## 3 Results
### High-Energy Spectroscopy Experiment Results
As detailed in Tables 2 and 3, variations in the concentrations of major oxides and rare earth elements (REEs) among the five serpentinite compositions significantly influence these neutron-interaction parameters. Notably, the elevated macroscopic cross-sections are primarily attributed to the incorporation of REEs--especially gadolinium (Gd), which possesses an exceptionally high thermal neutron cross-section of 49,700 barns [41]. This is evident in Sr-2, which not only exhibits the highest REE/HREE ratio (Table 2) but also greater Gd content compared to the other samples. Even slight fluctuations in Gd concentration lead to pronounced changes in thermal neutron behavior, as previously demonstrated [42; 43]. Specifically, a reduction in Gd from 0.24 ppm to 0.18 ppm corresponds to a notable decrease in RPE, from 72.87% down to 61.75%. This underscores  
Figure 8: (**a**) MFP and (**b**) HVL values of the serpentinite samples. Figure 9: \(Z_{\text{eff}}\) values of the serpentinite samples. how closely the macroscopic cross-section governs the composite's neutron-shielding performance, with Sr-2 emerging as the most effective barrier against thermal neutrons in this study, in line with observations reported by [PERSON] et al. [44]. When neutrons pass through a material that can scatter or absorb them, they interact in ways that depend on both their energy and the atomic makeup of the medium. These interactions generally fall into a few main categories, like elastic or inelastic scattering, absorption, and, though less common, nuclear fission. The microscopic cross-section gives a measure of how likely it is for a neutron of a certain energy to interact with the nuclei  
Figure 11: Thermal neutron macroscopic cross-section and RPE graph of serpentinite samples. Figure 10: EBF values of the serpentinite samples. through any of these processes, adding up the probabilities for scattering and absorption separately [29; 42; 43; 44; 45]. On a larger scale, the macroscopic fast neutron removal cross-section is used to describe the probability that a high-energy neutron will be effectively taken out of the uncollided flux by some kind of interaction. It is worth noting that this does not represent the chance of any single, specific type of neutron-nucleus event. Because fast neutrons usually lose energy by bumping into atoms multiple times, the removal cross-section tends to be close to, but a bit less than, the total macroscopic cross-section. Although this concept is most commonly applied to materials that contain hydrogen--since hydrogen is particularly good at slowing down fast neutrons--it can also be extended to other materials that include hydrogen in their structure. This approach generally works well for neutrons in the 2-12 MeV energy range [7; 44]. Figures 12 and 13 display the calculated fast neutron macroscopic cross-sections and RPEs, as well as the fast neutron removal cross-sections and corresponding RPEs for serpentinite samples of 16 mm thickness. According to these results, the fast neutron macroscopic cross-section reaches its highest value in the Sr-2 sample (0.3820 cm\({}^{-1}\)), followed by Sr-5, Sr-3, Sr-4, and finally Sr-1, which shows the lowest value at 0.3405 cm\({}^{-1}\). This ordering correlates well with the samples' loss on ignition (LOI) percentages listed in Table 2, where Sr-2 exhibits the highest LOI% and Sr-1 the lowest. The LOI parameter serves as an indirect indicator of volatile and light element content--often associated  
Figure 12: Fast neutron macroscopic cross-section and RPE graph of serpentinite samples. Figure 13: Fast neutron removal cross-section and RPE graph of serpentinite samples. with bound water or hydroxyl groups--which contributes significantly to neutron moderation due to elastic scattering by hydrogen and other light nuclei [37]. This moderation effect enhances the probability of neutron interactions, thereby increasing the macroscopic cross-section.