I am given that the mass deficit of 114-Cd is -90.01 MeV, and asked to calculate the binding energy, which should simply be 90.01 MeV then, due to the use of natural units (i.e. where $c=1$). I'm then asked to calculate the binding energy per nucleon which should simply be $\frac{90.01}{114}$. However, according to the solutions manual, the binding energy per nucleon is 8.54 MeV instead. I'm not entirely sure where the discrepancy arises. Any help would be appreciated.
1 Answer
The mass deficit is related to, but different from, the binding energy. The bare neutron and bare proton have zero binding energy, while the canonical source for mass deficits defines $\Delta[{}^{12}\rm C] = 0$. Note also that the NNDC mass deficits are for neutral atoms, and therefore include electron masses.