained by Monte Carlo simulation. The results show that the albedo factors of single-element and multi-element materials increase rapidly with an increase in the material thickness. When the thickness of the material increases to a certain value, the albedo factors do not increase further but rather tend to the saturation value. The saturation values for the albedo factors of the gamma photons, and energies and the reflection thickness are related not only to the type of material but also to the incident gamma energy and incidence angle of the gamma rays. At a given incident gamma energy, which is between 0.2 and 2.5 MeV, the smaller the effective atomic number of the multi-element material is, the higher the saturation values of the albedo factors are. The larger the incidence angle of the gamma ray is, the greater the saturation value of the gamma albedo factor, saturation reflection thickness, and average saturation energy of the reflected gamma photons are.