Evidence for a neutron skin in "2"0N

Nuclear interaction and charge-changing cross sections were measured for 950.A MeV "2"0N, "2"0O, "2"0F, "2"0Ne, "2"0Na and "2"0Mg beams incident on a carbon target. The experimental results are compared to other data, in particular to those obtained for stable nuclei. Root mean square nuclear matter radii and upper limits of root mean square proton radii are derived from the experimental data. Evidence is presented for the existence of a neutron skin in "2"0N. (orig.)Available from FIZ Karlsruhe / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Invariant mass spectrum and #alpha# - n correlation function studied in the fragmentation of "6He on a carbon target

Momentum distributions and invariant mass spectra from the breakup of "6He ions with an energy of 250 MeV/u interacting with a carbon target have been studied. The data were used to extract information about the reaction mechanism which is influenced by the structure of "6He. It is found that the dominant reaction mechanism is a two-step process: knock out of one neutron followed by the decay of the "5He resonance. The shape of the (#alpha#+n) two-body invariant mass spectrum is interpreted as mainly reflecting the "5He ground state which is a J "#pi# =3/2"- resonance. However, no evidence for correlations between #alpha# particles and neutrons is observed in the momentum widths of the distributions. It is demonstrated that a combined analysis of the two-body invariant mass spectrum and an appropriate correlation function may be used to determine the properties of the intermediate resonance. (orig.)Available from TIB Hannover: RO 801(97-61) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Large spin alignment of the unbound "5He fragment after fragmentation of 240 MeV/u"6He

Peripheral fragmentation of a 240 MeV/u beam of the halo nucleus "6He incident on carbon target has been studied in a kinematically complete experiment. It is found that one-neutron stripping to the unbound nucleus "5He is the dominant fragmentation mechanism and that it leads to a spin alignment of "5He in a plane perpendicular to the "5He momentum vector. This is expected to be a common feature for all neutron halo nuclei. (orig.)Available from FIZ Karlsruhe / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman