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Inverse beta decay

  1. May 10, 2010 #1
    With this mechanism a nuclear proton can capture an inner orbit electron and change to a neutron with the emisssion of a neutrino.Can this mechanism also operate with free protons if ,say, bombarded by free electrons?I have tried researching this but have found no reference other than a Wiki article which claims that free protons cannot normally be changed to free neutrons by the process of electron capture.To me this implies that it can happen but that such events are rarely observed,possibly due to energy considerations.I will be grateful if someone could clarify this for me and if possible provide a reference.Thank you.
  2. jcsd
  3. May 10, 2010 #2
    Beta decay of a neutron obtains three particles: proton, electron and an electron neutrino (antineutrino?)

    In any case, the reverse reaction for a free proton would require the happenstance of the proton meeting up with an electron and a neutrino at the same time, in just the right way so that all the requisite conservation laws are met. This is what is meant by "not normally".
  4. May 10, 2010 #3


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    Staff: Mentor

    The reaction [itex]e^{-} + p \rightarrow \nu_e + n[/itex] is possible, but I would be suprised if it's actually been detected because of the obvious technical difficulty of detecting two neutral particles in the final state.
    Last edited: May 10, 2010
  5. May 10, 2010 #4
    Thank you Phrak and jtbell.So it seems that such events may be unlikely and difficult to detect but are theoretically possible.I think energy plays a major part in the event because it seems likely free protons and free electrons at "low" KE values will readily come together to form hydrogen atoms.Also ,if any free neutrons are produced these will be unstable and decay into protons electrons and anti neutrinos.
  6. May 10, 2010 #5
    This is how we make neutron stars right.
  7. May 11, 2010 #6
    I'm something of a novice at particle Physics; can someone explain to me the conditions and instance of neutrino production? I think they're neutral particles with no mass and near-light speed but I'm not sure...The wikipedia article seems to be somehwat ambiguous on this topic.
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