ABSTRACT
The discovery of neutrons and positrons opened a new epoch in the understanding of nature. It was established that protons and neutrons are nuclear components, with nuclear interactions playing the main role in the structure of nuclei. The character of the scattering of particles by nuclei or bounded states of nuclei are investigated by such particles, whereas nuclear methods such as inelastic scattering and nuclear reactions are mediated by particles which are sensitive to nuclear matter. The nucleus is located at the centre of the atom, and the electron–nucleus interaction is dominant, inter-electron interactions leading only to a decrease of the effective nuclear charge acting upon the electrons, that is electrons screen nuclear charge. The strong dependence of major shells on deformation gives rise to an increasing local stiffness of the nuclear shape change. In the quantum theory of fields the interaction of particles is considered in terms of the creation or absorption of particles by free particles or, alternatively, that every particle is surrounded by a cloud of virtual particles.
