ABSTRACT
This chapter examines electromagnetic effects in which the nucleus interacts with electromagnetic systems separated from it by distances that are large on the nuclear scale. Knowledge of the multipoles gives information about the size, shape, density, and motion of the matter in nuclei. In many instances only a few multipoles of the lower orders need be considered, and it is this feature that makes the use of the series convenient. The simplification depends on two conditions: the velocity of the nuclear particles must be small compared with the speed of light, and the fractional change of the applied field across the nucleus must be small. The total angular momentum of a nucleus is the vector sum of the angular momenta of the constituent nucleons, which in turn consist of both orbital angular momenta due to the motion about the center of the nucleus and of the intrinsic spin angular momentum of 12ℏ per nucleon.
