If gamma rays undergo pair production is there a way to say, deflect and collect the positrons using magnetic fields?

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    $\begingroup$ yes, the problem is more likely to be getting a strong enough source of gamma rays $\endgroup$ Jul 26, 2015 at 0:07
  • $\begingroup$ And, since the electron and positron are heading in opposite directions with opposite charge, they will both deflect towards the same direction (assuming a constant magnetic field). $\endgroup$
    – Jon Custer
    Jul 26, 2015 at 0:22
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    $\begingroup$ This PDF from the snowmass process describes conceptual design of a positron source for the NLC (Next Linear Collider; clever name, eh?) which is modeled as a improvement on the SLAC positron source. The SLAC sources evidently uses an electron beam to generate showers rather than a gamma source, presumably because electron beams are easy to create and manipulate on demand. $\endgroup$ Jul 26, 2015 at 0:58

1 Answer 1


Rather than using a magnetic field, you are better off using a strong electric field to separate them - since the initial direction of the electron / positron is somewhat random, a magnetic field will deflect but not separate in a meaningful way. An electric field can pull the positrons one way, and the electrons the other way - regardless of their initial direction. Thus the positrons can always be directed towards your "collector"; of course you will need a confinement device (magnetic, presumably) which means you will ultimately need both. But if you use just a magnetic field, you will trap both electrons and positrons and they won't stay apart for long - it's not in their nature.


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