Elemental quantification of large gunshot residues

• Published in: Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms Vol. 348; pp. 170 - 173
• Main Authors: Duarte, A., Silva, L.M., de Souza, C.T., Stori, E.M., Boufleur, L.A., Amaral, L., Dias, J.F.
• Format: Journal Article
• Language: English
• Published: 01.04.2015
• Subjects: Ammunition; Antimony; Cartridges; Ejection; Forensic engineering; Proton beams; Residues; Stemming
• ISSN: 0168-583X
• DOI: 10.1016/j.nimb.2014.11.116

In the present work we embarked on the evaluation of the Sb/Pb, Ba/Pb and Sb/Ba elemental ratios found in relatively large particles (of the order of 50-150 mu m across) ejected in the forward direction when a gun is fired. These particles are commonly referred to as gunshot residues (GSR). The aim of this work is to compare the elemental ratios of the GSR with those found in the primer of pristine cartridges in order to check for possible correlations. To that end, the elemental concentration of gunshot residues and the respective ammunition were investigated through PIXE (Particle-Induced X-ray Emission) and micro-PIXE techniques. The ammunition consisted of a .38 SPL caliber (ogival lead type) charged in a Taurus revolver. Pristine cartridges were taken apart for the PIXE measurements. The shooting sessions were carried out in a restricted area at the Forensic Institute at Porto Alegre. Residues ejected at forward directions were collected on a microporous tape. The PIXE experiments were carried out employing 2.0MeV proton beams with a beam spot size of 1mm2. For the micro-PIXE experiments, the samples were irradiated with 2.2MeV proton beams of 22 mu m2. The results found for the ratios of Sb/Pb, Ba/Pb and Sb/Ba do not correlate with those stemming from the analysis of the primer.