Evolution of nuclear structure along the chain of Zr-isotopes: shell model approach

Experimental results suggest that the chain of Zr-isotopes (with A ∼ 80-108) show a variety of nuclear structure as the number of neutrons vary from a mid-open-shell deformed region (⁸⁰Zr₄₀), through a closed neutron shell (⁹⁰Zr₅₀), to a closed neutron sub- shell (⁹⁶Zr₅₆), and then to a sudden reappearance of deformation (¹⁰⁰Zr₆₀), which persists to a mid-open-shell region (¹⁰⁸Zr₆₈). This behavior is unprecedented anywhere on the nuclear mass surface. From the theoretical point of view, it would be interesting to see whether the trend of this variation of nuclear structure as a function of neutron number can be reproduced within the limit of common theoretical platform: that is to say that when the calculations are to be carried out through shell model approach, importance to be given to the use of the same model space and interaction. However, because of the computational complexity, quite often different types of truncation schemes are adopted. Here, we are bringing out the results of our shell model calculations using a modest model space. The calculations are mainly motivated by the availability of new and revised experimental lifetime data for the semi-magic ⁹⁴Zr nucleus at low-spin, low-excitation regime