Seven experimentally observed bands of 155Tb are analyzed in detail,using the particle-number-conserving method for treating the cranked shell model with monopole and quadrupole pairing interactions.We satisfactorily reproduce the experimental alignments and especially focus on the microscopic mechanism of the second back-bending and the influence of pair interaction on ultrahigh spins.Our calculated results show that the πi13/2 orbitals are too high to give a contribution to the moment of inertia below ω≈ 0.7 MeV.Instead,the crossing between the π[541]1/2 and other proton orbitals is responsible for the second back-bending.We assign a possible configuration to the decoupled band found in 155Tb and predict eleven bands which are experimentally unobserved.
152^Dy is the first observed superdeformed nucleus, whose band structure reflects the typical distribution of high j low Ω orbitals of superdeformed nuclei in A-150 mass region. The particle-number conserving treatment of the cranked shell model with monopole and quadrupole paring interactions is adopted to investigate the observed six superdeformed bands in 152^Dy. The π[523]7/2 orbital is emphasized for the first time to interpret the microscopic structure of band 2 and 3 of 152^Dy. A new comprehension is proposed on the basis of ever existing experimental and theoretical results, and the reliability is illustrated by several superdeformed bands of neighboring nuclei.
The experimental high-K 2- and 3-quasiparticle bands of well deformed rare-earth nuclei are analyzed. It is found that there exists significant nonadditivity in moments of inertia （MOIs） for these bands. The microscopic mechanism of the rotational bands is investigated by the particle number conserving （PNC） method in the frame of cranked shell model with pairing, in which the blocking effects are taken care of exactly. The experimental rotational frequency dependence of these bands is well reproduced in PNC calculations. The nonadditivity in MOIs originates from the destructive interference between Pauli blocking effects.
The microscopic mechanism of four experimentally observed bands in 172Tm is investigated using the particle-number conserving method of the cranked shell model with monopole and quadrupole paring interactions.The experimental results,including the moments of inertia and angular momentum alignments of four bands in 172Tm are reproduced well by the particle-number conserving calculations.The ω variation of the occupation probability of each cranked orbital and the contribution to moment of inertia from each cranked orbital are analyzed.Other unobserved low-lying bands of 2-quansiparticles in 172Tm are predicted.
CHEN BaoRen1,LI Tao1 & LIU ShuXin1,2 1 School of Physics,Peking University,Beijing 100871,China
The experimental one-, three-, and five-quasiparticle bands in 177Lu are analyzed by the particle-number conserving （PNC） method for treating the cranked shell model with pairing interaction, in which the blocking effects are taken into account exactly. The experimental moments of inertia are reproduced very well by PNC calculations with us free parameter.
