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!"