Integrated Ion Beam Analysis (IBA) in Gunshot Residue (GSR) characterisation.

Area of Science:

• Forensic Science
• Analytical Chemistry
• Nuclear Physics

Background:

• Traditional Gunshot Residue (GSR) analysis relies on heavy metals, which are being phased out in modern ammunition manufacturing.
• The advent of Heavy Metal Free (HMF) primers necessitates the development of novel forensic techniques for GSR identification.
• Existing methods face limitations in sensitivity and scope for analyzing emerging GSR compositions.

Purpose of the Study:

• To introduce and validate Proton Scanning Microbeam Ion Beam Analysis (IBA) as a viable forensic tool for GSR analysis.
• To develop and test a standardized procedure for relocating and analyzing individual GSR particles using SEM-EDS and IBA.
• To assess the capability of IBA techniques, including PIXE and PIGE, for characterizing GSR particles from both traditional and HMF ammunition.

Main Methods:

• Utilized Scanning Electron Microscope with Energy Dispersive X-ray Spectrometer (SEM-EDS) for initial particle analysis and imaging.
• Developed a relocation procedure using secondary electron (SE) and X-ray imaging for precise particle targeting.
• Employed Particle Induced X-ray Emission (PIXE) and Particle-induced gamma-ray emission (PIGE) mapping for elemental analysis and identification of GSR particles.

Main Results:

• Elemental PIXE mapping enabled the precise relocation and analysis of even 1 μm GSR particles.
• IBA-PIXE demonstrated significantly higher sensitivity for mid-to-high energy elements compared to SEM-EDS.
• PIGE successfully identified Boron and Sodium in GSR particles from HMF cartridges, crucial for new ammunition types.
• Demonstrated quantitative elemental analysis capabilities of IBA for individual GSR particles.

Conclusions:

• The integrated IBA procedure, utilizing multiple signals, offers unprecedented characterization and discrimination power for GSR analysis.
• IBA provides a powerful solution for analyzing GSR from both traditional and emerging Heavy Metal Free ammunition.
• This technique represents a significant advancement in forensic GSR research, opening new avenues for evidence analysis.