Speaker
Description
It is well known that nucleons are arranged in specific shells resulting in greater stability, analogous to the electron shells in the atom and that this shell structure was expected to be very robust in the whole nuclear chart. However, with advance experimental and theoretical works during the last two decays, we are aware that the shell structure changes when moving far away from stability and it is related to the large neutron excess and nuclear forces. In other words, the Shell Model described in 1949 by Mayer and Jensen is not valid throughout the nuclear chart and nuclear forces have to be reconsidered in the nuclear Hamiltonian which was initially described by harmonic oscillator potential and spin–orbit interaction.
The possible consequences expected for neutron-rich nuclei are shell evolution in which changes in ordering and location of the single particle orbits are significant, and the shape coexistence where particle-hole excitations over a major shell and quadrupole correlations are favored due to inversion of orbitals and reduced shell gaps. In extreme cases proven in the lighter mass regions, new magic numbers appear and some other conventional ones disappear and intruder correlations change the ground state deformation, causing the phenomena called island of inversion. In the present manuscript, these aspects will be discussed in the 78Ni region. Recent experiments performed at RIKEN radioactive beam facility using different methodologies will be presented.
