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What happens when an electron and positron collide

by robertjford80
Tags: collide, electron, positron
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Jan27-14, 06:16 PM
P: 392
I was listening to this radio program (Google: In Our Time Antimatter) and they kept saying that when an electron and a positron collide they annihilate and radiate energy. I have a feeling that that's not right. I have a hunch that the particles turn into something else which then radiates outward, carrying the heart with them.
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Jan27-14, 06:26 PM
P: 1,028
you meant heat :p hahaha
As for the post, why do you have this feeling? I mean why is it so weird to accept them turning into photons and isn't it weird to accept they'd become something else that would afterwards emit photons.
In fact that they turn into photons is what we observe and it's energy-consistent. Also we haven't observed that "something" you proposed.
Jan27-14, 07:00 PM
P: 12,055
They can turn into photons - and at low energies, that is the only possible process.*
They do not "radiate energy", energy is not a particle. They radiate photons.

If the collision happens with sufficient energy, other particles can get created.

*neglecting the extremely tiny probability to get neutrinos.

Jan28-14, 02:24 AM
P: 45
What happens when an electron and positron collide

Quote Quote by mfb View Post
They can turn into photons - and at low energies, that is the only possible process.*
Of course, there is also the possibility of elastic scattering:
Elastic scattering of electrons and positrons
Jan28-14, 11:29 AM
P: 12,055
Well, sure. You can also count positronium formation.
Jan28-14, 11:36 AM
P: 1,028
But still the OP has not made clear what he has in mind...
Jan28-14, 03:45 PM
P: 4
Just the usual collision/scattering. One of the two:
1. elastic collision (positron+electron coming out, with same of different momentum; lab frame of centre of mass frame)
2. inelastic collision (produces other particles such as photons, and anything else allowed by kinematics; to calculate the probabilities of different final product particles you need to evaluate associated Feynman integral)


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