Breakup of exotic nuclei and correlations of halo neutrons

We show that cross sections for nuclear fragmentation and Coulomb dissociation depend essentially on the correlation between halo neutrons, and thus the experimental data for the given processes may serve as a source of information on this correlation. The recently obtained data on the Coulomb dissociation of ⁶He, when combined with the data on the proton elastic scattering, have allowed us to conclude that the motion of the halo neutrons in ⁶He is significantly correlated, the size of the dineutron cluster, in particular, being 2.0±0.5 fm.