Shrunk halo and quenched shell gap at N=16 in 22C: Inversion of sd states and deformation effects

We explore the interplays among the formation of a halo, deformation effects, the inversion of sd states, the shell evolution, and changes of nuclear magicities in C-22 by using a deformed relativistic Hartree-Bogoliubov model in continuum. It is revealed that there is an inversion between the two spherical orbitals 2s(1/2) and 1d(5/2) in C-22 compared with the conventional single particle shell structure in stable nuclei. This inversion, together with deformation effects, results in a shrunk halo and a quenched shell gap at N = 16. It is predicted that the core of C-22 is oblate but the halo is prolate. Therefore several exotic nuclear phenomena, including the halo, the shape decoupling effects, the inversion of sd states, and the evolution of shell structure which results in (dis) appearance of magic numbers, coexist in one single nucleus C-22. (c) 2018 The Author(s). Published by Elsevier B.V.