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Homework Help: Beta plus decay

  1. May 14, 2013 #1
    1. The problem statement, all variables and given/known data
    What is the mass difference of the following process:
    13N → 13C + e+ + ve

    2. Relevant equations
    Δm = m(A,Z) - m(A, Z-1) - m(e+)

    Neutrino has negligible mass.
    Z proton number
    A = N + Z, where N is number of neutrons

    3. The attempt at a solution

    \Delta m &= m(^{13}N) - m(^{13}C) - m(e^{+})\\
    &= (7\cdot m_{p} + 6\cdot m_{n}) - (6\cdot m_{p} + 7\cdot m_{n}) - m_{e}\\
    &= m_{p} - m_{n} - m_{e} = const < 0

    so the energy of all beta decay is the same and negative?
  2. jcsd
  3. May 14, 2013 #2


    User Avatar

    Staff: Mentor

    It is a long time since my first year physics, but I reckon you need the isotopic mass of each of these isotopes, at this point. http://en.wikipedia.org/wiki/Isotopes_of_carbon

    My money's on "NO". :smile:
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