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Beta disintegration

  1. Mar 7, 2007 #1
    I was studying Beta decay in my nuclear courses few minutes ago, and something came to my attention.
    A nucleus can absorb an electron and undergo a beta decay like this:
    p + e- ----> n + neutrino
    Is the following one possible?
    n + e+ ----> p + anti-neutrino?
    where a nucleus absorb an positron and undergo a beta decay?
  2. jcsd
  3. Mar 7, 2007 #2


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    I'm not sure whether you're talking about beta decay here, since the beta (minus) decay I recall learning was n--->p+e-+ anti-neutrino. This is called beta-minus, since the beta particle emitted (here the electron) is negative. Of course, to this there is a corresponding beta plus decay: p--->n+ e+ +neutrino, however this requires energy, and so cannot occur in isolation, unlike the beta- decay.

    What you seem to be describing, p+e- ---> n+neutrino is what I would call "electron capture," where the nucleus captures an orbiting electron. Thus, I don't think that your second scenario would be allowed, since there are no orbiting positrons.
    Last edited: Mar 7, 2007
  4. Mar 7, 2007 #3
    Sorry for that, it's a problem when you know something in a 2nd language, and try to explain it in a third one.
    (From French to English, and neither are my maternal language)
    What I want to know is :
    since p + e- ----> n + neutrino is allowed
    is n + e+ ----> p + anti-neutrino allowed?
    I know that there is no positrons orbiting, but is that the only reason, or is there something else?
    if there is no way for a nucleus to absorb a positron , how about (e+,n) scattering? will it be possible then?
  5. Mar 7, 2007 #4
    There's really nothing that could forbid a positron capture. It won't happen very often, simply because positrons are rare to begin with and would be repelled by the protons in a nucleus, while lone neutrons decay. However, it should certainly be possible.
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