Influence of the sample density in γ spectrometry

The determination of γ activities of radionuclides in the environment is of great interest and good accuracy is required in the results of these measurements. However, one of the main sources of error in this technology is the difference in the densities of the samples, because the effects of self-absorption, within the samples, become significant. We have produced Monte Carlo simulations for samples with different densities and for photons with energies in the range of interest, obtaining the peak efficiency as a function of density and energy. We fitted it to obtain a two-dimensional mathematical representation of this function, so we can use this fitted function saving the time of Monte Carlo simulation. To verify the validity of our proposal, the natural radioactivity of soil samples were determined using a GeHP solid state detector and very good results were obtained.