New nuclear structure phenomena in the vicinity of closed shells

Abstract

The proceedings of the international symposium on "New Nuclear Structure Phenomena in the Vicinity of Closed Shells – SELMA 94", held in Stockholm, Uppsala and on the Baltic Sea from Aug. 30 – Sep. 3 are collected in this volume. Since almost 40% of the session time was kept open for discussions, it is difficult to give full justice to the character of the meeting in a written report. However, since also many posters are presented in this volume, we hope that some of the flavour of this lively symposium will pass onto the reader. We have chosen to group related contributions in order to facilitate the reading. Several articles, though, may fit into several categories.With the event of large detector arrays there has been a tremendous development in the field of nuclear spectroscopy.The discovery of super-deformation has been followed by detailed spectroscopy in the second well. Hence, the concept ofshell closure is reinterpreted in general terms, involving shapes different from spherical. Close to the drip lines, we expectnew shells and new structure effects to emerge. Loosely bound neutrons may form a new state of nuclear matter. Theregions of the nuclear chart far from the line of stability can be explored in the future by means of radioactive ion beams.New structure effects, that one might encounter far from the line of stability was one of the themes of this conference. Thestrong impact of the nuclear shell model is also evident in other branches of physics, like the structure of metal-clusters.Special attention was paid to the Sn-isotopes. In the Sn-isotopic chain, spectroscopic measurements are extendingbeyond the doubly-magic nucleus 132Sn. Large efforts have recently been made to study nuclei in the vicinity of the doubly-magic nucleus 100Sn, the other extreme end of the chain. Spectroscopic data on 100Sn would open the entire shell for nuclear structure studies, ranging over a number of 32 neutrons. During the organization of this meeting, the first 100Sn nuclei were observed at GSI, Germany, and in a subsequent experiment at GANIL, France. Results from these experiments were reported during the symposium as were much of the recent data around "classical" shell model nuclei. Neutron deficient nuclei in the Sn region show a variety of phenomena, such as coexisting shapes, enhanced quadrupole transitions etc. The role of intruder states in this mass region as well as the excitation pattern is still a puzzle for experimentalists and theoreticians and was discussed during the meeting. More work is needed until a unified picture of the structure of these nuclei will emerge.The combination of powerful mean-field models, large scale shell model calculations as well as new algebraic approachesto nuclear structure shows the strong and lively development in the field of nuclear theory as was evident from thepresentations. It is obvious that great effort is needed to match the rapid development in the field of experimental nuclearstructure.The organizing committee expresses special thanks to the Royal Swedish Academy of Sciences, through its Nobel Institute for Physics, for its generous support. We also want to thank the Royal Institute of Technology and Uppsala Universityfor supporting this symposium. All this support was extremely essential for organizing the meeting as well as for renderingit success. We are very pleased about the possibility to print the proceedings of this meeting in Physics Scripta and thanktheir staff for helpful collaboration. Thanks also to the international advisory committee for its helpful workto select speakers and for suggestions. Conference secretary Inger Ericson's assistance during the meeting as well as thework of the organizing committee is highly appreciated. Finally, we like to thank all speakers and participants formaking this symposium extremely lively and exciting. Last but not least: this symposium got its name from little Selma,born 19 January 1994, daughter of A Atac and J Nyberg.