Fine structure of the isovector giant dipole resonance in Pb 208: Characteristic scales and level densities
Fine structure of the isovector giant dipole resonance in Pb 208: Characteristic scales and level densities
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DOI：
10.1103/physrevc.89.054322
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发表时间：
2014-03
影响因子：
3.1
通讯作者：
I. Poltoratska;R. Fearick;A. Krumbholz;E. Litvinova;H. Matsubara;P. Neumann-Cosel;V. Ponomarev;A. Richter;A. R. I. F. Kernphysik;Technische Universitat Darmstadt;H Germany;D. Physics;U. C. Town;S. Africa;Western Michigan University;Usa;National Superconducting Cyclotron Laboratory;M. University;R. I. F. Physics;O. University;Japan.;N. U. O. Sciences
中科院分区：
文献类型：
--
作者：
I. Poltoratska;R. Fearick;A. Krumbholz;E. Litvinova;H. Matsubara;P. Neumann-Cosel;V. Ponomarev;A. Richter;A. R. I. F. Kernphysik;Technische Universitat Darmstadt;H Germany;D. Physics;U. C. Town;S. Africa;Western Michigan University;Usa;National Superconducting Cyclotron Laboratory;M. University;R. I. F. Physics;O. University;Japan.;N. U. O. Sciences
的状态是有关的局部波动的横截面的能量区域的IVGDR，其中可以忽略不计的贡献与其他自旋宇称的状态。波动的幅度由自相关函数确定。结果：在80、130、220、430、640、960 keV和1.75 MeV处发现了208 Pb中IVGDR精细结构的尺度。最突出的尺度的值可以合理地很好地再现微观计算，虽然他们通常产生一个较小的规模。计算中包含复杂的配置改变了E1强度分布，但对小波功率谱和特征尺度的影响是有限的。在激发能量范围9 - 12.5 MeV内提取1 −态的能级密度，并与各种唯象和微观模型进行比较。结论：在这两个模型中，主要尺度都已经存在于单粒子单孔水平，这表明朗道阻尼是IVGDR精细结构的主导机制，而不是等尺度的Argiantquadrupole共振，后者的精细结构是从耦合到低表面振动中产生的。Rauscher等人的后移费米气体模型参数化，Phys.Rev.C56，1613（1997）很好地描述了能级密度数据，而其他唯象和微观方法不能再现绝对值或能量依赖性或两者。
states is related to local fluctuations of the cross sections in the energy region of the IVGDR, where contributions from states with other spin parities can be neglected. The magnitude of the fluctuations is determined by the autocorrelation function. Results: Scales in the fine structure of the IVGDR in 208 Pb are found at 80, 130, 220, 430, 640, and 960 keV, and at 1.75 MeV. The values of the most prominent scales can be reasonably well reproduced by the microscopic calculations although they generally yield a smaller number of scales. The inclusion of complex configurations in the calculations changes the E1 strength distributions but the impact on the wavelet power spectra and characteristic scales is limited. The level density of 1 − states is extracted in the excitation energy range 9‐12.5 MeV and compared to a variety of phenomenological and microscopic models. Conclusions: In both models the major scales are already present at the one-particle one-hole level indicating Landau damping as a dominant mechanism responsible for the fine structure of the IVGDR in contrast to the isoscalargiantquadrupoleresonance,wherefinestructurearisesfromthecouplingtolow-lyingsurfacevibrations. The back-shifted Fermi gas model parametrization of Rauscher et al., Phys. Rev. C 56, 1613 (1997) describes the level-density data well, while other phenomenological and microscopic approaches fail to reproduce absolute values or the energy dependence or both.