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arXiv 0909.2092nucl-th
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锡同位素偶极和四极振动的耦合

Couplings between dipole and quadrupole vibrations in tin isotopes

Cédric Simenel, Philippe Chomaz

摘要:

在含时Hartree-Fock理论框架下,采用Skyrme能量密度泛函,研究了锡同位素中等矢巨偶极共振和等幅巨四极共振等集体振动之间的耦合.这些耦合是多声子谱中非谐性的一个来源。特别是,剩余的相互作用是已知的,以耦合的isovector巨偶极共振与isoscillator巨四极共振建立在它的顶部,诱导四极矩的非线性演化后的偶极升压。这种耦合也影响偶极运动的原子核的静态或动态变形所引起的四极约束或助推分别。提出了三种与这些不同表现形式的耦合相关联的方法来提取剩余相互作用的相应矩阵元素。不同方法对~(132)Sn的数值计算结果吻合较好。最后,几个锡同位素被认为是调查的作用,这种耦合的同位旋和质量数。一个简单的1/A的剩余矩阵元素的依赖性被发现没有明显的贡献,从同位旋。这一结果在Goldhaber-Teller模型中得到了解释。

英文摘要:

We study the couplings between collective vibrations such as the isovector giant dipole and isoscalar giant quadrupole resonances in tin isotopes in the framework of the time-dependent Hartree-Fock theory with a Skyrme energy density functional. These couplings are a source of anharmonicity in the multiphonon spectrum. In particular, the residual interaction is known to couple the isovector giant dipole resonance with the isoscalar giant quadrupole resonance built on top of it, inducing a nonlinear evolution of the quadrupole moment after a dipole boost. This coupling also affects the dipole motion in a nucleus with a static or dynamical deformation induced by a quadrupole constraint or boost respectively. Three methods associated with these different manifestations of the coupling are proposed to extract the corresponding matrix elements of the residual interaction. Numerical applications of the different methods to 132Sn are in good agreement with each other. Finally, several tin isotopes are considered to investigate the role of isospin and mass number on this coupling. A simple 1/A dependence of the residual matrix elements is found with no noticeable contribution from the isospin. This result is interpreted within the Goldhaber-Teller model.

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