Nuclear pairing reduction due to rotation and blocking

TL;DR

This paper investigates how nuclear pairing gaps are affected by rotation and blocking effects using a particle-number conserving formalism, revealing a generally decreasing trend with rotation but with notable seniority dependence.

Contribution

It applies the particle-number conserving formalism to study rotational and seniority effects on nuclear pairing gaps, providing more accurate insights than previous approaches.

Findings

Pairing gaps decrease with increasing rotational frequency, but less so than in other models.

Multiquasiparticle bands show almost no dependence of pairing gaps on rotation.

High seniority bands still retain over 70% of the pairing gap at zero seniority.

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 $\omega$-dependence and seniority (number of unpaired particles) $\nu$-dependence of the pairing gap $\tilde{\Delta}$ are investigated. For the ground-state bands of even-even nuclei, PNC calculations show that in general $\tilde{\Delta}$ decreases with increasing $\omega$, but the $\omega$-dependence is much weaker than that calculated by the number-projected Hartree-Fock-Bogolyubov approach. For the multiquasiparticle bands (seniority $\nu> 2$), the pairing gaps keep almost $\omega$-independent. As a function of the seniority $\nu$, the bandhead pairing gaps $\tilde{\Delta}(\nu,\omega=0)$ decrease slowly with increasing $\nu$. Even for the highest seniority $\nu$ bands identified so far, $\tilde{\Delta}(\nu,\omega=0)$ remains greater than 70% of $\tilde{\Delta}(\nu=0,\omega=0)$.