Research Articles (Physics)
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Browsing Research Articles (Physics) by Subject "Angular momentum (Nuclear physics)"
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- ItemMultiple chiral bands built on the same many-particle nucleon configuration In the 100 mass region(Jagellonian University, 2018) Shirinda, O.; Lawrie, E. A.Multi-particle-plus-triaxial-rotor (MPR) model calculations were performed for chiral partner bands associated with the multi-particle πg¯¹9/2⊗ vh²11/2 nucleon configuration in the 100 mass region. Multiple chiral systems were found, but they may not necessarily form well-defined pairs of near-degenerate bands.
- ItemMultiple chiral doublets in four-j shells particle rotor model : five possible chiral doublets in ¹³⁶₆₀Nd₇₆(Elsevier, 2018) Chen, Q. B.; Lv, B. F.; Petrache, C. M.; Meng, JieA particle rotor model, which couples nucleons in four single-jshells to a triaxial rotor core, is developed to investigate the five pairs of nearly degenerate doublet bands recently reported in the even-even nucleus 136Nd. The experimental energy spectra and available B(M1)/B(E2)values are successfully reproduced. The angular momentum geometries of the valence nucleons and the core support the chiral rotation interpretations not only for the previously reported chiral doublet, but also for the other four candidates. Hence, 136Nd is the first even-even candidate nucleus in which the multiple chiral doublets exist. Five pairs of chiral doublet bands in a single nucleus is also a new record in the study of nuclear chirality.
- ItemNew candidate chiral nucleus in the A ≈ 80 mass region : 82 35 Br 47(American Physical Society, 2019-11-07) Liu, C.; Wang, S. Y.; Qi, B.; Wang, S.; Sun, D. P.; Li, Z. Q.; Bark, R. A.; Jones, P.; Lawrie, J. J.; Masebi, L.; Wiedeking, M.; Meng, J.; Zhang, S. Q.; Hua, H.; Li, X. Q.; Li, C. G.; Han, R.; Wyngaardt, S. M.; Sun, B. H.; Zhu, L. H.; Bucher, T. D.; Kheswa, B. V.; Malatji, K. L.; Ndayishimye, J.; Shirinda, O.; Dinoko, T.; Khumalo, N.; Lawrie, E. A.; Ntshangase, S. S.A pair of nearly degenerate positive-parity bands were observed in 82 Br for the first time using the 82 Se(α,p3n) reaction. The positive-parity doublet bands are proposed to be chiral doublet bands based on the triaxial particle rotor model and the potential energy surface calculations. The root-mean-square values of the angular momentum components and their probability distributions are discussed in detail to exhibit the chiral geometry and its evolution in 82 Br.
- ItemReexamining nuclear chiral geometry from the orientation of the angular momentum(American Physical Society, 2018) Chen, Q. B.; Meng, JieThe paradox on the previous interpretation for the nuclear chiral geometry based on the effective angle has been clarified by reexamining the system with the particle-hole configuration π(1h11/2)1⊗ν(1h11/2)−1 and a rotor with the deformation parameter γ=30∘. It is found that the paradox is caused by the fact that the angular momentum of the rotor is much smaller than those of the proton and the neutron near the bandhead. Hence, it does not support a chiral rotation interpretation near the bandhead. The nuclear chiral geometry based on the effective angle makes sense only when the angular momentum of the rotor becomes comparable with those of the proton and neutron for a particular range of spin values.
- ItemSpin symmetry in the Dirac sea derived from the bare nucleon–nucleon interaction(Elsevier, 2018) Shen, Shihang; Liang, Haozhao; Meng, Jie; Ring, Peter; Zhang, ShuangquanThe spin symmetry in the Dirac sea has been investigated with relativistic Brueckner–Hartree–Fock theory using the bare nucleon–nucleon interaction. Taking the nucleus 16O as an example and comparing the theoretical results with the data, the definition of the single-particle potential in the Dirac sea is studied in detail. It is found that if the single-particle states in the Dirac sea are treated as occupied states, the ground state properties are in better agreement with experimental data. Moreover, in this case, the spin symmetry in the Dirac sea is better conserved and it is more consistent with the findings using phenomenological relativistic density functionals.
- Item“Stapler” mechanism for a dipole band in 79Se(American Physical Society, 2019-10-24) Li, C. G.; Chen, Q. B.; Zhang, S. Q.; Xu, C.; Hua, H.; Wang, S. Y.; Bark, R. A.; Wyngaardt, S. M.; Shi, Z.; Dai, A. C.; Wang, C. G.; Li, X. Q.; Li, Z. H.; Meng, J.; Xu, F. R.; Ye, Y. L.; Jiang, D. X.; Han, R.; Niu, C. Y.; Chen, Z. Q.; Wu, H. Y.; Wang, X.; Luo, D. W.; Wu, C. G.; Wang, S.; Sun, D. P.; Liu, C.; Li, Z. Q.; Sun, B. H.; Jones, P.; Msebi, L.; Sharpey-Schafer, J. F.; Dinoko, T.; Lawrie, E. A.; Ntshangase, S. S.; Kheswa, B. V.; Shirinda, O.; Khumalo, N.; Bucher, T. D.; Malatji, K. L.The spectroscopy of 79 Se is studied via the 82 Se(α, α3n)79Se fusion-evaporation reaction. A negative-parity magnetic dipole band in 79Se is established for the first time. Based on the calculations by the self-consistent tilted axis cranking covariant density functional theory, this new dipole band can be classified as a “stapler” band, which has a relatively stable symmetric prolate deformation as a function of rotational frequency. Hence, it is demonstrated that the stapler bands exist not only in the oblate and triaxial nuclei, but also in prolate nuclei. By examining the angular momentum coupling, it is found that the five valence nucleons in the high-j orbitals play a major role in the closing of the stapler.
- ItemUnderstanding the chiral geometry with K-Plot and Azimuthal-Plot(Jagellonian University, 2018) Chen, F. Q.; Meng, JieThe chiral geometry of the angular momentum in the intrinsic frame is extracted from angular momentum projected wave functions in the laboratory frame by the K-Plot and Azimuthal-Plot. The method is demonstrated by an application to the chiral doublet bands in 128Cs, based on the standard pairing-plus-quadrupole Hamiltonian. The observed energy spectra and the electromagnetic transitions are well-reproduced, and the K-Plot and Azimuthal-Plot obtained give evolution of angular momentum geometry with spin, by which the chirality is demonstrated.