CO2 laser enables long-range detection of radioactive material
24 comments
·March 21, 2025magnat
> 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?
adrian_b
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.
PaulHoule
Makes me think of https://en.wikipedia.org/wiki/Ionization_chamber which can work at atmospheric pressure.
MisterTea
The multiplier effect invokes this: https://en.wikipedia.org/wiki/Scintillation_counter
ziknard
Easily defeated by a large Tupperware container.
gh02t
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.
CamperBob2
Very interesting effect, but yes, the real imagination comes in when you have to explain how it might be used in practice.
SiempreViernes
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.
ricksunny
>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.
Animats
Yes. 10 meter range, must have line of sight to the radioactive material. When does that come up in practice?
drjasonharrison
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-...
Terr_
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
notfed
Erm... how?
drjasonharrison
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.
ggm
TSA will be buying.
elcritch
Only if a congressman owns part of the company. https://www.opensecrets.org/news/2010/11/several-federal-law...
curtisszmania
[dead]
keepamovin
Lol I knew this was possible!
neuroelectron
I'm no nuclear scientist, but doesn't this seem like a very basic way to detect radiation that we should have discovered before?
notfed
There's no claim of a new discovery here, just an impressive feat of engineering. Remember that nuclear fusion is also pretty basic.
titzer
> nuclear fusion is also pretty basic.
Get 'em hot and smash 'em is a remarkably effective method at multiple scales :)
null
The free preprint of the research paper:
https://arxiv.org/abs/2408.13640