Automatic routine

GSR imaged using the backscattered electron detector.

Low magnification image using the backscattered electron detector thresholds to separate and locate particles.

The analysis of gunshot residue is performed using dedicated software which ensures fast, reliable and fully unattended analysis. The Eastern Analytical software also identifies other indicative particles similar to the large amounts of Lead (Pb) particles from the bullet. These include Titanium (Ti) and Zinc (Zn), which are found in lead-free ammunition. Other environment-related particles can also provide additional information about the subject. The steps to perform an analysis are as follows:

  • Tape is mounted on stubs.
  • Stubs are placed on a multi-stub holder.
  • The multi-stub holder is mounted on the SEM specimen stage.
  • The stub is split into multiple fields which are scanned one-by-one.
  • Each area is scanned for particles using backscattered imaging.
  • The position and size of the candidate particles are recorded.
  • The particles are revisited by the electron beam to perform X-ray analysis.
  • The emitted X-ray spectrum from each individual particle is compared to a classification scheme.
  • All results are stored (on disc).
  • A report of all detected particles is produced after each sample.
  • The backscattered electron signal is used to detect the particles. Typical GSR particles appear as bright objects within the image. By applying a threshold to the signal, the particles are distinguished and located by the GSR software.