Experimental determination of gamma-ray attenuation coefficients of lunar regolith simulants for habitat shielding applications

Establishing a permanent human base on the Moon requires effective reduction of ionizing radiation, which reaches levels on the lunar surface that far exceed exposure on Earth (due to the lack of a global magnetic field and atmosphere). One of the most promising shielding strategies is to use local resources, in particular lunar regolith, as a building material for surface habitats. In this study, the shielding properties of four high fidelity lunar soil simulants (LMS-1, LHS-1, LSP-2 and AGK-2010) were experimentally determined and compared with CEN sand as a reference material. Samples with thicknesses of 40, 60, 80, 100 and 200 mm were used in the attenuation measurements. Linear attenuation coefficients ( μ ), mass attenuation coefficients ( μ m ), half-value layer (HVL) and tenth-value layer (TVL) were determined in this way. In addition, scattering was taken into account and described using the determined relative values of the accretion factor B r . All tested simulants showed very similar attenuation effectiveness, with average values of μ ≈ 0.094 cm⁻¹ and μ m ≈ 0.054 cm²/g. The corresponding HVL and TVL values were approximately equal to 7–8 cm and 24–26 cm, respectively. The relative accretion factor reached maximum values ranging from 1.57 to 1.97. A comparative analysis showed that the shielding effectiveness of the tested materials is comparable to that of lightweight concrete with an apparent density of approximately 1.5 g/cm³ . Despite minor differences between the individual simulants, their attenuation characteristics were statistically consistent, indicating similar suitability for radiation protection applications.