The nucleus 8He is the most neutron-rich nucleus known. Its structure, consisting of a 4He core surrounded by four neutrons makes it an ideal case to study phenomena in highly neutron-proton asymmetric systems and neutron correlations at the nuclear surface.
The effects of the valence neutrons were investigated experimentally using proton elastic and inelastic scattering of 8He at the IRIS facility at ISAC-II at TRIUMF at 8.25 A MeV. The two-neutron transfer from 8He was also measured to gain insight into pairing of the valence neutrons.
The presentation will give an overview of the IRIS reaction spectroscopy facility. It utilizes the novel solid H2 target in combination with a low-pressure ionization chamber to identify the incoming beam particles, and two Delta E-E telescopes to measure the reaction products.
Results of the data analysis will be presented featuring excited states in 8He from inelastic scattering. The elastic scattering cross section will be discussed in comparison to semi-microscopic optical potential calculations. A preliminary comparison of the cross sections for the population of the ground and first excited state in 6He from two-neutron transfer will be discussed as well.