Isospin dependence of ⁶He+p optical potential and the symmetry energy

A consistent folding analysis of the elastic p(⁶He,⁶He)p scattering and charge exchange p(⁶He,⁶Li^*)n reaction data measured at E_lab=41.6A MeV has been performed within the coupled channels formalism. We have used the isovector coupling to link the isospin dependence of ⁶He+p optical potential to the cross section of p(⁶He,⁶Li^*)n reaction exciting the 0⁺ isobaric analog state (IAS) at 3.563 MeV in ⁶Li. Based on these results and the Hartree-Fock calculation of asymmetric nuclear matter using the same isospin-dependent effective nucleon-nucleon interaction, we were able to confirm that the most realistic value of the symmetry energy E_sym is around 31 MeV. Our analysis has also shown that the measured charge exchange p(⁶He,⁶Li^*)n data are quite sensitive to the halo tail of the ⁶He density used in the folding calculation and the IAS of ⁶Li is likely to have a halo structure similar to that established for the ground state of ⁶He.