Abstract. The experimental study of the fusion of light neutron-rich nucleus 8 He with 206 Pb is reported in this work. A fusion stack of 206 Pb targets has been used for this study. The most prominent evaporation residue ( 210 Po), which has half-life of 138 days and decays by alpha emission, is populated in the reaction. Radiochemical analysis technique is used to extract the yield of this evaporation residue.

Dramatic differences in the elastic scattering of the neutron rich nuclei 6 He and 8 He are found when new high quality data for the 8 He + 208 Pb system are compared with previously published 6 He + 208 Pb data at the same laboratory frame incident energy. The new 8 He data are of the same level of detail as for stable beams. When comparing them with those previously obtained for 6 He + 208 Pb at the same energy, it is possible to determine from the data alone that 6 He has a much longer range absorption than 8 He. However, both nuclei show significant absorption beyond their strong absorption radii. While it has been known for a long time that elastic scattering at energies around the barrier only determines the optical potential over a small distance in radial space, typically ±0.5 fm or so, both the 6 He and the 8 He imaginary potentials obtained from various optical model fits to these data are the same over a much wider range of ±1.5 fm.

No abstract

The dynamics of 8 He around the Coulomb barrier is investigated by measuring the energy and angular distribution of the elastic 8 He and the 6 He and 4 He fragment yields in the collision process with a 208 Pb target. The experiment was carried out at SPIRAL/GANIL in October 2010. The experimental results will provide information about the relevant reaction mechanisms and the validity of the optical model (OM) when applied to exotic nuclei. In this paper, details of the experimental setup and preliminary results on the elastic scattering for the collision at 22 MeV are presented.

The structure and dynamics of 8 He have been studied through the collision process with a 208 Pb target at energies of 22 and 16 MeV, above and below the Coulomb barrier, respectively. The energy and angular distributions of the elastically scattered 8 He and the 6,4 He fragments were measured. In this paper, we discuss the method used to determine the effective position of the beam spot on the reaction target and the scattering and solid angles of each pixel of the detector array.