A novel methodology for self-attenuation effect corrections using LabSOCS

The proper measurement of natural radionuclides by gamma-ray spectrometry is very important because of their multiple applications in environmental radioactivity. The self-attenuation effect correction factor, f a , is essential to calculate the full-energy peak efficiency for a wide range of sample mass attenuation coefficients, η , and apparent densities, ρ . Using experimental procedures, the accurate f a obtention is complicated for significant differences between the calibration and problem samples regarding their η and ρ , especially true at 46 keV ( 210 Pb) and 63 keV ( 234 Th). The software LabSOCS is widely used but it has important limitations regarding the chemical composition that is possible to be specified for each sample. This is the first study aims to develop a robust methodology for the f a obtention achieving a general and analytical f a function at 46 keV and 63 keV, f a 46 , 63 ( ρ , η 46 , 63 ) , using LabSOCS for a wide η and ρ range. For this, justified intervals for η (0.23–8.00 cm 2 g −1 and 0.19–3.55 cm 2 g −1 at 46 keV and 63 keV, respectively) and ρ (0.5–5 g cm −3 ) were selected for the problem samples, using water as the calibration sample and a cylindrical geometry with 25 mm of sample thickness. For the previous η and ρ ranges, the f a obtained by LabSOCS was fitted versus ρ fixing η , where its behaviour was found to be of exponential type. Then, the resulting parameters were fitted in turn varying η , where exponential and polynomial fits were used, achieving f a 46 , 63 ( ρ , η 46 , 63 ) . The residuals obtained from fitting the parameters involved in f a 46 , 63 ( ρ , η 46 , 63 ) were generally very good, less than 10 %. In addition, f a 46 , 63 ( ρ , η 46 , 63 ) was validated for a wide η and ρ range obtaining satisfactory z score values for all cases. • A novel and robust methodology for self-attenuation effect corrections was developed using LabSOCS. • A general and analytical function of f a was obtained for the most complicated cases like 46 keV ( 210 Pb) and 63 keV ( 234 Th). • A multiple fit procedure of the f a obtained using LabSOCS was developed for a very wide range of the η and ρ. • Very good residual values were generally obtained from the multiple fit procedure. • The general f a function was validated for a very wide range of η and ρ using certified and non-certified reference materials.