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Teen Builds Nuclear Bomb Detector
DaneM writes "An enterprising teenage boy named Taylor Wilson, 17, has created a homemade, hand-held nuclear bomb detector. It utilizes a small fusion reactor that he made when he was 14, and detects nuclear materials by shooting neutrons at closed containers and exciting any nuclear materials inside — which, in turn, causes more radiation to be produced, and is detected by the device. This may provide a simpler, more effective alternative to searching containers visually, one-at-a-time. No information is given about how safe such a practice is. Taylor also has some choice things to say about how science is, in fact, very cool."
Must be nice to have your own portable fusion reactor.
Parity: What to do when the weekend comes.
As someone pointed out: building a fusion reactor, while not trivial, is routinely done by tinkerers worldwide: see e.g. this Instructables guide .
No, the truly amazing thing here is what I found when I clicked through to the original story (as usual, not linked in the summary):
Allow me to be the first to say, WHAT THE YELLOW RUBBERY FUCK? In every university department I've ever had experience of, researchers and grad students fight tooth and nail to get funding for anything more expensive than an alligator clip. Meanwhile, these guys have sufficient resources to start handing out equipment and lab space to enterprising teenagers for science fair projects! Hmm, time to start looking for a postdoc position there, I think...
This boy is clearly a genius with unlimited potential. How extraordinarily sad that he is applying all that potential to something as fucking idiotic as counter-terrorism.
Well, there's not much potential use for a fusor in investment banking, so I guess counter-terrorism is where the money is.
Set your phasers on "funky"!
"Fusion reactor" is dumbed-down terminology for the masses. What he's built is probably a Farnsworthâ"Hirsch Fusor which can be made quite small. It's not useful for generating energy as it's very inefficient, but it's a good neutron source. Also, you're missing the point of how his contraption is supposed to work. The radiation detector isn't the part that uses the fusor. The fusor is used to send a neutron beam through the package under test. If it contains enriched uranium or plutonium, the interaction with neutrons will cause it to emit far higher levels of neutron flux and gamma radiation than most other materials. If you see this effect, you might want to inspect the package. I don't know how effective it is in practice, but the premise of operation makes sense.
I assure you, Farnsworthâ"Hirsch fusors exist, fit the dictionary definition of "reactor", are well within the capabilities of teenagers to build, and do emit neutrons.
And I also assure you that when you bombard fissile material with neutrons, its rate of activity goes up, and that increase in activity makes it easier to detect the fissile material with radiation detectors.
The operating principle is given in the second sentence of the goddamn summary: Fire neutrons in, watch radiation from activation products. As others have pointed out, otherwise known as Neutron Activation Spectroscopy.
The fusor is used to send a neutron beam through the package under test. If it contains enriched uranium or plutonium, the interaction with neutrons will cause it to emit far higher levels of neutron flux and gamma radiation than most other materials
And if he does that trick on a barely subcritical mass of uranium 235 or plutonium, it goes bang.
http://michaelsmith.id.au
Read the paper. He bought or built a "Farnsworth Fusor" to send 2.5 MeV neutrons into a package, and then look for high energy products of neutron induced fission from the package. These would be high enough in energy that the natural background would be quite low, making false positives low. There is no reason why this shouldn't work (although whether its practical is another question.)
He tested it on "20 grams of Natural Uranium Trioxide (UO3) containing - 99.3% U238 and 0.7% U235." (In other words, about 0.1 grams of U235.) The integration time he found he needed was 10 minutes, rather than the 15 seconds desired by DHS, but it's an interesting concept. He doesn't do any calculations as to the expected return from an interesting about of U235 (say, 100 grams), but it would be higher, and so integration times should be less.
He also says that the incident beam is low enough not to be harmful : "the system has low enough does as to not affect the health or functionality of the cargo and operator, However, he doesn't state any dosage information, which I would fault him on if I were grading this paper.
You might have misunderstood me. I didn't mean passive neutron radiation detectors, I meant something like this kid built: an active scanner, that's capable of analyzing the contents of the crate without opening it (that's what the article implies). I go a bit further, the real news is not making this, it's how he crunches the data to get the contents from the reflected neutron flux/induced radiation pattern, whichever he uses.
A passive neutron scanner is all dandy and fine, but can be defeated with shielding. This active scanner, developed far enough for sensitivity/crunching capacity, could detect the presence of shielding (though not its contents), which itself would be grounds for suspicion. The passive scanner would just indicate a zero or very low flux, which might be mistaken for background radiation or other, similarly innocuous, explanation.
Chill the f*ck out, and respond civilly, I did not insult you.
Hyperbole: I use it liberally!
I would guess that it is a Farnsworth-Hirsch fusor which is a commercially produced device to produce free neutrons. In terms of application I'd be a little concerned what this device is used to probe. Neutrons are readily absorbed by many nuclei and can produce radioactive isotopes. So scanning an object will result in making it radioactive. While I would hope the number of neutrons required would be small, and so the activation minimal, this is still probably a concern for foodstuffs since radioactive material is a lot more dangerous inside the body than outside. Same applies for clothing too probably.
The other issue is that since a nuclear device is a sub-critical mass of fissile material bombarding it with enough neutrons may actually make it supercritical while it is in the beam if the beam balances the neutrons lost. This would let you "detect" the bomb put perhaps not in a very constructive way...although again I would guess that the number of neutrons used for scanning would probably be too small to do this.