How are positrons made?

  • #1

Main Question or Discussion Point

Hi awesome physicists!
I'm interested in particles and particle accelerators. I've been wondering about how anti-matter is made. I've researched (using the infinite power of google) and have discovered that positrons (or anti-electrons) can be made by firing an electron at a heavy element, which, when the electron changes path and gives off high-energy photons which supposedly can spontaneously turn into a positron-electron pair. This sounds wierd to me as I don't understand this spontaneous change stage.
What really goes on here?

Thanks,
Joe
 

Answers and Replies

  • #2
QuantumPion
Science Advisor
Gold Member
902
42
The phenomenon you are referring to is called pair production, where by a photon of energy greater than two times the rest mass of an electron, when interacting with a nucleus, can turn into an electron and positron pair.
 
  • #3
Thanks. And with regard to the experiment I referred to earlier (when electrons are fired at a heavy element etc), if a cold cathode was used to fire the electrons, would the experiment be successful in the sense that an electron-positron pair would be created? And if so, would the amount of gamma radiation produced be harmful if a human was standing next to it as it happened?
 
  • #4
34,391
10,478
Thanks. And with regard to the experiment I referred to earlier (when electrons are fired at a heavy element etc), if a cold cathode was used to fire the electrons, would the experiment be successful in the sense that an electron-positron pair would be created?
If you accelerate the electrons sufficiently, sure.
And if so, would the amount of gamma radiation produced be harmful if a human was standing next to it as it happened?
That just depends on the intensity.
 
  • #5
57
0
Can I make a silly post and say

When a mommy electron and a daddy photon get really excited...
Sorry, I'll just shut up
 
  • #6
3
0
Cool. Could anyone tell me how many electrons produce how many antiparticle pairs (theoretically)?
 
  • #7
34,391
10,478
That really depends on the energy. High-energetic electrons in matter can produce many (10, 100, 1000, ... just depends on the energy) electron/positron pairs in their showers.
 

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