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Creating a beam of antiprotons allows to create antineutrons by charge exchange. How does this exchange work? The question pops up after the question "Is there a strong evidence of antineutron existance?"

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HolgerFiedler
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  • Can you formulate a question that seems to make borderline sense? All I am getting here is the equivalent of "A ship is powered by a 3MW gas turbine. How old is the captain?". – CuriousOne Sep 06 '14 at 14:56
  • A number of possible antineutron production schemes (including a new one) can be found in http://www-elsa.physik.uni-bonn.de/ELAN/ps/1.pdf. – CuriousOne Sep 06 '14 at 15:32
  • @Rob: In the source mentioned by CuriousOne above I read "charge exchange reaction $ p + \bar{p} \rightarrow n + \bar{n} $". Google search zero. Do you could explain? – HolgerFiedler Sep 07 '14 at 18:46
  • When I google charge exchange reaction, I am getting plenty of hits. I also noticed that the full reaction was explained to you yesterday... so I am wondering when you are going to take "yes" for an answer. At this point it seems to me, that you are simply trolling. – CuriousOne Sep 07 '14 at 20:38

1 Answers1

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There are lots of possibilities, depending on the energy of the antiproton beam. The hadron spectrum is quite complicated.

Probably the most likely channel is pion production: $$ \bar p \to \bar n + \pi^-. $$ This reaction requires a "spectator" nucleus to exchange energy and momentum with the $\bar p$, and so might be more properly written as $$ A + \bar p \to A^* + \bar n + \pi^- $$ where by $A^*$ I mean that the spectator nucleus might also end up in an excited state. The negative pions will eventually either decay (mostly $\pi^-\to\mu^-+\bar\nu_\mu$) or be captured on another nucleus in a reaction like $$ \pi^- + p \to n. $$ That's not the only available channel: with a spectator nucleus, you can make other antibaryons and mesons, for instance \begin{align} \bar p &\to \bar\Delta + \pi && \text{(which could make $\pi^\pm$ or $\pi^0$)} \\ \bar p &\to \bar\Lambda + K^- \\ \bar p &\to \bar\Sigma + K && \text{(could be a $K^0$ or a $K^-$)} \\ &\vdots \end{align}

Here's a review of low-energy nucleon-antinucleon interactions, which I haven't yet read.

rob
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  • Do you know which facilities have an antineutron factory? Is anybody making antineutrons on a regular basis? Thank you! – CuriousOne Sep 06 '14 at 15:42
  • @CuriousOne There are several antiproton factories, but I suspect that the antineutrons are mostly a contaminant. Fast neutrons are challenging enough to work with when they are made of matter, since they can't be steered by electric and magnetic fields. I'd be fascinated to learn differently, though. – rob Sep 06 '14 at 15:50