Determination of the full-energy peak efficiency of a detection system is significant in the activity calculation of the measured radioactive samples. In this work, we present an experimental method to determine the absolute efficiency calibration of a NaI(Tl) detector, considering that a standard source of interest is unavailable and by using the known specific activity of a standard sample measured using a HPGe detector. The efficiency of a gamma-ray spectrometer that consists of a coaxial HPGe detector is calculated using Canberra ISOCS/LabSOCS software and a fabricated calibration source. To validate our method, environmental samples (rock and soil samples) were analyzed on both the detectors. The obtained activity concentrations were checked by means of the IAEA proficiency test procedure. The performance criteria evaluation results were found to be ‘Acceptable’ for all the analytical determinations of all the radionuclides under study, except for the samples with low activity (<15 Bq kg⁻¹ and <10 Bq kg⁻¹ for ²²⁶Ra and ²³²Th, respectively). The precision of the low-activity samples was not considered ‘Acceptable’ as the results were slightly inaccurate; in this case, the results were considered as ‘Warning’ because the relative bias (RB) was less than the maximum acceptable bias (MAB).

The study investigated new nanocomposites’ γ-ray and neutron shielding properties based on raw attapulgite, a clay matrix intercalated with different weight percentages of mixed nano metal oxides CdO and PbO. The various percentages were as follows: (100–2x)% Attapulgite + x%CdO + x%PbO, abbreviated as (AT_100–2x Cd_xPb _x ), where x = 5, 10, 15%. The nanocomposites were characterized using XRD, FTIR, and EDX, confirming their successful preparation. SEM images revealed that the mixed oxide nanoparticles were successfully intercalated into the layers of attapulgite clay, with an average particle size of approximately 31.46 nm. The bulk densities of the prepared nanocomposites were measured to be in the range of 2.034 to 2.555 g/cm³. GEANT4 simulations were employed to evaluate the nanocomposites’ γ-ray and neutron shielding performance in the photon energy range of 0.015 to 15 MeV. Phys-X code was used for verification. The simulation results showed a maximum difference of approximately 9.5% between GEANT4 and Phys-X predictions. To assess the γ-ray shielding performance, various shielding parameters were calculated at selected photon energies. The μ _m values ranged from 4.589 to 0.020 cm².g⁻¹, 6.311 to 0.021 cm².g⁻¹, 8.350 to 0.022 cm².g⁻¹ and 10.804 to 0.023 cm².g⁻¹ for raw attapulgite, AT₉₀Pb₅Cd₅, AT₈₀Pb₁₀Cd₁₀, AT₇₀Pb₁₅Cd₁₅ across the photon energy range. The AT₇₀Pb₁₅Cd₁₅ nanocomposite exhibited the highest μ _m , Z _eff , Z _eq , and the lowest T _1/2, T _1/10, and MFP values. Notably, it also demonstrated the highest FNRCS (approximately 0.1 cm⁻¹). These findings suggest that clay-based nanocomposites represent a new class of low-cost, locally available advanced materials with potential applications in γ-ray and neutron shielding characteristics.