Characterisation of Shotgun Pellets and Gunshot Residues by Trace Element Concentration Patterns by Neutron Activation Analysis Using the Slowpoke Reactor

Publisher Website
Google Scholar
Abstract
The new Canadian SLOWPOKE reactor has unique capabilities compared with conventional pool reactors, making multi-element trace analysis by neutron activation analysis (NAA) faster and simpler for applications such as forensic science. In this work, trace element concentration patterns obtained by NAA using the SLOWPOKE reactor have been evaluated for the characterisation of shotgun pellets, the analysis of hand samples for gunshot residues (GSR) and target to muzzle distance determinations. Little work has been reported on the characterisation of shotgun pellets, despite their frequent presence in criminal cases and the impossibility of identifying them due to the lack of rifling marks. Analysis by NAA can be performed within 3 minutes and the comparison of several samples done in 3 stages viz. qualitative examination of X-Y gamma ray spectra to eliminate obviously different samples, examination of antimony and arsenic concentrations of similar samples and finally a more conclusive characterisation using a set of up to 18 different comparison peaks on a quantitative basis with easily prepared concentration bar charts. The results proved useful for differentiating pellets. Because of the simplicity of NAA techniques based on SLOWPOKE, the method was also used to examine two elements characteristic of gunshot residues. Antimony and barium in gunshot residues removed from hands can be determined simultaneously by NAA within 5 minutes. Flameless atomic absorption, however, has better sensitivity and may be the preferred method. For firing distance determination through the antimony content of targets, the maximum range of effectiveness is comparable for NAA and atomic absorption, however NAA can be accomplished within a few minutes with very little sample preparation and operator's time.

This publication has 4 references indexed in Scilit: