An exclusive measurement has been made of the Coulomb dissociation of the two-neutron halo nucleus Li11 at 70MeV/nucleon at RIKEN. Strong low-energy (soft) E1 excitation is observed, peaked at about Ex=0.6MeV with B(E1)=1.42(18)e2fm2 for Erel≤3MeV, which was largely missed in previous measurements. This excitation represents the strongest E1 transition ever observed at such low excitation energies. The spectrum is reproduced well by a three-body model with a strong two-neutron correlation, which is further supported by the E1 non-energy-weighted cluster sum rule.
ASJC Scopus subject areas
- Physics and Astronomy(all)