Influence of the pairing interaction at ultrahigh spin

The pairing effect plays a very important role in nuclear phenomena. We analyze the influence of pairing interaction on angular momentum alignments and backbending frequencies near the ultrahigh spin $\ensuremath{\hbar}\ensuremath{\omega}\ensuremath{\approx}0.8$ MeV. Although the moment of inertia of rotational bands tends to be the same with or without pairing interaction, their angular momentum alignments and backbending frequencies still have large differences even at the ultrahigh spin region. For the normal orbitals, the alignment difference keeps almost constant from the larger spin region to the ultrahigh spin region. The high-$j$orbitals always cause drastic changes of alignment and lead to changes of backbending frequencies. Therefore, even at the ultrahigh spin region, to understand some nuclear phenomena, the pairing correlations should be included in some theoretical models.