Suppression of Coulomb-nuclear interference in the near-barrier elastic scattering of 17Ne from 208Pb

The proton drip-line nucleus 17Ne is considered a good candidate for a Borromean two-proton halo with a 15O + p + p structure. Angular distributions of the elastic scattering and inclusive 15O production for a 136 MeV 17Ne beam incident on a 208Pb target were measured for the first time at the SPIRAL1 facility, GANIL. Use of the GLORIA detector array allowed high-resolution data over a wide angular range from 20∘ up to 95∘ in the laboratory frame to be obtained. The elastic scattering angular distribution shows similarities with those for both 6He and 20Ne at equivalent collision energies with respect to the corresponding Coulomb barriers, exhibiting the suppression of the Coulomb rainbow peak characteristic of strong coupling. Optical model and coupled channel fits suggest that this is due to a combination of coupling to low-lying quadrupole resonances and Coulomb dipole coupling to the low-lying continuum, although their relative importance depends on the relevant B(E2) values which remain to be firmly determined.