Ricardo Americo Broglia – författare

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.

The last few years have seen great progress in the understanding of nuclei far from stability, i.e. nuclei with a composition that differs radically from that of the stable nuclei that we encounter in Nature. It has become clear that the study of exotic nuclear species reveals many new phenomena, which may make us go back, armed with new insight, to more familiar nuclear systems. The proceedings at the 4th course of the International School of Heavy Ion Physics — Exotic Nuclei, containing the lectures and seminars by world specialists in the field, cover some of the central themes of the physics of exotic nuclei which lie at the forefront of nuclear research.

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.