Instituto de Estructura de la Materia CSIC, E28006 Madrid, Spain.
Phys Rev Lett. 2012 Dec 28;109(26):262701. doi: 10.1103/PhysRevLett.109.262701. Epub 2012 Dec 26.
The first measurement of the elastic scattering of the halo nucleus 11Li and its core 9Li on 208Pb at energies near the Coulomb barrier is presented. The 11Li+208Pb elastic scattering shows a strong reduction with respect to the Rutherford cross section, even at energies well below the barrier and down to very small scattering angles. This drastic change of the elastic differential cross section observed in 11Li+208Pb is the consequence of the halo structure of 11Li, as it is not observed in the elastic scattering of its core 9Li at the same energies. Four-body continuum-discretized coupled-channels calculations, based on a three-body model of the 11Li projectile, are found to explain the measured angular distributions and confirm that the observed reduction is mainly due to the strong Coulomb coupling to the dipole states in the low-lying continuum of 11Li. These calculations suggest the presence of a low-lying dipole resonance in 11Li close to the breakup threshold.
首次测量了在接近库仑位垒的能量下，晕核 11Li 及其核 9Li 对 208Pb 的弹性散射。11Li+208Pb 的弹性散射相对于卢瑟福截面表现出强烈的减少，即使在能量远低于位垒的情况下，甚至在非常小的散射角度下也是如此。在 11Li+208Pb 中观察到的弹性微分截面的这种剧烈变化是 11Li 晕结构的结果，因为在相同能量下，其核 9Li 的弹性散射中没有观察到这种变化。基于 11Li 射弹的三体模型的四体连续离散耦合通道计算被发现可以解释所测量的角分布，并证实观察到的减少主要归因于与 11Li 低能连续体中的偶极态的强库仑耦合。这些计算表明，在接近分裂阈值的位置，11Li 中存在一个低能偶极共振。
