Imaging Neutron Activation Analysis

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This Small Business Innovation Research (SBIR) Phase I project is in the general area of analytical and surface chemistry and in the subfield of trace surface analysis. The thrust of this activity is the construction and testing of an imaging neutron activation analysis detector capable of discerning element concentrations on a point by point basis. Neutron activation analysis is an extremely powerful method for measuring major, minor, and trace element concentrations in a wide variety of samples. In this method, analyte elements absorb a neutron to form a radionuclide which usually decays by emitting a B particle and a gamma ray. The gamma ray energies are characteristic of the analyte element and they are normally measured with a germanium detector. Secondary electrons produced at a sample surface as a B-particle passes out of a thin sample can be accelerated and imaged. When gamma rays and B-particles are detected in coincidence, the gamma ray energy answers the question "what" and the secondary electron position answers the question "where" for an individual radionuclide disintegration. This information will be organized into element maps and local area gamma ray spectra. Successful pursuit of this research should facilitate the application of imaging neutron activation analysis to the characterization of heterogeneous solids. Following a coupled successful Phase II effort, widespread applications in fields such as geology, biology, materials science, and particle analysis can be anticipated.