Insight into nuclear midshell structures by study of $K$-isomers in rare-earth neutron-rich nuclei

Abstract

Inspired by the newly discovered isomeric states in the rare-earth neutron-rich nuclei, high-$K$ isomeric states in neutron-rich samarium and gadolinium isotopes are investigated within the framework of the cranked shell model (CSM) with pairing correlation treated by a particle-number-conserving (PNC) method. The experimental multi-particle state energies and moments of inertia are reproduced quite well by the PNC-CSM calculations. A remarkable effect from the high-order deformation ${\epsilon }_6$ is demonstrated. Based on the occupation probabilities, the configurations are assigned to the observed high-$K$ isomeric states. The lower $5^{-}$ isomeric state in ${}^{158}$Sm is preferred as the two-proton state with configuration $\pi {\frac{5}{2}}^{+}[413]\otimes \pi {\frac{5}{2}}^{-}[532]$. More low-lying two-particle states are predicted. The systematics of the electronic quadrupole transition probabilities, $B(E2)$ values along the neodymium, samarium, gadolinium and dysprosium isotopes and $N=96,98,100,102$ isotones chains is investigated to reveal the midshell collectivities.

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Cited by in corpus (6)

• Rotational excitations in rare-earth nuclei: a comparative study within three cranking models with different mean fields and the treatments of pairing correlations
• The alternating-parity bands of \element{236,238}{U} and \element{238,240}{Pu} in a particle-number conserving method based on cranked shell model
• High-K isomer and the rotational properties in the odd-Z neutron-rich nucleus ${}^{163}$Eu
• Configuration and bandhead spin assignments for the 2-quasiparticle rotational bands in the neutron-rich nuclei ${}^{154,156}$Pm
• $K$-isomeric states in the isotopic and isotonic chains of ${}^{178}$Hf
• Effects of high-$j$ orbitals, pairing and deformed neutron shells on upbendings of ground-state bands in neutron-rich even-even isotopes ${}^{170-184}$Hf