Experimental study of the level structure in 90Nb and systematics of level structure characteristics near A=90

In beam gamma -ray spectroscopic investigations of the 90Nb nucleus have been explored by employing the 76Ge(19F, 5n) 90Nb reaction. Twenty-eight new transitions belonging to 90Nb have been identified and placed in the proposed level scheme through the analysis of gamma -gamma coincidence spectra. Shell model calculations have been performed in the restricted pi (p3/2, f5/2, p1/2, g9/2) circle times nu(p1/2, g9/2, d5/2, g7/2) configuration space, and compared to the new level scheme. According to the calculations, the newly observed 2614.6 keV gamma ray depopulating the (15+3 ) level at 4421.2 keV is explicated as the breakup of the N = 50 neutron closed shell, while the gamma ray with 2774.0 keV feeding the (13-1) level at 2812.9 keV is interpreted as protons excitation across the Z = 38 subshell.