Low-energy total cross section measurements for electron scattering from helium and argon

A time-of-flight electron spectrometer has been used to measure absolute total collision cross sections for electrons scattered from helium and argon over the energy range 0.1-20 eV. The measured cross sections are in good agreement with other recent beam experiments and theoretical calculations. At energies below 1 eV modified effective-range theory has been used to enable a comparison of the present work with swarm-derived momentum transfer cross sections. Some limitations of the applicability of the MERT analysis are discussed.