Keywords and Phrases
Explosives; Forensics; Identification; Neutron activation analysis; Taggants
"For the last several decades, it has been apparent that new methods of identifying explosives can help investigators trace their origins. One way to identify an explosive is through the use of taggants: materials added to a product that encodes information about the product such as when it was manufactured.
This research investigates the survivability of a new identification taggant called the Nuclear Barcode that overcomes some of the downfalls that have been identified in prior taggants. The Nuclear Barcode encodes information as a unique combination of concentrations of rare earths (Ho, Eu, Sm, Lu, and Dy) and precious metals (Ir, Rh, and Re) that is then identified using Neutron Activation Analysis (NAA). The concept of "survivability" was tested through a series of experiments on aqueous solutions and postblast residues containing three rare earths (Ho, Eu, and Sm).
The tests have shown that the three candidate taggant elements can be identified by NAA in an aqueous solution at concentrations as low as 100 parts per billion (ppb) with uncertainties in the concentration measurement as low as 5 ppb. These elements can be identified in post-blast residue produced by a detonating explosive at higher concentrations of 1,000 ppb. Being able to identify the taggant elements at these concentrations is critical for the practical implementation of the Nuclear Barcode, which requires uncertainties below 50 ppb. Five parameters were identified as contributing to the uncertainty and the effect of the delay time was investigated. After a period of 2.5 half-lives, the uncertainty in the concentration was found to be higher than the uncertainty immediately afterward, suggesting that samples be measured as soon as possible and eliminating some candidates"--Abstract, page iii.
Johnson, Catherine E.
Castano Giraldo, Carlos Henry
Worsey, Paul Nicholas
Alajo, Ayodeji Babatunde
Worsey, Gillian M.
Ph. D. in Mining Engineering
Missouri University of Science and Technology
xv, 178 pages
© 2018 James Thomas Seman, All rights reserved.
Dissertation - Open Access
Electronic OCLC #
Seman, James Thomas, "Correlation between delay time and measured concentration and concentration uncertainty by neutron activation analysis" (2018). Doctoral Dissertations. 2729.