b'Application of the AssociatedImproving the sensitivity and speed of nondestructive detection of chemical and Particle Technique to Fieldablebiological agents in hidden threat objects.Prompt Gamma-Ray NeutronP rompt gamma-ray neutron activation analysis is useful for determining the chemical elements inside an unknown object. This is done using a source Activation Analysis Systems of neutrons to irradiate the object, which induces characteristic gamma rays through nuclear reactions with the constituent atoms. The gamma rays are then detected and identified using an external spectrometer. Deuterium-tritium neutron generators are useful because they produce energetic 14 MeV neutrons that are highly penetrating and able to excite nuclei within light atoms that typically require a high threshold energy to induce gamma-ray emission. However, these TOTAL APPROVED AMOUNT:energetic neutrons easily excite nuclei in the surrounding environment, which causes $80,000 over 1 year a large background signal in the gamma-ray spectrometer. This study investigated PROJECT NUMBER:the potential of the associated particle technique to suppress the high background 21A1055-016 signal. The associated particle technique uses a specialized neutron generator that can identify the precise moment in time when a neutron is emitted in the direction PRINCIPAL INVESTIGATOR:of the test object, thus providing a gate signal for the spectrometer to identify which Brian Bucher detected gamma rays are coincident with neutrons that were directed toward the CO-INVESTIGATOR: sample and which gamma rays likely came from the surrounding environment.Jayson Wharton, INL The tested samples were field assays of armaments containing chemical warfare agents and high explosives. Three different gamma-ray detectors were examined: sodium iodide, lanthanum bromide, and high-purity germanium. In each case, using the associated particle technique clearly reduced the background. The high-purity germanium was the most promising for field assessments because of its superior energy resolution, despite its much poorer timing resolution compared to the other detectors. Even with the poor gamma-ray time resolution, the associated particle technique suppressed background radiation to such a low level that a spectral background subtraction was no longer needed.130'