Apparently, nanograms / micrograms is enough to create a "antimatter catalyzed" fission/fusion propulsion system with enormous specific impulse / efficacy.
PDF: https://www.niac.usra.edu/files/studies/final_report/1071Bic...
Physicists trap a single antimatter particle for a month (scientificamerican.com)
303 pointsby mooreds4 days ago86 comments
nickpinkston 18 hours ago
Very cool! There's some wild ideas about antimatter capture in space via giant arrays of superconducting magnets trapping naturally occurring antimatter.
arbuge 15 hours ago
This might be of interest:
fsh 20 hours ago
Exciting results. The electron's magnetic moment is probably the most precise standard model prediction, and Gabrielse's group has measured it with 13 digits of accuracy. The positron is predicted to have exactly the same magnetic moment, but this has not been measured since 1987. With the new trap, they should be able to finally match the electron's precision.
kurthr 3 hours ago
And yet the lifetime of free "thermal" neutrons is unknown (there are two measurements that give results off by ~1%) between 888 and 878 seconds.
Notably, neutrons are quite unstable outside of a nucleus and decay generating a proton, electron, and a neutrino. There are many theories on the discrepancy.
https://journals.aps.org/prd/abstract/10.1103/PhysRevD.110.0...
foobarbecue 20 hours ago
I don't get how they know they have exactly one in there. I mean they're measuring the magnetic field but how on earth do you make sufficiently precise measurements to detect a single particle!?!
Edit: this is explained pretty extensively in the paper (https://cfp.physics.northwestern.edu/documents/2026OnePositr...). I'm gonna need to do some background reading though...
sandworm101 20 hours ago
They let it go and listen for the pop? Let it fall from the magnetic containment and you should see a predictable emission as it collides with some normal matter. Detecting single photons is what detectors are all about.
tomrod 19 hours ago
This made me laugh very hard. Thank you.
I think this is a fascinating technology. I wonder if it is currently energy positive (so that we can engineer it into a functional source) or at least if it can be extended to be captured in bulk (antimatter rockets!).
sandworm101 19 hours ago
Energy positive? That made me laugh. Making antimatter is more energy negative than building a 747 out of gold. They burn through enough power to light a town in order to capture a literal handful of antimater particles.
In a rocket it would not be useful. It has the energy but would emit it as all sorts of highly penetrating radiation rather than hot gas for a rocket nozzle to turn into thrust.
One particle has enough energy to, maybe, if it hit a speck of dust it might result in a perceptible twitch of that speck of dust... if you were watching the spec under a good optical microscope.
gus_massa 19 hours ago
In this case they are using 22Na that produces positrons. A quick search says that they cost like $50-$300. (I guess I'm in yet another list now.) I used one in the physic lab a few years ago. They are good enough to get a few blips in a Geiger counter or something similar.
I agree that if someone wants to make enough antiprotons and positrons to make enough antimater to power a rocket, the cost is prohibitive and there is absolutely no hope to make it cost efficient.
suzzer99 18 hours ago
They really missed out on a chance to go with 'negatrons' instead of antiprotons.
dekhn 16 hours ago
That would too easily get confused with positrons (anti-electrons).
greenbit 15 hours ago
Or even "notorp". Notorps could have been a thing.
tomrod 18 hours ago
I appreciate your comment as it sets expectations on what the technology can do today.
What would need to be true for the capability of creating and using antimatter to become feasible?
vlovich123 17 hours ago
I know you’re being facetious but a 747 made out of gold is going to be ~24 billion dollars if you are doing a weight conversion. A 747 by itself is ~$400 million. The entire CERN annual electricity cost is $~25-50M.
No way this experiment had that kind of funding. I would bet the experiment itself had a few million dollars in funding at most + another few for the salaries. Max 10M all in. Probably closer to 2-5M. Expensive but not prohibitive like a 747. But for a single particle.
Scaling up no one really knows because we only do this for single particles and that’s really inefficient. At scale it’s unclear what it could look like.
sandworm101 16 hours ago
But electrons/positrons cannot become fuel. Positrons repel each other. So to make any real amount of antimater, beyond counting individual particles, you need anti-protons to keep the positrons happy and containable at scale. Creating the sort of anti-hydrogen one might want to collect as fuel, THAT requires golden 747s of energy.
vlovich123 16 hours ago
I could be wrong but my understanding is that’s purely a function of our technological limitations in how we create antimatter, not in the fundamental energy required. Our tech of a particle acceleration is ~1e9 times less efficient than the actual energy required because most of the energy is lost, not converted. A gram would be $~6.2M/gram if we could get to 1% energy conversion efficiency. No one bothers of course to even try because it’s not worth it - expensive, difficult, and huge energy losses. Fusion reactors for space ships will probably come before antimatter gets cracked as a battery source.
mr_toad 16 hours ago
Positrons aren’t useful because they annihilate to produce gamma rays, which can’t be contained. However, anti-proton annihilation produces a bunch of particles, including pions, which could be contained in a magnetic bottle and directed for thrust.
sdeframond 11 hours ago
Veritasium made a video about CERN's "antimatter factory"
pennomi 3 hours ago
“A literal handful of antimater particles” would be quite potent, even if your hands are very tiny.
BobbyTables2 4 hours ago
Sounds like that classic joke about a hunter finding his friend unconscious - the one where the dispatcher asks if the friend is dead…
gus_massa 19 hours ago
Relevant paragraphs, near figure 4, page 3:
> In order to determine ωz and the number of trapped positrons, the axial oscillation of a positron is driven with oscillating potentials applied to the trap electrodes. The frequency of the drive ωd is swept through resonance with ωz.
> For the center-of-mass axial motion of more than one positron, the damping (and hence the observed signal width) increases in proportion to the number of particles. A confirmation that only one positron is trapped comes from spin flip observations that are discussed presently
maho 11 hours ago
The simple explanation: The positrons fly around the trap center. In the z-direction, this is a simple "up and down" oscillation. There are electrodes in the top and bottom of the trap called the "end-caps". The end-caps are connected to each other with a large resistor (technically, a coil forming an LC resonator with the parasitic capacitance, but on resonance it looks like a large resistor).
When the positrons are at the top, they attract negative charges into the top end-cap. This is called an "image charge". When the positrons are close to the bottom end-cap, the image charge into bottom end-cap. This forms a current, the "image current". The more positrons you have, the larger the image current.
Since the image current (on the order of femtoamperes) has to flow through the large resistor, it is turned into a voltage that can be amplified and measured by cryogenic amplifiers. But it has a second effect: The voltage "back-acts" on the positrons, damping their motion. If you have more positrons in the trap, this damping gets stronger, because each positron experiences the back-action of all other positrons.
In the paper, you can see pictures of the driven axial motion, where you take an RF excitation and sweep the frequency over the resonance, recording the positrons' amplitude as a response. The more positrons you have, the "wider" this resonance, because of the damping effect.
As you reduce the number of positrons by doing a "dip" (making the trap really shallow, hoping that some, but not all, positrons escape), you can see the width getting smaller and smaller in discrete steps. That's how you know you are dealing with individual particles.
I haven't worked on Gabrielse's setup, but I have worked on other, very similar (better, ha!) experiments 10 years ago. I don't see what's so special about this trap, but putting antimatter into it always makes for a nice headline.
dguest a day ago
Direct link to article: https://arxiv.org/abs/2605.08147
mattanimation 9 hours ago
Quantunamo Bay
networkOne 9 hours ago
Hope Aristotle with his 'telos' is wrong, and the antimatter particle does not have a purpose to annihilate itself with a +-matter particle. The universe will complain if it doesn't.
bilsbie 18 hours ago
What happens if an anti proton hits a normal hydrogen atom?
gus_massa 18 hours ago
Someone has done the experiment: https://journals.aps.org/pra/abstract/10.1103/PhysRevA.108.0...
The link is cherry picked from a very good explanation by Gemini https://www.google.com/search?q=antiproton+hidrogen+colissio...
retrac 18 hours ago
Annihilation. At low collision energies the antiproton and proton go through an interaction which ultimately results in photons (light energy). Matter is converted into energy as e = mc^2. Though the interaction passes through a number of exotic intermediate stages first.
mr_toad 16 hours ago
It gets complicated, because protons and anti-protons are composite particles.
To simplify somewhat, one quark from each will annihilate, leaving four quarks and a lot of energy, which re-arrange into mesons (two quarks each), which then decay into photons, electrons, positrons and neutrinos.
lol8675309 9 hours ago
That seems super safe. At least they are wearing gloves.
androiddrew 21 hours ago
I kind of want to know how they safely deal with its release (destruction)
Retr0id 21 hours ago
If it's a single particle I don't think there's much to worry about?
SwellJoe 21 hours ago
It's one particle. It's not a bomb.
brippalcharrid 16 hours ago
Yes, you'd need another 6x10^15 of them to even act as a trigger for a battlefield thermonuclear weapon to destroy something like a tank, apparently.
ungovernableCat 20 hours ago
E=mc*2 but m is really really tiny
gus_massa 20 hours ago
As the sibling comments say, it's a single positron so the energy released is tiny. I tried to find positrons sources in common life, the best I could find was https://en.wikipedia.org/wiki/Positron_emission_tomography The relevant paragraph are
> For a typical dose (245 MBq) of FDG, one of the most common radiotracers used for PET neuroimaging and cancer patient management,[48] the effective radiation dose is 4.7 mSv.[49]
and
> This limitation restricts clinical PET primarily to the use of tracers labelled with fluorine-18, which has a half-life of 110 minutes and can be transported a reasonable distance before use.
Where "245 MBq" means 2*10^8 positrons per second for. And "110 minutes" means a half disappears every 2 hours, so the total sum is equivalent to 4 hours but I'm missing some small constant and they ae probably averaging the dose. I guess "3 hours" is a good compromise but multiply it by 2 or 4 if you prefer a smaller or bigger number. Anyway, 3 hours are 10^4 seconds, so the total numbers of positrons in a PET is approximately 2*10^8 * 10^4 = 2*10^12.
Sharlin 20 hours ago
And whether it’s a positron or an electron (beta+ or beta- decay) doesn’t seem to matter that much as far as equivalent dose is concerned, the energy deposited is only fractionally higher in the case of a positron. (But PET can only work with positrons because it’s exactly the pairs of 0.511 MeV annihilation gammas that it’s designed to detect!)
Razengan 19 hours ago
> I tried to find positrons sources in common life
Good. Reject electrons. Positive vibes only.
goda90 20 hours ago
Ejecting the warp core is a common strategy.
analog31 16 hours ago
In addition to knowing how much stuff is released by one particle, we have a decent handle on how much is needed in order to be dangerous, due to us being constantly bombarded by various cosmic rays. That's how we can say that it's not dangerous.
The article is behind a paywall, but it seems likely that the bigger safety concern is whatever produced the large quantity of particles needed to have a chance of trapping just one. And those kinds of experiments are conducted in regulated facilities for good reason.
snailshare 4 days ago
Does this hurt the positron?
brenkc a day ago
Call PETA (People for the Ethical Treatment of Antimatter)
sirlancer a day ago
Physicists for the Ethical Treatment of Atoms
arj a day ago
Poor thing, all alone
Razengan a day ago
It could have been an entire universe, like ours, if some theories/cosmologies are correct :)
largbae 19 hours ago
The end annihilation was actually the electron switching to backwards through time. At the beginning of the experiment the positron switches back to forward and continues on its way.
chamomeal 16 hours ago
What a crazy and fun idea. Good Wikipedia article. Everything in the Feynman cinematic universe is awesome
tclancy 19 hours ago
I was thinking of trying to spin up a campaign on bluesky to be upset about this.
dataflow 12 hours ago
> Every time they bang into something, there’s a chance of annihilation, but it doesn’t always happen
This goes against everything I've ever been told about antimatter. So a positron and electron can collide and not annihilate each other? How does that work? What happens to them in that case, and why does everybody say otherwise?
CamperBob2 13 hours ago
Similar work is done at the CERN LHC facility, where they can deliver antimatter to your door. Got a couple of hours? Check out Marco Reps' tour: https://www.youtube.com/watch?v=Yibef6nLCv8
Or cut to the chase at the 'antimatter factory', at https://www.youtube.com/watch?v=Yibef6nLCv8&t=3186s
rkagerer 13 hours ago
where they can deliver antimatter to your door
You mean if you live on the 4km loop 'serviced' by BASE-STEP?
CamperBob2 12 hours ago
I shudder to think of the paperwork the EU would require for authorization to transport antimatter off-campus. But they have hauled it around for up to 20 minutes (https://www.antimatter.hhu.de/en/about-us/base-step) so in principle it could go a bit farther!
solyin 3 hours ago
Now I'm imagining Klaus driving around with just a bit of anti-matter.
BobbyTables2 4 hours ago
Wonder when this will be done by DoorDash…
DoctorOetker a day ago
whats up with all the comments making analogies with AI torture repository?
One might measure the "amount of computation going on" as a proxy for consciousness, but "number of dissipative logic gates" can't be right since one can construct larger reversible circuits containing the same computation (and hence dissipation is a poor measure), although one could then use the total number of bits (including trash bits) as the measure.
but I don't understand why particle physics?
having all other comments (at the time of writing) be about consciousness of individual particles, seems to indicate these commenters specifically believe particle physics or antimatter to directly describe consciousness?
Or is this some kind of "disinfo inoculation campaign" to render us immune to "sentient rights propaganda"?
KPGv2 a day ago
I don't see comments on SI's website. I assume you mean here. Those are jokes.
swores 20 hours ago
To be fair, I can see why they didn't realise that considering none of them are remotely funny.
jatora 21 hours ago
It's definitely just jokes due to using the word 'trap'. You might need to get some sleep lol
boothby 15 hours ago
Don’t worry! If the single electron theory is correct, then this torture only represents an infinitesimal portion of its total lifetime, which is actually experienced in reverse and so it may feel increasing relief over time rather than increasing anxiety over being trapped.
pizzafeelsright a day ago
of course the cyclotron going clockwise.
gus_massa 20 hours ago
The title of the research article is "One-Positron Quantum Cyclotron" https://cfp.physics.northwestern.edu/documents/2026OnePositr... so you are right.
kennywinker 15 hours ago
South of the equator they go counter-clockwise
drsalt 11 hours ago
...and will have to deal with the consequences
bozdemir a day ago
That's matter cruelty. We need more ethical ways to study those poor things. Does anyone know what happened after the experiment ? Did they finally let it go?
consensus1 a day ago
It's worse than that. They annihilated it completely.
mixtureoftakes a day ago
Drawing the line at matter welfare when the world still has this much human suffering will never stop being wild to me
pelagicAustral a day ago
Definitely a matter of perspective.
saidnooneever a day ago
humans are also matter
ta8903 a day ago
But some humans are more matter than the others.
greenchair 21 hours ago
They have a pill that can help with that now.
kennywinker 15 hours ago
It’s a shot, actually
gcascio a day ago
Matter rights matter.
Scarblac a day ago
But antimatter rights antimatter? Or do they become lefts.
myaccountonhn a day ago
It doesn't matter if it's antimatter.
thelastgallon 21 hours ago
What if antimatter is load-bearing?
timcobb 20 hours ago
You're right. And I overstated it.
exe34 a day ago
I was going to comment "I bet it's pissed" and then worried about drawing dang on myself, but you started it... Also: https://www.facebook.com/watch/?v=1254917172263794.
"Wild? I was absolutely livid!"
saidnooneever a day ago
I sure hope it doesnt come back for revenge damn
tomaskafka 21 hours ago
It was given freedom at the end of experiment, and was immediately eaten by its abundant natural predator, just like it happens in nature.
svnt 18 hours ago
Don’t eat Jimmy!
jimnotgym a day ago
I hope they took precautions against the Camerlengo stealing it
ButlerianJihad a day ago
Positrons are just as Catholic as electrons: they both have the same mass!
BobbyTables2 4 hours ago
Except they draw the line at welcoming the other in…
lifeisstillgood 20 hours ago
The parents of the anti-matter particle then freeze time just as the containment is about to explode, allowing Picard and Geordi to wander
around the facility looking for clues - until one scientists head slowly turns - they are also awake !!
shireboy 20 hours ago
The Ackbar Effect
condour75 18 hours ago
It probably got Copenhagen syndrome