arXiv subjects

Takuya Shoji

Publications and source records attributed to Takuya Shoji.

3 recordsLinked to original sources

arXiv2008

Microscopic calculation of the wobbling excitations by using the Woods-Saxon potential as a nuclear mean-field

The wobbling excitations of the triaxial superdeformed (TSD) bands in the Lu and Hf region are studied by the microscopic framework of the cranked mean-field and the random-phase approximation (RPA). In contrast to the previous works, where the Nilsson potential was used, the more realistic Woods-Saxon potential is employed as a nuclear mean-field. The wobbling-like RPA solutions have been found systematically in the nuclei studied and their characteristic properties are investigated in details. This confirms the wobbling phonon excitations in TSD nuclei from the microscopic calculations. The result of $B(E2)$ values indicates that the triaxial deformation is increasing as a function of spin in the observed TSD bands in $^{163}$Lu.

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arXiv2007

Parametrizations of triaxial deformation and E2 transitions of the wobbling band

By the very definition the triaxial deformation parameter $γ$ is related to the expectation values of the K=0 and K=2 components of the intrinsic quadrupole tensor operator. On the other hand, using the same symbol "$γ$", various different parametrizations of triaxial deformation have been employed, which are suitable for various types of the mean-field potentials. It is pointed out that the values of various "$γ$" are quite different for the same actual triaxial deformation, especially for the large deformation; for example, the difference can be almost a factor two for the case of the triaxial superdeformed bands recently observed in the Hf and Lu nuclei. In our previous work, we have studied the wobbling band in Lu nuclei by using the microscopic framework of the cranked Nilsson mean-field and the random phase approximation, where the most serious problem is that the calculated B(E2) value is about factor two smaller. It is shown that the origin of this underestimation can be mainly attributed to the small triaxial deformation; if is used the same triaxial deformation as in the analysis of the particle-rotor model, the calculated B(E2) increases and gives correct magnitude compared with the experimental data.

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arXiv2006

Microscopic Description of Nuclear Wobbling Motion -- Rotation of traxially deformed nuclei --

The nuclear wobbling motion in the Lu region is studied by the microscopic cranked mean-field plus RPA method. The Woods-Saxon potential is used as a mean-field with a new parameterization which gives reliable description of rapidly rotating nuclei. The prescription of symmetry-preserving residual interaction makes the calculation of the RPA step parameter-free, and we find the wobbling-like RPA solution if the triaxial deformation of the mean-field is suitably chosen. It is shown that the calculated out-of-band $B(E2)$ of the wobbling-like solution depends on the triaxial deformation in the same way as in the macroscopic rotor model, and can be used to probe the triaxiality of the nuclear mean-field.

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