Particle-number-conserving treatment for the backbending in Yb isotopes Original Research Article

The particle-number conserving (PNC) treatment for the cranked shell model with monopole and quadrupole pairing interactions is used to investigate the microscopic mechanism of backbending in nuclear moments of inertia of Yb isotopes, including the variation with rotational frequency ω of the occupation nμ of each cranked orbital μ, the contributions to angular momentum alignment from each unclosed major shell, and the individual contributions jx(μ) from the particle in the orbital μ, and the interference jx(μν) between the particles in orbitals μ and ν. PNC calculations show that the occurrence of sharp backbending in some nuclei (e.g., 170Yb), comes mainly from contribution of the interference effect between a high j intruder orbital quite near the Fermi surface and neighboring high j orbitals.