Coulomb dissociation of halo nuclei

Coulomb dissociation of one neutron halo nuclei ¹¹Be and ^15,19C has been studied at energies around 70A MeV by kinematically complete measurements of breakup particles at RIKEN. The experiment of ¹¹Be breakup on a Pb target aims at studying the characteristic features of low-lying E1 strength. In particular the effects of higher order excitation and nuclear contribution have been closely studied by using the impact parameter analysis. We have found that these contributions are very small, and the selection of the large impact parameter is useful to extract the spectroscopic information of the halo ground state. We have then successfully applied this analysis method to ¹⁵C and ¹⁹C, where we have extracted the spectroscopic factor for the s-wave halo configuration. We also show preliminary results on the breakup of ¹¹Be on a carbon target in order to study the nuclear breakup mechanism and low-lying discrete states of the halo nucleus.