Nuclear Technique Laboratory, University of Science, Ho Chi Minh City, Vietnam , nvthang@hcmus.edu.vn
Abstract: (402 Views)
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 K-separation 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.