Direct Evidence of Octupole Deformation in Neutron-Rich ^{144}Ba.
Direct Evidence of Octupole Deformation in Neutron-Rich ^{144}Ba.
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DOI：
10.1103/physrevlett.116.112503
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发表时间：
2016-02
影响因子：
8.6
通讯作者：
B. Bucher;S. Zhu;C. Wu;R. Janssens;D. Cline;A. Hayes;M. Albers;A. D. Ayangeakaa;P. Butler-P.-Butle
中科院分区：
文献类型：
--
作者：
B. Bucher;S. Zhu;C. Wu;R. Janssens;D. Cline;A. Hayes;M. Albers;A. D. Ayangeakaa;P. Butler-P.-Butle
丰中子核^{144}Ba（t_{1/2}=11.5 s）在质量数A小于200的核中表现出最强的八极关联。到目前为止，这种强相关性的间接证据已经从增强的E1跃迁和基态带中交错的正负宇称能级等观测中推断出来。在这个实验中，八极强度是通过在1.0 mg/cm^{2} ^{208}Pb靶上对加速后的650 MeV ^{144}Ba束进行亚势垒、多步库仑激发直接测量的。矩阵元素的测量值，<$3_{1}^{-}<$M（E3）<$0_{1}^{+}<$=0.65（+17/-23）eb^{3/2}，对应于48（+25/-34）W. u的降低的B（E3）跃迁概率。这一结果代表了一个明确的确定八极集体，是大于任何可用的理论预测，并与八极形变是一致的。
The neutron-rich nucleus ^{144}Ba (t_{1/2}=11.5 s) is expected to exhibit some of the strongest octupole correlations among nuclei with mass numbers A less than 200. Until now, indirect evidence for such strong correlations has been inferred from observations such as enhanced E1 transitions and interleaving positive- and negative-parity levels in the ground-state band. In this experiment, the octupole strength was measured directly by sub-barrier, multistep Coulomb excitation of a post-accelerated 650-MeV ^{144}Ba beam on a 1.0-mg/cm^{2} ^{208}Pb target. The measured value of the matrix element, ⟨3_{1}^{-}∥M(E3)∥0_{1}^{+}⟩=0.65(+17/-23) eb^{3/2}, corresponds to a reduced B(E3) transition probability of 48(+25/-34) W.u. This result represents an unambiguous determination of the octupole collectivity, is larger than any available theoretical prediction, and is consistent with octupole deformation.