Eigen-Property of Single-j System and Seniority Conservation Condition

In this paper we study the system with three nucleons within a single-j shell, which can be described as the angular momentum coupling of a nucleon pair and the odd nucleon. The overlaps between these non-orthonormal states form a special matrix coincidental with the one obtained by Rowe and Rosensteel. They proposed a proposition related to the eigenvalue problems of that matrix and dimensions of the associated subspaces. We prove their proposition with the help of the symmetric properties of the six-j symbols. We also derive algebraic expressions for eigen energies as well as conditions for conservation of seniority through the decomposition of the angular momentum.     

Four-Quasiparticle High-K States in Neutron-Deficient Lead and Polonium Nuclei

Configuration-constrained potential energy surface calculations have been performed to investigate four-quasiparticle high-K configurations in neutron-deficient lead and polonium isotopes. A good agreement between the calculations and the experimental data has been found for the excitation energy of the observed Kπ = 19- state in 188Pb. Several lowly excited high-K states are predicted, and the large oblate deformation and low energy indicate high-K isomerism in these nuclei.     

三轴超形变研究的新进展

自20世纪90年代中期发现三轴超形变以来,近年来这一领域的研究已成为高自旋超形变研究的热门课题之一。进入新世纪,三轴超形变研究取得了几项突破性进展。 2001年以丹麦玻尔所为首的合作组观测到~(163)Lu两个三轴超形变带之间的9条连接跃迁,宣布首次找到了Wobbling Mode的实验证据。早在70年代A.Bohr和B.R.Mottelson已预言具有非     

Angular Momentum Projected Potential-Energy-Surface Calculation:Application to 178Hf

An angular momentum projected potential-energy-surface (PES) calculation, which takes both rotational symmetry restoration and multi-quasiparticle excitation into account, is developed by using the macroscopic-microscopic model and the projected shell model (PSM). Within this method, it may become possible to modify the excitation spectra which are influenced by shape-softness of nuclei, including high-K states. As our first example, this method is adopted to study the collective and multi-quasiparticle excitations of 178Hf, and the results are in good agreement with the existing experimental data. In addition, as for the dominant structure of noncollective 6 + bands, the conflict between experimental result and the previous PSM calculation is clarified.     

Shape Co-Existence in the Transitional Nuclide 157yb

High-spin states in 157yb have been populated in the 144Sm(16O, 3n)157yb fusion-evaporation reaction at a beam energy of 85 MeV, and two rotational bands have been established for the first time. Within the framework of the triaxial particle-rotor model, the energy spectra and single-particle configurations of 157yb are investigated. The calculated energy spectra agree well with the experimental data. The newly observed vf7/2 band, and the previously known vi13/2 band in 157yb, are also discussed by means of Total-Routhian-Surface methods. The structural characters observed in 157Yb provide evidence for the shape coexistence of three distinct shapes: prolate, triaxial and oblate. At higher spins, both the vf7/2 band and the vi13/2 band in 157yb undergo a shape evolution with sizable alignments occurring.