~(19)C in halo EFT: Effective-range parameters from Coulomb dissociation experiments

摘要

We study the Coulomb dissociation of the ~(19)C nucleus in an effective field theory that uses the ~(18)C core and the neutron as effective degrees of freedom and exploits the separation of scales in this halo system. We extract the effective-range parameters and the separation energy of the halo neutron from the experimental data reported in Refs. [31,35], taken at RIKEN by Nakamura et al. (1999, 2003). We obtain a value of (575 ± 55(stat) ± 20(EFT))keV for the one-neutron separation energy of ~(19)C, and (7.75 ± 0.35(stat) ± 0.3(EFT))fm for the ~(18)C-neutron scattering length. The width of the longitudinal momentum distribution predicted by EFT using this separation energy agrees well with the experimental data taken at NSCL by Bazin et al. (1998) [9], reaffirming the dominance of the s-wave configuration of the valence neutron.