Engineering topics

Zheng, K. K.

Publications and source records attributed to Zheng, K. K..

4 records

DOE OSTI2021

Evidence against the wobbling nature of low-spin bands in 135 Pr

The electromagnetic character of the ΔI=1 transitions connecting the 1- to 0-phonon and the 2- to 1-phonon wobbling bands should be dominated by an E2 component, due to the collective motion of the entire nuclear charge. In the present work it is shown, based on combined angular correlation and linear polarization measurements, that the mixing ratios of all analyzed connecting transitions between low-lying bands in 135 Pr interpreted as 0-, 1-, and 2-phonon wobbling bands, have absolute values smaller than one. This indicates predominant M1 magnetic character, which is incompatible with the proposed wobbling nature. All experimental observables are instead in good agreement with quasiparticle-plus-triaxial-rotor model calculations, which describe the bands as resulting from a rapid re-alignment of the total angular momentum from the short to the intermediate nuclear axis

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

DOE OSTI2021

Signature splitting of the g 7 / 2 [ 404 ] 7 / 2 + bands in Ba 131 and Ce 133

Excited states in Ba 131 and Ce 133 were studied using in-beam γ -ray spectroscopy through the Sn 122 ( C 13 , 4 n ) Ba 131 and Te 125 ( C 12 , 4 n ) Ce 133 reactions, respectively. A strongly coupled band, associated with the ν g 7 / 2 [ 404 ] 7 / 2 + configuration, was identified in Ba 131 and Ce 133 . It is the first time to observe the ν g 7 / 2 [ 404 ] 7 / 2 + bands in the N = 75 isotones. The signature partners exhibit considerable energy splitting in comparison with those in the π g 7 / 2 [ 404 ] 7 / 2 + bands in the odd- A Ta and Re isotopes. Here, extensive cranked shell model and quasiparticle-plus-triaxial-rotor model calculations reveal the origin of the signature splitting, which depends not only on the triaxiality, but also on the configuration mixing with nearby low- j orbitals.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

DOE OSTI2020

Multiple chiral bands in $^{137}$Nd

Two new bands have been identified in 137 Nd from a high-statistics JUROGAM II gamma-ray spectroscopy experiment. Constrained density functional theory and particle rotor model calculations are used to assign configurations and investigate the band properties, which are well described and understood. It is demonstrated that these two new bands can be interpreted as chiral partners of previously known three-quasiparticle positive- and negative-parity bands. The newly observed chiral doublet bands in 137 Nd represent an important support to the existence of multiple chiral bands in nuclei. Overall, the present results constitute the missing stone in the series of Nd nuclei showing multiple chiral bands, which becomes the most extended sequence of odd-even and even-even nuclei presenting multiple chiral bands in the Segre chart.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2020

Signatures of enhanced octupole correlations at high spin in 136 Nd

We report experimental signatures of moderately enhanced octupole correlations at high spin in 136 Nd are indicated for the first time. The extracted dipole moments of two negative-parity bands are only two times smaller than those of the lanthanide nuclei with $\textit{N}$ ≈ 90 which present well-established octupole correlations. Calculations using the cranked quasiparticle random phase approximation and a model of quadrupole-octupole rotations with octupole vibrations reveal the structure of the bands and the enhanced octupole correlations at high spin in 136 Nd .

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗