Coulomb dissociation ofLi11

Kinematically complete measurements for Coulomb dissociation of ${}_{}{}^{11}{}_{}{}^{}\mathrm{Li}$ into ${}_{}{}^9{}_{}{}^{}\mathrm{Li}$+2n were made at 28 MeV/nucleon. The n-n correlation function suggests a large source size for the two-neutron emission. The electromagnetic excitation spectrum of ${}_{}{}^{11}{}_{}{}^{}\mathrm{Li}$ has a peak, as anticipated in low-energy dipole resonance models, but a large post-breakup Coulomb acceleration of the ${}_{}{}^9{}_{}{}^{}\mathrm{Li}$ fragment is observed, indicating a very short lifetime of the excited state and favoring direct breakup as the dissociation mechanism.