Improvement of the accuracy of radioactivity analysis using gamma spectroscopy by reducing the compton continuum of 40K gamma spectrum.

Background: During the analysis of certain natural radionuclides in plant samples using gamma spectroscopy, the presence of ⁴⁰K in the sample causes the overlap of its Compton region with the full energy peaks of ²³⁸U, ²³²Th, and their daughter. Therefore, it is necessary to remove potassium before the measurement to enhance analytical accuracy. Materials and Methods: Five different plant samples were used to validate the method. For each sample, the analysis was performed using two separation methods (original and K-separation), and both were measured with the gamma detector. Comparison of the results achieved using the two methods with regard to spectrum, peak-to-total ratio, obtained activity, and minimum detectable activity (MDA) indicated that the proposed method yielded improved results. Results: The separation procedure removed most of potassium present in the samples. The peak-to-total of energy peaks < 1000 keV increased significantly. The spectrum after Kseparation exhibited a lower continuum under the peaks, and the shapes of the peaks were more identifiable. Comparison of MDA values derived before and after the application of K-separation showed an improvement in analytical accuracy. Conclusion: The removal of potassium from plant samples is effective in decreasing the MDA of the spectroscopy by reducing the Compton continuum of the ⁴⁰K isotope under the energy peaks of interest. Therefore, the application of this method can augment the measurement possibilities for samples with low radioactivity. [ABSTRACT FROM AUTHOR]