High-angular-momentum states inAg106and their rotational interpretation

Levels in ${}_{}{}^{106}{}_{}{}^{}\mathrm{Ag}$ have been studied using heavy-ion reactions. The experiments included $\gamma$-ray yields as a function of bombarding energy, $\gamma$-ray angular distributions, $\gamma$-ray linear polarizations, and three-detector $\gamma -\gamma$ coincidence measurements. The decay scheme includes four collective bands with low-lying bandheads. The energies, $\gamma$-ray mixing ratios, and branching ratios of states in these bands are shown to be in good agreement with the corresponding quantities calculated using a two-particles-plus-rotor model at a small, symmetric deformation ($\delta =0.12\mathrm{}$). The Coriolis and recoil effects are explicitly included and a variable moment of inertia is used. The calculation also shows that the four bands have predominant configurations $\nu \left(d_{\frac{5}{2}}\right)\otimes \pi \left(g_{\frac{9}{2}}\right)$, $\nu \left(g_{\frac{7}{2}}\right)\otimes \pi \left(g_{\frac{9}{2}}\right)$, $\nu \left(h_{\frac{11}{2}}\right)\otimes \pi \left(p_{\frac{1}{2}}\right)$, and $\nu \left(h_{\frac{11}{2}}\right)\otimes \pi \left(g_{\frac{9}{2}}\right)$, respectively. The $\Delta I=1\mathrm{}$ and $\Delta I=2\mathrm{}$ level sequences in the bands can be understood on the basis of the positions of the neutron and proton Fermi surfaces in the respective Nilsson bases. Another band observed experimentally on a ${10}^{-}$ bandhead at 2.4416 MeV is thought to have a four-quasiparticle structure.