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I am not asking about electron positron annihilation, nor positronium.

Electrons (when accelerated in some cases non-uniformly), could emit photons.

Though, I have not found any experiment that would do the same with accelerated positrons emitting photons. After the comments, there is brehmsstralung from positrons interacting with crystals.

I have read this question:

Photon emission between an electron and positron

What happens if a photon emitted from an electron hits a positron?

But these do not answer my question.

Does destructive interference occurs between lights emitted from matter and antimatter?

Does the Advanced Photon Source use electrons or positrons?

where DarioP says:

A positron beam radiates exactly in the same way as an electron beam, so the physics is mostly the same except for one effect: the ion/electron cloud.

These ones state that antimatter can emit photons the same way as matter. Tough, there is no reference nor experiment.

We are able to produce positrons, maybe accelerate them, but I have not found any experiment that would do this or in any way see if positrons can emit photons.

Question:

  1. Can positrons (when accelerated) emit photons?
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    $\begingroup$ Of course they do! People have built electron-positron collider. If positrons didn’t behave just as expected (i.e. just like electrons but with opposite charge) these machines wouldn’t have worked at all. $\endgroup$
    – knzhou
    Jan 12, 2020 at 17:58
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    $\begingroup$ Are you just looking for an answer to your question at the end or are you looking for an actually performed experiment that tests this? It's not quite clear to me from the way your question is written. $\endgroup$
    – ACuriousMind ♦
    Jan 12, 2020 at 17:59
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    $\begingroup$ LEP was an electron positron collider at high energies, reached 220 Gev the last years. $\endgroup$
    – anna v
    Jan 12, 2020 at 18:04
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    $\begingroup$ see this jetp.ac.ru/cgi-bin/dn/e_045_02_0229.pdf ,brehmstrahlun spectra of electrons and positrons measured in crystals. There are also a number of theoretical papers. $\endgroup$
    – anna v
    Jan 12, 2020 at 18:16
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    $\begingroup$ they used the electrons and separately the positrons to get the brehms spectra. These are different because there is no symmetry with the atoms. As far as colliders, if the two beams had different behavior in their synchrotron radiations it would be new physics, and it would show , because the two beams are travelling in opposite directions in the same turnnel wth the same magnets.. They obey the same calculations. $\endgroup$
    – anna v
    Jan 12, 2020 at 18:33

1 Answer 1

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There is no doubt that a positron can be accelerated with an electrical potential difference and that every acceleration is accompanied by a photon emission. One should be able to draw this conclusion from Anna's comment on the bremsstrahlung spectra of electrons and positrons.

But there is another point to think about. Accelerating electrons in an antenna rod, the emitted EM radiation is not only synchronized with their electric field direction but also with their magnetic field direction. At the moment, the positive direction of the electric field points upwards, the magnetic north pole points to the right (thumb up and the second finger to the right). What prevents the electrons to radiate lefthanded?
It is an asymmetricity which is not mentioned anywhere. Perhaps future research could show that positrons radiate left-handed.

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  • $\begingroup$ "What prevents the electrons to radiate lefthanded?" The direction of the magnetic field is just by convention, because we use the right-hand rule. If we switched to the left-hand rule the magnetic field would flip in sign. $\endgroup$
    – knzhou
    Jan 19, 2020 at 6:45
  • $\begingroup$ @knzhou If you take two vectors, perpendicular on each other, how many possibilities do you have to arrange them on a third vector, perpendicular to the first two? Do you agree, that you have exactly two possibilities? And about the conventions, they are conventions not to discuss anymore about the directions of electric nor magnetic fields. They are fixed. And beeng fixed, you can see, that exist two possibilities for the directions of the magnetic and the electric field in relation to the direction of propagation. $\endgroup$
    – HolgerFiedler
    Jan 19, 2020 at 7:11
  • $\begingroup$ The problem is that the magnetic field is not a vector. It is a more abstract object (a rank 2 antisymmetric tensor) that should be visualized in terms of a plane. And when you take two vectors, perpendicular to each other, there is exactly one plane: the plane the vectors lie in. $\endgroup$
    – knzhou
    Jan 19, 2020 at 7:13
  • $\begingroup$ @knzhou This doesn’t answer my questions. Secondly, I don’t care about is something a vector or not. As long as I may measure the direction of the magnetic field at some point and so I may do for the electric field, I’ll see that they form a right handed system. For radio waves you will not measure the left handed case. $\endgroup$
    – HolgerFiedler
    Jan 19, 2020 at 7:17
  • $\begingroup$ If you think about the measuring devices you have for magnetic fields, you'll see that every single one of them includes an arbitrary sign convention that is ultimately tied to the choice of the right hand rule. $\endgroup$
    – knzhou
    Jan 19, 2020 at 7:24

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