Identification and decay of neutron-richSr102and level structure ofA∼100Y nuclei

The previously unreported decay of ${}_{}{}^{102}{}_{}{}^{}\mathrm{Sr}$ to levels in ${}_{}{}^{102}{}_{}{}^{}\mathrm{Y}$ has been studied from mass-separated activity produced in the thermal neutron fission of ${}_{}{}^{235}{}_{}{}^{}\mathrm{U}$. A half-life for ${}_{}{}^{102}{}_{}{}^{}\mathrm{Sr}$ was measured to be 68±8 ms. Based on γ singles and coincidence measurements, 24 γ rays were placed in a level scheme for ${}_{}{}^{102}{}_{}{}^{}\mathrm{Y}$ with nine excited states up to 1689 keV. Four excited states were assigned a $J^{\pi }$ of $1^{+}$ from logft values. Evidence for delayed-neutron emission from ${}_{}{}^{102}{}_{}{}^{}\mathrm{Sr}$ is reported. These results are compared with systematics for other neighboring, highly deformed, odd-odd Y and Nb nuclei. The level structure of A∼100 Y nuclei, which exhibit a very abrupt transition from spherical to highly deformed shapes, is reviewed. The possibility of the existence of bands with moments of inertia close to that of a rigid rotor is discussed.