RIKEN Nishina Center, Wako
BNL, Upton, Long Island, New York
RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama
Electron stripping process from heavy ion in material is a useful tool in accelerator complex to give higher charge state of the ion, allowing its effective acceleration. This process is competed with electron capture process and reach to the equilibrium charge state. Carbon foils is convenient for charge stripper but have short lifetime due to thermal stress and sputtering. Gas is basically free from lifetime but gives lower charge state due to density effect. Therefore, charge stripper especially for uranium beams at 10-20 MeV/u will be a bottle-neck problem in high power heavy ion facility such as RIBF, FRIB and FAIR. Electron stripping and capture cross section of uranium ion beams in helium gas were measured as a function of their charge state at 11, 14 and 15 MeV/u with expectation that low-Z gas (H2 and He) would provide a better stripping media than nitrogen with a higher charge state. We will show the promising results with discussion about plasma confinement of low-Z gas.
