December 26th, 2007

Conservation of energy and momentum concerning pair annihilation?

Bob B asked:


Use the conservation of energy and momentum to show that pair annihilation CANNOT produce only on photon.

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This entry was posted on Wednesday, December 26th, 2007 at 8:46 am and is filed under Uncategorized. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.

2 Responses to “Conservation of energy and momentum concerning pair annihilation?”

  1. (Ω)Mistress Bekki Says:
    December 27th, 2007 at 2:48 am

    Work in the center of mass frame.

    Initial momentum = 0
    - Final momentum = 0

    But a single photon carrying all that energy can’t have zero momentum. So it won’t work.

  2. ♘EgYpTiAn♘ ☢GuY☢ ☠☠☠☠☠ Says:
    December 29th, 2007 at 12:49 am

    Suppose an electron and a positron assumed to be initially at rest annihilate each other, then then if they produced one photon it would have momentum, so momentum won’t be conserved.

    Theoretically another photon must be produced to conserve momentum, in this case, the two photons would have opposite directions, thus their total momentum would be zero, and momentum would be conserved.