How Are Positrons Created in Particle Accelerators?

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Discussion Overview

The discussion centers around the creation of positrons in particle accelerators, specifically exploring the process of pair production and the conditions under which electron-positron pairs can be generated. Participants delve into theoretical aspects, experimental setups, and potential safety concerns related to gamma radiation.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Experimental/applied

Main Points Raised

  • One participant, Joe, questions the process of positron creation and expresses confusion about the spontaneous change involved in pair production when high-energy photons interact with heavy elements.
  • Another participant explains that pair production occurs when a photon with energy greater than twice the rest mass of an electron interacts with a nucleus, resulting in an electron-positron pair.
  • Joe inquires about the effectiveness of using a cold cathode to fire electrons and whether this would lead to positron production, as well as concerns about the potential harm from gamma radiation produced during the process.
  • A response indicates that if electrons are accelerated sufficiently, positron production is possible, but the safety regarding gamma radiation depends on its intensity.
  • Another participant humorously suggests a whimsical explanation for positron creation involving "mommy electrons" and "daddy photons."
  • A later post asks about the theoretical relationship between the number of electrons and the number of antiparticle pairs produced, noting that this depends on the energy of the electrons involved.
  • It is mentioned that high-energetic electrons can produce varying numbers of electron-positron pairs, depending on their energy levels.

Areas of Agreement / Disagreement

Participants express varying levels of understanding and curiosity about the processes involved in positron creation, with some technical explanations provided. However, there is no consensus on the specifics of the experimental conditions or safety implications regarding gamma radiation.

Contextual Notes

Limitations in the discussion include the dependence on specific energy levels for pair production and the lack of detailed mathematical descriptions of the processes involved. The safety of gamma radiation is also presented as conditional on intensity, which remains unspecified.

Who May Find This Useful

This discussion may be useful for individuals interested in particle physics, experimental physics, and the mechanisms of antimatter production in particle accelerators.

tinypositrons
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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 weird to me as I don't understand this spontaneous change stage.
What really goes on here?

Thanks,
Joe
 
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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.
 
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?
 
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.
 
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
 
Cool. Could anyone tell me how many electrons produce how many antiparticle pairs (theoretically)?
 
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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