Description
Super-deformed bands known in some nuclei close to $^{40}$Ca can be interpreted in terms of the shell model, cluster approach or mean-field theory. It is expected that the SD bands in this region may be related, through the emission of $\alpha$-particles or high-energy photons, to the rapid rotation of hot highly deformed compound nucleus. However, the lack of the high-spin experimental data makes it difficult to conclusively explain the origin of collectivity in these nuclei. On the other hand, the advantage of nuclei of interest is that the deformed low spin members of the collective bands can be studied in detail, including direct measurements of their quadrupole moments, which reflect their shape. Furthermore, exotic shape isomers are expected to coexist here with the spherical ground states.
The use of the new generation of $\gamma$-ray spectrometers, such as AGATA and PARIS, in combination with particle detectors, will enable investigations of the rotational bands in the full angular momentum range, from the band-heads up to or beyond the band termination. These studies will include the search for possible feeding of the SD bands by $\alpha$-particles or high-energy $\gamma$-radiation. Also, the unprecedented sensitivity of these novel instruments will facilitate the quest for structures corresponding to exotic nuclear symmetries.