The systematics of nuclear sizes, shapes, binding energies, and other nuclear properties are the data that nuclear models are challenged to explain. The Shell Model mentioned in Chapters 2 and 6 has combined the large body of nuclear data into a coherent theory of nuclear structure. Most of this data was the result of elastic and inelastic scattering of electrons, protons, and neutrons from nuclei found in the chart of the nuclides. At high enough excitation energies, a nucleus can undergo a series of normal modes of collective oscillations called giant resonances. The nucleus rings like a bell at distinct frequencies with all the nucleons participating and sharing the excitation energy.
Fusion reactions are the combining of two nuclei to form a more massive nucleus.
Many fusion reactions release large amounts of energy. This reaction as a potential electric power source is discussed in Chapter 14 . The net energy output from this chain is 26.7 MeV for each helium-4 nucleus formed. This topic is discussed in Chapter 14 . The statistical nature of this process teaches us about the average properties of excited states of complex nuclei.