Systematic investigation of the high-spin structures in the odd-odd nuclei $^{166, 168, 170, 172}$Re by a particle-number conserving method

The recently observed two and four-quasiparticle high-spin rotational bands in the odd-odd nuclei $^{166, 168, 170, 172}$Re are investigated using the cranked shell model with pairing correlations treated by a particle-number conserving method. The experimental moments of inertia and alignments can be reproduced well by the present calculation if appropriate bandhead spins and configurations are assigned for these bands, which in turn confirms their spin and configuration assignments. It is found that the bandhead spins of those two rotational bands observed in $^{166}$Re~[Li {it et al.}, Phys. Rev. C 92 014310 (2015)] should be both increased by $2hbar$ to get in consistent with the systematics of the experimental and calculated moments of inertia for the same configurations in $^{168, 170, 172}$Re. The variations of the backbendings/upbendings with increasing neutron number in these nuclei are investigated. The level crossing mechanism is well understood by analysing the variations of the occupation probabilities of the single-particle states close to the Fermi surface and their contributions to the angular momentum alignment with rotational frequency. In addition, the influence of the deformation driving effects of the proton $1/2^-[541]$ ($h_{9/2}$) orbtial on the level crossing in $^{172}$Re is also discussed.

Configuration and bandhead spin assignments for the 2-quasiparticle rotational bands in the neutron-rich nuclei $^{154, 156}$Pm

The rotational bands in the neutron-rich nuclei $^{153-157}$Pm are investigated by a particle-number conserving method. The kinematic moments of inertia for the 1-quasiparticle bands in odd-$A$ Pm isotopes $^{153, 155, 157}$Pm are reproduced quite well by the present calculation. By comparison between the experimental and calculated moments of inertia for the three 2-quasiparticle bands in the odd-odd nuclei $^{154, 156}$Pm, their configurations and bandhead spins have been assigned properly. For the 2-quasiparticle band in $^{154}$Pm, the configuration is assigned as $pi5/2^-[532]otimes u3/2^-[521]$ ($K^pi=4^+$) with the bandhead spin $I_0=4hbar$. In $^{156}$Pm, the same configuration and bandhead spin assignments have been made for the 2-quasiparticle band with lower excitation energy. The configuration $pi5/2^+[413]otimes u5/2^+[642]$ ($K^pi=5^+$) with the bandhead spin $I_0=5hbar$ is assigned for that with higher excitation energy.