Level structure of the Nb93 nucleus and systematics of features in neighboring nuclei

Excited states of the $^{93}\mathrm{Nb}$ nucleus are produced through the fusion-evaporation reactions $^{82}\mathrm{Se}\phantom{\rule{0.16em}{0ex}}(^{14}\mathrm{N},3n)\phantom{\rule{0.16em}{0ex}}^{93}\mathrm{Nb}$ and $^{82}\mathrm{Se}\phantom{\rule{0.16em}{0ex}}(^{16}\mathrm{O},1p4n)\phantom{\rule{0.16em}{0ex}}^{93}\mathrm{Nb}$. On the basis of new experimental data, the previously known level scheme is extended. Level structure is discussed in comparison to a shell-model calculation. The calculation results demonstrate that the low-lying states can be interpreted as the excitation of the protons from the $1{p}_{1/2}$ orbit, through the $Z=40$ subshell closure, to the $0{g}_{9/2}$ orbit. The moderate-spin states involve not only the proton excitation through the $Z=38$ or 40 subshell ($0{f}_{5/2}1{p}_{3/2}1{p}_{1/2}\ensuremath{\rightarrow}\phantom{\rule{4pt}{0ex}}0{g}_{9/2}$), but also the neutron excitation through the $N=56$ subshell ($1{d}_{5/2}\ensuremath{\rightarrow}\phantom{\rule{4pt}{0ex}}0{g}_{7/2}$). For the high-spin states above 9.1 MeV, the neutron excitation across the $N=50$ closed shell plays a dominant role.