One example of gamma ray production due to radionuclide decay is the decay scheme for cobalt-60, as illustrated in the accompanying diagram. First,  decays to excited  by beta decay emission of an electron of . Then the excited  decays to the ground state (see nuclear shell model) by emitting gamma rays in succession of 1.17 MeV followed by . This path is followed 99.88% of the time:
Another example is the alpha decay of  to form ; which is followed by gamma emission. In some cases, the gamma emission spectrum of the daughter nucleus is quite simple, (e.g. /) while in other cases, such as with (/ and /), the gamma emission spectrum is complex, revealing that a series of nuclear energy levels exist.