Frequency and Alignment Classification of Multiple Band Crossings

Abstract

Experiments on $^{160}\mathrm{Yb}$ indicate three negative-parity bands up to $I>~21\ensuremath{\hbar}$. All three experience a band crossing around a frequency $\ensuremath{\hbar}\ensuremath{\omega}=0.36$ MeV, a value intermediate to those of the first and second yrast backbends. The ${i}_{\frac{13}{2}}$ band in $^{161}\mathrm{Yb}$ is observed up to ${\frac{49}{2}}^{+}$; it also has a strong upbend at this intermediate frequency. The fingerprint of a band crossing based upon the crossing frequency and gain in aligned angular momentum is demonstrated and the results compared to cranking-model calculations to suggest quasiparticle assignments for the bands.