Fragmentation and systematics of the Pygmy Dipole Resonance in the stable N=82 isotones
Fragmentation and systematics of the Pygmy Dipole Resonance in the stable N=82 isotones
复制标题
稳定 N=82 等位素中俾格米偶极子共振的碎裂和系统学
DOI：
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发表时间：
2011
期刊：
影响因子：
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通讯作者：
A. Zilges
中科院分区：
文献类型：
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作者：
D. Savran;M. Elvers;J. Endres;M. Fritzsche;B. Loher;N. Pietralla;V. Ponomarev;C. Romig;L. Schnorrenberger;K. Sonnabend;A. Zilges
测量了半像核Xe中低激发态电偶极子(e1$)的强度，完成了利用入射通道中的真实光子进行核共振荧光方法研究所有稳定偶极子中的侏儒偶极子共振(PDR)的系统测量.在所有情况下，在5-8 MeV能区都观察到强度为$e1$的碎裂类共振态结构。对碎裂强度的分析表明，对于缺质子的同位素，碎裂程度减小，而总的综合强度增加，表明总强度与中质子比有关。将实验结果与准粒子声子模型下的微观计算结果进行了比较。计算包括多达三个声子的复杂组态，并能够再现$e1$强度的碎裂，这使我们能够得出关于PDR衰减的结论。如果考虑到实验的灵敏度极限，计算结果与实验数据在碎裂程度和综合强度上是很好地吻合的。
The low-lying electric dipole ($E1$) strength in the semimagic nucleus ${}^{136}$Xe has been measured, which finalizes the systematic survey to investigate the so-called pygmy dipole resonance (PDR) in all stable even $N=82$ isotones with the method of nuclear resonance fluorescence using real photons in the entrance channel. In all cases, a fragmented resonance-like structure of $E1$ strength is observed in the energy region 5--8 MeV. An analysis of the fragmentation of the strength reveals that the degree of fragmentation decreases toward the proton-deficient isotones, while the total integrated strength increases, indicating a dependence of the total strength on the neutron-to-proton ratio. The experimental results are compared to microscopic calculations within the quasiparticle phonon model. The calculation includes complex configurations of up to three phonons and is able to reproduce also the fragmentation of the $E1$ strength, which allows us to draw conclusions on the damping of the PDR. Calculations and experimental data are in good agreement on the degree of fragmentation and also on the integrated strength if the sensitivity limit of the experiments is taken into account.