Giant Quadrupole Resonances in 208Pb, the nuclear symmetry energy and the neutron skin thickness
Giant Quadrupole Resonances in 208Pb, the nuclear symmetry energy and the neutron skin thickness
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DOI：
10.1103/physrevc.87.034301
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发表时间：
2012-12
影响因子：
3.1
通讯作者：
X. Roca-Maza;M. Brenna;B. K. Agrawal;P. Bortignon;G. Colò;Ligang Cao;N. Paar;D. Vretenar
中科院分区：
文献类型：
--
作者：
X. Roca-Maza;M. Brenna;B. K. Agrawal;P. Bortignon;G. Colò;Ligang Cao;N. Paar;D. Vretenar
最近在等矢量巨四极共振 (IVGQR) 特性的实验测定方面取得了进展，如 A=208 质量区域所示，可能有助于表征有效核相互作用的等矢量通道。我们使用宏观和微观方法分析 208Pb 中 IVGQR 的特性。微观方法基于非相对论和协变能量密度泛函 (EDF) 系列，其特征是相应核物质状态方程的等标量和等矢量属性的系统变化。宏观方法产生了某些次饱和密度下的核对称能（例如 S(ρ=0.1 fm−3)）或重核的中子皮厚度 Δrnp 对等标量和等矢量 GQR 的激发能的明确依赖性。使用可用数据发现S(ρ=0.1 fm−3)=23.3±0.6 MeV。通过微观框架获得的结果证实了 Δrnp 与等标量和等矢量 GQR 能量的相关性，正如宏观模型所预测的那样。通过利用这种相关性以及等标量和等矢量 GQR 能量的实验值，我们估计 208Pb 的 Δrnp=0.14±0.03 fm，以及对称能量的斜率参数：L=37±18 MeV。
Recent improvements in the experimental determination of properties of the isovector giant quadrupole resonance (IVGQR), as demonstrated in the A=208 mass region, may be instrumental for characterizing the isovector channel of the effective nuclear interaction. We analyze properties of the IVGQR in 208Pb, using both macroscopic and microscopic approaches. The microscopic method is based on families of nonrelativistic and covariant energy density functionals (EDF), characterized by a systematic variation of isoscalar and isovector properties of the corresponding nuclear matter equations of state. The macroscopic approach yields an explicit dependence of the nuclear symmetry energy at some subsaturation density, for instance S(ρ=0.1 fm−3), or the neutron skin thickness Δrnp of a heavy nucleus, on the excitation energies of isoscalar and isovector GQRs. Using available data it is found that S(ρ=0.1 fm−3)=23.3±0.6 MeV. Results obtained with the microscopic framework confirm the correlation of the Δrnp to the isoscalar and isovector GQR energies, as predicted by the macroscopic model. By exploiting this correlation together with the experimental values for the isoscalar and isovector GQR energies, we estimate Δrnp=0.14±0.03 fm for 208Pb, and the slope parameter of the symmetry energy: L=37±18 MeV.