Isoscalar dipole transition as a probe for asymmetric clustering
Isoscalar dipole transition as a probe for asymmetric clustering
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DOI：
10.1103/physrevc.93.034319
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发表时间：
2015-12
影响因子：
3.1
通讯作者：
Y. Chiba;M. Kimura;Y. Taniguchi
中科院分区：
文献类型：
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作者：
Y. Chiba;M. Kimura;Y. Taniguchi
背景资料：在许多轻核中，在相对较小的激发能量下，可以观察到尖锐的1−共振和增强的等腰偶极跃迁强度，但它们的性质还不清楚。目的：我们发现这些共振可以归因于具有非对称构型的团簇态，如α+ O 16。我们解释了为什么不对称团簇态被等标偶极跃迁强烈激发。我们还提供了一个理论预测的Isoscillate偶极跃迁在Ne 20和Ti 44。方法：通过解析推导传递矩阵，阐明激发机制。利用Brink-Bloch波函数和反对称化分子动力学的核模型计算结果对Ne 20和Ti 44进行了理论预测。结果表明，即使基态是理想的壳模型态，跃迁矩阵也与Weisskopf估计一样大。此外，如果基态具有团簇关联，则它会被显著放大。核模型的计算结果表明，α+ O 16和α+ Ca 40团簇态的跃迁矩阵较大，与Weisskopf估计值相当或更大。结论：我们认为非对称团簇态是由等密度偶极跃迁激发的。与填充0+团簇态的等密度跃迁相结合，等密度跃迁是非对称团簇的有前途的探针。
Background: The sharp 1− resonances with enhanced isoscalar dipole transition strengths are observed in many light nuclei at relatively small excitation energies, but their nature has been unclear. Purpose: We show those resonances can be attributed to the cluster states with asymmetric configurations such as α+O16. We explain why asymmetric cluster states are strongly excited by the isoscalar dipole transition. We also provide a theoretical prediction of the isoscalar dipole transitions in Ne20 and Ti44. Method: The transition matrix is analytically derived to clarify the excitation mechanism. The nuclear model calculations by Brink–Bloch wave function and antisymmetrized molecular dynamics are also performed to provide a theoretical prediction for Ne20 and Ti44. Results: It is shown that the transition matrix is as large as the Weisskopf estimate even though the ground state is an ideal shell-model state. Furthermore, it is considerably amplified if the ground state has cluster correlation. The nuclear model calculations predict large transition matrix to the α+O16 and α+Ca40 cluster states comparable with or larger than the Weisskopf estimate. Conclusions: We conclude that the asymmetric cluster states are strongly excited by the isoscalar dipole transition. Combined with the isoscalar monopole transition that populates the 0+ cluster states, the isoscalar transitions are promising probes for asymmetric clusters.