CO2 laser enables long-range detection of radioactive material | Hacker News Reader

CO2 laser enables long-range detection of radioactive material

physicsworld.com

113 pointsEA-316723 comments

The free preprint of the research paper:

Makes me think of https://en.wikipedia.org/wiki/Ionization_chamber which can work at atmospheric pressure.

The multiplier effect invokes this: https://en.wikipedia.org/wiki/Scintillation_counter

> The team also used a CMOS camera to capture visible-light emissions from the microplasmas (...) The CMOS imagers, however, had to be placed close to the measured radiation source, reducing their applicability to remote sensing

How can it be called long-range detector, if literally the detector has to be placed at measured object?

The detector using the scattering of the infrared light emitted by the laser is long range.

They have used a second detection method with a CMOS camera that detected the fluorescence of the plasma produced by ionizing radiation.

The second short-range method was used for comparison with the investigated method, to assess its efficiency.

Easily defeated by a large Tupperware container.

Kinda, but at least for gamma radiation (which is the main one you care about finding at standoff), the same radiation that induces the ionization these lasers detect will go right through tupperware and ionize the air outside, which will be just as detectable as long as it's strong enough to still produce enough ionization outside the tupperware.

Shielding the source with something that actually absorbs gammas like steel or lead is something that would actually render this laser detection null, but that's also true of conventional direct radiation detection methods too. No real way to find something that's not emitting something.

Regardless, this method is probably more intended for scenarios like nuclear accidents where you don't really have to worry about someone hiding the source from you. Though I still don't see that many applications for it even within that niche (and I did my PhD on finding radiation sources and currently work full time on it, so I'm fairly knowledgeable on the subject...), as there are a lot of limitations to this.

Very interesting effect, but yes, the real imagination comes in when you have to explain how it might be used in practice.

I think this is for the, now depressingly remote, situation where you want to verify that something at the end of a adversaries missile is really not a nuclear weapon because a treaty says that would be one too many.

In that context a way to measure radioactivity by non-invasive means is great!

Shame that a nuclear weapons treaty with limits and an inspections regime is more sci-fi than the technology needed to remotely verify the presence of a warhead.

Most of warhead verification is actually verifying a given weapon IS a real weapon (without giving away its internal design, which is the hard part), not that something is not a weapon because generally you're trying to keep an account of how many/where warheads are. Verifying a given missile isn't nuclear tipped is largely a non-issue at least in the current arms control regimes.

This method has no real way to identify materials, which is what you really need for warhead verification. It would be easily fooled by replacing a warhead with a dummy source, which is a big no-no because now there is a potential hole in the bookkeeping. Weapons grade material isn't actually that radioactive anyway; warheads aren't inert but measuring radiation from them is fairly challenging. Probably not hot enough to see easily with this laser approach, though I'm only speculating on that.

>Shame that a nuclear weapons treaty with limits and an inspections regime is more sci-fi than the technology needed to remotely verify the presence of a warhead

Well articulated. The early history of atomic weapons regulation hinges on precisely the difficulty of independent verification means (as well as judgements on whether or not an adversary would let you into their country without whack-a-mole style circumvention). I still think that verification technology is the main stumbling block. Neutrino detection is what I (and I bet ongoing orograms in the DoE) focus on for this purpose. We need to be able to figure out how to sense neutrinos order of magnitude more effectively than we can currently. Right now it feels like panning for gold silt with sieves as sparse as chicken-wire.

> We need to be able to figure out how to sense neutrinos order of magnitude more effectively than we can currently.

I don't see any reason to believe that's possible though. I guess I don't know how close we are to the theoretical limit, but anything made of atoms will feel like a chicken-wire sieve, right? Unless there's something big you/DoE know that I don't.

Yes. 10 meter range, must have line of sight to the radioactive material. When does that come up in practice?

Could it be useful in a nuclear-reactor context?

If the sensor is further away, it might be easier to maintain, have a longer lifetime, and could even be re-aimed to cover a wider area or identify where a specific hotspot is.

Depending on how l

https://www.npr.org/2023/01/31/1152870649/australia-missing-...

A small capsule of radioactive cesium-137 was lost during transit, and the search for it was difficult due to the distance the truck carrying the device had travelled and the size of the capsule.

"When you consider the challenge of finding an object smaller than a 10-cent coin along a 1,400-kilometer stretch of Great Northern Highway, it is a tremendous result."

https://www.npr.org/2023/01/31/1152870649/australia-missing-...

Erm... how?

Alpha and Beta particles are easily blocked with a thin amount of material. Their comment is both accurate and not constructive as gamma radiation is what we're interested in detecting.

TSA will be buying.

Only if a congressman owns part of the company. https://www.opensecrets.org/news/2010/11/several-federal-law...

Lol I knew this was possible!

I'm no nuclear scientist, but doesn't this seem like a very basic way to detect radiation that we should have discovered before?

There's no claim of a new discovery here, just an impressive feat of engineering. Remember that nuclear fusion is also pretty basic.

> nuclear fusion is also pretty basic.

Get 'em hot and smash 'em is a remarkably effective method at multiple scales :)

Reply on news.ycombinator.com