A simple method for fast negative atomic and molecular ion studies in tandem accelerators

A simple method is proposed for measuring cross-sections of fast negative a tomic and molecular ions colliding with atoms and molecules. The method, ap plicable to tandem accelerators, uses the stripping process of the negative ions, occurring at the gas target placed in the accelerator high-voltage t erminal. The target (stripper) gas pressure, not directly measurable, is me asured with an improved version of a method that we have recently proposed. The total destruction cross-sections of negative atomic or molecular ion p rojectiles may be obtained, as well as those for each specific destruction channel. As an example of the validity of the method, we measured the destr uction cross-sections of Si; in Ar, from 30 keV to 1.3 MeV laboratory energ ies. (C) 2000 Elsevier Science B.V. All rights reserved.