Gamma-ray attenuation properties and photon fluence buildup factors of transition metal dichalcogenides using XCOM calculations and FLUKA simulations

This work presents a comprehensive characterization of the photon shielding properties of four transition metal dichalcogenides (TMDs): MoS 2 , MoSe 2 , WS 2 , and WSe 2 . Theoretical mass attenuation coefficients were derived from the NIST XCOM database over the 0.001–20 MeV energy range, while photon fluence buildup factors were computed using high-statistics FLUKA Monte Carlo simulations for selected photon energies between 0.05 and 10 MeV and optical thicknesses up to 40 mean free paths (mfp). The simulated buildup data were parameterized using the Geometric-Progression (G–P) fitting formalism. The attenuation results showed that tungsten-based TMDs exhibit the highest shielding efficiency per unit thickness among the investigated compounds; for example, at 0.5 MeV the mean free path decreases from 2.24 cm for MoS 2 to 0.96 cm for WSe 2 , while at 1.0 MeV it decreases from 3.27 cm to 1.74 cm. In the buildup analysis, W-based TMDs consistently exhibited lower buildup factors than Mo-based TMDs for energies above 0.15 MeV, indicating reduced scattered-photon contributions under broad-beam conditions. The extracted G–P parameters reproduced the Monte Carlo data with high fidelity ( R ¯ 2 ≈ 0 . 9945 , NRMSE ¯ ≈ 0 . 0472 ), providing a validated and compact dataset for radiation-informed design in nuclear and space applications. • Comprehensive gamma-ray shielding dataset for MoS 2 , MoSe 2 , WS 2 , and WSe 2 . • Fluence buildup factors computed via FLUKA Monte Carlo up to 40 mean free paths. • Tungsten-based TMDs exhibit superior attenuation and reduced scattering buildup. • G–P fitting parameters provided for rapid engineering and space shielding design.