Revised Funnel Calculations for Heavy Particles with High dE/dx

A modification to the effective funnel length model is presented. This modification is based on the assumption that for high dE/dx particles with short track lengths, most of the potential is dropped beyond the end of the track. The revised model then calculates an average field along the track which is smaller than the field calculated by the original model. The revised model results are compared with experimental results for several ions incident on n-type and p-type Si and n-type GaAs. Agreement with experiment for heavy ions is generally much better for the revised model than for the original model. For alpha particles and Be ions, where the original model worked well, the original result is recovered.