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Annihilation and anti-matter interactions

  1. Mar 21, 2008 #1
    We are learning particle physics at the moment in school.

    My teacher was telling me that when matter meets anti matter, they annihilate each other out. My question is what happens when an anti proton meets a positron or when an anti neutrino meets an electron. Would they annihilate each other or do the particles hav to exist in their pairs to annihilate?

    Please reply,
  2. jcsd
  3. Mar 21, 2008 #2
    Particles are only annihilated when they meet their respectively anti-partice.
    So if antiproton meets a positron the positron is not annihilated.
  4. Mar 21, 2008 #3
    so..they would continue to exist then?
  5. Mar 21, 2008 #4


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    yes, correct!
  6. Mar 21, 2008 #5
  7. Mar 22, 2008 #6


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    The word "annihilated" is a special term in particle physics and really doesn't mean what the term is literally defined in the usual English dictionary. A better term would be "replaced by something else," as in, when matter and antimatter meet, they are replaced by something else. The something else could be photons (or gamma rays), or it could be various other things including some other particle / antiparticle combinations.

    The other half of the "annihilated" term is "created," which could be translated as "replaces something else." So an elementary particle is created and later annihilated, this would mean that it replaces something else and eventually is itself replaced.
  8. Mar 22, 2008 #7

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