arXiv subjects

Yu-Chun Li

Publications and source records attributed to Yu-Chun Li.

3 recordsLinked to original sources

arXiv2020

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

The particle-number conserving (PNC) method in the framework of cranked shell model (CSM) is developed to deal with the reflection-asymmetric nuclear system by applying the $S_x$ symmetry. Based on an octupole-deformed Nilsson potential, the alternating-parity bands in \element{236,238}{U} and \element{238,240}{Pu} are investigated. The experimental kinematic moments of inertia (MoI) and the angular momentum alignments of all studied bands are reproduced well in the PNC-CSM calculations. The striking difference of rotational behaviors between U and Pu isotopes can be linked to the strength of octupole correlations. The upbendings of the alternating-parity bands in\element{236,238}{U} are due to the alignments of pairs of nucleons occupying $νg_{9/2}$, $πf_{7/2}$ orbitals and $νj_{15/2}$, $πi_{13/2}$ high-$j$ intruder orbitals. Particularly, the interference terms of nucleon occupying the octupole-correlation pairs of $ν^2 j_{15/2} g_{9/2}$ and of $π^2 i_{13/2} f_{7/2}$ give a very important contribution to the suddenly gained alignments.

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arXiv2018

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

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 $\varepsilon_{6}$ 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 $π\frac{5}{2}^{+}[413]\otimesπ\frac{5}{2}^{-}[532]$. 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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arXiv2016

Rotational Properties of the Odd-$Z$ Transfermium Nucleus $^{255}$Lr by a Particle-number-conserving Method in the Cranked Shell Model

Experimentally observed ground state band based on the $1/2^{-}[521]$ Nilsson state and the first exited band based on the $7/2^{-}[514]$ Nilsson state in the odd-$Z$ nucleus $^{255}$Lr are studied by the cranked shell model (CSM) with the paring correlations treated by the particle-number-conserving (PNC) method. This is the first time the detailed theoretical investigations being performed on these rotational bands. Both the experimental kinematic and dynamic moment of inertia ($\mathcal{J}^{(1)}$ and $\mathcal{J}^{(2)}$) versus rotational frequency are reproduced quite well by the PNC-CSM calculations. By comparing the theoretical kinematic moment of inertia $\mathcal{J}^{(1)}$ with the experimental ones extracted from different spin assignments, the spin $17/2^{-}\rightarrow13/2^{-}$ is assigned to the lowest-lying $196.6(5)$ keV transition of the $1/2^{-}[521]$ band, and $15/2^{-}\rightarrow11/2^{-}$ to the $189(1)$ keV transition of the $7/2^{-}[514]$ band, respectively. The proton $N=7$ major shell is included in the calculations. The intruder of the high$-j$ low$-Ω$ orbitals $1j_{15/2}$ $ (1/2^{-}[770])$ at the high spin leads to the band-crossing at $\hbarω\approx0.20$ ($\hbarω\approx0.25$) MeV for the $7/2^{-}[514]$ $α=-1/2$ ($α=+1/2$) band, and at $\hbarω\approx0.175$ MeV for the $1/2^{-}[521]$ $α=-1/2$ band, respectively. Further investigations show that the band-crossing frequencies are quadrupole deformation dependent.

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