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Note: I do research in explosives detection With the exception of the last one, banning box cutters, requiring people to take off their shoes, and limiting exp
by physcab 17y ago
Note: I do research in explosives detection
With the exception of the last one, banning box cutters, requiring people to take off their shoes, and limiting explosives are actually quite reasonable for security. Current detection technologies can't really detect explosive substances, except for the X-ray machine, but the best it can do is tell you the density of the materials in question, not necessarily what type of explosive it is. So running your shoes through the machine makes sense, as enough dangerous solid explosive can be packed into the sole of a shoe.
Liquid explosives are extremely unstable. The explosive power is probably not enough to blow up a plane, but it can definitely injure or kill many people or set fire to the plane. Plus, no machine exists to distinguish explosive liquids from non-explosive liquids at the scale that an airport requires.
For the curious, I'll just briefly list some of the detection systems that are out on the market, and what their capabilities are:
- Metal detector
- X-ray machine - Densities of materials
- Ion Mobility Scanner (eg. Puffers or Swipers) - Trace explosives detection, but easily confused by other nitro compounds such as hand cremes, fertilizer, and uh..jet fuel.
- Millimeter Wave Scanner (eg. Whole Body Scanner) - Anomaly detection (eg. can penetrate clothing), but cannot identify explosives.
- Terahertz Imaging - Can penetrate clothing and can identify materials, including explosives, but can be blocked by water and hasn't reached commercialization.
- Other wavelength imaging - Our group uses UV light and can detect trace amounts of explosives, but does not penetrate clothing. It's only a surface technique.
- adam-_- 17y agoThere is some work been done by Durham Uni to detect liquid explosives: http://www.governmentbusiness.co.uk/content/view/2072/1/ http://www.governmentbusiness.co.uk/content/view/2072/1/ http://www.kromek.com/products_liquiddetectionscanner.asp?Ident=Identifier#Ident http://www.kromek.com/products_liquiddetectionscanner.asp?Id...
- physcab 17y agoI couldn't really tell what their technology is, but it looks like a deviation of ion mobility or gas chromatography. Either way, it probably isn't robust enough for widespread use, since it looks like it has to ingest a sample, and that just isn't practical when you have hundreds of people waiting in line.
- Daniel_Newby 17y ago"Current detection technologies can't really detect explosive substances ..." There are plenty of direct explosives detectors, such as the ICx products: http://www.icxt.com/products/icx-detection/explosives/ http://www.icxt.com/products/icx-detection/explosives/
- physcab 17y agoFido isn't for airport security. It's for small applications where you want to inspect explosive traces in particular situations. As far as I know it's single use, and you have to replace the polymeric/chemical sensor on each application.
- Daniel_Newby 17y agoFido sensing elements are generally good for many hours of operation. The PaxPoint product is specifically intended for liquid screening in airports. The main limitation is that they need a focused target to work on. The holy grail is a walk-through chemical sensor, but the physics of that is challenging.
- doughsmith 17y agoThe sensing element in the Fido XT can be used for several hours, depending on the environment you are testing in. If you are testing and have not found any type of explosive substance then the sensing element will not 'clog' up as fast because there is not particulates that are attaching themselves to the side of the element; quenching the light.
- chromatic 17y ago> Liquid explosives are extremely unstable. They're stable enough when TSA makes passengers throw them all in a trash can before passing through screening.
- physcab 17y agoThe rule is meant to be a deterrent. I doubt there is any terrorist who has a bottle of liquid explosives and reads the TSA sign and thinks, "damn, I guess I gotta throw this away". While I'm on the topic, I read recently (can't remember where) that the proportion of successful detonations of a liquid explosive was actually pretty low, since many potential terrorists are killed in accidental explosions. As a side anecdote, we once had an FBI officer bring in a canister of some unknown liquid explosive for our group to test using our equipment, and I remember he was carrying it with the hand he "didn't use much" just in case it detonated.