The last decade has witnessed both quantitative and qualitative progresses in Shell Model studies, which have resulted in remarkable gains in our understanding of the structure of the nucleus. Indeed, it is now possible to diagonalize matrices in determinantal spaces of dimensionality up to 10^9 using the Lanczos tridiagonal construction, whose formal and numerical aspects we will analyze. Besides, many new approximation methods have been developed in order to overcome the dimensionality limitations. Furthermore, new effective nucleon-nucleon interactions have been constructed that contain both two and three-body contributions. The former are derived from realistic potentials (i.e., consistent with two nucleon data). The latter incorporate the pure monopole terms necessary to correct the bad saturation and shell-formation properties of the realistic two-body forces. This combination appears to solve a number of hitherto puzzling problems. In the present review we will concentrate on those results which illustrate the global features of the approach: the universality of the effective interaction and the capacity of the Shell Model to describe simultaneously all the manifestations of the nuclear dynamics either of single particle or collective nature. We will also treat in some detail the problems associated with rotational motion, the origin of quenching of the Gamow Teller transitions, the double beta-decays, the effect of isospin non conserving nuclear forces, and the specificities of the very neutron rich nuclei. Many other calculations--that appear to have ``merely'' spectroscopic interest--are touched upon briefly, although we are fully aware that much of the credibility of the Shell Model rests on them.

The shell model as a unified view of nuclear structure

Nuclear magic numbers: New features far from stability

Recent experimental data and progress in nuclear structure modeling have led to improved descriptions of astrophysically important weak-interaction processes. This review discusses these advances and their applications to hydrostatic solar and stellar burning, to the slow and rapid neutron-capture processes, to neutrino nucleosynthesis, and to explosive hydrogen burning. Special emphasis is given to the weak-interaction processes associated with core-collapse supernovae. Despite significant progress, improvements in the modeling of these processes are still warranted and are expected to come from future radioactive ion-beam facilities.

Nuclear weak-interaction processes in stars

The nuclear shell model towards the drip lines

Presented are features of the in-flight radioactive isotope (RI) beam separators in Japan as well as of a next-generation separator BigRIPS being built at RIKEN for the RI-beam factory project. Characteristic features and present status of the existing separators are reviewed for the RIPS at RIKEN, the Secondary Beam Line at RCNP, the Secondary Beam Course at NIRS, the CRIB at CNS and the RMS at JAERI. Design features are outlined for the BigRIPS, which is characterized by two major features: large acceptances and a tandem (or two-stage) separator scheme. The large acceptances allow one to produce RI beams efficiently by using in-flight fission of uranium ions, being achieved by using superconducting quadrupoles with a large aperture. The tandem separator scheme allows one to deliver tagged RI beam. The integrated capability of the BigRIPS and the accelerators of the project can significantly enlarge the scope of future RI-beam experiments. A low-energy course following the BigRIPS can provide energy-degraded and -bunched RI beams to be applied for a gas catcher system with an RF ion guide, aiming at realizing a projectile fragmentation based ISOL system.

M. Inoue

Papers

Large deformation of the very neutron-rich nucleus 32Mg from intermediate-energy Coulomb excitation