Multiphonon<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>γ</mml:mi></mml:math>-vibrational bands and the triaxial projected shell model

Abstract

We present a fully quantum-mechanical, microscopic, unified treatment of ground-state band and multiphonon $\ensuremath{\gamma}$-vibrational bands using shell model diagonalization with the triaxial projected shell model. The results, which agree very well with data on the g- and $\ensuremath{\gamma}$-band spectra in ${}^{156\ensuremath{-}170}\mathrm{Er},$ as well as with recently measured ${4}^{+}$ two-phonon $\ensuremath{\gamma}$-bandhead energies in ${}^{166}\mathrm{Er}$ and ${}^{168}\mathrm{Er},$ are discussed in terms of the K mixing. Multiphonon $\ensuremath{\gamma}$-excitation energies are predicted.