The isotopes 91,93Y are located close to 90Zr, a nucleus that has a neutron shell closure (N = 50) and a proton subshell closure (Z = 40), and close to the stability line. However, relatively little is known about excitations above their 9/2+ isomers. In the present work the isotopes 91,93Y have been studied in the fission of compound systems formed in two heavy-ion-induced reactions using the Gammasphere array for γ-ray spectroscopy. States with excitation energies up to 6.9 and 7.1MeV above the previously known 9/2+ isomers of 91,93Y were established, respectively. The coupling of a proton-hole occupying the g9/2 orbital to the yrast states in the core nuclei of 90Sr and 92Zr can account for the first excited states of 91Y. A comparison with the first excited states in the neighboring N = 52, 54 isotopes is also considered. The experimental results are compared to predictions from previously reported shell-model calculations. The present results enhance previous knowledge on 91,93Y from fusion-evaporation reactions and multinucleon transfer reactions, and highlight the roles of these complementary reactions in probing moderate spin excitations in this mass region.
All Science Journal Classification (ASJC) codes
- Nuclear and High Energy Physics