Abstract
Approximate expressions are given for the fraction of scattering events which contribute to the attenuation of the transmitted electron current in cylindrically symmetric electron spectrometers, with and without an imposed axial magnetic field. The sensitivity to scattering is shown to decrease strongly with increasing magnetic field strength owing to the trapping of scattered electrons by the magnetic field and multiple scattering effects due to the path length being a function of the magnetic field strength. The effect of applying a retarding electric field to electrons leaving the interaction region is shown to leave the conclusions substantially the same.