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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.

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  • $\begingroup$ The mass deficit of cadmium appears to be about 1AMU or 931MeV. (1.0086654 neutron * 48 + 1.00727647 proton * 66 - 113.9033585(29) mass cadmium= delta m = 0.99282772 aprox 1) $\endgroup$ – JMLCarter Jan 29 '17 at 1:52
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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.

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