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Science Technology

Using Radio Waves to Detect Explosives 99

Posted by samzenpus from the tuned-to-boom dept.
deadmantyping writes "A Japanese research group published a paper describing a method to detect explosives in luggage using radio waves. The method relies upon nitrogen nuclear quadrapole resonance (NQR) and is able to distinguish between different white powders, whereas currently used x-ray technology is not."
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Using Radio Waves to Detect Explosives More

Using Radio Waves to Detect Explosives

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  • White powders? (Score:3, Insightful)

    by Some_Llama ( 763766 ) on Wednesday January 24, 2007 @08:47PM (#17746168) Homepage Journal
    SO will it detect Cocaine, herion, anthrax, flour? What if I add some gun powder to my Coke?
  • Hmmm.... seems plausable, since if my memory serves me correctly, all matter gives off a distinct waveform. Just one question (or problem?), what happens if the crazy terrorist (er.. freedom fighter) decides to make a trigger which works off of radio waves (or whatever particular radio wave) said name future machine may use?

    • Re:Interesting idea, but one caveat I perceve... (Score:5, Insightful)

      by Dr. Eggman ( 932300 ) on Wednesday January 24, 2007 @08:52PM (#17746218)
      What if a crazy man just straps some bombs on, walks up to the security checkpoint and sets himself off? There's no security check to protect the first security check. Better add one.

      ...and recurse.

      • Re: (Score:1)

        by yerM)M ( 720808 )
        Having recently travelled extensively around the world, many foreign airports have checkpoints as you enter the airport. It seems stupid that our major airports do not do this. I can guarantee that there are far fewer people at the checkpoint than standing at line at the ticket counter.

      • Re: (Score:2)

        by mpe ( 36238 )
        What if a crazy man just straps some bombs on, walks up to the security checkpoint and sets himself off? There's no security check to protect the first security check. Better add one.

        What you'd need would be explosive detectors at the main doors to the airport. But also at train stations, sports stadiums, etc. There is no reason to assume that suicide bombers (or the people who pick their targets) are obsessed with air travel.
        You also need a low rate of false positives. As well as being able to deal with

    • Re: (Score:3, Insightful)

      by CosmeticLobotamy ( 155360 )
      what happens if the crazy terrorist (er.. freedom fighter) decides to make a trigger which works off of radio waves (or whatever particular radio wave) said name future machine may use?

      Given the availability of both clocks and button, it seems unlikely to come up often.

    • Re: (Score:2)

      by Goaway ( 82658 )
      Pretty much the same thing that happens if a terrorist walks up to the check-in and presses the trigger in his pocket. Why do you ask?
    • hey! i was going to say that! :)
    • Hmm... And how many billions would it take to roll this toy out everywhere and would it detect the guy carrying something fun in his briefcase before he detonates it while in the security check line? Any how many billions would it take to just simply treat the third-world with some dignity and respect?

      --Neth
  • Cool! When can the new technology allow us to walk through the security with dignity again?

    • Re:So, no more taking shoes off? (Score:5, Interesting)

      by QuantumG ( 50515 ) * <qg@biodome.org> on Wednesday January 24, 2007 @09:16PM (#17746414) Homepage Journal
      Please take off your: jacket, shoes, backpack (and take the laptop out of the backpack and put it in a seperate tray), hat, belt, mobile phone, keys, wallet (if it contains more than 3 rfid based entry keycards). Yes, I travelled international recently. It's not even consistent.. some places they'll make you take off your belt, other places, no, that's fine.

      Time before last I took a suit coat with me. Big solid metal coat hanger with nice sharp edges. They just let me carry it onto the plane. Had I tried to take a similar piece of metal on (say, a boxcutter) they would have denied me. Hmmm, wonder if there's a little big of class disparity there.

      The illusion of safety.

      • Re: (Score:3, Insightful)

        by bram ( 490 )
        Last time I took Sri Lankan from EU to CMB. I'm not allowed to have my swiss army knife in the cabin so I put it in my cargo luggage.
        When we got our meal it came with nice metal cutlery.

        On arrival I put the metal meal knife in my hand luggage and walk out of the airport.
        One month later I go back to EU wondering what security would tell me checking in with one of their own knifes.

        Nobody saw anything, now it's laying somewhere here around the house.

        So much for regulations and security.

        • That is such crap. If I am expected to surrender my concealed weapons, then I think that I should expect an armed escort by military personnel.

          The current airport *security* plan is a joke. I have never felt more threatened in my life except when I have been in airports. They should issue all citizens complimentary handguns, then I'd feel a bit safer, and if there was a shootout, we'd have the numbers on our side at least.

      • Re: (Score:3, Funny)

        by ari_j ( 90255 )
        Two things:
        1. I have just started stripping down to my underwear every time I fly. There's no sense having to be asked to take off any article of clothing, so just take 'em all off and throw them in the tray. It saves everyone time and embarrassment.
        2. Why not use a real man's portable hanger [indyprops.com]?
        • Just be very glad that Richard Reed tried to blow up his shoes and not his underwear

          • Re: (Score:2)

            by ari_j ( 90255 )
            I'm still waiting for the breast implant bomber. Once someone tries that, I'm going to sign up for a security job immediately.
    • TSA Memorandum

      We will be integrating a new explosives detection device to all screening areas which uses radio waves in some crazy science fashion. Unfortunately, the radio waves can't pierce the human body and provide accurate results. Therefore, all domestic and international flights are required for a pre-security cavity search. Passengers concerned about mantaining dignity must be additionally screened as they may be supporting terrorism.

      That is all.

    • Re: (Score:2)

      by Builder ( 103701 )
      You can walk through your airport with dignity again just as soon as all the sheeple realise who actually owns a democracy. As soon as the people decide this is too much, it will be over.

      This means that it will never be over :(

  • That's easy!

    All you have to do is go through all the frequencies being used by the radio triggers and send a "detonate" signal on each such frequency.

    I guarantee you'll detect the explosive when it goes off...

    Hey, it's better than having it go off on the plane, right? :-)

    • A similar approach has been used in Iraq to detonate roadside bombs in advance of convoy movement. A commander discovered that the detonators transmitted the same frequency as RC car controllers. He thus taped down the controls on such a controller and - voila - IEDs would detonate a safe distance in front of his convoy.

      Never underestimate the utility of relatively low-tech solutions.
  • I remember hearing warnings about having transmitters near my explosives, something about accidentally triggering professional grade gear;
    Exposing high strength radio waves to homemade devices might result in detection by detonation.......

  • Interesting... (Score:2, Informative)

    by thedarknite ( 1031380 )
    It appears to be a slightly more advanced system than SNUPA http://www.abc.net.au/quantum/stories/s112369.htm [abc.net.au] developed at the University of Melbourne, which I believe didn't differentiate between different explosive compounds.
  • Nothing (plausible) can detect everything that might be explosive, but it would seem this targets the most easily-obtained explosives and should raise the bar significantly in terms of the technical competence it takes to defeat the security measures.

    That said, it would seem to have a ways to go before it's practical.

    • Re: (Score:3, Interesting)

      by budgenator ( 254554 )
      Nothing (plausible) can detect everything that might be explosive, Actually even what an explosive is can be kind of ambiguous; still I've read that terrorists are more likely to use peroxide based explosives rather than nitrate based explosives. I see the nitrogen nuclear quadrupole resonance as have more potential in finding IED in the road beds in places like Iraq.

      • Re: (Score:3, Interesting)

        by Entrope ( 68843 )
        NQR detectors tend to be relatively slow to examine an area, and a very important factor in Iraq is a fast rate of advance. NQR might work for airports, but other systems -- like metal detectors and backscatter radars -- work better when you need to go fast. The military mostly looks at NQR as a confirmation technology for other detectors and not as the first line of explosive threat detection. (Google "NQR rate of advance" for various papers and studies on the issue.)

        • Re: (Score:2)

          by jstott ( 212041 )

          The military mostly looks at NQR as a confirmation technology for other detectors and not as the first line of explosive threat detection.

          It's also being looked at for landmine detection (I did some work on a competing technology for a time once). NQR has better sensitivity than the WWII-vintage metal-detectors at a comparable rate of forward advance. Also, most mines have very little metal any more, mostly because using plastic is cheaper. That plastic also makes it harder for a metal detector to fi

      • Re: (Score:3, Informative)

        by calidoscope ( 312571 )

        I see the nitrogen nuclear quadrupole resonance as have more potential in finding IED in the road beds in places like Iraq.

        Snicker....

        As was pointed out by 'Entrope', NQR is probably not the best choice for detecting roadside IED's - there are other methods better suited for rapid scanning. What NQR would be good for is confirming whether or not a non-conducting anomaly picked up ground penetrating radar contains explosives.

        You are correct in stating that NQR would be ineffective against peroxide explosives. The explosives that NQR is especially effective at detecting are also the ones with essentially zero vapor pressu

  • up the wattage a bit and you'll stop all explosives from ever getting onboard.

    ...course, it might be a bit hazardous to bystanders and make a mess, but if they're really serious...

    /P

    • that would make everyione undress, give them on orange jump suit and send all there things in a cargo plane to meet them.

      Possible medicate them into a stupor.
      • Don't give them ideas. Air travel's bad enough as it is. If you absolutely must fly, don't fly out of international airports- fly out of local trans-border/civil aviation ones, where security is much more lax.

      • Re: (Score:2)

        by rlp ( 11898 )
        > would make everyone undress, give them an orange jump suit and send
        > all their things on a cargo plane to meet them.

        Yeah, I've flown that airline.

        > Possibly medicate them into a stupor.

        Only, if you get the upgrade to first class.
    • guarding the planes. To hell with the people on the ground. Why do you think that security is set up in the MIDDLE of the airport? What if a bad guy wanted to kill people in the terminal? Wide open. That is why in Israel, the security is at the front gate., not the flight gate.

  • That's nice (Score:5, Insightful)

    by overshoot ( 39700 ) on Wednesday January 24, 2007 @09:02PM (#17746332)
    I wonder how it is at distinguishing between common metallic solids and thermite?

    A little oxidized iron, a little aluminum powder, a tiny amount of binder, press, and you have the makings of some attractive plaques or statuary. A bit of magnesium wire and a battery and you have everything you need to start a large mass of aluminum burning. Spectacularly.

    Good thing none of the Bad Guys have the brains of a flatworm. Or at least, that's what our whole air travel security strategy assumes.

    • Re: (Score:2)

      by Kozz ( 7764 )
      Okay, well, thermite is some really fun stuff, but it's hardly an explosive. Damned hot molten iron, to be sure, but it's not going to go "ka-boom". Or do you know something I don't?
      • Damned hot molten iron, to be sure, but it's not going to go "ka-boom". Or do you know something I don't?
        Yeah. Airplanes are made of aluminum and have a 600 kph forced air feed.
        • hows about this you setup your rig it gets put in the cargo hold and then at 30K it goes off and turns into a glob of metal

          possibles
          1 fire on the plane torch the luggage (fail the airframe)
          2 very large hole in the plane (the cargo hold drops to not many psi or 0.0?? atmospheres)
          3 get very lucky and you might sever the flyby wire system (oops backups should get the plane on the ground)
          4 depending on what the plane is doing you might hit a fuel tank (fails the airframe OOH NIFTY KABOOM)

          • Thermite in luggage probably won't work (Score:4, Insightful)

            by Harmonious Botch ( 921977 ) on Thursday January 25, 2007 @01:06AM (#17747970) Homepage Journal
            Luggage probably does not burn very well. The suitcase and its contents are mostly fabric / leather / plastic of some type. ( think about what you packed last time... ) Most clothing has passed some kind of won't-sustain-combustion test, and that in the presence of lots of oxygen at or near sea level. Leather won't sustain a fire on its own. Plastics, who knows? But few are highly exothermic.
            And add to that the fact that there is not a whole lot of air available in the luggage container - it's mostly luggage. Even if there is enough fuel to sustain a low-temp fire, it soon suffocates itself. The only jet that has crashed in the last few decades due to a cargo fire was because there was an oxygen tank in the luggage.

            Also, according to federal law, all luggage compartments on commercial airliners are required to have fire-resistant walls.

            • I hate to break it to you but thermite does not need oxygen to burn.. It will just melt through the suitcases and then the fuselage....
              • I agree, it does not need 02. Thermite has it's own oxygen bound up in Fe203. I never assumed otherwise.
                Of my ten-sentence post, nine sentences are devoted to the question of whether or not luggage will burn.
                The tenth sentence notes that when the thermite does finally get thru the luggage ( if the terrorist is lucky enough to have his suitcase on the bottom layer ) it will hit the fire-resistant wall/floor of the container.

                Please RTFP.

          • hows about this you setup your rig it gets put in the cargo hold and then at 30K it goes off and turns into a glob of metal

            possibles
            1 fire on the plane torch the luggage (fail the airframe)
            2 very large hole in the plane (the cargo hold drops to not many psi or 0.0?? atmospheres)
            3 get very lucky and you might sever the flyby wire system (oops backups should get the plane on the ground)
            4 depending on what the plane is doing you might hit a fuel tank (fails the airframe OOH NIFTY KABOOM)

            Never been mu

          • Re: (Score:2)

            by mpe ( 36238 )
            hows about this you setup your rig it gets put in the cargo hold and then at 30K it goes off and turns into a glob of metal

            Thermite creates moltern iron. Which will follow the force of gravity until it encounters something strong (and heat resistant enough) to stop it.

            1 fire on the plane torch the luggage (fail the airframe)

            Even if the luggage is entirely flame retardant it's unlikely to do much to stop the molten iron.

            2 very large hole in the plane (the cargo hold drops to not many psi or 0.0?? atm

      • Re: (Score:2)

        by mpe ( 36238 )
        Okay, well, thermite is some really fun stuff, but it's hardly an explosive. Damned hot molten iron, to be sure, but it's not going to go "ka-boom". Or do you know something I don't?

        Melting through the skin of an airliner in flight is quite likely to cause an explosive decompression. Possibly more dangerous if set off above the cargo areas than the Centre Wing Tank.

  • nuclear resonance is MRI without the "imaging" (Score:5, Informative)

    by kris_lang ( 466170 ) on Wednesday January 24, 2007 @09:03PM (#17746340)
    so this is called nuclear magnetic resonance spectroscopy.

    Doing it with a gradient field and a special pulse sequence lets you get the
    vibrational amplitudes of your protons based on their position within the gradient field.
    That's what gets you MRI images. Before MRI images, nuclear spectroscopy was used to
    resonate the "nucleus" of atoms/molecules/conglomerations of molecules at varying radio-frequencies to see if there was any resulting resonance and output RF (radiofrequency) signal.

    Protons resonate at 2.4 GHz approximately (which is the frequency used in microwaves to resonate the H's in the {H}_2{0} molecules in your food and heat it.

    • Re:nuclear resonance is MRI without the "imaging" (Score:5, Informative)

      by Anonymous Coward on Wednesday January 24, 2007 @09:24PM (#17746476)
      ... but this is NQR which is examing the 4th order (as I can recall, maybe is was 2nd-order, I don't remember anymore:-p) of the nucleus. It's very similar underlying principles as MRI and NMR (and thus implementatin scheme is similar) but the physical interaction mechanism is the quadrapole momeent rather than the dipole moment of the nucleus.

      The problem with NQR and SQUID is that the measurement is extremely sensitive and it is difficult to filter out false positives. SQUIDs are very sensitive to magnetic perturbations and noise. Heck in the lab it can pick up the noise caused by the underground train. So the design has to be extremely precise and the filters need to be carefully designed. Also NQR technique only can detect certain substances that contain the molecular signature of interest (in this case N14 (i think?)). You need to induce a very large magnetic field (relative to the nucleus) to induce NQR. The SQUID can pick up the magnetic distrubance, but you still need to induce the field. DARPA showed some demos of remote systems that could acheive this. The problem was the false positives were pretty high, because it turns out shoe soles haave N14 which can trigger a false positive.

      Nevertheless, it's a great acheivement and I hope they can iron out the kinks in this technology.

      So don't put those shoes in your baggage! :-)
      • You need to induce a very large magnetic field (relative to the nucleus) to induce NQR

        I'd say there's the rub. I'm sure everyone here has seen the enormous magnets used in nuclear magnetic imaging, if only on the television. And at that an MRI patient has to sit still for half an hour. You can't take half an hour to scan a bag, you've got to do it in a second or two. So that means you need a truly huge, multimillion-dollar magnet, to collect your signal fast enough.

        Sheesh. Much cheaper to just put a bi
      • not all n14 is equal. NQR frequencies and pulse patterns are specific the the quadrupolar crystaline structure that the nitrogen is bound in. Thus ALL n14 containing substances discovered so far that exibite NQR signals have distinct "fingerprints'. N14 in shoe leather is a non-issue. That said, NQR does have many limitations that make it best for a complimentary technology and not a magic bullet.

    • Re: (Score:2, Informative)

      by candover ( 39486 )

      Protons resonate at 2.4 GHz approximately

      No they don't. Nuclear magnetic resonance requires a strong external magnetic field. The strongest superconducting magnet you can buy today induces a resonance (the Larmor frequency [gsu.edu]) in protons at 950 MHz... but it costs about ten million dollars and only does that over a tube about five centimeters wide. The absolute strongest MRI magnets today top out at about 1/3 of that magnetic field, and most are far less.

      Microwaves heat food via RF heating [wikipedia.org], which is an

    • As someone who uses NMR literally every single day and has taken graduate courses in the subject, let me correct a few major issues with your statement.

      1) "Doing it with a gradient field and a special pulse sequence lets you get the vibrational amplitudes of your protons based on their position within the gradient field." In NMR (NOT MRI), gradients most commonly come up the form of gradient shimming, which is a technique for homogenizing the magnetic field applied to a sample. In general, gradient fields

      • Re: (Score:2)

        by Rich0 ( 548339 )
        Agreed with you in general but the grandparent was right about the use of field gradients in MRI. In NMR as you indicated they tend to only be used for shimming, solvent suppression, and some more exotic experiments (I think diffusion measurements are one - molecule moves during experiment it is affected by gradient pulses - if it doesn't move pulses cancel out - possibly useful in measuring small molecule binding to big molecule).

        MRI does use field gradients - because it needs some way of measuring T1/T2

  • I much prefer... (Score:4, Funny)

    by StikyPad ( 445176 ) on Wednesday January 24, 2007 @09:26PM (#17746496) Homepage
    ...using explosions to detect radio waves.

  • Not all explosives contain nitrogen (Score:5, Insightful)

    by dsci ( 658278 ) on Wednesday January 24, 2007 @09:33PM (#17746556) Homepage
    And not all nitrogen containing explosives are white powders. :)
  • Beat the hell out of the bag. If you hear a "kaboom" (where's the kaboom? there's supposed to be an earth-shattering kaboom!), then there was a bomb in it. Simple.

    Also helps greatly reduce the volume of checked and carry-on luggage.

  • Prototype mine detectors based on NQR have been built and tested. The signals are very weak, even with tens of watts of excitation which makes this a difficult techique for practical use. See http://maic.jmu.edu/JOURNAL/9.2/RD/williams/willia ms.htm [jmu.edu] for more info.

    • The signals are very weak, even with tens of watts of excitation

      Make that several kilowatts (peak) of excitation...

      The maximum signal amplitude is directly proportional to the mass of material and inversely proportional to the absolute temperature (until you get to the micro-kelvin temperature). The effective noise is inversely proportional to the square root of the available signal averaging time and that time is a messy function of material, excitation power, receiver recovery time and temperature.

      The novel aspect from TFA is the use of SQUIDs for detection wh

  • Only thing new is using a SQUID (Score:4, Informative)

    by calidoscope ( 312571 ) on Wednesday January 24, 2007 @09:51PM (#17746676)
    Research into using NQR for explosive detection dates back to the 1970's. The first NQR baggage scanner was built by Al Garroway's group at NRL in the early 1990's using room temperature coils and room temperature electronics.


    Ron Sager and Alan Sheldon of Quantum Design used a SQUID in 1992 for detecting the NQR response of ammonium perchlorate (~38kHz), so the Japanese group isn't even the first to use SQUIDs for NQR...

  • I have a much simpler method: if america doesn't like country X it follows that X has explosives...
  • Having yet another nitrogen explosives detector is not very interesting. It does not solve the problem of peroxide and oxyhalide based explosives, the former having already proven to be popular with terrorists, and both types having seen limited military application in the 20th century.

    A truly effective explosives detection technology will need to target a broader range of high explosive chemistries, and preferably not the same ones over and over. When the corner store is out of C4, people bent on blowing
    • Most explosves are based on nitrates, especially commercial ones because of their stability and energy density. Yes, the bad guys can move to something else, but it makes manufacture more difficult and increases the risk of detonation before deployment or squibs (the chappati bombs used in the UK).
  • And how about explosives without nitrogen? I personally know two high explosives, which were successfully used in WWII and which doesn't contain nitrogen.

    And I also know some other compounds that can serve as explosives and does not contain nitrogen or chlorine.

    And I'm not a professional chemist, chemistry was just my hobby at school and high-school.
    • Bzzzt. Fat Man and Little Boy were tiggered using high powered nitrogen based (TNT or similar) explosives.

      Perhaps you had some others in mind, but these are what will pop into people's minds.

      • Re: (Score:2)

        by Cyberax ( 705495 )
        Nope. There was another explosive, which was used in landmines. It can be fairly easy synthesized in any laboratory (I synthesized small quantities for different pranks).

  • Not all "useful" or "effective" explosives are nitrogen based.
  • Now I won't have to deal with homeland security cutting open my 5lb bag of grits anymore when I leave The South for work.
  • You just have to send the correct frequency, and bam, it explodes!
  • When are we going to bypass this whole mess and just invent the teleporter?
    • When are we going to bypass this whole mess and just invent the teleporter?
      But then the evil terrorists could beam explosives/small nukes anywhere they wanted to.

      You haven't really thought this through, have you?

  • The SQUID operates at a temperature of 77 Kelvin (minus 196 degrees centigrade) which we achieve by using liquid nitrogen.

    Wouldn't it be difficult to detect small amounts of nitrogen bound in substances when your SQUID detector is bathed in the same substance you're trying to detect?

  • >distinguish between different white powders

    I would think that black powder would be more of a concern here...

  • There is nothing new about using radio waves for explosives detection. The navel research labs and russians have been working on NQR explosives detection for 40 years. Many other groups worldwide are also working on the technology. Two companies have products out and in airports, GE and QR Sciences, although currently the number of units deployed is quit low. The somewhat novel thing in the article is the use of squids. This is not entirely novel because the russian, GE and others have looked at this ov

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