# Beta plus decay

1. May 14, 2013

### sunrah

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

\begin{align} \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 \end{align}

so the energy of all beta decay is the same and negative?

2. May 14, 2013

### 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".