Halo Effects in the Low-energy Scattering of 15 C with Heavy Targets

The neutron-rich carbon isotope 15C was postulated to be a halo nucleus (Sn = 1215 keV, S2n = 9395 keV) according to different high-energy experiments. If so, it would be the only halo nucleus exhibiting a “pure” s-wave structure of the ground state. At low collision energies, the effect of this halo structure should manifest as a strong absorption pattern in the angular distribution of the elastic cross section, with a total suppression of the nuclear rainbow due to the large neutron transfer and breakup probabilities, enhanced by the halo configuration. The IS619 experiment, carried out at the HIE-ISOLDE facility at CERN (Switzerland), is the first dynamical study of this nucleus at energies around the Coulomb barrier. It aims to probe the halo structure via the measurement of the elastic cross section on a high-Z 208Pb target. Preliminary results of the elastic cross section are discussed and compared to Optical Model calculations.Martel and O. Tengblad, as spokespersons, are grateful to the IS619 Collaboration and to the HIE-ISOLDE team for delivering the radioactive beam. J.D. Ovejas is grateful to AEI/FEDER/EU for the Ph.D. fellowship BES2016-077059. Work partially supported by the Spanish research grants FPA2015-64969-P, FPA2017-87568-P (both AEI/FEDER/EU), PGC 2018- 095640-B-I00 and ENSAR2 from EU H2020 under contract number 65400