Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Pair Production and Annihilation

  1. Jun 4, 2009 #1
    When a photon, with the help of a nucleus experiences pair production to make a positron and an electron, the energy of the photon will equal the rest mass of both the electron and positron together right?

    Then when the electron and positron annihilate, the two photons produces will each have energy equal to the rest mass of a positron/electron.

    The new photons will have half the energy of the original photon each.

    Is this correct?
  2. jcsd
  3. Jun 4, 2009 #2


    User Avatar
    Science Advisor

    Not quite true. The incoming photon will in general have more energy than that required to create the pair. The extra energy ends up as kinetic energy of the pair.
  4. Jun 4, 2009 #3
    Should it be expected that the parent photon will have a smaller wavelength than the two daughter photons?
  5. Jun 5, 2009 #4


    User Avatar
    Science Advisor

    Since wavelength is inversely proportional to energy, the parent photon has less than half the wavelength of the daughters.

    Small correction, the extra energy of the photon in pair production goes into kinetic energy of the nucleus.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Similar Threads - Pair Production Annihilation Date
B Entanglement and pair-production and annihilation Jan 24, 2018
I Requirements for pair production Nov 16, 2017
New: Quantum teleportation Apr 10, 2015
Pair production and pair annihilation Jan 25, 2013
Regarding pair production and annihilation Apr 30, 2012