The concept of nuclear forensic signatures for interdicted special nuclear materials is generally understood to include isotopic ratios, trace element impurity ratios, and morphological aspects of any solids present. In contrast, radiological forensic signatures for sealed radiological sources focus more on the physical design and chemical composition of the source capsule and containers, physical markings indicative of an owner or manufacturer, and isotopically determined material age. The isotopic and trace element ratios and material morphology are important in radiological forensics, but generally less so than for nuclear forensics. To enable forensic identification and attribution of radiological sources, Argonne and Idaho National Laboratories maintain and continually augment a searchable database of international sealed sources and devices. The database contains physical characteristics of the source (or device) including shape, dimensions, schematic diagram, pictures, and labeling; chemical and isotopic characteristics including chemical form, impurities, and processing information; and manufacturer and distributor information including facility locations, points of contact, and dates of operation. While it is rare to have complete information about any source, information is continually added to the database as we interview manufacturers, tour production facilities, and translate foreign advertisements and technical publications. Trace element and isotopic composition of selected radiological materials is determined by analysis of sources disassembled in our hot cells and examined using advanced radiography, microscopy, and isotopic analysis methods.
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