Decay ofSr101and the rotational structure ofY101

The level structure of ${}_{}{}^{101}{}_{}{}^{}\mathrm{Y}$ has been studied through the β decay of ${}_{}{}^{101}{}_{}{}^{}\mathrm{Sr}$. Ninety-six γ rays are placed in a level scheme with 34 levels. The first 14 levels of ${}_{}{}^{101}{}_{}{}^{}\mathrm{Y}$ (below 1.1 MeV) are identified as members of the four rotational bands associated with the Nilsson orbitals (with bandhead energies in keV) (5/2[422] (0), (3/2[301] (510), (5/2[303] (666), and 1/2[301] (890). Above 1.2 MeV occur six low-spin (I≤(7/2) levels that have features expected for members of 1/2[431] and (3/2[431] bands, but it is not possible to make unambiguous assignments of all six levels to these two bands. The level energies and γ-decay patterns (both intraband and interband) are well reproduced by simple particle-rotor calculations consisting of single quasiparticles coupled to an axially symmetric core. As is the case for ${}_{}{}^{99}{}_{}{}^{}\mathrm{Y}$, the rotational structure of ${}_{}{}^{101}{}_{}{}^{}\mathrm{Y}$ indicates an axially symmetric deformation ε near the middle of the range of 0.3<ε<0.4. Similarities and differences between the bands observed in ${}_{}{}^{99}{}_{}{}^{}\mathrm{Y}$ and ${}_{}{}^{101}{}_{}{}^{}\mathrm{Y}$ are discussed and compared to model predictions.