The range of unstable nuclei accessible with Radioactive Nuclear Beam (RNB) facilities opens up enormous opportunities for the study of nuclear structure and exotic new phenomena. Intriguing possibilities occur both at the drip lines and in the long iso-chains of nuclei, especially between the valley of stability and the neutron-rich extreme of nuclear existence.
Exotica in the latter region are almost sure to appear since the mean field in weakly bound neutron-rich nuclei is likely to be modified relative to nuclei near stability, and since reduced nuclear densities and the large reservoir of continuum scattering states should modify residual interactions among the outermost nucleons [1]. Together, these effects may modify the microscopic foundations of nuclei to the extent that the concept of single-particle motion itself loses validity. Between the regions of known and near-drip-line nuclei lies an extensive zone (typically, 20-40 neutrons wide in medium mass and heavy nuclei) where studies will reveal much about the microscopy of structural evolution and will undoubtedly disclose new types of correlations and collectivity.
RNB experimentation is expected to expand the range of known nuclei. By going to nuclei with extreme N/Z ratios, one can magnify the isospin-dependent terms of the effective interaction (which are small in ``normal" nuclei). On the other hand, by going to very high spins, one can probe those components of the effective interaction which depend on the spin degrees of freedom. Clearly, by studying the response of neutron-rich nuclei to rotation, one can obtain very unique information about basic properties of the nuclear many-body system.
This paper contains discussion of high-spin phenomena that are expected to occur in neutron-rich nuclei. Most of the examples shown are very ``theoretical". The authors are well aware that many nuclei discussed in this study cannot be accessed experimentally. Nevertheless, the ``impossible-to-reach" nuclei, such as 208Er, represent extreme cases where certain structual effects manifest themselves in a clear and transparent way. Fingerprints of these effects will be looked for experimentally by systematically extending our knowledge of the neutron-rich terra incognita.