Coriolis coupling in two-quasiparticle rotational bands of deformed even-even nuclei.

Abstract

The experimental data on two-quasiparticle rotational bands of doubly-even nuclei in the rare-earth region are analyzed; both the ${\mathit{K}}_{\mathrm{\ensuremath{-}}}$=\ensuremath{\Vert}${\mathrm{\ensuremath{\Omega}}}_{1}$-${\mathrm{\ensuremath{\Omega}}}_{2}$\ensuremath{\Vert} and many of the ${\mathit{K}}_{+}$=(${\mathrm{\ensuremath{\Omega}}}_{1}$+${\mathrm{\ensuremath{\Omega}}}_{2}$) bands exhibit an odd-even staggering in energy. A formalism for Coriolis coupling within the framework of the two-quasiparticle plus axially symmetric rotor model is presented. A detailed application of the model is made to the 27 known two-quasiparticle bands in $^{168}\mathrm{Er}$. The odd-even staggering in all the bands is reproduced very well. A discussion of the mixing effects in some of the bands is also presented. The Coriolis mixing is able to resolve the apparent violation of the Gallagher rule in the configuration {5/2[642${]}_{\mathit{n}}$\ensuremath{\bigotimes}1/2[521${]}_{\mathit{n}}$}.