Coulomb Energies In Isobaric Multiplets

Examination of fundamental symmetries is one of the key aspirations in physics research. In nuclear physics, the most fundamental of these is the exchange symmetry between neutrons and protons. The approximate charge symmetry and charge independence of the nuclear force results in striking symmetries in nuclear behavior between isobaric analogue states (IAS) - states of the same isospin quantum number in a set of nuclei of the same total number of nucleons (an isobaric multiplet). The Coulomb force breaks this symmetry and is the dominating factor in producing the large shifts in absolute binding energy between IAS. Until recently, progress in understanding these energy shifts in detail was broadly restricted to the lowest energy states for a given isospin (e.g. the difference in ground state masses of a pair of mirror nuclei). However, the recent advances in spectroscopic techniques - especially the development of large gamma-ray spectrometers - has resulted in a wealth of information on IAS at high excitation energy and high angular momentum. The very small differences in excitation energy between the IAS can be interpreted, principally, in terms of Coulomb effects. The analysis of these Coulomb differences has been shown to be a remarkably sensitive probe of nuclear structure effects as well as providing stringent tests of state-of-the-art shell-model calculations. In this review, some of the latest results and their interpretation are presented