Microscopic study of triaxial deformation and non-principal-axis rotation in rapidly rotating nuclei

快速旋转核中三轴变形和非主轴旋转的微观研究

• 批准号: 14540269
• 负责人: SHIMIZU Yoshihumi
• 金额: $ 1.47万
• 依托单位: KYUSHU UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2002
• 资助国家: 日本
• 起止时间: 2002 至 2003
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-14540269/
• 关键词: rapidly rotating nuclei; triaxil deformation; cranking model; tilted axis cranking; wobbling motion; chiral rotational band; quadrupole Pairing correlation

Recent experimental data suggest that an interesting phenomenon of the triaxial deformation, in which all three lengths of principal axes of the nuclear mean-field are different from each other, appears near the yrast states. In this resarch, with this triaxial deformation as a keyword, we shed new light on mechanism of the appearance of new non-principal-axis rotations, which is a consequence of triaxiality and leads to a tilting of rotation-axis with respect to the deformation axes.In these two year's of research, we have accomplished several important achievements, but still there are some parts which remains to be finished. Especially, the subject to solve the quantum mechanical equation with respect to the collective degrees of freedom for the tilting angles has not been accomplished. In the following, the physical results obtained are summarized.1)The strongly-coupled rotational one-quasiparticle bands, based on the orbits with the high-angular momentum component with respect to the symmetry axis, has been investigated in terms of the tilted axis cranking method. It is found that the problem of underestimating the angular frequency of starting tilting point is nicely sovled by including the quadrupole residual interaction, especially its K=1 component.2)The recently observed wobbling rotational band excited on the triaxial superdeformated band in Hf, Lu nuclei has been studied by using the random-phase-approximation. If assuming the positive-gamma triaxial deformation, one cannot expect the wobbling motion because of the irrotational behavior of three moments of inertia. It is, however; clarified that the quasiparticle alignment, inherent in the microscopic random-phase-approximation calculation, changes the ratio of three moments of inertia from their irrotational behavior, and then the wobbling motion became possible to exist.

最近的实验数据表明，核平均场主轴的三个长度都不相同的三轴变形现象出现在热态附近。在本研究中，以这种三轴变形为关键词，我们揭示了新的非主轴旋转出现的机理，这种非主轴旋转是三轴性的结果，导致旋转轴相对于变形轴倾斜。在这两年的研究中，我们取得了一些重要的成果，但仍有一些有待完成的部分。特别是，关于倾斜角的集体自由度的量子力学方程的求解问题尚未完成。下面对得到的物理结果进行总结。1)利用倾斜轴曲柄方法研究了基于相对于对称轴具有高角动量分量的轨道的强耦合旋转准粒子带。结果表明，通过引入四极子残余相互作用，特别是其K=1分量，可以很好地解决起倾点角频率低估的问题。2)用随机相位近似法研究了最近观测到的Hf， Lu原子核三轴超变形带上的摆动旋转带。如果假定为正三轴变形，由于三个转动惯量的不旋转行为，就不能期望有摆动运动。然而，它是；阐明了微观随机相位近似计算中固有的准粒子排列改变了它们的无旋转行为的三个转动惯量之比，从而使摆动运动成为可能。

项目成果

Y.R.Shimizu, et al.: "Nuclear Moments of Inertia and Wobbling Motions in Triaxial Superdeformed Nuclei"Physical Review C. (in press). (2004)

Y.R.Shimizu 等人：“三轴超变形核中的核惯性矩和摆动运动”物理评论 C.（出版中）。

T.Shizuma, Y.R.Shimizu, T.Hayakawa: "Tunneling in High-K Isomeric Decays"Journal of Nuclear Science and Technology. Vol.39, No.11. 1137-1141 (2002)

T.Shizuma、Y.R.Shimizu、T.Hayakawa：“高 K 异构体衰变中的隧道效应”核科学与技术杂志。

M.Matuzaki, Y.R.Shimizu, K.Matsuyanagi: "Wobbling Motion in Atomic Nuclei with Positive-Gamma Shapes"Physical Review. Vol.C65, Issue 4. 041303(R)-1-041303(R)-4 (2002)

M.Matuzaki、Y.R.Shimizu、K.Matsuyanagi：“正伽马形状原子核中的摆动运动”物理评论。

S.-I.Ohtsubo, Y.R.Shimizu: "Calculation of Strongly-Coupled Rotational Bands in Terms of the Tilted Axis Cranking Model"Nuclear Physics. Vol.A714, No.1-2. 44-62 (2003)

S.-I.Ohtsubo，Y.R.Shimizu：“根据倾斜轴曲柄模型计算强耦合旋转带”核物理。

S.Yasumoto, Y.R.Shimizu, K.Takada: "A Comment on the New Formulation of a Many-Level Shell Model"Progress of Theoretical Physics. Vol.110, No.5. 1037-1041 (2003)

S.Yasumoto、Y.R.Shimizu、K.Takada：“对多级壳模型新公式的评论”理论物理进展。