ELECTRON LOSS CROSS-SECTIONS OF HIGH-VELOCITY H-LIKE IONS IN CARBON

The attenuation of hydrogen atoms and H-like He, Li, C and O ions of a bout 10-MeV/amu due to the electron loss collisions in thin carbon foi ls was measured as a function of foil thickness. At the thinner foil r egion, the incident beams attenuated exponentially as the foil thickne ss increased. From the attenuation rates, we have determined the elect ron loss cross sections of the ground slate H-like ions. The obtained cross sections are larger than the theoretical predictions based on th e Born approximation, especially for projectiles of higher atomic numb er. They can be well explained quantitatively taking account of the co ntribution from the projectile excitation which leads to the ionizatio n by the subsequent collision in the foils. (C) 1998 Published by Else vier Science B.V.