Ricardo Americo Broglia – författare

Aage Bohr (1922-2009) was the central artificer of the unification of the independent (shell) - and of the collective (liquid drop) - models of the atomic nucleus. This unification constitutes the basis of what can be called the second discovery of the atomic nucleus, for which Aage Bohr and his close collaborator Ben Mottelson co-shared the 1975 Nobel Prize in Physics.The selected papers of Aage Bohr published in the present volume provide a clear account of Aage Bohr's ideas concerning the finite quantal many-body system. These ideas changed the nuclear paradigm and connected the field of nuclear physics with that of quantum condensed matter physics as well as with Quantum Electrodynamics (QED). It has also inspired a whole generation of theorists and experimentalists, helping to create the 'Copenhagen School of Nuclear Physics' which turned the Niels Bohr Institute into the Mecca for research in this subject during the 1960s and 1970s. The legacy of Aage Bohr's scientific achievements and that of the school he founded are felt to this day in connection with the cutting-edge research carried out at the forefront of nuclear structure and nuclear reaction studies.Remembering the words of the sage that 'We are dwarfs mounted on the shoulders of giants, so that we can see more and further than they', the present volume is an attempt at seeking illumination from Aage Bohr, through the reading of his masterfully written papers, and by reflecting over commonly experienced events. Furthermore, it may help practitioners acquire an overall view of the basis of modern theory of nuclear structure.

This unique volume reviews more than fifty years of theoretical and experimental developments of the concept that properties of atomic nuclei up to a great extent are defined by the pair correlations of nuclear constituents — protons and neutrons. Such correlations in condensed matter are responsible for quantum phenomena on a macroscopic level — superfluidity and superconductivity. After introducing Bardeen-Cooper-Schrieffer (BCS) theory of superconductivity of metals, it became clear that atomic nuclei have properties of superfluid drops, and practically all features of nuclei strongly depend on the pair correlations. Presenting a comprehensive overview of the progress of nuclear science, the contributions from leading physicists around the world, cover the whole spectrum of studies in nuclear physics and physics of other small systems. With the most updated information written in an accessible way, the volume will serve as an irreplaceable source of references covering many years of development and insight into several new problems at the frontiers of science. It will be useful not only for physicists working in nuclear and condensed matter physics, astrophysicists, chemists and historians of science, but will also help students understand the current status and perspectives for the future.

Major developments have taken place during the last few years in the study of the nuclear paradigm as a result of recent detector and accelerator developments, and of improved theoretical models.The active use of 4-π detectors to measure the gamma decay of excited nuclei has been instrumental in exploring the consequences of extremely high rotational frequencies and excitation energies in the nuclear structure. The identification of superdeformed bands, of limiting temperature for the detection of giant resonances, and of rotational damping, are conspicuous examples of this novel type of research. Studies of the disassembling of the nucleus have been systematically carried out, and the results interpreted in terms of transport models.At even higher temperatures one expects to have a completely new regime of hot dense matter, where the hadronic properties become strongly renormalized by the medium.Furthermore, studies of the properties of the nucleon as a many-body system of quarks and gluons displaying collective degrees of freedom which are damped by couplings to more complicated states, are providing a detailed and consistent picture of the nuclear paradigm.Important progress is also taking place in situations essentially opposite to the scenarios described above, namely in the study of correlations in nuclear matter at very low temperature and density.