The Plateau of Moment of Inertia and the Energy Gap in ^161−168Yb

The influence of the gap at Z=70 on the alignment in ^161−168Yb is studied using the particle number conserving method. If there is a gap at the Fermi surface, the occupation probability of the 5237/2 proton orbital does not change as much as when there is no gap. The formation of the plateau of moment of inertia is sensitive to the relative position of the orbital π4047/2, π4111/2 and π5237/2. A third backbending caused by π5411/2 is predicted.