Understanding the different rotational behaviors of $^{252}$No and $^{254}$No

TL;DR

This study uses total Routhian surface calculations to explain the contrasting rotational behaviors of $^{252}$No and $^{254}$No, highlighting the role of high-order deformations in nuclear structure.

Contribution

It demonstrates for the first time that $eta_6$ deformation explains the different rotational behaviors of these nuclei, advancing understanding of superheavy element structure.

Findings

Fast alignment in $^{252}$No is reproduced by calculations.

Slow alignment in $^{254}$No is explained by $eta_6$ deformation.

High-order deformation is crucial for modeling rotational spectra.

Abstract

Total Routhian surface calculations have been performed to investigate rapidly rotating transfermium nuclei, the heaviest nuclei accessible by detailed spectroscopy experiments. The observed fast alignment in $^{252}$No and slow alignment in $^{254}$No are well reproduced by the calculations incorporating high-order deformations. The different rotational behaviors of $^{252}$No and $^{254}$No can be understood for the first time in terms of $\beta_6$ deformation that decreases the energies of the $\nu j_{15/2}$ intruder orbitals below the N=152 gap. Our investigations reveal the importance of high-order deformation in describing not only the multi-quasiparticle states but also the rotational spectra, both providing probes of the single-particle structure concerning the expected doubly-magic superheavy nuclei.