DETECTION
ETD systems have been used in turn the colour orange – but This conjunction with X-ray as part of a with these HMEs they will example of a comprehensive screening process for typically always turn DSA enhanced years. The ETDs being used today have green. The fix is a sample trap allows the detection of the ability to detect very small trace combination of X-ray chlorate-based amounts of explosive residue contained operator training and explosives. in a fingerprint. They provide a detection system software updates capability unlike any other explosive that will enhance chlorate and detection systems on the market and also aluminized HME detection. ©DSA Detection provide very good deterrence. However, The fact that these chemical just like any screening technology they have mixtures turn green vs the more their limitations which must be accounted for common orange result for explosives when deploying an ETD unit. means we must ensure our X-ray operators are trained to detect a chlorate-based threat – and also understand how this will respond in a X-ray system (or Enhanced sample trap not). One of the most popular and well-known terrorist The problem with chlorates being detected in an ETD is mixtures for chlorates is called ‘poor man’s C-4’ and has that they do not desorb (turn to a vapour) when sampled been around for years. by the units. This inability to desorb makes them seem If a chlorate-based HME is used in something like a undetectable by current ETD units. That issue appears to laptop it blends in with all of the surrounding materials have been solved with sample traps specifically designed far better than an organic-based explosive. X-ray to detect chlorates being developed, and these have operators are typically trained to look for any shown in testing that they work. Zeff ranges organic mass inside electronic items because it MIT and DSA Detection are working on the for X-ray colour is not normal to see this on X-ray. This is also development of a new sample trap for ETD chart shows the reason why they make you remove your units. This will be called an ‘enhanced’ sample green for ‘non-organic laptop from your bag – so that they can get a trap and will provide not only an improved aluminium’.
©DSA Detection
ATOMIC NUMBER 1-10
11-18
19-100
100+
Orange
Green
Blue
Black
Mainly Organic Elements of Oxygen, Nitrogen and Hydro Carbons Explosives, Cloth, Food, Wood and Paper
Mainly non Organic Aluminum, light metals and Organic material over atomic number 10 Electronic gadgets
Steel and dense metals Gun, Blade of knife Tools and Gold
Items that cannot be penetrated by X-rays
clear view of the item, and that any of the organic items you have in your bag do not combine with the image. X-ray operators and the detection systems must therefore be trained or adjusted to detect a threat using a chlorate or aluminized HME because its response is so much different from normal organic explosives. Explosives trace detection The other system affected by chlorates (but not the aluminized commercial or HME explosives) is explosive trace detection (ETD). ETD systems using ion mobility spectrometry (IMS) currently cannot detect a chloratebased HME. However, they can detect the aluminized commercial and HMEs because part of their mixture is a chemical they can detect (e.g. AN – ammonium nitrate).
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This DSA chlorate X-ray shows live potassium chlorate and potassium perchlorate on a Smiths Detection X-ray system, taken at the DSA laboratory in North Andover, MA.
capability in sample collection, but also the detection of chlorates. This enhanced trap will allow the extended use of ETD systems currently in the field without the requirement for a new technology to be deployed. History has shown that terrorists will always try and come up with a new way or tool to try to avoid detection. Typically it is after the fact that most agencies try and figure out a new method of detection. This has proven to be a very poor model for detection and deterrence in the field. Being proactive and thinking like a terrorist are the keys to being one step ahead of the bad guys.✺
John Howell is a US Marine and US Army Explosive Ordnance Disposal Technician and is currently a Counter-IED Subject Matter Expert on the detection of threats with screening technologies and training.
36 XPLOSIVE
SEPTEMBER 2018