Seniority v=5 states in 4189Nb48.

Abstract

Yrast and yrare states in the nucleus $^{89}\mathrm{Nb}$ have been studied in the reaction $^{58}\mathrm{Ni}$${(}^{36}$Ar,5p) by measuring \ensuremath{\gamma}\ensuremath{\gamma} coincidences and directional correlation orientation with the OSIRIS array. In addition, \ensuremath{\gamma}-ray singles angular distributions have been taken with the reaction $^{58}\mathrm{Ni}$${(}^{35}$Cl,4p). Up to the highest spins observed (37/${2}^{+}$,33/${2}^{\mathrm{\ensuremath{-}}}$), the states identified line up with the ones predicted by the spherical shell model, taking into account three proton particles and two neutron holes in the ${\mathit{g}}_{9/2}$ and ${\mathit{p}}_{1/2}$ single-particle orbits. The shell model also reproduces most of the measured branching and E2/M1 mixing ratios. The mean lifetime of the 2152 keV 17/${2}^{\mathrm{\ensuremath{-}}}$ yrast state was determined as 0.74(7) ns.