Large-scale antimatter production

From what I can find, presently the only known means of producing antimatter consist of directing particle accelerators at various targets, and only infrequently getting positrons or anti-protons as byproducts of particle interactions.

Assuming a sufficiently large source of energy: Have more efficient means of producing antimatter been conceived?

And based on these is there a known upper bound on antimatter production efficiency? For example:

1. If all known theory requires that an anti-particle be produced with its particle pair, then efficiency will always be under 50%.
2. Are there known processes for "transmuting" matter into anti-matter? If so, do these allow for a theoretical upper-bound on production greater than 50% of input energy?
• Note that you get vast numbers of positrons (and every other light anti-particle) out of energetic hadron interactions. It's just that cooling them into beams is difficult and inefficient. Jul 14, 2016 at 22:00
• @dmckee - So, ignoring the "engineering" problem, can hadron colliders produce a nearly 50% ratio of antimatter that is theoretically harvestable (i.e., before the antimatter annihilates/decays in a time or distance so small that it is theoretically inseparable)? Or is the "harvestable" ratio of anti-matter to input-energy known for such interactions? Jul 14, 2016 at 22:03
• Pair production makes particles and anti-particles in equal numbers, though in some cases they are the same thing (i.e. $\pi^0$s), but most decay too fast to do anything with them. The positrons can be captured and cooled into beams as can $\mu^+$s. Charged anti-pions can be partially focused and used to make neutrino beams., as can charged anti-kaons to a lesser extent. Collecting anti-protons in order to make neutral anti-hydrogen is hard but has been done. Jul 15, 2016 at 0:34
• There is no known mechanism that would allow matter to antimatter conversion. You can only produce particle antiparticle pairs. Aug 17, 2021 at 12:26
• There are some experiments with very powerful lasers to produce large quantities of matter/antimatter pairs. Aug 18, 2021 at 12:19

This Centauri Dreams article claims that a 0.01% efficiency is possible with current technology if there was a dedicated production facility.

Having searched for information on this problem myself, I have found nothing more of significance.

If you can get past the google scholar paywalls, you may want to look through the articles by Robert Forward who is referred to as the source of the information.

Magnetic field containers can be used for the storage of antimatter. Also, increasing the size of the particle accelerator will increase the volume output of antimatter, the key fuel in warp drives. The size of particle accelerator can be 100 miles around by diameter and 30 stories high.

• This site is about real-world physics, not the fictional Star Trek universe. Aug 17, 2021 at 13:08
• Some comments removed. Note that the question is not about “warp drives.”
– rob
Aug 17, 2021 at 13:20