Nuclear pairing reduction due to rotation and blocking

Abstract

Nuclear pairing gaps of normally deformed and superdeformed nuclei are investigated using the particle-number conserving (PNC) formalism for the cranked shell model, in which the blocking effects are treated exactly. Both rotational frequency $ω$-dependence and seniority (number of unpaired particles) $ν$-dependence of the pairing gap $\tildeΔ$ are investigated. For the ground-state bands of even-even nuclei, PNC calculations show that in general $\tildeΔ$ decreases with increasing $ω$, but the $ω$-dependence is much weaker than that calculated by the number-projected Hartree-Fock-Bogolyubov approach. For the multiquasiparticle bands (seniority $ν> 2$), the pairing gaps keep almost $ω$-independent. As a function of the seniority $ν$, the bandhead pairing gaps $\tildeΔ(ν,ω=0)$ decrease slowly with increasing $ν$. Even for the highest seniority $ν$ bands identified so far, $\tildeΔ(ν,ω=0)$ remains greater than 70% of $\tildeΔ(ν=0,ω=0)$.

15 pages, 5 figures