Expert system for nuclide identification in gamma spectrum analysis

Abstract

Gamma spectrum analysis is a standard tool in many fields today. Often the task is to find out the exact composition and concentrations of radionuclides in a measured spectrum. A full manual identification of a complex spectrum requires considerable expertise on the part of the laboratory personnel and takes usually several hours.

An expert system coupled with the gamma spectrum analysis system SAMPO has been developed for automating the qualitative identification of radionuclides as well as for determinating the quantitative parameters of the spectrum components. The program is written in C-language and runs in various environments ranging from PCs to UNIX workstations. The expert system utilizes a complete gamma library with over 2600 nuclides and 80 000 lines, and a rule base of about fifty criteria including energies, relative peak intensities, genesis modes, half-lives, parent-daughter relationships etc. The rule base is furthermore extensible by the user.

The performance of the expert system has been evaluated using test cases from environmental samples, sets of standard sources and activation analysis measurements, which have been carefully analyzed manually. Also. synthesized spectra have been used, where the exact composition of the sample is known in advance. Results from these tests show that the expert system performs very well, even for difficult spectra.