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Security Science

Muon Detector Could Thwart Nuclear Smugglers 54

Posted by Hemos
from the interesting-applicatons dept.
Ben Sullivan writes "Cosmic rays that bombard Earth could help catch smugglers trying to bring nuclear weapons into the U.S. Los Alamos scientists say they've developed a detector that can see through lead or other heavy shielding in truck trailers or cargo containers to detect uranium, plutonium or other n-bomb materials. Their technique, muon radiography, is reportedly far more sensitive than x-rays, with none of the radiation hazards of x-ray or gamma-ray detectors now used at border crossings. From Science Blog."
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Muon Detector Could Thwart Nuclear Smugglers

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  • by 3waygeek (58990) on Monday March 07, 2005 @08:28AM (#11864244)
    than what these guys used. [10news.com]
    • by sgant (178166) on Monday March 07, 2005 @08:43AM (#11864293) Homepage Journal
      Of COURSE they're going to have this on the news and general media...they will certainly play up "hey, we have detection equipment so sensitive that it picked up on someone getting radiation treatment".

      It's a propaganda tactic, play up that they can detect almost anything to make the bad guys think twice in trying to slip something in undetected. Since plutonium etc is hard to get as it is, perhaps the bad guys wouldn't want to risk losing it so easily (the risk here is losing the plutonium, not "getting caught" as human life means nothing to them as they've shown over and over).
      • by Anonymous Coward
        Remember when they couldn't find that lost nuclear weapon right off our shoreline for, like, damn near years? Inpenetrable detection net my ass. There could be a lot of material moving in and out and we might never know it.

        The same people who buy that silly SDI crap believe this too.
      • Police: Sir are you carrying a nuclear weapon or materials?

        Evildoer: No, sir. I just left my doctor's office and had received a radiation treat

        Police: (Calls doctor) Sir your story checks out sorry for the trouble.

        Evildoer: Thank you, sir. I understand completely...

        Police: Hey wait! Why does it say "Evildoer" next to your line in the script?!? I think I'd better have another look here. I knew that false leg with the timer counting down looked a little suspicious!
      • ... we've the story being forwarded of one of our coworkers stopped at the border coming into the US from Canada for the very thing you say isn't possible.

        Seeing as how he is a rather highly placed and takes a rather cynical view of the government leads me to believe his story about being yanked out of the Customs line and asked to undergo a radiological exam (geiger counter?).

        Apparently he had been surrounded by officers since he'd gotten onto the bridge- don't ask me how because the next few cars were w
      • I don't think organized, committed nuclear terrorists will be as gullible as we Americans who foot the bill.
    • Lesson learned. Next time you try to smuggle radioactive material through a border, send someone who verifiably has had recent radioactive treatements.

      Customs officer: It's OK, we checked with your doctor. You can bring in that... uh... strange glowing giant lead cat toy!

    • by DustMagnet (453493) on Monday March 07, 2005 @02:09PM (#11867371) Journal
      False alarms are a huge problem with any detection system. I had a coworker stopped while entering the U.S. because they detected explosive residue. He'd been working with explosives for months. The residue level was so high they couldn't get the machine clean again. It kept detecting explosives without any sample. It cost a lot of people a lot of time to verify that he was safe.
  • This has been around for years - and the BBC reported it (in spite of it being old news) about 2 weeks ago.
  • Safety (Score:3, Insightful)

    by Urkki (668283) on Monday March 07, 2005 @08:40AM (#11864286)
    • with none of the radiation hazards of x-ray or gamma-ray detectors now used at border crossings.

    Yeah, right. It will harmlessly pass through a bag of water like a human body, because water is such a lousy material at stopping radiation. That's why it's not used in nuclear reactors or cosmic ray detectors...
    • Re:Safety (Score:5, Insightful)

      by ecotax (303198) on Monday March 07, 2005 @08:49AM (#11864304)
      Regardless of how harmful these muons are when passing through your body, there is certainly no *added* harm in this detection method, because the muons used are the ones from space that has passed through you anyhow.
      • Good point. Might have been a good idea if I had RTFA before hitting reply ;-)
      • Re:Safety (Score:3, Insightful)

        by jfdawes (254678)
        Sensationalism ... we just can't avoid it. From the article:


        With refinement, inspectors could declare most vehicles harmless in a border setting with as little as 20 seconds of muon exposure.


        Sure sounds like they are capable of producing masses of 3Gev particles to me.
        • Re:Safety (Score:1, Informative)

          by Anonymous Coward
          This system doesn't produce anything it merely detects changes in existing particles. Because the system relies on existing radiation rather than trying to make it's own there are no safety issues with regard to the radiation used.
    • Is the muon detecter a passive system? If so, it would detect radiation as it propogates from a target object and not have to 'illuminate' or 'stimulate' it to return a result.
  • Even though its old news, maybe we should still keep our eye on the rise of cancer cases coming from the border areas now.
  • by Patrik_AKA_RedX (624423) <(moc.liamg) (ta) (neyeatsonav.kirtap)> on Monday March 07, 2005 @09:07AM (#11864395) Journal
    We should have seen it coming: tin foil hats are useless now...
  • ... for the muon-detector-industry.

    As for delivering delivering plutonium to the US, it seems using trucks isn't necessary at all, this [missilethreat.com] seems much more practical.
    • this seems much more practical.

      Indeed. At least until we deploy this [missilethreat.com] all over the Sea of Japan in 2005.
    • Yes, But as John Stewart pointed out those missiles can only reach Blue states so the White house isn't concerned about them
    • You can't trust what MissileThreat.com says about missile threats. Every page declars they're promoting SDI. They're interested in contracts, not truth.
      • Point taken.

        The point that I was trying to make, in a cynical way, is that if/when people really want to get something in, they will. Compare it to the 'war on drugs': it may have had an influence on the price of drugs, and the prisons may be a bit fuller, but that's about it. Everything is still available, if you're willing to pay the price. And the price won't be an issue in the case of plutonium.
        • I like this muon detector - better than X-rays etc, at least. And it seems like "dual use" tech for government investment. I just distrust the whole system, because I expect they'll deemphasize nonproliferation (at the source), which will increase the global nuclear weapons industry, with inevitable catastrophes, here or abroad.
  • by PiMuNu (865592) on Monday March 07, 2005 @09:21AM (#11864485)

    The reason muons don't stop inside our bodies is because they (a) don't interact with atomic nuclei much and (b) are quite heavy.

    So there are lots of different particles, like protons and neutrons or electrons, that you could use.

    But protons bounce off atomic nuclei because they see something called the "strong force". This means they stop very quickly.

    On the other hand, electrons don't see the strong force, which means they don't bounce off the atomic nuclei much at all. In fact, electrons spend all their time bouncing off the electrons that whizz round the outside of the atom.

    The thing is though that electrons are much lighter than protons, so even though they only see the electrons in the atom, they still bounce right off them. The same goes with photons (e.g. light, x-rays).

    This means that the electrons (and x-rays) get stopped very quickly too.

    So both the electrons and protons get stopped very quickly, which means they deposit much more energy inside you = nasty radiation damage!

    Muons, OTOH, will zip straight through as they don't see the atomic nuclei and are relatively heavy. This means they do less radiation damage, and you need fewer of them.

    This is why you can get away with using atmospheric muons. It also explains why the atmospheric muons are there in the first place - all the other particles get stopped in the atmosphere.*

    *Except some special particles called neutrinos - but let's not go there.

    Here's a general particle physics wikipedia [wikipedia.org]

    • *Except some special particles called neutrinos - but let's not go there.

      Because nutrinos go through just about everything... even if you could build a detector smaller than, say, the earth, it'd be like trying to x-ray a paper bomb inside of a paper suitcase, wrapped in paper... on the other hand it'd be GREAT at finding people smuggling suitcases full of neutronium. Then again the 450,000,000 forklifts the guy uses to move his suitcase would also be an indicator.
    • Oops, muons [wikipedia.org] are leptons [wikipedia.org] just like electrons [wikipedia.org] . They have electric charge and interact with electrons via the electromagnetic force. As such, at relativistic velocities (which they are at, otherwise their half life would prevent them from descending so far into the atmosphere) they act as "minimum ionizing particles" and deposit about 2 MeV per cm^2/gram. multiply the density of an object and its track length and you will get about the amount of energy a meuon will give up while traversing it. For lead (densi
    • It also explains why the atmospheric muons are there in the first place - all the other particles get stopped in the atmosphere.

      Atmospheric muons are not what is left over because all the other particles have been stopped, they are actually secondary particles created by the primary particle interactions in the atmosphere. There are basically no primary muons. Muons survive to the ground because they are created further down in the atmosphere, and as another person pointed out, they are at least minim

      • Fair point, I was sacrificing accuracy to simplicity. Simplicity is happy but now accuracy rears it's ugly head...

        I do stand by my comment that muons of a certain energy penetrate much further through the atmosphere than pions or protons or electrons or gamma at that energy, for the reasons I outlined. Ditto for going through materials like lead. (Except certain special cases like visible light)

        • At the relativistic energies we're talking about here (a few GeV), the dominant energy loss mechanism is through ionization and atomic excitation (for muons and protons, these energies are too low for radiative effects to be important, but as you pointed out earlier they dominate for electrons), which are described by the Bethe-Bloch [web.cern.ch] equation. Basically in this energy range the energy loss is determined only by the particle velocity, so a muon and a proton moving at the same velocity will have the same ran
          • Okay, I'm half swayed - but two things I don't understand:

            1) Where does the energy for all these pions come from? That's 140 MeV per pion... and a pion is a quark anti-quark pair so at least half has to come from the cosmic proton.

            2) Why do hadronic calorimeters stop hadronic showers but not muons? Why do hadrons shower whereas muons don't?

            Both these points boil down to my previous argument, that protons will have hadronic (i.e. strong force) interactions that the muons won't have, which is the domina

            • I am a cosmic ray physicist expatriate, so bear with me as I dust off some brain cells:

              1) The energies of the protons hitting the top of the atmosphere are very very high. The muons themselves at the ground have energies of a few GeV, and they themselves have lost 2 GeV just getting down through the atmosphere. The primary particles (mostly protons) creating the detectable ground-level showers have energies from tens of GeV's on up (TeV's, PeV's, etc.) The fluxes of these particles drop off as a power

              • Okay, so I think the answer is that hadrons do lose more energy going through the atmosphere because of strong force interactions - but some still manage to get through because they have much higher energy to start with. Is that a fair paraphrase?

                So I guess I was right about penetrating the lead briefcase or whatever, but perhaps a little dodgy wrt the atmospheric comment...

                You can't construct and analyze a particle detector these days without a very good physical model of it.

                Don't I know it...

        • well, you also said, "So both the electrons and protons get stopped very quickly, which means they deposit much more energy inside you = nasty radiation damage!"

          An electron and a muon with a few GeV will deposit the same amount of energy in something so long as they exit also at relativistic velocities. So, not quite.

          • No, the electrons will have pair production and brehmstrahlung. Muons will only have ionisation. See other posts.

            Nb: this is a technical subject and not my speciality, but an interesting one - I may be wrong, but I stand by my reference the PDG (linked previously). If you can produce a counter reference, I would be intersted to see it.

            • Oh, this is something that I'm actively researching, so it is my area of speciality. But the theoretical physics isn't the core of what I do so it somewhat isn't. Anyway, read the link to Bethe-Bloch up above to see what I'm talking about. It's the third paragraph that I'm talking about.
  • by Anonymous Coward
    Troy, inventor of such far-out yet functional devices like the bear encounter suit and fire paste, has finally flipped out [baytoday.ca], or maybe he's on to something.
  • by radtea (464814) on Monday March 07, 2005 @11:02AM (#11865380)
    ...3% false positives is still orders of magnitude too high for a deployable system. There are a range of interesting things they might do to improve the accuracy.

    The natural move from my point of view is to look at mu-N interactions, where a muon blows apart a nucleus in the target material, producing a shower of excited nuclear fragments and neutrons. Heavy materials such as plutonium will have a much different cascade signature than relatively light things like iron, so it may be possible to develop a quite specific finger-printing mechanism that would be hard to work around. With a muon detector on top to act as a trigger, and some combination of gamma and neutron detectors nearby, this is might be able to both speed up processing and improve accuracy dramatically.

    Of course, terrorists could always fall back to the obvious plan B: smuggling the weapon in hidden in a bale of marijuana.

    --Tom
    • by Anonymous Coward
      The natural move from my point of view is to look at mu-N interactions, where a muon blows apart a nucleus in the target material, producing a shower of excited nuclear fragments and neutrons . . . . this is might be able to both speed up processing and improve accuracy dramatically.

      Since the inelastic scattering rate is so low, this will end up taking much longer. For 10 kg of plutonium, expect to wait on the order of an hour to see a single inelastic (shower) event, and a single event is not going to b
    • Of course, terrorists could always fall back to the obvious plan B: smuggling the weapon in hidden in a bale of marijuana.

      Or you could just hide it in a shipment of cocaine and let the CIA transport it for you...

  • by Kiriwas (627289)
    We can now see through lead? I feel my childhood collapsing around me... Science has just surpased Superman [wikipedia.org]

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