Application of the coincidence summing-in peaks in spectrum analysis of CTBT Proficiency test exercises sample

Abstract In the proficiency test exercise (PTE) organized by the Provisional Technical Secretariat (PTS) of the Comprehensive Nuclear-Test-Ban Treaty (CTBT), the spectrum of the reference sample is acquired by the HPGe gamma spectrometer. In the spectrum many summing-in peaks are generated due to the close measurement geometry. To avoid missing any possible radionuclides in the sample, the origin radionuclides must be identified to every peak in the spectrum. Unlike the characteristic gamma-rays, the characteristic parameters of the summing-in peaks such as the energies and the probabilities do not exist in the radionuclide library of the common spectrum analysis software. Hence the origin radionuclides of the summing-in peaks cannot be identified rapidly and accurately. In order to improve the efficiency of the origin radionuclide identification to the summing-in peaks, the formation mechanism of different summing-in peaks is discussed, and the characteristic parameters of 263 summing-in peaks derived from 84 CTBT-relevant radionuclides have been determined and added to the radionuclide library of a spectrum analysis software (AATAMI). With the help of the friendly GUI for interactive analysis of AATAMI and the upgraded radionuclide library, the origin radionuclides of summing-peaks are identified conveniently. The improved ability to identify the origin radionuclides of three type summing-in peaks has been demonstrated through the example of radionuclide 140La.