David R. Barstow
Gamma ray activation spectra are used by nuclear physicists to identify the elemental composition of unknown substances. Neutron bombardment causes some of the atoms of a sample to change into unstable isotopes, which then decay, emitting gamma radiation at characteristic energies and intensities. By identifying these isotopes, the composition of the original substance can be determined. GAMMA is an expert system for performing this interpretation task. It has a detailed model of its domain and can exploit this model for a variety of purposes, including ratings for individual isotopes and elements, ratings based on multiple spectra, complete interpretations, and even calibration. GAMMA’s performance is generally quite good when compared with human performance.