Decay of a Three-Quasiparticle State in ${}_{}{}^{177}{}_{}{}^{}\mathrm{Ta}$

The decay of a three-quasiparticle isomeric state at 1355 keV in ${}_{}{}^{177}{}_{}{}^{}\mathrm{Ta}$ was studied using in-beam $\gamma$-ray spectroscopic techniques. Tantalum isotopes were produced by the ${}_{}{}^{175,176}{}_{}{}^{}\mathrm{L}\mathrm{u}-(\alpha ,xn)$ reactions with $\alpha$-particle energies between 24 and 48 MeV. The half-life of the isomer was measured to be $t_{\frac{1}{2}}\left(1355\mathrm{} \mathrm{keV}\right)=5.02\mathrm{}\pm 0.20$ μsec, and its spin and parity were determined to be $I^{\pi }={\frac{21}{2}}^{-}$. The $\frac{E2\mathrm{}}{M1\mathrm{}}$ mixing ratios and the rotational-model parameters $\frac{{(g_K-g_R)}^2}{{Q_0}^2}$ were deduced for five $\Delta I=1\mathrm{}$ transitions between members of the rotational band based on the $\frac{9}{2}\mathrm{}\left[514\right]\mathrm{}$ state.