Instrumental neutron activation analysis applications in materials science and in forensic surveys

Abstract

Neutron Activation Analysis (NAA) was applied to the characterization of lithious ceramic materials to be used as tritiogenic breeders in future fusion reactors. After neutron irradiation, measurements by γ-spectrometry were performed on the activated impurities, particularly on the ones with large neutron cross section. Irradiated samples were then annealed at rising temperatures, to obtain a fractional release of the tritium [formed by (n,α) reaction on lithium] as element (HT/T₂) or tritiated water (HTO/T₂O). Barium and antimony were determined by NAA, on request of Italian Courts, as evidence of gunshot residues (GSR), on hands and clothes of suspected people. The sample is left unchanged, even if slightly radioactive, allowing further examinations, in case of controversial results. In some actual cases, NAA was performed on sample already examined by scanning electron microscopy (SEM/EDX), allowing the determination of several more elements and a more definite identification of the ammunitions involved in the crime.