Author/Authors :
K. Markenroth، نويسنده , , M. Meister، نويسنده , , B. Eberlein، نويسنده , , D. Aleksandrov، نويسنده , , T. Aumann، نويسنده , , L. Axelsson، نويسنده , , T. Baumann، نويسنده , , M.J.G. Borge، نويسنده , , L.V. Chulkov، نويسنده , , W. Dostal، نويسنده , , Th.W. Elze، نويسنده , , H. Emling، نويسنده , , H. Geissel، نويسنده , , A. Grünschlo?، نويسنده , , M. Hellstrom، نويسنده , , J. Holeczek، نويسنده , , B. Jonson، نويسنده , , J.V. Kratz، نويسنده , , R. Kulessa، نويسنده , , A. Leistenschneider، نويسنده , , et al.، نويسنده ,
Abstract :
Dissociation of 227 MeV/u 8He in a carbon target has been studied in kinematically complete experiments. The data include the relative energy spectrum, angular distributions in the neutron knock-out channel (6He+n) as well as diffractive dissociation and inelastic scattering into the (6He+2n) channel. The data are compared with corresponding results from the well-known halo nucleus 6He. In both cases it is found that neutron knock-out is the dominating reaction channel. The relative energy spectrum (6He+n) shows a structure, which is interpreted as being due to the Iπ=3/2− resonance in the 7He ground state with about equal contribution from its Iπ=1/2− spin–orbit partner.
The 7He resonance shows a spin alignment similar to that observed in 5He, but with a smaller anisotropy indicating that the structure of the 8He ground state is more complicated than that of 6He.
The data in the (6He+2n) channel were used to identify resonances in the excitation energy spectrum of 8He. If the spectrum is interpreted as two overlapping resonances, the spin-parity assignment for these is found to be 2+ and 1−, respectively.
