75th Anniversary of a Paper that Changed Nuclear Physics: “Quadrupole and dipole gamma emission from nuclei” by A. B. Migdal

Fifty (seventy five now) years ago, in his paper on “Quadrupole and dipole y emission from nuclei”, A B Migdal introduced implicitly the concept of a dynamic collective model in nuclear physics and used this concept to predict a giant dipole resonance. Evolution of the theory of this resonance has had an enormous influence on the formation of modern concepts relating to the dynamics of nuclei. A brief historical introduction is followed in this paper by an
account of the conceptual aspects of the subsequent evolution of the ideas on the nature of the giant dipole resonance. This evolution has followed a complex path
from the initial identification of a nucleus with a liquid drop
to its representation as a system of independent nucleons.
Recent investigations have made it possible to understand
the interrelationships between these apparently diametrically
opposed concepts, to bring them closer together, and
to demonstrate the equivalence of the description of the giant dipole resonance with either concept.

M Danos, B S Ishkhanov, N P Yudin, R A Eramzhyan

Physics-Uspekhi 37(12) 1297-1307 (1995)