Remarkable triaxiality is found in the high-K isomeric states of A-130 nuclei using the configuration-constrained calculations of potential-energy surfaces. The triaxiality gives the further understanding of the decay...Remarkable triaxiality is found in the high-K isomeric states of A-130 nuclei using the configuration-constrained calculations of potential-energy surfaces. The triaxiality gives the further understanding of the decay properties of the isomers. The calculation with triaxiality can well explain the measured quadrupole moment of the K^z=7^- isomer in ^130Ce.展开更多
The charge-exchange spin-dipole （SD） and spin-quadrupole （SQ） strength functions of 90Zr are calculated with and without the tensor terms of the Skyrme interaction in self-consistent HF＋RPA approach. It is found ...The charge-exchange spin-dipole （SD） and spin-quadrupole （SQ） strength functions of 90Zr are calculated with and without the tensor terms of the Skyrme interaction in self-consistent HF＋RPA approach. It is found that, in SD and SQ transitions, the RPA correlations associated with the tensor terms shin dramatically the strengths of （Ylσ）λ = l？1 and （Ylσ）λ = 1 modes upward and downward, respectively, and also shift the strengths of （Ylσ）λ = l ＋ 1 modes upward. The coupling between （Yl = λ ？ 1σ）λ and （Yl = λ ＋ 1σ）λ modes arising from the tensor correlation is noticeable. The RPA tensor correlations produce strengths of SD and SQ modes, which are distributed in a much wider energy range, and the （Ylσ）λ = l ？ 1 modes dominate the high energy part of the strength functions. These energy shifts and coupling effects of different modes can be understood qualitatively by expressing a finite range tensor force in a separable form.展开更多
High-spin states in 157Yb have been populated in the 144Sm（160, 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 framewo...High-spin states in 157Yb have been populated in the 144Sm（160, 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.展开更多
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 ...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.展开更多
The high-spin level structure of 186 Au is re-investigated by means of in-beam γ-ray spectroscopy via the 172 Yb(19 F,5nγ )186 Au reaction.The oblate bands previously reported are revised and extended to higher-spin...The high-spin level structure of 186 Au is re-investigated by means of in-beam γ-ray spectroscopy via the 172 Yb(19 F,5nγ )186 Au reaction.The oblate bands previously reported are revised and extended to higher-spin states.A new Iπ =(20+) excited state has been identified and assigned to the πh-111/2 (×) vi-213/2h-19/2 configuration.The total Routhian surface and cranked shell model calculations suggest that the πh-111/2 (×) vi-213/2h-19/2 band in 186Au has a non-axial deformation.展开更多
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-micro...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 non- collective 6＋ bands, the conflict between experimental result and the previous PSM calculation is clarified.展开更多
We investigate β decays of the neutron-rich nucleus ^18 N and the structure of the daughter nucleus ^18 O using the shell model. The reduced transition strengths B（GT） and branching ratios of the/3 decays in ^18 N ...We investigate β decays of the neutron-rich nucleus ^18 N and the structure of the daughter nucleus ^18 O using the shell model. The reduced transition strengths B（GT） and branching ratios of the/3 decays in ^18 N are calculated in the psd and spsdpf shell spaces with the WBT interaction. The calculations in the two different spaces are compared. The psd calculations obtain a better agreement with the observation of the β-delayed neutron emission, which seems to show that the observed properties of ^18 N and ^18 O are mainly produced by one particle being excited from the p-shell to the sd-shell.展开更多
基金Supported by the National Natural Science Foundation of China under Grant Nos 10735010, 10525520 and 10475002, and the National Basic Research Programme of China under Grant No 2007CB815000.
文摘Remarkable triaxiality is found in the high-K isomeric states of A-130 nuclei using the configuration-constrained calculations of potential-energy surfaces. The triaxiality gives the further understanding of the decay properties of the isomers. The calculation with triaxiality can well explain the measured quadrupole moment of the K^z=7^- isomer in ^130Ce.
基金Supported by the National Natural Science Foundation of China under Grant Nos 10875172, 10275092 and 10675169, the National Key Basic Research Program of China under Grant No 2007CB815000, the Project of Knowledge Innovation Program （PKIP） of Chinese Academy of Sciences under Grant No KJCX2.YW.W10.
文摘The charge-exchange spin-dipole （SD） and spin-quadrupole （SQ） strength functions of 90Zr are calculated with and without the tensor terms of the Skyrme interaction in self-consistent HF＋RPA approach. It is found that, in SD and SQ transitions, the RPA correlations associated with the tensor terms shin dramatically the strengths of （Ylσ）λ = l？1 and （Ylσ）λ = 1 modes upward and downward, respectively, and also shift the strengths of （Ylσ）λ = l ＋ 1 modes upward. The coupling between （Yl = λ ？ 1σ）λ and （Yl = λ ＋ 1σ）λ modes arising from the tensor correlation is noticeable. The RPA tensor correlations produce strengths of SD and SQ modes, which are distributed in a much wider energy range, and the （Ylσ）λ = l ？ 1 modes dominate the high energy part of the strength functions. These energy shifts and coupling effects of different modes can be understood qualitatively by expressing a finite range tensor force in a separable form.
基金supported by Natural Science Foundation of China (Nos. 10775005, 10405001, 10875002, 10735010, 10975007, 10875157, J0730316)the Chinese Major State Basic Research Development Program (No. 2007CB815002)
文摘High-spin states in 157Yb have been populated in the 144Sm（160, 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.
基金supported by National Natural Science Foundation of China (Nos.10735010,10975006)the Chinese Major State Basic Research Development Program (No.2007CB815000)Qi C. has been supported by the Swedish Research Council (VR)
文摘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.
基金Supported by the National Natural Science Foundation of China under Grant Nos 10905075,10825522,10735010,and 10975006the National Basic Research Program of China under Grant No 2007CB815005the Chinese Academy of Sciences.
文摘The high-spin level structure of 186 Au is re-investigated by means of in-beam γ-ray spectroscopy via the 172 Yb(19 F,5nγ )186 Au reaction.The oblate bands previously reported are revised and extended to higher-spin states.A new Iπ =(20+) excited state has been identified and assigned to the πh-111/2 (×) vi-213/2h-19/2 configuration.The total Routhian surface and cranked shell model calculations suggest that the πh-111/2 (×) vi-213/2h-19/2 band in 186Au has a non-axial deformation.
基金supported by Natural Science Foundation of China (Nos. 10735010, 10975006)the Chinese Major State Basic Research Development Program (No. 2007CB815000)
文摘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 non- collective 6＋ bands, the conflict between experimental result and the previous PSM calculation is clarified.
基金Supported by the National Natural Science Foundation of China under Grant Nos. 10525520 and 10475002, the Doctoral Foundation of the Ministry of Education of China （20030001088）, and the Key Project of the Ministry of Education of China under Grant No 305001.
文摘We investigate β decays of the neutron-rich nucleus ^18 N and the structure of the daughter nucleus ^18 O using the shell model. The reduced transition strengths B（GT） and branching ratios of the/3 decays in ^18 N are calculated in the psd and spsdpf shell spaces with the WBT interaction. The calculations in the two different spaces are compared. The psd calculations obtain a better agreement with the observation of the β-delayed neutron emission, which seems to show that the observed properties of ^18 N and ^18 O are mainly produced by one particle being excited from the p-shell to the sd-shell.
