The research is part of a collaboration with the Transportation Security Agency to develop metrology for designing, characterizing and calibrating trace explosive detection systems.
Thousands of enhanced trace explosive detection systems already are deployed in airports to collect particles from luggage and other surfaces, and analyze these samples in a tabletop instrument. Research also is under way on new systems that will use "air showers" to blow particles off people as they walk through portals.
The detection of trace explosives involves three basic processes: particle collection on cloth or mesh filters, particle heating to produce vapors and vapor analysis to identify the chemicals.
NIST is using its measurement expertise to develop methods to better understand and optimize particle collection and heating processes.
One set of NIST experiments focuses on how evenly current tabletop analytical instruments heat the filters that collect particles. Heat control is important because explosive particles need to get hot enough to vaporize within seconds for rapid analysis, and uneven heating may lead to variation in analytical results.
To assist in the testing and design of walk-through portal systems, NIST scientists developed a way to visualize a few individual explosive particles surrounded by millions of background particles collected on filters.
Additional NIST experiments focus on the size of particles knocked off a test surface by various air jet designs. Such information can be used to help design next-generation detection systems.