Band crossings in ¹⁶⁸Ta: a particle-number conserving analysis

The structures of two observed high-spin rotational bands in the doubly-odd nucleus ${}^{168}$Ta are investigated using the cranked shell model with pairing correlations treated by a particle-number conserving method, in which the blocking effects are taken into account exactly. The experimental moments of inertia and alignments are reproduced very well by the calculations, which confirms the configuration assignments for these two bands in previous works. The backbending and upbending mechanisms in these two bands are analyzed in detail by calculating the occupation probabilities of each orbital close to the Fermi surface and the contributions of each orbital to the total angular momentum alignments. The investigation shows that the level crossings in the first backbending is the neutron $i_{13/2}$ crossing and the in second upbending is the proton $h_{11/2}$ crossing.