Scanning Cargo for Nuclear Material and Conventional Explosives

Still experimental:

The team propose using a particle accelerator to alternately smash ionised hydrogen molecules and deuterium ions into targets of carbon and boron respectively. The collisions produce beams of gamma rays of various energies as well as neutrons. These beams are then passed through the cargo.

By measuring the way the beams are absorbed, Goldberg and company say they can work out whether the cargo contains explosives or nuclear materials. And they say they can do it at the rate of 20 containers per hour.

That's an ambitious goal that presents numerous challenges.

For example, the beam currents will provide relatively sparse data so the team will have to employ a technique called few-view tomography to fill in the gaps. It will also mean that each container will have to be zapped several times. That may not be entirely desirable for certain types of goods such as food and equipment with delicate electronics.

Just how beams of gamma rays and neutrons affect these kinds of goods is something that will have to be determined

Then there is the question of false positives. One advantage of a machine like this is that it has several scanning modes is that if one reveals something suspicious, it can switch to another to look in more detail. That should build up a decent picture of the cargo's contents and reduce false positives.

Posted on January 27, 2010 at 6:53 AM • 47 Comments

Comments

BF SkinnerJanuary 27, 2010 7:27 AM

So all we have to do is route all shipping via Bern and the Swiss get a cut of the tolls? I KNEW pulling the plug on the SSC was shortsighted.

MarcosJanuary 27, 2010 7:34 AM

"Just how beams of gamma rays and neutrons affect these kinds of goods is something that will have to be determined"

No, what gamma rays do to MOS eletronic is quite well known and understood. It does destroy them.

GrantelJanuary 27, 2010 8:14 AM

"Just how beams of gamma rays and neutrons affect these kinds of goods is something that will have to be determined"

"No, what gamma rays do to MOS eletronic is quite well known and understood. It does destroy them."

And neutrons tend to activate ("make radioactive") materials through neutron capture. This might pose a problem, especially for foodstuff...

Clive RobinsonJanuary 27, 2010 8:40 AM

With all those stow aways on lorries trying to get into certain countries I can see the headline now,

"Crispy Fried Illegal found at DXXXr Docks".

This of course rases the question of moving live stock around.

Tom Sharp did a nice book that had exploding Ostriches in it (and gave a possible way to get them into the bird).

The other thing is of course how much energy is released and how...

You'd need to ask an expert (and there are not that many around who would know the answer though) but, if some chemicals decompose on being subjected to IR/visable/UV EM Radiation some of which are explosives, are there any that would decompose explosivly when subjected to alpha/beta/gamma radiation?

I know this was a concern during early A-Bomb developmet but more interms of explosives aging more rapidly.

Even if they don't blow by themselves it might well be in a criminals interests to add a GM tube etc just to make sure they get some ROI on the package...

Thus I don't know how much this machine costs but it could be counter productive...

I wonder how the TSA would react if a baggage bomb was triggered in the scanner, it would only need to be a few tens of grams to start a whole new scare (especialy for TSA staff).

I guess therefore it's time to get a gander at the specs ;)

bitmongerJanuary 27, 2010 8:47 AM

So now we will risk dosing smuggled animals and people with gamma radiation and neutron radiation on a routine basis ... Ug...

It depend on the energy, but neutron radiation induces radioactivity in other materials.

This does not seem like a good idea. A better idea would be improving tracking of radioactive people and their material.

How is this thing not a proliferation risk...
I mean are we talking about putting a piece of equipment on the market and in major ports that could be used to manufacture nuclear materials ?

If I were a terrorist, this is what I would steal it not worry about how to get past it.

Then I could sell it to someone who wanted to make nuclear materials...

Clive RobinsonJanuary 27, 2010 8:50 AM

Oh just one thing the question is going to be in some peoples minds,

"Why gamma rays and neutrons"

Overly simplisticaly gamma rays alow you to profile things like metals (as in looking at welds etc) and neutrons tend to profile organic things like water for instance.

Does anybody know of a link to the 1980's footage of a kettle in a neutron scanner showing the water clearly boiling and the steam rising, or something similar?

Clive RobinsonJanuary 27, 2010 9:06 AM

@ bitmonger,

"Then I could sell it to someone who wanted to make nuclear materials..."

Hmm how long and how much energy to make say a gram of a material like Polonium 210?

It's a very very long time since I did the calculation with a lady friend based on then available information but If I remeber correctly we came to the conclusion you'd do better just chucking stuff in the reactor core and waiting for it to drop out the other side.

The early weapons material reactors where quite literaly a stack of graphite bricks with carefully machined holes through them in a latice pattern. Every other hole had a neutron source and those in between had the "feed stock" to be converted and was quite literaly just pushed through very slowly. The cores of these reactors where well up in the megawatt equivalent and where force air cooled into chimnes, which is why you can go arround Cumbria (UK) with a GM tube and tweezers and pick the stuff out of peoples back gardens etc...

Gary SmithJanuary 27, 2010 9:08 AM

Of course, nuclear material in shipping containers is a huge problem, causing countless deaths and costing the US taxpayers billions, ... oh wait, no it isn't.

bitmongerJanuary 27, 2010 9:13 AM

@Clive

Neutrons are also useful to discern specific isotopes present in material.

No idea where any good neutron imaging footage is... There is also a fantastic demonstration showing a holograph of a nuclear reactor created with neutrons I saw long ago...

I don't know much about gamma rays and spectroscopy ... but gamma rays penetrate nearly everything very effectively so I would expect the combination of gamma and neutron would have excellent contrast if used for imaging cargo.

I still think this is a horrible idea.

bitmongerJanuary 27, 2010 9:24 AM

@Clive

I agree with your assessment.

Yeah, I am not sure what the neutron flux or neutron energy from this device would be, but
this was exactly my thinking.

bitmongerJanuary 27, 2010 9:34 AM

@Clive

Oh one more thing....
Sorry, I missed you point about energy.

Yeah I am willing to be cost and electricity would be conspicuous for actually doing this... unless you only needed small quantities ... its a very good point.

... It might just be simpler to make a conventional pile.

Moving radioactive material might be less conspicuous than private power source...

I am not sure...

uk visaJanuary 27, 2010 9:35 AM

"In 2007, the U.S. government set itself the goal of screening all aviation cargo loaded onto passenger planes and all maritime cargo entering the country for both explosives and nuclear materials. And to set up a system to do this within five years."
or, in other words, I George W hand my friends in the defence industries a blank cheque from US taxpayers.

BF SkinnerJanuary 27, 2010 9:48 AM

@Clive "a nice book that had exploding Ostriches in it "

That's it! Final straw...No more reading stories to the kiddies for you. No wonder they wake up screamin'.

gregJanuary 27, 2010 9:52 AM

The radation levels of these things are so low you really don't need to worry about them.

the neutron sources give out about 10^8 neutrons. (or even far less). We use a >10^12 neutrons per second source for neutron scattering experiments.... And activation is not really a problem.

So there are two important things that these types of instruments do. Most do not detect neutrons due to cost. But instead look at the gamma rays emmited with the capture of a neutron. Also many elements once they capture a neutron quickly decay with beta emmision, often also with an gamma ray of a particular energy. How much tomography you do with this is really just a matter of cost. But avoiding serious activation is pretty easy.

As for electronics. Gamma rays do not do pernament damage generally. Neutrons and high energy charged particles are far worse. Also if the item is off most electrons is about 10x more resistant to radiation (latch on damage is non exsitant).

Again the levels are generally so low that its not a problem. We have *very* sensitive radiation detectors so very low levels can and do work rather well.

How much security is provided by such devices is however very debatable. They can't detect bonds. So a container with nitrogen and oxygen and carbon (aka explosives) will give the same signal regardless of if its a plastic or a plastic explosive....

spaceman spiffJanuary 27, 2010 10:04 AM

We need one of those amazing Star Trek tricorders. AFAIK, they have no harmful emissions, can detect the smallest amounts of anything, and can be carried around in one hand. Oh wait, that's fiction... Not to say that a lot of fictional stuff has made it into our reality, but I think this is a bit over the horizon as yet. How about neutrino back-scatter imaging? :-)

GeorgeOJanuary 27, 2010 10:07 AM

Of course, if the container is already in LA/LB harbor, and it explodes, then the damage is already done.

Scanning would need to happen at the originating port. Good luck with that...

JoeJanuary 27, 2010 10:43 AM

There are container ships that can carry over 14,000 TEUs (20 foot containers) - at 20 per hour that is almost a month to scan. For one ship's cargo... Hmmm.

I guess to do a proper cost/benefit analysis we are going to have to know:
1) What are the chances of a dockworker being accidentally exposed to gamma radiation and turning into a giant green raging humanoid monster.
2) Of these "hulkified" dock workers, what percent will be classified super-heroes.
3) Does the good that a hero-hulk does outweigh the collateral damage he/she inflicts? If so, to what extent?

I realize that I am ignoring the possibility of the accidental creation of a glowing blue self-omniscient being with control over sub-atomic particles. I think, however, you have to start with a nuclear physicist for that to happen. Maybe we also need to know how many dock workers have post-doctorate degrees in a physical science? I don't know - this is getting too complicated for me.

Clive RobinsonJanuary 27, 2010 11:03 AM

@ Martin Schröder,

"3 minutes per can? I suggest the scientists visit a real container port like Rotterdam."

Yup that thought crossed my mind. I was in hospital a couple of weeks ago and the guy in the bed next to me was a very long distance driver.

And I was chatting to him about the CO2 breathing/heart beat systems and he said that,

Even with a 20,000GBP fine per illegal immigrant the time taken out of a drivers alloted work day was such they could not meet company deadlines. Thus damed if they do damed if they don't and the authorities and the courts know this very very we andif it's a self employed person they hit them with POCA just so they cannot defend themselves...

Apparently it's not the time the test takes but how long you have to wait etc apparently it can be over an hour.

Rick MerrickJanuary 27, 2010 11:58 AM

Interesting tech I'm sure, but it's still just one more version of the "Fortress America" (or "Fortress Airport") vision of national security that breaks again and again and again. To begin with, there's the borderline madness of trying to scan hundreds of thousands of crates filled with vastly variant materials, some of which may very well get easy-to-obtain screening waivers thanks to their contents being radiation sensitive, to track down a warhead the size of a duffel bag- good luck with that. Second is of course the notion that, when your opponent is a few dudes with the aforementioned few hundred pounds of warhead, that there is *any* target-side procedures you can take. In the exceptionally unlikely chance the ports look "secure," you build it into the structure of a private airplane. Or drop it offshore and bring it in with divers. Or spam the Mexican border with attempted migrant crossings and drive it across. Or bring it in with drug-running semisubmersibles. Or....

And why is anyone even bothering talking about this when facilities that can supply warheads are single points with preexisting security presence that can frogmarch personal in and out naked if they choose?

Volker HetzerJanuary 27, 2010 12:09 PM

To all those 3min/scan people:
Figure out the amount of containers per minute arriving in a container terminal and you've got the number of scanners to deploy.

On the other hand, setting a container nuke to detonate when it detects neutron or gamma radiation shouldn't be too difficult either.

GeoduckJanuary 27, 2010 12:27 PM

About 7+ years ago, I was project manager for such a device. Our team (Univ at Cal Berkeley and others) designed a neutron time of flight system for commercial cargo scanning. We had a good neutron source, good detectors, and enough software to demonstrate the system worked. We could distinguish different types of explosives, or drugs, quite small amounts ( To address another observation. The neutron flux typically is low enough that neutron activation is a non issue.

BF SkinnerJanuary 27, 2010 12:32 PM

@Volker "setting a container nuke to detonate when it detects neutron or gamma radiation "

And tactically while you may not kill a lot of people taking out a container facility IS significant. (and in LA, Seattle and NYC are as close to Downtown anyway that it makes no never mind)

Dulles has a nice screen facility now that separates the chaos of ticketing from the chaos of screening. When I was on travel recently I thought about the screening point being the "organizationally defined level of risk" boundary.

This is the point at which any explosive should be detected yes? So this is the limit of where DHS is willing to let a bomb go off.

So the terrorist just recalibrateds (like Volker's example) to detonate at the screening point. I was in line a good hour. Several thousand passengers was my estimate. there's certain to be mass casulty, good publicity and he can carry a much larger payload (i'm thinking a Swordfish scenario) than panty-waist boy was on the Christmas attempt.

EscapedWestOfTheBigMuddyJanuary 27, 2010 12:32 PM

I've seen talks on similar technologies since 2004. They all have a similar set of strengths and issues.

Problems:

* Radiation exposure to people. Very low risk, except to stowaways. Mitigation is possible and cheep using acustic detection before the irradiating step. Side effect is catching more illegal aliens, but it adds to the cost.
* Radiation damage to contents. Most technologies use relatively low doses. Living cargo will have to be marked and tracked and inspected some other way as will anything especially sensitive (but that doesn't include ordinary electronics).
* Speed. This is the stinker. You can buy more scanners, but they are expensive. And you can set a loose heuristic (fast, but many false positives) for the first scan, and re-scan with tighter limits (thus taking longer) on everything that fails the initial pass. Tune the parameters right and you get a modest speed up without a lot of false negatives.
* Cost. But this is for the War On Terror (tm), so the politicians assure us that this is no object.

Advantages:

* Heavy elements stick out like sore thumbs, as do any high activity radio-actives in the cargo. Nuclear devices and dirty bombs are easy.
* Many explosives are also easy, and most of the ones that aren't are low yield (meaning you need a lot) or easy for sniffer dogs.
* It will make the guy who thought it up rich, and employ a few physicists. What? That is so an advantage.

JohnJanuary 27, 2010 1:05 PM

Yes indeed. Through put is a definite issue. Some rough back of envelope calculations using the number of TEU's handled by the 5 busiest ports in the US would require them to scan 8 containers per minute at LA down to 3 containers per minute at Oakland. This is assuming operations run 24/7 for the full year and that the operations load is evenly distributed over each day and the entire year. This also allows for no excess capacity, and also assumes that the scanning doesn't decrease the handling capacity of the port.

Given the backlog that the LA port currently has, anything that slows down their handling times would be strongly argued against.

Northern SkepticJanuary 27, 2010 1:26 PM

And of course no one who is smuggling nuclear or conventional explosives would ever think to use a gamma ray detector as a trigger...

...or at least wrap all manner of things in lead foils so as to force the security teams into lots of diversionary busy work busy having to search everything by hand...

Northern SkepticJanuary 27, 2010 1:34 PM

I wonder when the US will resort to something like Dale Brown's "Hammerhead" novel in which the effort to combat drug smuggling results in refurbishing and re-deploying oil platforms as customs posts near the territorial water limits.

Clive RobinsonJanuary 27, 2010 1:37 PM

@ BF Skinner,

"That's it! Final straw...No more reading stories to the kiddies for you. No wonder they wake up screamin'."

You've obviously not met my son he's almost eight. And on hearing about the exploding birds pointed out very seriously that hippos have bigger mouths and stomachs...

He's of a very observant nature and does for some unfathonable reason keep talking disaster senarios... Why I don't know I'm told he'll grow out of it as it's "just a phase".

The trouble is you are sitting on a train and he say's "Daddy if we smash into another train..." or some such and will frequently elaborate... Fellow travelers have been known to develop itchs, twitches, restless legs, and the desire to get off before their usuall stop...

Personaly I blaim Jermy Clarkson (Top Gear) who once used old cars and caravans to play skittels. Alex was two and less than ten minutes later was doing the same thing with his toys, and full sound effects.

Needless to say his fav TV programes are Top Gear, Braniac, Myth Busters, X-Machines, etc.

Ho hum just another ten years and he can become his own responsability ;)

Clive RobinsonJanuary 27, 2010 2:04 PM

@ Northern Skeptic,

"results in refurbishing and re-deploying oil platforms as customs posts near the territorial water limits."

A thought occurs ;)

Ever try to land a 747-700 on chopy seas?

No, me neither, and I don't think I've heard of anybody who has done it twice and kept their job ;)

ScottJanuary 27, 2010 3:55 PM

Houston's Barbour's Cut Terminal handled 1,794,309 TEU containers in 2008, which comes to roughly one per 17.6 seconds in round the clock operation. Given eleven scanners (plus another one or two for downtime, and/or rescanning of positives) the throughput could be handled.

The bigger question is if the scanners themselves are worth anything (can you imagine a 10% false positive rate in this?), and if they can be made to operate in tandem without mutual interference or cooking some poor worker outright and if the ports, which already depend on precision logistics -- a fragility in its own right -- will tolerate the kind of rerouting nightmares that will ensue.

BF SkinnerJanuary 27, 2010 4:51 PM

@Clive "pointed out hippos have bigger mouths and stomachs..."

Hippos? THEY HUGH! You'll never get that out of the carpet (or the walls, the ceiling...my pores....gack the taste like the amazon that's been left out on the counter)

Excuse me-- I'll just curl up here into a fetal ball with twitches and restless leg syndrome shall I?

"Just a phase" If that's a genetic prediction shouldn't they be looking at dad before they get so...definite?

Mythbusters? The kid is cool no ifs ands or buts. 8? Maybe time to start him on scam school too.

BF SkinnerJanuary 27, 2010 4:54 PM

@Northern Skeptic "re-deploying oil platforms as customs posts "

Kidding aside this is their intent on doing these inspections in originating ports.

Move that kill zone out of the container yard into someone else's downtown.

DeniJanuary 27, 2010 7:26 PM

About 7+ years ago, I was project manager for such a device. Our team (Univ at Cal Berkeley and others) designed a neutron time of flight system for commercial cargo scanning. We had a good neutron source, good detectors, and enough software to demonstrate the system worked. We could distinguish different types of explosives, or drugs, quite small amounts (

Snarki, child of LokiJanuary 28, 2010 12:25 AM

"...or at least wrap all manner of things in lead foils so as to force the security teams into lots of diversionary busy work busy having to search everything by hand..."

Make a cut-out in the shape of a handgun/grenade out of thin lead foil. Glue it into the lining of a carry-on bag. Give it to someone else to take through carry-on screening. "Hilarity" ensues, assuming the TSA even notices it.

But for the plutonium, wrap it in borated plastic. Neutrons get in, they don't get out. There are counter-measures of course, and counter-counter-measures (like put a leaky bottle of Gd-containing MRI contrast agent in whatever gets scanned before the Pu; while the TSA is going nuts from the Gd, the Pu slips through).

The gamma/neutron scanners are mostly a waste of time and money. The exception is if you can reliably detect single "hot" spontaneous-fission neutrons. Just one such neutron tells you that there's something suspicious in the area.

GregJanuary 28, 2010 3:00 AM

@Snarki

All those neutron absorbers have 2 main features. First they absorb thermal neutrons mainly. Some neutron systems use 14MeV and 2MeV neutrons from DT and DD fusion. The second is the emmited gamma ray/s from neutron absorption. The gamma ray type neutron scanners (more common since gamma ray detectors are far cheaper) would detect this easily. Having either Boron or Gd in your luggage is not that normal...

BF skinnerJanuary 28, 2010 6:50 AM

@Deni "not many people in the world who know how to design or even build a compact particle accelerator"

Just get Spengler and Stanz. They've done it.

BeanCounterJanuary 28, 2010 8:50 AM

Terrorism is in part economic warfare. If a type of terrorist attack is inexpensive, and the defense is very expensive, then they do economic harm. And if we use one expensive defense, but they are able to circumvent that defense with a different inexpensive attack, then again, they succeed in doing economic harm.

Using a particle accelorator to check the contents of shipping containers would be absurdly expensive. The number of cargo containers that would need to be check is very large. And the terrorists could simply switch to a different means of getting a weapon into the country. This would be an economic win for them, and a loss for us. Not a good approach at all.

Clive RobinsonJanuary 28, 2010 9:32 AM

@ BF Skinner,

"Maybe time to start him on scam school too."

Do you remember one of Bruce's pages about biased coin flips?

And I told people how to game a coin toss in various ways?

Well he's learnt that one from me doing it to him. (If he refused to do something I'd offer him a choice do it or take a chance with the coin flip, if he won he got a choc biscuite and not to do the task, if he lost then he had to do two tasks. I made the mistake of getting greedy and he worked out he was being cheated...)

Also he knows how to fake fingerprints with the red wax from around the outside of a ball of Edam cheese. Oh and one or to other things.

To my anoyance rather than learn lockpicking and such he is nagging me to build a 16ft x 12ft OO model railway with DCC with him.

I'm not sure which is going to give him more "life skills"...

Snarki, child of LokiJanuary 28, 2010 10:08 AM

Greg:
so what if they're 2MeV or 14MeV neutrons from their scanner? To have any significant interaction probability, the neutrons have to get down to much lower (epithermal) energies. 1/beta cross-section, baby! The s-wave rules.

Plastic is a pretty efficient moderator, so most neutrons getting into the boron will be slowed down. Boron has a significant epithermal capture cross-section, only emits gammas for a fraction of captures, and with considerably less gamma energy than most nuclei. So chances are, they won't be seen at all. A little lead outside the borated plastic would help with that, if necessary.

Not good enough? Use lithium. Sheesh.

The point of the Gd scenario is to purposefully SET OFF the alarms with a huge signal. That signal causes a lot of excitement, but only finds a little bottle of MRI contrast agent (which does contain Gd) and is a clearly not a WMD...just some specialized medical supply. During the head-scratching 'wtf is wrong with the scanner?' interval afterwards, other stuff can slip through.

Visible, IR and x-ray photons are a much better way of detecting stuff that isn't supposed to be there, but like other technologies, it doesn't scale well for scanning containers in a busy port.

DavidEJanuary 28, 2010 10:28 AM

ROFLMAO! I can think of few things funnier than security experts discussing physics... (although there do seem to be a few physics-knowledgeable ppl lurking, thank goodness)

I did much of the safety analysis for one of these projects.

False positive rates on all the projects I read up on were way lower than 10%. As mentioned, throughput and training costs are the big inhibiters.

@Northern Skeptic: lead is pretty much transparent to neutrons...

EscapedWestOfTheBigMuddyJanuary 28, 2010 1:03 PM

Using a particle accelorator to check the contents of shipping containers would be absurdly expensive. The number of cargo containers that would need to be check is very large. And the terrorists could simply switch to a different means of getting a weapon into the country. This would be an economic win for them, and a loss for us. Not a good approach at all.

All "particle accelerators" are not created equal. We are past the days when there was one in every home (a tube type color TV is a 100 keV electron accelerator), but there is still one (often more) in every dentist's office.

Certainly the machine at CERN is absurdly expensive, to be sure CEBAF is very costly, no doubt the Spallation Neutron Source is a major line item for a government lab. But a few MeV, low current, broad spectrum electron machine is simple, compact and cheap by comparison to the damage that a container bomb could do.

Which still doesn't insure that these scanners are cost effective, but don't blame the accelerator component: the detector elements will cost more.

Northern SkepticJanuary 28, 2010 1:17 PM

@Clive Robinson
"Ever try to land a 747-700 on chopy seas?

No, me neither, and I don't think I've heard of anybody who has done it twice and kept their job ;)"

Sorry, should have clarified the story dealt with maritime searches only --- but read the book, I think you'll find it interesting...

FPJanuary 29, 2010 4:18 AM

"ionised hydrogen molecules"

Wow, what a frustratingly PC way of saying "proton". They have to avoid the "nuclear" associations? And yet they still use "neutron".

Or maybe it was just written by another clueless journalist.

Peter A.January 29, 2010 4:48 AM

@FP:

Yea, particularly as there are no ionized hydrogen *molecules* as opposed to *atoms*. A molecule of hydrogen, the natural state of the element in a wide range of conditions (H_2) has its bond composed of the only two electrons available. Once you ionize it by taking one electron the bond is gone :-)

A funny thing, in the next sentence there are deuterium ions mentioned. While it's technically correct, there's only one deuterium ion, namely the sole nucleus :-)

Someone's afraid of the word "nucleus" or what?

GregJanuary 29, 2010 5:51 AM

@Snarki

All true of course. However 14Mev neutron tends to excite nucleus via inelastic scattering etc. The poor interaction probabilities (also aids penetration which xrays don't do well at with shipping container sizes) in one of the reasons these "scanners" take so long.

I miss understood your usage of Gd, i was assuming that were using it to absorb neutrons and hide something behind it. I find Gd pretty weird (up there with 135Xe), its like a black hole for neutrons...

Of course the ideal neutron method with be with a spallation source and a large number of time of flight neutron detectors, and a bunch of gamma ray detectors. But considering how long it takes to set up a neutron scattering experiment..... it may not be tenable for the real world ;)

-ac-January 29, 2010 9:00 AM

Scanning containers with gamma rays and neutrons + stowaways = ?

A very angry illegal immigrant with super powers!

Movie plot time :)

Ulf L.February 4, 2010 8:36 AM

One thing I do not understand, and which has been raised by a previous poster:

With the low flux that these machines have, you cannot do real scattering, you can only identify isotopes of specific _atoms_ in the container. While this might be enough when scanning for nuclear material, how are you supposed to find explosives?

You can use neutrons, and maybe gamma rays for this task, but then you need a much higher flux, and/or a few minutes exposure time...

Intuitively, I would file this under vaporware, as I would do with the content of the poster who claims his team once built such a machine. Anyone has more information or details how such a machine is supposed to work?

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