Observation of isoscalar and isovector dipole excitations in neutroni-rich 20O
Observation of isoscalar and isovector dipole excitations in neutroni-rich 20O
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富中子 20O 中等标量和等矢量偶极子激发的观察
DOI：
10.1016/j.physletb.2017.03.017
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发表时间：
2017
影响因子：
4.4
通讯作者：
Y. Togano et al.
中科院分区：
文献类型：
--
作者：
N. Nakatsuka;H. Baba,Y. Kondo;T. Nakamura;Y. Togano et al.
首次研究了富中子不稳定核 20 O 中低能偶极子激发的同位旋特征。通过畸变波玻恩近似对从主等矢量探针（O 20+ Au）和主等标量探针（O 20+ α）获得的两个光谱进行比较和分析，以独立提取等矢量和等标量偶极子强度。等标量探针还激发了两个已知的 1− 态，其能量分别为 5.36 (5) MeV (1 1−) 和 6.84 (7) MeV (1 2−)，具有较大的等矢量偶极子强度。在穷尽等标量偶极子能量加权和规则时，发现这两种状态具有不同的等标量偶极子强度，分别为 2.70 (32)%(1 1−) 和 0.67 (12)%(1 2−)。等标量强度的差异表明它们具有不同的基础结构。
The isospin characters of low-energy dipole excitations in neutron-rich unstable nucleus 20 O were investigated, for the first time in unstable nuclei. Two spectra obtained from a dominant isovector probe (O 20+ Au) and a dominant isoscalar probe (O 20+ α) were compared and analyzed by the distorted-wave Born approximation to extract independently the isovector and isoscalar dipole strengths. Two known 1− states with large isovector dipole strengths at energies of 5.36 (5) MeV (1 1−) and 6.84 (7) MeV (1 2−) were also excited by the isoscalar probe. These two states were found to have different isoscalar dipole strengths, 2.70 (32)%(1 1−) and 0.67 (12)%(1 2−), respectively, in exhaustion of the isoscalar dipole-energy-weighted sum rule. The difference in isoscalar strength indicated that they have different underlying structures.