Frequency and Alignment Classification of Multiple Band Crossings

Experiments on Yb160 indicate three negative-parity bands up to I>~21ℏ. All three experience a band crossing around a frequency ℏω=0.36 MeV, a value intermediate to those of the first and second yrast backbends. The i132 band in Yb161 is observed up to 492+; 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.