Angular resolved energy gain spectroscopy to study double electron-captureprocesses in very slow C4+-He collisions

Angular distribution of C2+ ions produced in C4+(ls(2)) + He --> C2+(ls(2)2 s(2)) + He2+ at collision energy of 270 and 470 eV are presented. Measureme nts have been carried out with an experimental setup for the state selectiv e differential cross section measurements of electron capture processes whi ch utilizes the 14.5GHz Caprice Electron Cyclotron Resonance (ECR) ion sour ce at RIKEN. It is found that results of calculations based on the potentia l, which was obtained from the previous experimental results at 1520 eV, do not reproduce the present experimental results at 270 and 470 eV.