High-spin states in odd-massSb113−119:ΔJ=1bands on92+proton-hole states

Abstract

Properties of high-spin states in $^{113,115,117,119}\mathrm{Sb}$ have been studied via the $^{A}\mathrm{Cd}(^{6}\mathrm{Li},3n)^{A+3}\mathrm{Sb}$ reactions. Using Ge(Li) and Si(Li) detectors, in-beam measurements of $\ensuremath{\gamma}$-ray excitation functions, $\ensuremath{\gamma}\ensuremath{-}\ensuremath{\gamma}$ coincidences, $\ensuremath{\gamma}$-ray angular distributions, and pulsed beam-$\ensuremath{\gamma}$ timing spectra were made to determine level energies, decay schemes, $\ensuremath{\gamma}$-ray multipolarities, ${J}^{\ensuremath{\pi}}$ assignments, isomeric lifetimes, and a $g$ factor. Systematic $\ensuremath{\Delta}J=1$ bands built on low-lying $\frac{9}{{2}^{+}}$ proton-hole (2p-1h) states were observed in these nuclei. The bandheads that involve the excitation of a $1{g}_{\frac{9}{2}}$ proton across the $Z=50$ shell achieve an energy minimum near the middle of the neutron shell. The observed properties of these bands are consistent with significant prolate deformations; the band spacings imply a deformation asymmetry of $\ensuremath{\gamma}=20$ in a triaxial rotor model. In addition, single-particle and single-particle plus core-excitation states were observed in these Sb nuclei. Two isomers were identified, a $\frac{19}{{2}^{(\ensuremath{-})}}$ state at 2796 keV in $^{115}\mathrm{Sb}$ ($\ensuremath{\tau}=230\ifmmode\pm\else\textpm\fi{}4$ ns and $g=+0.290\ifmmode\pm\else\textpm\fi{}0.005$) and a ($\frac{27}{{2}^{+}}$) state in $^{119}\mathrm{Sb}$ ($\ensuremath{\tau}=1.23\ifmmode\pm\else\textpm\fi{}0.13$ s).NUCLEAR REACTIONS $^{110\ensuremath{-}116}\mathrm{Cd}$ ($^{6}\mathrm{Li}$,$3n$)$^{113\ensuremath{-}119}\mathrm{Sb}$; measured $\ensuremath{\gamma}\ensuremath{-}\ensuremath{\gamma}$ coincidences, $\ensuremath{\gamma}(E,\ensuremath{\theta},t)$, spin rotation in $B=10.3$ kG; deduced level schemes in odd-mass $^{113\ensuremath{-}119}\mathrm{Sb}$, $\ensuremath{\gamma}$ multipolarities, ${J}^{\ensuremath{\pi}}$, ${T}_{\frac{1}{2}}$, $g$-factor. Enriched targets, Ge(Li) detectors.