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Particle physics question

  1. Dec 3, 2007 #1
    1. The problem statement, all variables and given/known data

    Consider the combination of an electron with positron(I) and an electron with proton(II).The possible processes are:

    (i)formation in positronium in (I)
    (ii)formation in Hydrogen ataom in (II)
    (iii)annihilation of each other and gamma emission in (I) and (II) both
    (iv)elastic scatterinh in (I) and (II) both

    2. Relevant equations

    3. The attempt at a solution

    I think all but (iv) may be correct---elastic scattering should not happen...
    Please check.
  2. jcsd
  3. Dec 3, 2007 #2


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    Maybe you should think a little longer about these, particularly 3 and 4.
  4. Dec 3, 2007 #3
    Possibly (III) is wrong:I mean e and p cannot annihilate but e and positron can

    elastic scattering occurs...?
  5. Dec 3, 2007 #4


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    Staff: Mentor

    Electron and positron certainly annihilate producing two 0.511 MeV gammas.

    An electron is not annhilated by a proton, but there is a phenomenon called 'electron capture'.
  6. Dec 4, 2007 #5


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    Typically, the term elastic scattering is used for events where the loss of energy between the scattered particle and the incident particle is small compared to the incident energy. Rutherford scattering, electron/neutron diffraction, etc. are examples of elastic scattering.
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