A new experimental approach to investigate intermediate-energy proton elastic scattering and breakup reactions on exotic nuclei in inverse kinematics

摘要

We report on a new experimental setup for the investigation of proton induced reactions on exotic nuclei in inverse kinematics. It was installed and successfully used in the scattering study of intermediate-energy protons (-~ 700 MeV/u) on neutron-rich nuclei ~(G,8)He produced with the FRagment Separator (FRS) at the GS1 facility, Darmstadt. A new pure liquid-hydrogen target was successfully adapted allowing to obtain low-background data as compared to commonly used (CH_2),, targets. Absolute differential cross-sections for elastic (p,~(G.8)He) scattering were obtained at angles corresponding to 0.05≤|t|≤0.125 (GeV/c)~2 of the four-momentum transfer squared (-t) leading to the first diffraction minimum and spanning more than two orders of magnitude. They complement an earlier measurement at smaller angles 0.0025 ≤|t|≤0.05 (GeV/c)~2 performed at the same energy with an active target. Both data sets agree well in the overlap region t« 0.05 (GeV/c)~2 and enable a refined and comparative study of the radial distribution of the nuclear matter density.