Level structure of the Nb-93 nucleus and systematics of features in neighboring nuclei

Excited states of the 93Nb nucleus are produced through the fusion-evaporation reactions Se-82 (N-14, 3n) Nb-93 and Se-82 (O-16, 1p4n) Nb-93. 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 1p(1/2) orbit, through the Z = 40 subshell closure, to the 0g(9/2) orbit. The moderate-spin states involve not only the proton excitation through the Z = 38 or 40 subshell (0 f(5/2)1p(3/2)1p(1/2) -> 0g(9/2)), but also the neutron excitation through the N = 56 subshell (1d(5/2) -> 0g(7/2)). For the high-spin states above 9.1 MeV, the neutron excitation across the N = 50 closed shell plays a dominant role.