Positron discovery in cloud chamber, how so?

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Discussion Overview

The discussion revolves around the discovery of positrons in a cloud chamber, exploring the conditions under which positrons can be observed without immediately annihilating upon encountering electrons. Participants examine the implications of positron-electron interactions in the context of cloud chamber experiments.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • DaTario questions whether positrons, as anti-particles of electrons, would naturally annihilate upon encountering electrons in a dense cloud, leading to photon production.
  • Another participant references a previous discussion that addresses the typical lifetime of positrons in matter, suggesting that this lifetime affects their ability to be detected in cloud chambers.
  • A third participant shares a personal experience with cloud chambers, noting the use of magnetic fields to differentiate the paths of electrons and positrons, which could provide insights into their energies.

Areas of Agreement / Disagreement

Participants do not appear to reach a consensus on the mechanisms that allow positrons to be detected in cloud chambers without immediate annihilation, indicating that multiple competing views remain regarding the conditions necessary for their observation.

Contextual Notes

The discussion highlights the uncertainty surrounding the interactions between positrons and electrons in dense media, particularly regarding the timescales involved and the experimental setups that may influence detection.

DaTario
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Hi All,

I was watching a video from Veritassium () when it was said that positron discovery was made in a cloud chamber. If the anti-particle of the electron is passing through a dense cloud of atoms and molecules, won't it be natural for this anti-particle to meet an electron and go through a fast pair anihilation, giving rise to photons?

Best wishes

DaTario
 
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IIRC, our school's cloud-chamber had an optional magnetic field via a pair of coils. Trails from the 'source' spiralled one way for electrons, other way for their anti-kin. And, if you were quick, measurement of curl's diameter allowed a useful estimate of energy etc...

Our school had a 'Treasure Trove' of Nuffield teaching equipment, akin to 1st-year Uni Physics level...
 

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