Calculating the Mass Difference for Beta Plus Decay: 13N → 13C + e+ + ve

[sunrah]

Homework Statement

What is the mass difference of the following process:
¹³N → ¹³C + e⁺ + v_e

Homework 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

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?

 

[NascentOxygen]

$\begin{align} \Delta m &= m(^{13}N) - m(^{13}C) - m(e^{+})\\ \end{align}$

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

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

My money's on "NO".