Total Routhian surface （TRS） calculations for even-even N = 76 isotones with 54 ≤ Z ≤ 68 have been performed in three-dimensional （β2,γ,β4） deformation space. Calculated results of the equilibrium deformation...Total Routhian surface （TRS） calculations for even-even N = 76 isotones with 54 ≤ Z ≤ 68 have been performed in three-dimensional （β2,γ,β4） deformation space. Calculated results of the equilibrium deformations are presented and compared with other theoretical predictions and available experimental data. The behavior of collective angular momentum shows the neutron rotation-alignment is preferred in the lighter N = 76 isotones, while for the heavier ones the proton alignment is favored. Moreover, multi-pair nucleon alignments and their competition （e.g., in 144Er） are predicted. It is pointed out that these nuclei in the N=76 isotonic chain exhibit triaxiality or γ softness in high-spin states as well as ground states. Based on deformation-energy curves with respect to axial and non-axial quadrupole deformations, the shape instabilities are evaluated in detail and predicted, particularly in γ direction. Such instabilities are also supported by the odd- and even-spin level staggering of the observed γ bands, which is usually used to distinguish between y-rigid and γ-soft asymmetry.展开更多
^186Pt was tested in the framework of IBM-1 and the X（3） model. The results show that ^186Pt is located close to the shape phase transition point, but the B（E2） values little agree with the X（3） model. The shape...^186Pt was tested in the framework of IBM-1 and the X（3） model. The results show that ^186Pt is located close to the shape phase transition point, but the B（E2） values little agree with the X（3） model. The shape evolution in the yrast states of186Pt is also discussed in detail. TRS calculation exhibits a flat bottomed potential at low spin states, but a relatively deep minimum at high spin states. It suggests that a shape evolution from vibrational mode to rotational mode happens in ^186Pt. The result is in agreement with the E-GOS calculation.展开更多
Two-dimensional total routhian surface （TRS） calculations are carried out to determine the triaxial superdeformation （TSD） of the even-even nucleus 174W, and the result indicates that TSD state exists with deforma...Two-dimensional total routhian surface （TRS） calculations are carried out to determine the triaxial superdeformation （TSD） of the even-even nucleus 174W, and the result indicates that TSD state exists with deformation parameters ε2=0.42 andγ=34.7°. In the same way, the total routhian surfaces for the nuclei ^172,176W are also calculated. It shows that the neutron shell correction energy plays a key role in the formation of TSD nuclei ^172,174,176W, while the high j intruder orbitals and rotational energy are also crucial in the formation mechanism.展开更多
基金Supported by National Natural Science Foundation of China(10805040,11175217)Foundation and Advanced Technology Rese Program of Henan Province(132300410125)S&T Research Key Program of Henan Province Education Department(13A140667)
文摘Total Routhian surface （TRS） calculations for even-even N = 76 isotones with 54 ≤ Z ≤ 68 have been performed in three-dimensional （β2,γ,β4） deformation space. Calculated results of the equilibrium deformations are presented and compared with other theoretical predictions and available experimental data. The behavior of collective angular momentum shows the neutron rotation-alignment is preferred in the lighter N = 76 isotones, while for the heavier ones the proton alignment is favored. Moreover, multi-pair nucleon alignments and their competition （e.g., in 144Er） are predicted. It is pointed out that these nuclei in the N=76 isotonic chain exhibit triaxiality or γ softness in high-spin states as well as ground states. Based on deformation-energy curves with respect to axial and non-axial quadrupole deformations, the shape instabilities are evaluated in detail and predicted, particularly in γ direction. Such instabilities are also supported by the odd- and even-spin level staggering of the observed γ bands, which is usually used to distinguish between y-rigid and γ-soft asymmetry.
基金Supported by National Natural Science Foundation of China(11175259,11075214,10927507)
文摘^186Pt was tested in the framework of IBM-1 and the X（3） model. The results show that ^186Pt is located close to the shape phase transition point, but the B（E2） values little agree with the X（3） model. The shape evolution in the yrast states of186Pt is also discussed in detail. TRS calculation exhibits a flat bottomed potential at low spin states, but a relatively deep minimum at high spin states. It suggests that a shape evolution from vibrational mode to rotational mode happens in ^186Pt. The result is in agreement with the E-GOS calculation.
基金Supported by National Natural Science Foundation of China (10575036, 10675046)Natural Science Foundation of Zhejiang Province (Y605476, Y604027)
文摘Two-dimensional total routhian surface （TRS） calculations are carried out to determine the triaxial superdeformation （TSD） of the even-even nucleus 174W, and the result indicates that TSD state exists with deformation parameters ε2=0.42 andγ=34.7°. In the same way, the total routhian surfaces for the nuclei ^172,176W are also calculated. It shows that the neutron shell correction energy plays a key role in the formation of TSD nuclei ^172,174,176W, while the high j intruder orbitals and rotational energy are also crucial in the formation mechanism.
