High-spin states and shell structure of the odd-odd nucleus Nb90

The high-spin states of the odd-odd nucleus Nb90 have been investigated with in-beam Î-spectroscopic techniques via the Ge76(F19,5n)Nb90 reaction at a beam energy of 80 MeV. Î-Î coincidences were measured using a Î-ray detector array. Twenty new Î rays have been assigned to Nb90 and the level scheme has been extended up to an excitation energy of 8.095 MeV at spin 18â.,. The level structure of Nb90 at high spin states has been well reproduced using semiempirical shell-model calculations in the model space Ï€(1p1/2,0f5/2,0g9/2)Î(0g9/2). The results show that the excitation of protons plays an important role in generating the high-spin states of Nb90.