Shell model description of the core excited level structure of 89Sr nucleus and systematic features of the N=51 odd-A isotones

Shell-model calculations are performed using NuShellX code in the model space π ( f 5 / 2 , p 3 / 2 , p 1 / 2 , g 9 / 2 ) ⊗ ν ( g 9 / 2 , g 7 / 2 , d 5 / 2 , h 11 / 2 ), which probe the proton core excitation from the interior of Z = 38 semiclosed shell and neutron core excitation from the interior of N = 56 semiclosed shell for the level structure of 89 Sr. Our calculations show that the excitation of a single d 5 / 2 neutron across N = 56 semiclosed shell into the h 11 / 2 orbit should have great effects on the excited states of 89 Sr. In addition, the systematic features of proton core excitation across Z = 38 semiclosed shell into the g 9 / 2 orbit and neutron core excitation across N = 56 semiclosed shell into the g 7 / 2 , s 1 / 2 , d 3 / 2 , h 11 / 2 orbits in N = 51 isotones are discussed.