Physics Questions People Ask Fermilab

Pure Antineutron Beams


I am a physics student in Germany. I haven't had particle physics yet, so I'd be glad if you answered me one question:

How do you create more or less pure anti-neutron beams in your accelerator??

I'm sure it's possible somehow but I just don't know the way to relize that.

The "options" I got to know by now:

  • collision of anti-protons with carbon nuclei can result in anti-neutrons
  • decay of lambda-particles (how would you create them?)
I guess the main problem is how to prevent neutron production during the processes or how to separate neutrons and anti-neutrons then....

I really thank you very much for helping me!
Please reply.

Yours sincerely,
Alexander Windel

Dear Alex,

It is nice to see an enthusiastic student asking questions like this, it made me stop and think for a while. My answer is based upon an article in Physics Letters, Vol 23, page 160-163, "Further Results on the charge exchange pbar p -> nbar n at 5, 6, 7 and 9 GeV/c. The basic idea would be to take a beam of relatively low energy antiprotons such as we have stored in the Accumulator (8.9 GeV/c) and interact them with a hydrogen target (either a liquid target or a gas jet) . By looking in the forward direction you would get mainly antineutrons since the the angular distribution of the antineutrons is very strongly peaked in the forward direction. A sweeping magnet after the target would get rid of charged particles produced in other unwanted interactions. I hope this helps.

Craig Moore

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