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 Yb161-168 is studied using the particle number conserving method. If there is a gap at the Fermi surface, the occupation probability of the [523]7/2 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 pi[404]7/2, pi[411]1/2 and pi[523]7/2. A third backbending caused by pi[541]1/2 is predicted.