The N=28 shell closure; from N=Z to the neutron drip line

Etienne Caurier (1) , Frédéric Nowacki (1) , Alfredo Poves (2)

1 IReS - Institut de Recherches Subatomiques
2 UAM - Departamento de Fisica Teorica

The evolution of the N=28 neutron shell closure is studied in the N=28 isotones from neutron drip line's $^{40}$Mg to N=Z doubly magic $^{56}$Ni. It is found that the N=28 closure vanishes at Z=12 in favor of a deformed ground state. For Z=14 and Z=16 closed shell and intruder configurations are almost degenerate, leading to highly mixed ground states and to very low lying excited 0$^+$ states. For Z$>$20 the intruder states are always above the closed shell ground states. We examine their structure and their possible existence as collective yrare bands of well defined particle-hole character.

Domaines: Physique Nucléaire Théorique [nucl-th]

Etienne Caurier, Frédéric Nowacki, Alfredo Poves. The N=28 shell closure; from N=Z to the neutron drip line. 2004. ⟨hal-00001364v2⟩