The image shell closure; from image to the neutron drip line Original Research Article

The evolution of the N=28 neutron shell closure is studied in the N=28 isotones from neutron drip lineʹs 40Mg to N=Z doubly magic 56Ni. 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.