Narrow Results

The nuclei ¹³¹I and ¹³³I have been populated in multi-nucleon transfer reactions between ¹³⁶Xe ions and various targets, and their structure investigated by time-correlated γ-ray coincidence spectroscopy and the measurement of γ-ray angular correlations. A 19/2^- isomer at 1918 keV, with a half-life of 24(1) µs, has been identified in ¹³¹I, as well as nanosecond isomers with J^π = 23/2⁺ in both isotopes. A T_1/2 = 25(3) ns isomer at 4308 keV in ¹³¹I is suggested to have J^π = (31/2^-, 33/2^-) and is primarily attributed to the coupling of an odd proton in the d_5/2 or g_7/2 orbit with the configuration in ¹³⁰Te, responsible for the 15^- isomer in that nucleus. The observed level properties are compared with predictions of a shell-model calculation.

Optical traps and lattices provide a new opportunity to study strongly correlated high spin systems with cold atoms. In this article, we review the recent progress on the hidden symmetry properties in the simplest high spin fermionic systems with hyperfine spin F=3/2, which may be realized with atoms of ¹³²Cs, ⁹Be, ¹³⁵Ba, ¹³⁷Ba, and ²⁰¹Hg. A generic SO(5) or isomorphically, Sp(4) symmetry is proved in such systems with the s-wave scattering interactions in optical traps, or with the on-site Hubbard interactions in optical lattices. Various important features from this high symmetry are studied in the Fermi liquid theory, the mean field phase diagram, and the sign problem in quantum Monte-Carlo simulations. In the s-wave quintet Cooper pairing phase, the half-quantum vortex exhibits the global analogue of the Alice string and non-Abelian Cheshire charge properties in gauge theories. The existence of the quartetting phase, a four-fermion counterpart of the Cooper pairing phase, and its competition with other orders are studied in one-dimensional spin-3/2 systems. We also show that counter-intuitively quantum fluctuations in spin-3/2 magnetic systems are even stronger than those in spin-1/2 systems.

The evolution of the octupole shape with rotation in pear-shaped nuclei is a topic of broad interest. Based on the cranking covariant density functional theory in 3D lattice space, a shell-model-like approach is implemented to take into account the pairing correlations, and applied for the interleaved positive- and negative-parity bands in ${}^{224}$Th. The experimental $I-\omega$ relations are well reproduced. It is found that the octupole deformation of yrast states in ${}^{224}$Th rises slightly and then declines with increasing spin. After the band crossing, the octupole deformation suddenly disappears, i.e., a sharp transition from an octupole shape to a nearly spherical shape takes place at high spins. This is explained by the evolution of the coupling strength between the proton $i_{13∕2}$ and $f_{7∕2}$ orbitals with spin.

We study the high spin fields coupled to topologically massive gravity in AdS₃, paying special attention to the nature of the theory at the critical point. We propose an action incorporating the high spin AdS₃ gravity and the topological Chern-Simons term for high spin fields. We discuss the fluctuation spectrum around the AdS₃ vacuum and find that besides the usual massless modes there are local massive modes.

The pairing correcting energies at high spins in ¹⁶¹Lu and ¹³⁸Nd are studied by comparing the results of the cranked-Nilsson-Strutinsky (CNS) and cranked-Nilsson-Strutinsky-Bogoliubov (CNSB) models. It is concluded that the Coriolis effect rather than the rotational alignment effect plays a major role in the reduction of the pairing correlations in the high spin region. Then we proposed an average pairing correction method which not only better reproduces the experimental data comparing with the CNS model but also enables a clean-cut tracing of the configurations thus the full-spin-range discussion on the various rotating bands.

High-spin states in ¹⁵⁹Lu were populated by fusion-evaporation reaction ¹⁴⁴Sm(¹⁹F, 4n) at a beam of 106 MeV. The level scheme for ¹⁵⁹Lu is established up to . with the addition of about 20 new transitions. The possible configurations of the updated bands are suggested by the experiments Routhians, alignments and B(M1)/B(E2) ratios.

High spin states of ¹¹⁶Sb were populated using the ¹¹⁴Cd(⁷Li, 5n) fusion evaporation reaction at a beam energy of 48 MeV. The previously reported rotational bands, built on πg_9/2 ⊗ νh_11/2 and πg_9/2 ⊗ νd_5/2 configurations, have been extended and a new ΔI = 1 band has been identified.

The evolution of the octupole shape with rotation in pear-shaped nuclei is a topic of broad interest. Based on the cranking covariant density functional theory in 3D lattice space, a shell-model-like approach is implemented to take into account the pairing correlations, and applied for the interleaved positive- and negative-parity bands in ²²⁴Th. The experimental I – ω relations are well reproduced. It is found that the octupole deformation of yrast states in ²²⁴Th rises slightly and then declines with increasing spin. After the band crossing, the octupole deformation suddenly disappears, i.e., a sharp transition from an octupole shape to a nearly spherical shape takes place at high spins. This is explained by the evolution of the coupling strength between the proton i_13/2 and f_7/2 orbitals with spin.