Very cool! There's some wild ideas about antimatter capture in space via giant arrays of superconducting magnets trapping naturally occurring antimatter.
Apparently, nanograms / micrograms is enough to create a "antimatter catalyzed" fission/fusion propulsion system with enormous specific impulse / efficacy.
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 4 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.
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!?!
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.
gus_massa 20 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
sandworm101 21 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 20 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 20 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.
vlovich123 18 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 18 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 17 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.
gus_massa 20 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 19 hours ago [-]
They really missed out on a chance to go with 'negatrons' instead of antiprotons.
dekhn 17 hours ago [-]
That would too easily get confused with positrons (anti-electrons).
greenbit 17 hours ago [-]
Or even "notorp". Notorps could have been a thing.
pennomi 4 hours ago [-]
“A literal handful of antimater particles” would be quite potent, even if your hands are very tiny.
mr_toad 17 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 12 hours ago [-]
Veritasium made a video about CERN's "antimatter factory"
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 19 hours ago [-]
What happens if an anti proton hits a normal hydrogen atom?
mr_toad 17 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.
retrac 19 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.
I kind of want to know how they safely deal with its release (destruction)
gus_massa 21 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 21 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 20 hours ago [-]
> I tried to find positrons sources in common life
Good. Reject electrons. Positive vibes only.
SwellJoe 22 hours ago [-]
It's one particle. It's not a bomb.
brippalcharrid 17 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.
goda90 21 hours ago [-]
Ejecting the warp core is a common strategy.
ungovernableCat 22 hours ago [-]
E=mc*2 but m is really really tiny
Retr0id 22 hours ago [-]
If it's a single particle I don't think there's much to worry about?
analog31 17 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.
lol8675309 10 hours ago [-]
That seems super safe. At least they are wearing gloves.
17 hours ago [-]
snailshare 4 days ago [-]
Does this hurt the positron?
brenkc 1 days ago [-]
Call PETA (People for the Ethical Treatment of Antimatter)
sirlancer 24 hours ago [-]
Physicists for the Ethical Treatment of Atoms
largbae 20 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.
What a crazy and fun idea. Good Wikipedia article. Everything in the Feynman cinematic universe is awesome
tclancy 20 hours ago [-]
I was thinking of trying to spin up a campaign on bluesky to be upset about this.
arj 1 days ago [-]
Poor thing, all alone
Razengan 1 days ago [-]
It could have been an entire universe, like ours, if some theories/cosmologies are correct :)
ggyyyg 1 days ago [-]
[flagged]
dataflow 13 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 14 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
You mean if you live on the 4km loop 'serviced' by BASE-STEP?
CamperBob2 13 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 4 hours ago [-]
Now I'm imagining Klaus driving around with just a bit of anti-matter.
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"?
jatora 22 hours ago [-]
It's definitely just jokes due to using the word 'trap'. You might need to get some sleep lol
boothby 16 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.
KPGv2 23 hours ago [-]
I don't see comments on SI's website. I assume you mean here. Those are jokes.
swores 21 hours ago [-]
To be fair, I can see why they didn't realise that considering none of them are remotely funny.
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?
tomaskafka 22 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 19 hours ago [-]
Don’t eat Jimmy!
gcascio 24 hours ago [-]
Matter rights matter.
Scarblac 24 hours ago [-]
But antimatter rights antimatter? Or do they become lefts.
myaccountonhn 23 hours ago [-]
It doesn't matter if it's antimatter.
thelastgallon 22 hours ago [-]
What if antimatter is load-bearing?
timcobb 21 hours ago [-]
You're right. And I overstated it.
saidnooneever 23 hours ago [-]
I sure hope it doesnt come back for revenge damn
22 hours ago [-]
1 days ago [-]
consensus1 24 hours ago [-]
It's worse than that. They annihilated it completely.
mixtureoftakes 24 hours ago [-]
Drawing the line at matter welfare when the world still has this much human suffering will never stop being wild to me
I hope they took precautions against the Camerlengo stealing it
ButlerianJihad 24 hours ago [-]
Positrons are just as Catholic as electrons: they both have the same mass!
BobbyTables2 5 hours ago [-]
Except they draw the line at welcoming the other in…
21 hours ago [-]
lifeisstillgood 21 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 !!
20 hours ago [-]
486sx33 10 hours ago [-]
[dead]
shireboy 21 hours ago [-]
The Ackbar Effect
21 hours ago [-]
condour75 19 hours ago [-]
It probably got Copenhagen syndrome
19 hours ago [-]
Rendered at 09:23:08 GMT+0000 (Coordinated Universal Time) with Vercel.
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...
https://en.wikipedia.org/wiki/Alpha_Magnetic_Spectrometer
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...
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...
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.
> 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
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!).
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.
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.
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.
https://m.youtube.com/watch?v=jjp3WC8Unj8
What would need to be true for the capability of creating and using antimatter to become feasible?
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.
The link is cherry picked from a very good explanation by Gemini https://www.google.com/search?q=antiproton+hidrogen+colissio...
> 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.
Good. Reject electrons. Positive vibes only.
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.
https://en.wikipedia.org/wiki/One-electron_universe
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?
Or cut to the chase at the 'antimatter factory', at https://www.youtube.com/watch?v=Yibef6nLCv8&t=3186s
You mean if you live on the 4km loop 'serviced' by BASE-STEP?
https://www.youtube.com/watch?v=ja7ap6AEuYU
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"?
"Wild? I was absolutely livid!"