Experimental investigation of shell-model excitations of89Zr up to high spin

Abstract

Near yrast states in ${}^{89}$Zr were investigated up to high spin using the fusion evaporation reaction ${}^{80}$Se(${}^{13}$C, 4$n$) at an incident beam energy of 50 MeV. Excited levels of ${}^{89}$Zr have been observed up to $\ensuremath{\sim}$10 MeV excitation energy and spin $\ensuremath{\sim}$37/2$\ensuremath{\hbar}$ using the prompt gamma spectroscopy technique with the Indian National Gamma Array (INGA). The angular distribution, directional correlation, and polarization measurements were carried out to assign the spin and parity of the newly reported states. The structures of both the positive and negative parity states up to highest spin observed in the present experiment have been compared with shell-model calculations using two recently developed residual interactions, JUN45 and jj44b. The role of proton excitations from ${p}_{3/2}$ and ${f}_{5/2}$ orbitals to the ${g}_{9/2}$ orbital for the higher spin states has been discussed.