Evolution of collectivity in exotic isotopes

Neutron-rich nuclei have been the subject of much recent investigations. From the recent studies, the weakening of the N=40 shell gap is ascribed to the strong interaction between nucleons in the $\pi$pf and the $\nu$g9/2 and $\nu$d5/2 orbitals, which induces energy shifts of the single-particle states, thereby leading to an increased collectivity in neutron-rich nuclei beyond and below the $^{68}$Ni$_{40}$ core. Studies in this context of selected neutron-rich nuclei will be conducted extensively at ATLAS with Gammasphere or GRETINA using reactions well above the Coulomb barrier. A number such experiments have demonstrated that the yrast states of hard-to-reach neutron-rich nuclei can be populated allowing experimental access to high-spin structures in regions inaccessible with conventional heavy-ion induced, fusion-evaporation reactions.