Positron - electron annihilation.

In summary, by selecting specific energies for the electron and positron beams, the LEP collider was able to produce a high rate of neutrino-antineutrino pairs. This experiment confirmed that there are only three types of neutrino and not a fourth, as the rate of electron-positron annihilation would have been higher if there were more types. This is because having more types of neutrino would provide more options for decay, resulting in a higher rate.
  • #1
JZR
4
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Here is an excerpt from my textbook:

"The mass of a Z boson is about 90 Gev. By selecting the energy of the electron and positron beams in the LEP collider to be 45 Gev each, a high rate was achieved for the production of neutrino-antineutrino pairs in the process. The experiment shows that there are no more types of neutrino than the three already discovered. Had there been a fourth type of neutrino, the rate of electron-positron annihilation would have been higher than observed."

My question is, why would the rate of annihilation be higher if there were four types of neutrino?
 
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  • #2
Basically you would have more possible channels in which your electron and positron can decay to. Providing more options for a decay will increase the rate.
 

1. What is positron-electron annihilation?

Positron-electron annihilation is a process in which a positron (a positively charged particle) and an electron (a negatively charged particle) collide and annihilate each other, producing energy in the form of gamma rays.

2. How does positron-electron annihilation occur?

Positron-electron annihilation occurs when the positron and electron approach each other and undergo a process called pair production, in which they convert their mass into energy. This energy is released in the form of gamma rays.

3. What is the significance of positron-electron annihilation in science?

Positron-electron annihilation is significant in science because it helps us understand the behavior of antimatter (particles with the same mass as regular particles but with opposite charge). It also has applications in medical imaging, such as in positron emission tomography (PET) scans.

4. Can positron-electron annihilation be observed in everyday life?

No, positron-electron annihilation cannot be observed in everyday life because it requires high-energy collisions between particles, which only occur in specific environments, such as particle accelerators or in space.

5. Are there any potential dangers associated with positron-electron annihilation?

No, there are no known dangers associated with positron-electron annihilation. The energy released is in the form of gamma rays, which can be harmful in high doses, but the amount produced in this process is very small and easily shielded against.

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