Collectivity of160,161Yb at high spin

Abstract
Lifetimes of high-spin states in 160,161Yb have been measured by the recoil-distance technique and, from these, changes in the nuclear shape due to the alignment of quasiparticles have been deduced. It is observed that the addition of the favored i13/2 quasineutron causes a reduction in collectivity at large rotational frequencies. This reduction is interpreted as due to induced triaxiality and is much larger than predicted by theory.