Spin in Nuclear Physics

An atomic nucleus is composed of protons and neutrons each with spin 1/2 and dictated by the Pauli principle. In contrast to thissimplicity based on the spin degrees of freedom, the forces acting between the ingredients have complex spin-dependent forms. Because of this characteristic composition including complexity and simplicity related to spin, the spin degrees of freedom play a crucial role in the understanding of phenomena in nuclei. For example, the concept of nuclear spin-orbit coupling, which was phenomenologically introduced by Mayer and Jensen in 1949 to explain nuclear magic numbers, is still guiding present nuclear physics, where radioactive isotopes (RI) far from the beta-stability line are actively studied in relation to broader fields such as the origin of elements. In this talk, recent developments will be reviewed with special focuses on nuclear studies using RI beams and spin-related experimental techniques.