Possibility of enlarged core structure of N=15 neutron-rich nuclei

The recently measured interaction cross section data for 22N, 23O, and 24F in a 12C target at relativistic energies have been analysed in a few body Glauber model approach. Conventional fixed core-plus-neutron model for halo nuclei is unable to explain the observed enhanced cross section for these nuclei by any selection of the neutron orbitals. Microscopic calculations like many-body Monte Carlo shell model, relativistic mean field theory and cluster model are also shown to fail in describing the large difference if interaction cross section between 22O and 23O. A possibility of core enlargement is suggested in these nuclei.