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

These proceedings comprise the contents of a major international conference on Perspectives of the Interacting Boson Model. Occasioned by the 20th Anniversary of this model, and attended by approx. 130 scientists from 29 countries, the topics focused on current and future research, which relates to the IBM. This model has now become one of the standard approaches to nuclear structure and has helped usher in a renaissance in that field and a new, unified perspective that focuses on dynamical symmetries and the key role of the valence nucleons. The algebraic approach fostered by the model is being extended to other fields, including nuclear reactions, molecular physics and baryon structure.

This thesis describes a novel and robust way of deriving a Hamiltonian of the interacting boson model based on microscopic nuclear energy density functional theory. Based on the fact that the multi-nucleon induced surface deformation of finite nucleus can be simulated by effective boson degrees of freedom, observables in the intrinsic frame, obtained from self-consistent mean-field method with a microscopic energy density functional, are mapped onto the boson analog. Thereby, the excitation spectra and the transition rates for the relevant collective states having good symmetry quantum numbers are calculated by the subsequent diagonalization of the mapped boson Hamiltonian. Because the density functional approach gives an accurate global description of nuclear bulk properties, the interacting boson model is derived for various situations of nuclear shape phenomena, including those of the exotic nuclei investigated at rare-isotope beam facilities around the world. This work provides, for the first time, crucial pieces of information about how the interacting boson model is justified and derived from nucleon degrees of freedom in a comprehensive manner.

The interacting boson-fermion model has become in recent years the standard model for the description of atomic nuclei with an odd number of protons and/or neutrons. This book describes the mathematical framework on which the interacting boson-fermion model is built and presents applications to a variety of situations encountered in nuclei. The book addresses both the analytical and the numerical aspects of the problem. The analytical aspect requires the introduction of rather complex group theoretic methods, including the use of graded (or super) Lie algebras. The first (and so far only) example of supersymmetry occurring in nature is also discussed. The book is the first comprehensive treatment of the subject and will appeal to both theoretical and experimental physicists. The large number of explicit formulas for level energies, electromagnetic transition rates and intensities of transfer reactions presented in the book provide a simple but detailed way to analyse experimental data. This book can also be used as a textbook for advanced graduate students.

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 book consists of pedagogical contributions on currently viable theories of nuclear structure and critical evaluative comments on each of these theories.