Geiger counters are so last summer. Lasers can detect radioactive material too, y'know Lasers could be used to detect radioactive material secretly transported to and from ports one day, according to a group of physicists from the University of Maryland in the US. The boffins describe a proof-of-concept method that can sniff out the particles emitted from radioactive decay using a technique known as an “electron …
but isn't the significant thing about an alpha decaying radioactive source the fact that alpha particles don't go all that far in air, and can be stopped in general by even packaging, let alone shielding? Unless of course it's such a strong emitter that it's glowing in the dark and already looking distinctly unhealthy to all and sundry?
The point being that someone smuggling radioactives is hardly likely to stick them conveniently on the outside of the box.
Or did I misunderstand something fundamental in either the piece, or in 40-year-old A-level physics?
My primary field is nuclear engineering and you aren't the only one a bit puzzled by this. Theoretically, that alpha particle should be moving at a very good clip so, perhaps, there is sufficient penetration outside any containment to be significant. I really need better numbers to say one way or the other. As to the assertion of radically improving the detection range, that's another wait and see. If you check the article (not paywalled, yay!) they use numerical simulations to make their case. I've enough engineering to know: "In theory, theory and practice are the same. In practice, they ain't."
By the way, this principle should also work for beta and fast neutron emitters which is promising right there. Now how the heck you'll distinguish natural sources (ceramics, bricks,...) from smuggled material is left as an exercise for the student.
I have the feeling that this would be very easy to get around even using low tech methods. Seeing as we are basically detecting electrons then simply pack your radioactive material in some material that will readily grab that electron and you can no longer detect it.
simply pack your radioactive material in some material that will readily grab that electron
Or just shield your radioactive material as normal, so that the alpha particle doesn't get as far as air in the first place.
This does seem more like a way of scanning for leaks rather than for looking for contraband materials, especially given the potential distance component. Not to say that contraband couldn't leak, but you'd expect considerable precautions to be taken by the smuggler anyway.
"but isn't the significant thing about an alpha decaying radioactive source the fact that alpha particles don't go all that far in air, and can be stopped in general by even packaging, let alone shielding?"
On the one hand, yes. But on the other hand, that applies to any method you might try to use to detect stuff. So this method won't be any worse in that respect, but may have benefits over other detection methods in other ways.
Exactly why they think anyone is smuggling large quantities of radioactive materials through American ports is a more difficult question to answer.
Uhm... this may be a silly question... but what makes you think that they are only monitoring US Ports?
Team America! World Police. (Yes the version w the gratuitous puppet sex!)
(Sorry its Monday.)
But seriously, the proliferation of nukes should scare the shit out of most. Even if you live in the UK and someone did an air burst above San Francisco, (think high EMP low casualties) ... You'd still be royally fscked.
Or NYC.
And vice-vesa. (Living in the US and London taken out w EMP burst.) Are your civilian data centers protected against EMP bursts? I doubt it.
Genuine question... you really think an EMP from an airburst nuke over SF would have enough energy after travelling 5351 miles to take out London?
Stuggling to believe that given inverse-square scaling of enery over distance, and that there's a significant amount of planet between SF and London.
Unless the airburst was pretty much in orbit. And even then it's gotta be a high orbit to see London from above SF.
Yes, an alpha particle emitted by a typical radioactive substance literally cannot fight its way out of a wet paper bag. As proven in Nuffield Physics (ah, those were the days) when our very much not H&S compliant radium sample had its three types of radiation blocked by, successively, blotting paper (another retro ref), aluminium and an inch or two of lead.
"We note that all radioactive sources of interest, whether α, β, or γ emitters, result in free-electron generation from the ionization of ambient air."
Alpha is used as a proof-of-concept. Likely because of containment/safety and convenience/what is available. Optical labs aren't the most spacious of places and things like this are typically built on 3 x 1 m optical tables that need access from all sides.
The advertising point is that this device can be operated in a stand-off manner up to 100 m (with higher pulse energy keep in mind). Seeing how the optics alone will cost more than an industrial Geiger, what's stopping a technician strapping a Geiger meter to a remote control car or a drone and doing the exact same thing?
If I underrstand this correctly...
The seed electron weakly attaches itself to an oxygen molecule. This makes this molecule negatively charged as it now has an excess electron. As the electron is only weakly attached, the laser can easily liberate this electron.
So perhaps the author could have said "[...] laser can liberate those seed electrons"
Overly sensitive radioactivity detectors make nuisance false alarms easy. Uranium is not difficult to obtain in small quantities (over 2000 uranium glass objects are on sale on eBay for example). A few milligrams of a uranium compound on the outside of a container will give as much of a signal as a large quantity of radioactive material shielded inside the container.
"Overly sensitive radioactivity detectors make nuisance false alarms easy"
Yup.
Truckloads of bananas are notorious for setting them off. (Yes, really)
And FWIW: Nuclear _WEAPONS_ use radioactives of very _LOW_ radioactivity - barely higher than background levels until they hit critical mass.
Contaminants like Colbalt 60 (or isotopes of uranium other than U235/U238, or non-bomb isotopes of Plutonium) are _too_ radioactive and cause things to go off prematurely, resulting in "fizzles" rather than "booms"
A good and potentially useful piece of research, but I am not sure how this might be useful in detecting radioactive material secretly transported to and from ports one day, as suggested. The most dangerous materials are alpha emitters (plutonium, polonium, radium etc) and would be contained in packaging that will stop all the alpha particles.
Plus, they are so toxic that only very small amounts are required for nefarious purposes - you aren't going to get a skip full of polonium coming through customs - perhaps a tiny 0.1 millilitre vial of some solution if you are very lucky, from which no radiation will escape.
Um, sorry, but if your method of finding a radioactive source starts with targeting it then your method doesn't work if you don't know where it is.
Geiger counters work because you just walk around and detect radioactivity. The laser method would mean you have to scan every individual package or crate, and that would only work if every incoming/outgoing crate passes through the same point. I don't think that's going to happen at a large port, or any port for that matter.
Obviously, I know nothing about ports (for ships, that is - for firewalls I know more).
If this method works then there is a chance for some improvement over a Geiger counter. I'm imagining here the origin of the laser beam does not need to be near the radiation source, whereas a Geiger counter does. If this is the case then scanning could be done from a distance and presumably at speed.
I think the idea is that instead of walking around a container with a geiger counter, or rigging up some way for a robotic arm / drone to move the geiger counter around, you instead have two lasers at opposite corners of the container. They quickly scan the whole container. Or you have two lasers each side of the gate that the lorries drive through, so you scan containers as they leave the port. Or you just have a laser on a van and drive around the port pointing it at things, you don't have to worry about climbing up close to the containers.
Alternatively, you could imagine that with enough development they may be able to make a hand-held device a bit like a FLIR infra-red scanner, which shows the operator a picture of the amount of radioacivity. They stand on the docks and point it at the containers from a distance, and look for radioactive hotspots to investigate further. This could also be useful to people working in radioactive cleanup (e.g. Chernobyl, Fukushima, Sellafield, reactors being decommissioned ...).
As soon as you start talking about your laser ionising the air (presumably that needs a decent power density) and then detecting the backscatter i.e. you either need incredibly sensitive detectors or need to increase the power some more, I'm starting to wonder if your laser is now a rather serious hazard to all eyes and even physical objects in the vicinity...
Also, there is a hint that they are proposing that this could be mildly covert (e.g. the "length of a football field" comment) which could be slightly compromised by the need to hand out safety goggles first...
"Why do I need these?"
"Oh, no particular reason, just a precaution"
"Oh, right, sure..."
"Seriously, don't take them off though."
I'm pretty sure a laser like that would demolish your eyes before you even had time to blink. The cheap green laser pointers that are sold online can cause permanent damage with only a short direct exposure, since they often don't have an IR filtering lens in them to keep the cost down.
Oh, and most types of safety glasses designed for use with lasers don't filter out IR either (as again, good quality lasers have a built in lens to filter that), so don't be surprised if ze goggles, they do nothing.
The article describes ionising molecules in the air. But doesn't a bit of static do that too?
Could it possibly be that the boffins have done an experiment in a controlled environment, but that in the real world their effect will be dwarfed by what you're wearing, and the carpet?
And what happens in a thunderstorm, when everything is ionised?
As I remember, the Russian assassins who did for Litvinenko didn't make any attempt to transport their polonium in an airtight lead box, so it would have showed up on one of these scanners. It would also have showed up on a Geiger counter, as the isotope they used is more than just a bit radioactive, but I guess maybe they aren't installed in British airports right now anyway.
@YAAC - "Most airports don't check for smuggling weapons off flights."
They do today. Search for "Project Cyclamen". I think that Cyclamen airport installs started in 2005/6, just a bit too late for Litvinenko.
You can spot them in some airports - in others they are built into the infrastructure and can't be seen. Look for beige plastic pillars or frames as you go through the red/green/blue channels when you exit the baggage claim area. Don't look too hard, though, otherwise it could be latex-glove time.
Polonium is an alpha emitter, you can transport it in a small glass bottle and absolutely nothing will leak out. So long as the glass doesn't contain anything that might emit other particles if hit by an alpha.
In fact, following Skripal, I suspect they had it in a perfume spray as was used there. It would look like any other duty free and, as I say, no external radiation. It was just that the assassins were amazingly careless how they used the stuff.
But, as has been pointed out elsewhere, secret service officers don't do the dirty work. They prefer to use the sort of deniable types that left the Hereford lot under a bit of a cloud due to over enthusiasm. Not people with physics degrees.
Incidentally, the trigger of the first plutonium bomb was a mixture of beryllium and polonium with, IIRC, the polonium gold plated to stop the alphas. When the shell was imploded, the trigger ("gadget") was compressed and the alphas from the polonium caused the beryllium to emit neutrons, thus causing the very rapid criticality rise needed to produce a bang rather than a whimper. But the half life of polonium is short, meaning you had a bomb which needed to be finished shortly before it was used.
But this miracle laser thing could, in theory, scan foreign airliners as they approach Stanstead, agilely dodging the usual squadrons of drones, to see if anyone is smuggling radioactives.
A quick sweep of the mighty laser across the airframe as it makes its approach and ... haaaang on. I think I see a problem.
These lovely people - proper British boffins - have been around since 2003 (possibly earlier) and their ultra-sensitive detection systems enable the DoHS to detect and identify radioactive materials and discriminate between the radiation signatures of bananas and strategic nuclear materials.
www.symetrica.com
These lovely people - proper British boffins - have been around since 2003 (possibly earlier) and their ultra-sensitive detection systems enable the DoHS to detect and identify radioactive materials and discriminate between the radiation signatures of bananas and strategic nuclear materials.
www.symetrica.com
With the exception of the neutron detector, symetrica's technology is nothing new, though refined with respect to previous implementations.
There are a couple of potential advantages to the IR laser based detection. The first is a much larger detector volume, since sensitivity is related to how many of the particles or photons interact with the detector - that's why neutrino detectors are HUGE. The flip side is that the detector can affectively b placed close to the source, getting around the inverse square law. The second is getting much quicker localization of the source.
One item not discussed in the article was spectral response, identifying a specific radionuclide may require energy resolution of better than 1%, and the method of operation suggests a very broad peak for a given energy (e.g. Tc99m at 140keV).
meanwhile the most significant radiation hazard seldom gets noted: Radon gas is estimated to cause 20,000 cases of lung cancer in the US annually, second only to smoking.
a person living in building with average annual Radon concentration of 60 Bq/m3, would take annual effective dose of 1 mSv (60 x 0.017 = 1.02).
Here is a map of the United States with radon risk by county - with my own personal suggestion that odds are one need please note that within any given county there can be areas much higher or lower than the average for the county.
https://www.epa.gov/sites/production/files/2015-07/documents/zonemapcolor.pdf
Radon Data
Zone 1: Counties with predicted average indoor radon screening levels greater than 4 pCi/L
Zone 2: Counties with predicted average indoor radon screening levels from 2 to 4 pCi/L
Zone 3: Counties with predicted average indoor radon screening levels less than 2 pCi/L
The laser one couldn't detect a source inside a lead box unless they had contaminated to the outside of the box when packing it. Muon tomography might be able to depending on what the source was and how much of it there was.
To get a source inside a lead box into the US would require the cooperation of the port of departure cos it would set off the baggage scanners on the way out.
With current technology (and nothing dramatic on the horizon as far as I know), the powerful mid-IR laser - say in the 3..5 um region - needed for a longer usable range is a fairly non-trivial proposition.
An interesting paper but, as other folks have noted, there may well be an awkward gap between the model and reality.
Er, actually, I _am_ a nuclear scientist.
On sensitivity, the calim is that a microgramme of cobalt 60 can be detected.
Firstly, cobalt 60 is a beta emitter, not an alpha emitter, so I fail to understand why this follows an explanation about alpha particles.
Secondly, one microgram of cobalt 60 (half life a tad over 5 years) is about a millicurie, which gives more than 40 million disintegrations per second, and that's not what anybody sane would call a tiny amount of radioactive material. For comparison, it's about ten thousand times the typical human body load of potassium 40 (something like 125 grammes, half life a bit more than a billion years, so very roughly 4000 disintegrations per second).
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