PNNL

Abstract

Characterization of the homogeneity of thin actinide deposits prior to and after irradiation is important to ensure measurement of high quality nuclear data in nuclear physics experiments. Autoradiography is frequently used to assess homogeneity, but geometric blur from source thickness, particle range, and source-detector gap can significantly degrade image resolution and introduce bias when estimating source uniformity and activity. We establish a method for minimizing geometric blur using a new autoradiography imaging technique with microcapillary array collimators and a new method to characterize the homogeneity of an imaged deposit. Also, we demonstrate that beta-/gamma-blind imaging is possible for alpha-particle autoradiography with ZnS:Ag scintillators and the ionizing-radiation quantum imaging detector (iQID). This iQID imaging approach can successfully discriminate alphas in the presence of a beta-gamma source in samples containing >106 dynamic range in activity. We apply this feature to characterize the uniformity of plutonium deposits before and after accelerator irradiation in the presence of a large beta-gamma background.