W-values for heavy ions in gases

The determination of W, an average energy to produce an ion pair, for heavy ions in gases at atmospheric pressures has been made using heavy-ion beams from an accelerator. The values of W were measured for He 2+ and C 6+ ( 6+ , the energy dependence of W was clearly observed, while W for He 2+ was approximately constant over a wide range of the energy. The differential values of W (w) were also measured for C 6+ ( 18+ (100 MeV/n) and are almost equal to the value of W for He 2+ .