Study of the break-up channel in 11Li+208Pb collisions at energies around the Coulomb barrier

Description

We present a study of 11Li+208 Pb collisions at energies around the Coulomb barrier (Elab = 24.3 and 29.8 MeV), measured at the post-accelerated beam facility, ISAC II, at TRIUMF (Vancouver, Canada). A remarkably large yield of 9Li has been observed, a result that is attributed to the weak binding of the 11Li nucleus. The angular distribution of this 9Li yield, relative to the elastic one, has been analysed in terms of first-order semiclassical calculations as well as four-body and three-body Continuum-Discretized Coupled-Channels (CDCC) calculations, based on a three-body and di-neutron model of the 11Li nucleus, respectively. The calculations reproduce well the trend of the data and support the existence of a large concentration of B (E1) strength at very low excitation energies. The connection of this large B (E1) with a possible low-lying dipole resonance is discussed.

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