Coulomb dipole strength distribution of neutron-rich carbon isotopes

We investigate the Coulomb dipole excitation (CDE) of neutron-rich carbon isotopes, focusing on ¹⁵ C and 19C, which consist of a core nucleus and one valence neutron. The Coulomb dipole strength distribution dB ( E 1)/ dE _x is extracted from experimental Coulomb dissociation cross sections using both general and relativistic calculations of virtual photon numbers. Despite similar beam energies, the dissociation cross section of ¹⁹ C is significantly larger than that of ¹⁵ C, reflecting their difference in neutron separation energy. We also compute theoretical strength distributions using a simple model involving the spectroscopic factor S and the potential radius r ₀ , achieving good agreement with the experimental data. The extracted parameters ( S, r ₀ ) are reasonable within physical expectations. This study confirms the importance of low neutron separation energy in enhancing Coulomb breakup reaction and provides a useful framework for understanding dipole excitation mechanisms in weakly bound neutron-rich nuclei. PACS numbers: 24.10.-i, 25.70.Jj