Excited states in the very neutron deficient isotope ${}_{}{}^{83}{}_{}{}^{}\mathrm{Nb}$ were observed for the first time in the reaction ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$${(}^{58}$Ni,2np${)}^{83}$Nb at 195 MeV. Identification was made with a recoil separator and a cross section of σ=180(80) μb estimated. Eight transitions were arranged in a level scheme which resembles the N=41 isotones ${}_{}{}^{77}{}_{}{}^{}\mathrm{Kr}$ and ${}_{}{}^{79}{}_{}{}^{}\mathrm{Sr}$ rather than the heavier, weakly deformed Nb isotopes. This suggests that a shape transition to a strong deformation exists in the light Nb isotopes. A ground state spin of 5/$2^{+}$ is suggested.

• Received 6 August 1990

DOI:https://doi.org/10.1103/PhysRevC.43.R5