There has been a great deal of attention given to the low-lying energy spectrum in a nucleus because of the abundance of experimental data. Likewise, perhaps to a lesser extent but still significant, the high end for a given configuration has been examined. Here, using single $j$ shell calculations as a guide, we examine the middle part of the spectrum resulting from single $j$ shell calculations. Seniority arguments are used to partially explain the midshell behaviors even though in general seniority is not a good quantum number for mixed systems of neutrons and protons.

• Received 2 January 2016

DOI:https://doi.org/10.1103/PhysRevC.93.034327