[Petrochemicals (OP)]

What is our control of antimatter like? Can we store energy efficiently and safely using it?

[Halc]

Can we store energy efficiently and safely using it?

Define 'efficient'.
I mean, for every unit of energy stored as antimatter, it takes over 20000 units of energy to produce it. I cannot think of an energy storage technology less efficient than that, and this assumes that no losses when the energy is subsequently used for the purpose for which it was stored.

[Bored chemist]

I wondered if your number was a bit on the generous side.
The best productivity I could find (via Quora) was this
https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.102.105001

Which says they got
"We measure up to
2×10^10 positrons per steradian ejected out the back of ∼mm thick gold targets when illuminated with short (∼1ps) ultra intense (∼1×10^20 W/cm2) laser pulses. "

They don't say in the abstract what the beam angle is. The diagrams seem to suggest it's small but to start, I will assume they get a whole steradian at that flux.
So they get something like 10^10 positrons
The annihilation energy is about 1MeV per positron.
So they get about 10^10 MeV of energy out
And the "cost" is about 100J i.e about 6 *10^14 MeV.
That's not as bad as I'd thought. about (10^10 MeV) / 96 *10^14 MeV.)
 1 in 6 * 10^4
But the beam output isn't really a steradian.
Let's do some guesswork.
The equipment diagram shows some angles for the alignments and they are specified to the nearest degree.
That  sort of implies that the beams aren't much bigger than 1 degree.
And a degree is about 1/400 of a circle so the solid angle of a beam about 1 degree in each direction is about 1/ 160000 of a sphere
And a sphere is about 12 steradians
So that's a beam size of about 10^-4 steradians
And that would imply something like 10^6 positrons per shot.
(and a corresponding roughly 10,000 fold reduction in the "efficiency").
So we are talking about 1 in 100 million.
And then there's the laser efficiency which is probably 1% on a good day.
Then you somehow have to play "catch the positrons".
If all my dodgy assumptions and arithmetic are correct, the efficiency overall is going to be well less than 1 in a billion or 1 in a trillion.

[paul cotter]

Even if it was energetically favourable how would one store it? Any contact with matter would lead to annihilation and explosive release of energy and most likely ionising radiation.

[alancalverd]

I guess there are plenty of positrons  in near-space, resulting from the interaction of solar gamma radIatoin with the upper atmosphere.

No problem separating them from electrons as they will traveL in the opposite direction in a magnetic field and you can trap them in a magnetic Klein bottle until you need them.

[Bored chemist]

problem separating them from electrons as they will traveL in the opposite direction in a magnetic field

until they hit some matter.

[Eternal Student]

Hi.

No problem separating them from electrons as they will traveL in the opposite direction in a magnetic field

   That separates positive fluff from negatively charged fluff.  To separate the positrons from the fluff needs a bit more precision which has an energy cost because you'll want to maintain some electric and magnetic fields.

you can trap them in a magnetic Klein bottle until you need them.

    I really didn't know it had be a Klein bottle.  If it's clean enough will that be OK?
In any case, they require a magnetic field to be maintained.   That seems like an energy cost again.

that's what I think @paul cotter  and the other earlier replies are getting at.  You can't realistically obtain OR store the anti-matter in a way that is likely to be efficient. 

Best Wishes.

[alancalverd]

problem separating them from electrons as they will traveL in the opposite direction in a magnetic field

until they hit some matter.

Of which there is very little in space, by definition.

So we put a permanent magnet with a Klein bottle shaped field in high orbit and wait. We can separate the positrons from ES's positive fluff by shaping the bottle entrance into a pretzel so the slower, massive particles get filtered out.

Come on, guys, as taxpayers you have been supporting this kind of stuff for about 100 years. Time for some payback!

[Eternal Student]

Hi.

    Do they really call it a magnetic Klein bottle?    A magnetic bottle, a magnetic trap or something with magnetic mirrors - these are terms I've heard of.
  It just seems that if you're using a Klein bottle then the whole universe can be considered to be inside it.  That probably saves a bit of trouble and cost getting the positrons into the bottle.


Best Wishes.

[Petrochemicals (OP)]

Even if it was energetically favourable how would one store it? Any contact with matter would lead to annihilation and explosive release of energy and most likely ionising radiation.

Hopefully anti matter will be repulsed from matter so problem solved.

[evan_au]

Storing positrons is fairly well understood - before the LHC was built at CERN, the 27km tunnel was used for LEP: the Large Electron-Positron collider. This stored electrons and positrons in a very good vacuum, guided by electric and magnetic fields. It cost about a billion swiss francs to build (around  $US 1 billion, in 1990 dollars).
https://en.wikipedia.org/wiki/Large_Electron%E2%80%93Positron_Collider

A more difficult item to store is is anti-hydrogen, since it doesn't have such a strong electric or magnetic field as positrons. Recent tests showed that scientists could store anti-hydrogen for 16 minutes (for use in studies of the gravitational attraction of anti-matter, among other things).
https://home.cern/science/physics/antimatter/storing-antihydrogen

[paul cotter]

Petrochemicals, on what basis do you expect matter and antimatter to be mutually repulsive?

[alancalverd]

It just seems that if you're using a Klein bottle then the whole universe can be considered to be inside it.  That probably saves a bit of trouble and cost getting the positrons into the bottle.

And makes it easy to extract them again since the entire universe is also outside it!

The re-entrant singularity is mathematically trivial so we can leave it to the engineers to sort out. A chat with a glassblower could be instructive.

[Petrochemicals (OP)]

Petrochemicals, on what basis do you expect matter and antimatter to be mutually repulsive?

Just the standard theory

[Bored chemist]

Of which there is very little in space, by definition.

True, but there's plenty in the upper atmosphere.

resulting from the interaction of solar gamma radIatoin with the upper atmosphere.

That's catch 22.
If there's enough matter for the solar gammas to hit + knock positrons off, then there's enough matter for the positrons to hit and be destroyed.

Hopefully anti matter will be repulsed from matter so problem solved.

That's wishful thinking, not science.

But PC won't read it.

If you point out reality to him, he blocks you and puts a childish comment in his signature.

[evan_au]

matter and antimatter to be mutually repulsive: Just the standard theory

An electron (charge -1) has as its antiparticle: the positron (charge +1). Since opposite charges attract, these will attract each other strongly. That is the standard theory.

However, when you come to uncharged particles (eg anti-neutrons and anti-Hydrogen), the electric field is minimal, and gravitation has a chance to assert itself.

At one time, some cosmologists tried to explain the dominance of matter in our part of the universe by imagining that matter and anti-matter would gravitationally repel each other to opposite ends of the universe.

Most physicists today expect that matter and antimatter will have equal gravitational attraction
- This comes from Einstein's Mass-Energy equivalence.
- A Hydrogen atom has a mass/energy of 939 Mev/c²
- An anti-Hydrogen atom has a mass/energy of 939 Mev/c²
- In Relativity, the gravitational force is between the units of Mass-Energy, and is always attractive
- This is why CERN is creating, storing & experimenting on anti-Hydrogen, to confirm these theories

[alancalverd]

If there's enough matter for the solar gammas to hit + knock positrons off, then there's enough matter for the positrons to hit and be destroyed.

It only takes one nucleus to convert a photon into a p-e pair. So if the atmosphere is very tenuous (which it is at very high altitude) and the magnetic field is very strong (which it will be in my bottle) there's a fair chance of capturing the occasional positron.

There are lots of atoms in Switzerland, but CERN seem to manage. 

[Bored chemist]

There are lots of atoms in Switzerland, but CERN seem to manage.

There are very few atoms in the place where CERN stores antimatter.

Incidentally, if your bottle selectively traps positively charged things, how will you stop it collecting things like oxygen ions like O2+ ?

[alancalverd]

They travel too slowly. Pretzels aren't just for eating.

[Petrochemicals (OP)]

matter and antimatter to be mutually repulsive: Just the standard theory

An electron (charge -1) has as its antiparticle: the positron (charge +1). Since opposite charges attract, these will attract each other strongly. That is the standard theory.

However, when you come to uncharged particles (eg anti-neutrons and anti-Hydrogen), the electric field is minimal, and gravitation has a chance to assert itself.

At one time, some cosmologists tried to explain the dominance of matter in our part of the universe by imagining that matter and anti-matter would gravitationally repel each other to opposite ends of the universe.

Most physicists today expect that matter and antimatter will have equal gravitational attraction
- This comes from Einstein's Mass-Energy equivalence.
- A Hydrogen atom has a mass/energy of 939 Mev/c²
- An anti-Hydrogen atom has a mass/energy of 939 Mev/c²
- In Relativity, the gravitational force is between the units of Mass-Energy, and is always attractive
- This is why CERN is creating, storing & experimenting on anti-Hydrogen, to confirm these theories

Quite right. It has been conclusively proved earlier this year.

https://www.space.com/matter-antimatter-same-response-to-gravity