During the week of June 6-9, 1978, a group of 36 physicists from 15 countries met in Erice, Sicily, for the first specialized seminar on "Interacting Bosons in Nuclear Physics". The countries represented were Argentina, Belgium, Denmark, Finland, France, the Federal Republic of Germany, Israel, Italy, Japan, the Netherlands, Poland, Sweden, the United Kingdom, the United States of America and Yugoslavia. The Seminar was sponsored by the Italian Ministry of Public Education (MPI), the Italian Ministry of Scientific and Technological Research (MRST), the North Atlantic Treaty Organiza tion (NATO) and the Regional Sicilian Government (ERS). The purpose of the Seminar was to discuss the present status of the Interacting Boson Model both from the theoretical and experi mental point of view. Some of the lectures presented in this book summarize particular aspects of the model and are based on previously published work (F. Iachello, R.F. Casten, Z. Sujkowski, L. Hassel gren, H. Emling, I. Talmi, T. Otsuka, J. McGrory, A.E.L. Dieperink and A. Arima). Others are entirely new. In particular, the lec tures of O. Scholten and A. Gelberg and V. Kaup present the first extensive set of calculations based on the proton-neutron boson model, while the lecture of J.N. Ginocchio describes a fermion model with properties identical to those of the interacting boson model. Also new are the le~tures of D.R. Bes, R.A. Broglia and P.F.

This volume contains the proceedings of a workshop held at Drexel University from September 1 to September 3, 1980, under the joint auspices of Drexel University, The University of Tennessee and Vanderbilt University. The workshop dealt with subjects of topical importance to the nuclear physics community: high spin phenomena, heavy ion reactions, transfer reactions, microscopic theories of nuclear structure and the interacting boson model, and miscellaneous topics. This pro ceedings contains all of the invited papers plus short manuscripts expanding on the materials of the invited papers. A total of about 85 participants came to the workshop. The format of the conference was kept informal on purpose, so as to facilitate the discussions. Unfortunately, these discussions, at times intense, could not be included in this volume due to the lack of secretarial help during the meeting. A great deal of current information was exchanged during the conference. However, the full impact of a conference can only be realized when the proceedings have been published and read by par ticipants as well as other colleagues in this field of physics who were not in attendance. We sincerely hope that these proceedings will be useful in this regard.

The fundamental model of nuclear structure is the shell model. However, its application has been limited to light nuclei (up to the sd shell) or heavier nuclei with only a few valence nucleons outside closed shells. Its application beyond these limits has been prohibited so far by the largescale of the calculations involved. For the description of nuclei beyond the sd shell having several valence nucleons the introduction of collective models becomes necessary.The first comprehensive phenomenological model of nuclear structure was the geometric collective model of A. Bohr and B.R. Mottelson. An alternative approach was proposed in 1974 by A. Arima and F. Iachello, known as the Interacting Boson Model. This model, which uses group theoretical techniquesin the description of nuclear collective properties, has the advantage of relative simplicity, allowing for detailed calculations of the properties of even medium and heavy nuclei which cannot be reached by the shell model yet. Several extensions and generalizations of the model have appeared overthe last decade. Algebraic descriptions for the effects of clustering, permanent octupole deformation, and giant resonances have also been given. For the description of odd nuclei the Interacting Boson-Fermion Model has been introduced, and nuclear supersymmetries associated with it have beenanalysed.The present text is designed to provide physicists with an accessible introduction to the subject.

This book gives an account of the properties of the interacting boson model.