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Science Technology

New Neutron Scatter Camera to Detect Smuggled Nukes 125

Posted by ScuttleMonkey
from the size-matters dept.
Researchers at Sandia National Laboratories in California are developing a new neutron scatter camera that they claim will be able to detect radiation through much more shielding and at much greater distances than traditional tech. "The neutron scatter camera consists of elements containing proton-rich liquid scintillators in two planes. As neutrons travel through the scintillator, they bounce off protons like billiard balls. This is where "scatter" comes into play -- with interactions in each plane of detector elements, the instrument can determine the direction of the radioactive source from which the neutron came. [...] Computers record data from the neutron scatter camera, and using kinematics, determine the energy of the incoming neutron and its direction. Pulse shape discrimination is employed to distinguish between neutrons and gamma rays."
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New Neutron Scatter Camera to Detect Smuggled Nukes

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  • by Anonymous Coward on Monday November 26, 2007 @02:22PM (#21482575)
    This is part of the problem with working under government contracts on projects and interests that are ultimately unrelated - you always have to justify the research. I worked in this department at Sandia for a few summers, and that was generally the opinion I heard. Everyone there is interested in fusion research to provide cheap power to the world, but they have to do this research under the auspices of supporting national security or nuclear stockpile stewardship. Everyone working there knows that that's not the actual reason for the research, but it keeps the funds flowing in.
    • To clarify (Score:3, Interesting)

      To clarify, this neutron camera is nice for nukes, but what they're actually using the technology for is to examine neutron emissions from fusion capsules compressed with their z-pinch machine.
      • I could be totally wrong about this, but I think this camera only detects radioactive material that is near critical mass. The instrument would send out a pulse of neutrons at cargo entering the country, and wait for an echo. If there is any bomb-grade uranium in near-critical concentrations, the neutron pulse should trigger a lot of reactions, which hopefully this camera would detect. I suspect it's still hard to detect the material, unless it's really close to critical, but I really don't know.

        Here's
  • Expected outcome (Score:4, Interesting)

    by TheMeuge (645043) on Monday November 26, 2007 @02:24PM (#21482593)
    1. DoD contractor produces a prototype, then obtains a $100M grant from the DoD to pursue it further.
    2. DoD contractor requests $50M for additional research and receives it
    3. DoD contractor delivers the detector as a proprietary black box, running Windows, at a price of $10M each. 50 units are ordered by the government.
    4. 5 CalTech students make a working detector for $20'000 out of an old scintillation counter, plumbing pipe, and a PentiumIII machine running BSD.
    5. Nobody cares.
    • I wish nobody cared, but this will only fuel the masses into thinking "wow... all this money spent on high-tech, super sci-fi counteterorism stuff is making me safer."

      Don't get me wrong being able to detect a nuke is a good thing. However, to me this seems to fit right in along with the whole security theater schtick that the government is pulling. Throw out some nifty vaporware. Have some conveniently thwarted plots and you have a carte blanche to do whatever you want with personal liberty.

      Without ge
      • by tjstork (137384) <todd.bandrowsky@gm a i l.com> on Monday November 26, 2007 @02:42PM (#21482849) Homepage Journal
        Don't get me wrong being able to detect a nuke is a good thing. However, to me this seems to fit right in along with the whole security theater schtick that the government is pulling. Throw out some nifty vaporware. Have some conveniently thwarted plots and you have a carte blanche to do whatever you want with personal liberty.


        Well, the whole point of having devices like this, is that, if you can directly detect somebody trying to smuggle in a nuke or even a backpack bomb, you don't need to spy on the whole country because you are afraid someone might.

        Advances such as these should be trumpeted, as much as possible, to indicate that we don't need to have our civil liberties trampled in order to defend ourselves. That is, defending against terrorism is something for grad students to work on with big defense grants, not, a bunch of jackasses that want to play rent-a-cop at the CIA.
        • Advances such as these should be trumpeted, as much as possible, to indicate that we don't need to have our civil liberties trampled in order to defend ourselves. That is, defending against terrorism is something for grad students to work on with big defense grants, not, a bunch of jackasses that want to play rent-a-cop at the CIA.

          Well put, and I agree. However that's not the connection that is going to be made. Due to whatever reason, the general public will only see this as the government hard at work
          • by tjstork (137384)
            Due to whatever reason, the general public will only see this as the government hard at work on protecting us. Successes like this lend credibility to the administration across the board

            See, I don't think that at all. I think people will be like, geez, why do I have to do all of this search crap, when all ya need to do is buy a scanner. Really, the RADAR gun used by police to catch speeders is the appropriate metaphor.
            • Somehow there must be more money to be made in methods more corrosive to personal liberty than in tools like these. If it be not the money, then it becomes a pure political (read: human nature in practice) issue whereby the obscenely wealthy few rule as $DEITY over the less fortunate many.

              Human depravity is the most controversial religious doctrine precisely because it is the most empirically provable.
        • "Well, the whole point of having devices like this, is that, if you can directly detect somebody trying to smuggle in a nuke or even a backpack bomb..."

          That is actually not the point of devices like this. The point of this device is to keep the federal funds flowing to Sandia researchers. This is because the researchers are interested in fusion research to provide cheap power to the world, but the government has always only cared about nukes and national security. So researchers are occasionally forced t
        • by 6Yankee (597075)
          if you can directly detect somebody trying to smuggle in a nuke or even a backpack bomb, you don't need to spy on the whole country because you are afraid someone might.

          But surely we still need to spy on the whole country, so we know when the Bad Guys have learned to get nukes past our nuke detectors?

          Although, the big mushroom cloud in the parking lot might clue us in.
        • by ZDRuX (1010435)

          Well, the whole point of having devices like this, is that, if you can directly detect somebody trying to smuggle in a nuke or even a backpack bomb, you don't need to spy on the whole country because you are afraid someone might.

          Riiiiight... because once they have this in place, they`ll stop spying on your phone calls right? I mean.. thats what it's for isn't it.. if no nukes/bombs can get into the country then we don't need to spy on our citizens because nobody has bombs right?!.. No ofcourse it's wrong

          • by tjstork (137384)
            Riiiiight... because once they have this in place, they`ll stop spying on your phone calls right? I mean.. thats what it's for isn't it.. if no nukes/bombs can get into the country then we don't need to spy on our citizens because nobody has bombs right?!.. No ofcourse it's wrong, the Orweillian state will such continue growing uncontrollably

            The hope is that Orwellian states are invariably made up of stupid people that don't give a shit.
      • I wish nobody cared, but this will only fuel the masses into thinking "wow... all this money spent on high-tech, super sci-fi counteterorism stuff is making me safer."

        And it isn't... How?

        I know I'm off-topic

        This, accompanied with "clueless" and "tinfoil hat" pretty much sums up your whole reply. Increasingly when I read comments on security - as soon as I see the buzzword[s] "security theatre" tossed out, it's prima facie evidence that the writer thereof has no fucking clue what he is t

        • Answer this in a free society threat is pretty much always extant whenever someone is determined enough. Short of everyone living in castles there is no way to neutralize any threat. Airport screenings and things of that nature are to some degree "theater" or whatever term you prefer. They are feel good measures. Do they have some measure of security provided? Yes. However, when it's all said and done without a completely closed society you're always vulnerable.
    • by ivan256 (17499)
      You've got the order backwards:

      1. 5 engineering students and one professor make a working prototype for under $20k
      2. DoD contractor requests $50m to productize the research
      3. 2 grad students (part of the original 5) improve the design as a product funded (Maybe $100k) by aformentioned DoD contractor
      4. The university and contractor get a co-patent
      5. The DoD contractor sells the $10k units for $10m to the US government. The university gets a 10% cut. The grad students get a $375/month student loan bill over 3
      • by megaditto (982598)
        Grad students that do research get a "free ride" on tuition from the uni in most cases, and even a small stipend.
        • by ivan256 (17499)
          That's true for many grad students... Not all grad students though. Usually they have to teach, or the like to get a deal like that, and few schools can offer it to all their grad students.

          Regardless, most of those students still have loans from their undergrad study which have been accruing interest while they were deferring payment to get their graduate degree.

          Incidentally, in recent times those interest rates have been high, since congress has funded all of their higher education affordability initiative
    • Re: (Score:2, Troll)

      by nasor (690345)
      Okay, let's see here...strokes kill about 150000 people each year in the U.S., and the government spends about $400 million on stroke research. Terrorists with radioactive materials have killed approximately zero people ever, and the government spends $650 million+ on (admittedly clever) directional radiation detectors. Yeah, we're clearly doing a great job of rationally allocating our money.
      • Yes, but consider how many people could be killed by a nuclear weapon being exploded in a major metropolitan area. Also, when people die of strokes, they tend not to do massive damage to surrounding infrastructure.
        • by davidsyes (765062)
          Why was the immediate parent marked 0, Troll?

          Hell, we attribute some things to "Mother Nature" and live with it. We don't call Her a "bitch", or "asshole", or such. Why not see Terrorists as reactionary cells (cancerous, whatever....) to other cells (white, whatever...)? When the cell count in the body goes out of the norm (being set by evolution, environment, local exposure...), white cells attack the "undesired" or rogue (rogue until THEY take over...) cells and attempt to snuff them out.

          We all have brain
      • by ArcherB (796902) *
        Okay, let's see here...strokes kill about 150000 people each year in the U.S., and the government spends about $400 million on stroke research. Terrorists with radioactive materials have killed approximately zero people ever, and the government spends $650 million+ on (admittedly clever) directional radiation detectors. Yeah, we're clearly doing a great job of rationally allocating our money.

        using your logic:
        100% of our security budget should go towards death prevention since 100% of people will die at some
        • by Torvaun (1040898)
          Given that we don't have airport security now, I could get behind spending a little less money on it.
        • Re: (Score:1, Troll)

          by nasor (690345)
          No, according to my logic if zero people died in plane hijackings last year but tens of thousands of people died due to X, we should probably be spending more money fighting X than we spend on preventing plane hijackings. I thought about writing out a long post about rationally fighting threats according to how dangerous they are, but judging by your post I doubt that you would be able to understand it.
          • by ArcherB (796902) *
            No, according to my logic if zero people died in plane hijackings last year but tens of thousands of people died due to X, we should probably be spending more money fighting X than we spend on preventing plane hijackings. I thought about writing out a long post about rationally fighting threats according to how dangerous they are, but judging by your post I doubt that you would be able to understand it.

            Now, now. No point in dropping to the level of personal attacks.

            Now back to your logic. That is a tired
            • by dgatwood (11270)

              That logic is pretty badly flawed. By your logic, my pet rock protects against tigers because I haven't been attacked by a tiger today. There are no hard numbers that suggest that the risk of terrorism has decreased; terrorist attacks are so infrequent (at least on U.S. soil) that measurement using statistics is not particularly practical. If we were looking at something common like murder rates, that's a different story... and all those things that you gave as counterexamples are things for which the ri

              • by ArcherB (796902) *
                Regarding nuclear plant safety, nobody has died recently in the United States. This is not true for the world as a whole.

                Very true. It is also true that regarding terrorism, nobody has died recently in the United States. This is not true for the world as a whole. Further, because these are maniacs, they will eventually succeed, so the question then becomes one of how quickly the population's interest typically degrades. With that information, you can then quantify the probability each year of a security m
                • by dgatwood (11270)

                  Your argument about power plant safety is silly. Power plants degrade with time. Failing to do things to ensure their safety will result in catastrophic failure. The only question is when it will occur, and those numbers are easily obtained. You can thus trivially calculate the number of people who will die and at what rate if power plants are not maintained. The fact that we have not had deaths due to that cause, then, can clearly be attributed to safety measures. This is not true for terrorism. Ind

                  • by ArcherB (796902) *
                    Your argument about power plant safety is silly.
                    I disagree, but let's look for something we can agree on. What about nuclear power plant security? What about the securing of nuclear weapons? More people have died from X than have from stolen nuclear weapons/sabotaged nuclear power plant. Why do we spend so much securing them? Shouldn't that money be spent preventing X. After all, that is what is killing us!

                    Oh, and you're also wrong. The latest major commercial airline crash in the U.S. was just a litt
            • by nasor (690345)

              Maybe you should consider the idea that all this money we are spending on fighting terrorism is working.
              This $650 million was money spent on even more security, not merely money spent to maintain our existing security. The issue here is whether or not we should be spending even more money on a "threat" that already wasn't killing anyone.
      • How many votes will additional money for stroke researching bring? As Nixon once said, "Fuck the Jews, they don't vote for us anyway." Which is to not to say that I liked Nixon or dislike Jews, but the politics of pork determine what gets spent where. And what government money IS spent on stroke research is probably because some medical lobbyist has a relationship with a Congressman or Senator, or the bribe was sent to the right place (Duke Cunningham or Jefferson maybe) rather than any real application
      • by Roger W Moore (538166) on Monday November 26, 2007 @04:46PM (#21484487) Journal
        Okay, let's see here...strokes kill about 150000 people each year in the U.S., and the government spends about $400 million on stroke research. Terrorists with radioactive materials have killed approximately zero people ever, and the government spends $650 million+ on (admittedly clever) directional radiation detectors. Yeah, we're clearly doing a great job of rationally allocating our money.

        You fail to understand statistics. The 150k strokes a year is a large statistical sample and thus it is easy to predict the number from one year to the nect with some degree of statistical accuracy.

        Now consider the nuclear case. There have been zero incidents since nuclear weapons existed in man-portable form, say 20 years ago. Now assuming a poisson distribution of events this means that we can conclude with a 95% confidence level that the rate of such events is less than 3.09 per 20 years i.e. less that a roughly 15.4% probability per year. Assuming that such an event would kill 1 million people this means that we are only 95% certain that the annual death rate from such terrorism is less than the death rate from strokes.

        However the above is a conservative estimate because technology is making it easier to build nuclear weapons so whereas the above calculation assumed a constant probability distribution of such events that is not correct and it is getting more and more probable. So really we are less than 95% certain. In addition comparing the death rate is not a fair statistic. A better comparison would be years of human life lost. A majority, but certainly not all, stroke victims are old or have recently suffered other life threatening conditions like a heart attack or aneurism. However a terrorist bomb would kill children as much as the elderly (and everyone in between).

        So while you cannot show that this is the most effective way of spending money to save life neither can you show that it is not. However given the uncertainties in any such calculation it is far from a total waste of time which is what you were suggesting.
    • Re:Expected outcome (Score:4, Interesting)

      by Joe the Lesser (533425) on Monday November 26, 2007 @03:26PM (#21483423) Homepage Journal
      Or:

      1. DoD contractor delivers working unit, thoroughly stress tested in the real world, has ability to mass produce unit quickly with solid quality control.

      2. CalTech students produce one for cheap that supposedly works in their lab, then graduate and go to work for DoD contractor and get paid six figures.
  • by Anonymous Coward
    It is funny how much of the federally funded research right now appears to be directly applied to counter-terrorism efforts. I am all for that being done, but from what I have noticed when going through the national labs web-pages, it seems that the majority of research dollars are going to these efforts. I think that if you counted military research labs, you might find that more federal dollars are going to counter-terrorism than are going to alternative energy projects.
    • by InvisblePinkUnicorn (1126837) on Monday November 26, 2007 @02:30PM (#21482703)
      The researchers in this case are interested only in the science, but in order to get the government funding, they need to think up ways that their research could be used by the government. A hot-button issue for the government is national security, so applications related to that are the best to mention. In reality this neutron camera is for fusion research that could ultimately provide cheap power to the world.
      • Your response was well reasoned, very insightful, and thought provoking.

        Are you sure you belong here? Judging by your user Id, I'm guessing your brains haven't yet been rotted by hot grits. You may want to run while there's still time.
      • Yep. Back in the 70's and 80's 'alternate energy' was the hot buzzword... every goverment agency and a huge chunk of goverment research contracts were working hard on 'em.
         
        We see how that worked out.
        • "We see how that worked out."

          Besides being limited by the amount of funding available, fusion research has been hindered by various complex interactions that were not originally known about. With greater understanding comes greater control. The ends will ultimately justify the means.
          • There's other forms of alternate energy than fusion. NASA, in particular, spent megabucks on windpower and solar cells. With little result.
            • The ambition was there, but not the technology. In the case of solar, it was not financially feasible yet, but is now becoming so due to technological advances. In the case of fusion, we're not even to the point yet of thinking about financial feasibility - we still have to work out how best to get the job done (my money's on inertial confinement), and then work on how best to repeatedly produce the reaction in a financially feasible way.
              • -5 misses the point.
                • I think you're missing the point. The only way we could made the advances we did would be through experimentation. Saying we spent a lot of money and got nowhere is ignoring the progress that has been made, especially with respect to the fusion research done at Sandia, the subject of the article.
      • I somehow doubt that the people will mind if this money is WASTED when the nuke-CARRYING ship just fires the damned nuke from a container picked up in transit, unmasked when at some optimal firing range, and then launched before entering the port supporting the background scanner.

        No, these scanners will make a BUNDLE of money for SOMEbodies. Why? They irrationality of port-of-entry scanners being land-locked will come to the fore and some enterprising person or company will propose mounting the scanners alo
    • In a perverse way, these seemingly misplaced priorities actually make sense. When conflict is possible in the distant future, you make long term strategic moves like under cutting your opponent's economy ( in this case alternative enrergy to undercut oil). When you believe that conflict is imminent, you go for defensive measures.

      A parallel example is Japanese aircraft in WWII. Right up to the surrender they were developing better and better fighters/interceptors. Yet their primary bomber - the 'Betty
    • It's all marketing. If you're not involved in the war on terror you get your funding cut. Maybe this will change in 2008, maybe not. In order to get people to give you money, they have to care about what you're doing. The most effective way to get people to care is to play the fear card.
    • Something that might be worth considering is that a lot of other uses (good or bad) tend to spin off research in one particular field. How many commonplace technologies today are credited with being derived from aerospace research (i.e. "Space Age" technologies)? Though more ominous sounding, there's a number of useful tech ideas that may result from such counter-terrorism research as well. I would agree however, that I'd prefer the primary focus of the initial research to be on something with a more no

      • by Kazrath (822492)
        When I was younger I worked at a resourt doing houskeeping and eventually interior painting as a Journeyman's helper. During the summer I would sit out on the beach and chat with individuals and families whom vacationed there. One Middle Eastern man was there with his family and during our conversation it turned out he did biological weapons research and methods to apply this technology directly to medicine.

        I am just indicating exactly what the parent already stated. Once the technology is created it is
  • Are we talking feet? Inches? Miles? What's the range of "traditional tech", and how much is "much greater"?
    • Re: (Score:3, Informative)

      by Zymergy (803632) *
      It has the "potential to detect through various types of shielding" and "through more shielding" (FTA) but what types of shielding and at what thicknesses? Soil, Rock, Water, Lead, Etc?...
      This Reads: 'fancy new-fangled oceanic Shipping Container Nuke Detector' all over it, and maybe something new for surveillance aircraft too.
    • Good point. If the distance is the range of say the whole earth, wouldn't the "Nuke Found" LED be on constantly?
  • This is good because I don't know about you but I wouldn't want my city to be
  • I ignore TV and only watch what my friends watch (sometimes) but I can't help but thinking that (based on my reading and understanding of the Iranian threat) the hit TV series "24" might have done America a favour in showing them how the next domestic terrorist attack will happen? They were theorizing as am I, but Iran sure sure scares me a lot more that Kim Jong Il. At least Iran has people to carry the bomb who wouldn't defect as soon as they got out of their country.
  • If you are going to smuggle a nuke, for terrorism or 'middle finger to the UN' purposes, why would it ever be that thoroughly shielded? I mean, you may or may not want it to kill everyone that comes into contact with it, but are you really THAT concerned with the radiation being detected from afar? If it were discovered, why not just detonate the SOB and then go around hinting that you have more of them?

    IANA[Nuclear Arms Dealer], but this seems more meant to detect the locations of nukes in established na
    • by cowscows (103644)
      Uhhh...it seems to me that generally a terrorist involved in a destructive act has as a main goal the largest body count they can manage. While a nuke going off on a ship in a harbor would no doubt be very destructive and possibly kill thousands of people and cause a lot of panic everywhere, the effect would certainly be greater if you managed to get the bomb into the downtown area of a big city and kill hundreds of thousands of people.

      Either way you're likely to see some serious retaliation, so why not tak
      • by BobMcD (601576)

        ...it seems to me that generally a terrorist involved in a destructive act has as a main goal the largest body count they can manage.

        I don't think you're basing this on any actual data or observations. I know that this is what we're told on a regular basis, but it just doesn't jive.

        It doesn't take very long to come up with some scenarios with a much-higher body count than we've seen thus far due to terrorism. Biological agents in the water supply comes to mind. I'm sure there are tons of others.

        None of these have been attempted yet, and I suspect there is a good reason for it. Personally, I look to the name - 'terrorism' implies th

        • by cowscows (103644)
          No, I'm not basing it on any sort of data or observations, because as far as I know no terrorists have detonated nukes lately. But, I sort of agree with your general point. Bin Laden isn't too concerned with blowing up parts of America right now because the ultimate goal of the attacks on the WTC and such were not just to kill people, it was to spur the US into making certain responses (and we've probably been following the script pretty closely). Even if the death count from 9/11 was much higher and 20,00
    • by vertinox (846076)
      If you are going to smuggle a nuke, for terrorism or 'middle finger to the UN' purposes,

      Why would you even need to smuggle it? A terrorist worth his salt could highjack a cargo ship without anyone know it, sail up into NYC harbor, get as close as possible to the docks (and or downtown) and then just detonate it as their about to be boarded by the authorities when they notice something is amiss.

      If they needed something further inland, they could construct a crude ballistic missile and launch it from a ship.
    • If the detection range is really far (as in satellite range) you can locate and potentially eliminate an enemy's arsenal before it launches.

      [I did not read the article.]

    • Think this through a little more carefully. Where do you find weapons-grade fissionables? Iranian centrifuges notwithstanding, it's still very difficult to enrich uranium unless you're a fairly wealthy country with a biggish industrial plant devoted to the cause (which then makes you a tempting target for IDF air raids, cf. Syria, recent mystery raid into). And to make Pu, you need a working nuclear reactor, plus some decent chemists on staff. Not likely if you're al-Wacko, the latest crazed Islamic sui
      • by BobMcD (601576)
        That's an excellent point.

        I'd wager, though, that due to the value of these items, the ones that are at risk would probably be sold before stolen in almost every case.
        • Oh aye. That's why I mentioned the Russians. It's certainly a lot cheaper to find a disgruntled Russian corporal who doesn't mind earning ten years' salary in ten minutes by turning a blind eye than mounting a Mission : Impossible operation to steal a warhead.

          That's also why I suggest an important use is to backstop the human component of nuclear stewardship. Put one of these guys next to the main gate of your storage depot, essentially. Even if SSgt. Ivan sells his soul for 30 pieces of silver, the ala
          • You'd never have the folly committed last month, when a bomber was accidentally loaded up with nuclear weapons and flew across the country with them ...

            Let's hope to God it was accidental. No way to be sure -- if it was deliberate, surely they wouldn't admit it.

            Not to get all paranoid, but weapons do get diverted into private hands. I can't find a link, but back in, oh, the late eighties, I remember reading about weapons diversions from Fort Bragg -- automatic rifles going over the wall and into th
  • Yes, but does it detect nucular weapons?
  • by t0qer (230538) on Monday November 26, 2007 @02:51PM (#21482961) Homepage Journal
    proton-rich liquid scintillators


    That kind of hot geek talk gets my protien rich liquid scintillator scintillated.
  • While some gamma rays can be blocked from detectors, neutrons are much more difficult to conceal. In a lab test, the camera easily detected and imaged a source placed across the hallway, through several walls and cabinets.

    I'm not a physicist, but I do know that slow neutrons are easily blocked by a several common elements like boron and hydrogen (I know there are more, but it's been a while). Shields can be easily built with a mixture of boron and wax, even a Google search for "neutron shield" returns products ready to buy. I'm not in any knowledgeable position to comment on the effectiveness of this device, but if it becomes widespread, wouldn't it be trivial for a large, evil entity hiding smuggled nuclear materials to in

    • by wattrlz (1162603)
      The detector is specifically designed to detect high energy neutrons, which are much more difficult to stop. AFAIK (and IANA[nuclear physicist]) the only way to stop fast neutrons is to bounce them off something until they are slow neutrons and can be dealt with normally.
      • Ah, makes sense. I just looked back over the article and I completely missed this bit the first time:

        "It doesn't have to worry about the low-energy nuisance neutrons that are always all around us because it can only see high energy neutrons, and the high-energy neutrons carry almost all of the imaging information," says Lasche.

        I guess you would need some kind of water cooling facility and a lot of effort to get them down to an acceptable energy. Well, nevermind then, thanks -Julius

      • I don't know the exact value for this type of neutron spectrum, but for graphite fast neutrons (from fission ) on average thermalise after traveling about 18cm. The hydrogen in light water has an even smaller mass than carbon, and thus moderate neutrons very effectively. I'm not quite sure what the average distance needed for thermalisation in water is, but I imagine it can't be much more than for graphite. Hydrogen is also quite a good neutron absorber.

        In addition, all fruits and plants contain some boron,
  • So detecting charged particles and figuring out how much energy they are ejected with is easy to do. But neutrons obviously lack Coulomb charge, so you couldn't use an applied field and see how much they bend, as you would with ejected electrons. Maybe I misunderstood and they aren't really detecting how much energy they are ejected with. Someone fill me in. How do you determine the trajectory and kinetic energy of chargeless particles?
  • Smuggling a nuke wrapped in a bale of marijuana will no longer be plausible option.
  • A few years ago, one of the TV network investigative shows did a piece where they smuggled some 'look-alike' fissionable material through customs. That was in the port of Long Beach, IIRC. The current technology detectors could have picked it up, but as red-faced law enforcement authorities explained, they were too understaffed to do adequate checks on incoming cargo.

    As a local LA radio personality put it: They don't have the manpower to check the ports out because all the cops are working undercover at the

    • by bcattwoo (737354)
      Why would they bother bringing it through a port at all? Drug smugglers and human traffickers have already developed efficient methods for getting goods into the country. There is no way that Osama, having finally gotten his hands on a nuke, is going to put it on a cargo ship and cross his fingers.
  • by ryanisflyboy (202507) * on Monday November 26, 2007 @03:23PM (#21483397) Homepage Journal
    A local nuclear physicist in our area recently commented about the current detection systems in use. He regarded them as so easily thwarted they are basically worthless. He even described how to do it on a local news broadcast (sorry, I couldn't find a link). It basically involved very low cost (common) materials. He indicated the type of technology talked about in this article is really the only meaningful method for detecting nuclear material. He further stated that the organizations responsible for detecting this material know what they are using is worthless, but are unwilling to spend the additional money needed for the correct technology. He was upset that they were more interested in putting on a 'show' of force, rather than offering real protection.

    Let's hope that isn't true, and places like Sandia are working on making nuetron detection less expensive.
  • by radtea (464814) on Monday November 26, 2007 @03:38PM (#21483571)
    Nick (assuming it's the same guy and not some other Nick Mascarenas) was a post-doc in the same lab as me at Caltech in the early '90's. We were working on a reactor neutrino experiment (now defunct) looking for neutrino oscillations. Discriminating against fast neutron backgrounds was an important part of the design problem.

    What has been done here is fairly clever, although I'm doubtful as to the ultimate viability due to low cross-sections and high backgrounds and easy work-arounds by the bad guys.

    Spontaneous fission produces fast neutrons, which are relatively hard to shield against. First they have to thermalize, then get captured. Things that are good at shielding gamma rays (heavy elements) are lousy at thermalizing neutrons (light elements), so it makes the bad guy's shielding problems harder to solve.

    Ergo, if you can detect fast neutrons, and determine where they are coming from, you have a backup bomb detector that is harder to beat. The way Nick is proposing to do this is with a setup in which you have two planar liquid scintillator detectors and look for coincidences (suitably delayed by the neutron's quite significant travel time) between them. Fast neutrons deposit energy into the detectors via proton recoil, which creates a distinct kind of optical event from electron-positron showers produced by gamma rays. Furthermore, you tend to get forward scattering, so you can at least tell which hemisphere the neutron originated from, most of the time.

    The data analysis is tricky, the neutron detection rates will be low, and if I was designing this I'd go for a thick secondary detector and count on thermalization and capture to create the secondary signal, rather than having a thin secondary detector looking for another recoil event. With a segmented detector or similar you'd be able to still do a reasonable job of the kinematics.

    Discriminating against cosmic ray neutrons is going to be painful for this technology, however, and furthermore the comment that another poster made that "this tech shows we don't need to give up our civil liberties to be safe because it proves we can catch stuff at the boarder" is to my mind utterly wrong-headed. It assumes the border can be made perfectly impermeable, and that is simply not the case, as a million kilos of grass or whatever it is a year proves. As long as there is a chance that one bad guy can slip something through, Americans have two choices: be willing to die for your freedom, or give up your freedom (and be willing to die anyway, because a police state will not protect you.)

    Final thought: we used to joke, back in the day, that we could sell our detector design to the U.S. navy as a means of detecting stationary nuclear submarines (it took a couple of days for useful neutrino statistics to build up when the prototype detector was about 10 m from a reactor core.) It looks like Nick might have found a way to do something very close to that after all...
    • by lucifig (255388)
      Er...that post made me feel really dumb. I'm going to come up with a Soviet Russia joke to compensate.
    • I have to say you are right about it being difficult to detect compared to a cosmic ray background.

      52kg of Uranium-235 ( the amount needed for a critical mass without a neutron reflector) will emit 156 neutrons per second due to spontaneous fission. The amount of uranium in an implosion-type nuclear weapon would be less since the critical mass decreases with density, but it would unavoidably contain some U-238 which has a higher spontaneous fission rate, so within an order of magnitude 100 fissions per seco
      • Seeing that fission neutrons on average thermalise after diffusing through about 18cm of reactor-grade graphite, and are absorbed after about 50cm, detecting only fast neutrons is probably not going to give many counts compared to the background.

        The key word here is "average", prompt neutrons from fission have energies ranging up to 15MeV, and total cross-sections trend downward with increasing energy for almost all materials (for En>1MeV). In addition, a large chunk of 235U will probably have more more fissions induced by cosmic ray induced neutrons than spontaneous fissions.

        You're right in that Pu is a lot easier to detect than 235U.

    • by Chris Burke (6130)
      Discriminating against cosmic ray neutrons is going to be painful for this technology, however, and furthermore the comment that another poster made that "this tech shows we don't need to give up our civil liberties to be safe because it proves we can catch stuff at the boarder" is to my mind utterly wrong-headed. It assumes the border can be made perfectly impermeable, and that is simply not the case, as a million kilos of grass or whatever it is a year proves. As long as there is a chance that one bad guy
  • by petes_PoV (912422) on Monday November 26, 2007 @03:57PM (#21483845)
    and now the bad people have one: get their nukes (or at least the fissionable components) into the USA before these detectors get rolled out.

    How long? let's see. if they're "developing" it now, say 3 years until it's in production and another year until it's at the major points of entry. But you've got to cover all the points of entry - sea, air(freight), land via Canada and Mexico. Make that about 10,000 PoE in all, so you're talking about another couple of years at least. That means about 6 years or until the beginning of 2014 to get a few grapefruit sized pieces of metal across the border.

    Really bad thought: maybe it would be easier to get material that's already in US stockpiles - what use are border checks then?

  • All one has to do it put a nuke on a ship and get it close to a major port city, then detonate it. Total destruction without going through Customs.
    • Exactly.

      Most of our major ports don't even screen until after the ship is unloaded.

      And forget about screening at regional ports.

      Never send a Red to do a decent security job - only a Blue will do.
  • Of note: if you use this system to scan containers, post office mail or airport luggage: it will destroy any photographic film in them (but have no effect on CCDs). Yes, I do work on nuclear reactors and neutron beams. Similar detectors are already in use at some large airports, for freight.
    • This detector is looking for the neutrons emitted by the nuclear material and doesn't involve using a neutron beam for interrogation.
      • by dargaud (518470)
        My bad. I'd skimmed the summary, thinking it was another kind of neutron tomography system. I'll have to read it to see how it's different from classic neutron detection (may be useful for our current experiments !)
  • Reminds me of that recent blurb about the Chinese nuke sub that surfaced in the middle of one of our naval exercises... maybe we could use a Neutron Scatter Camera to detect Chinese subs...?
    • by BCW2 (168187)
      It was not a nuke, it was a diesel electric. Since d/e boats have no cooling pumps they have always been quieter than nukes.

      Trust the word of an old sub sailor, I really do know what I'm talking about.
  • "containing proton-rich liquid scintillators in two planes."

    does this sound delicious to anyone else?

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