Electron-argon total cross section measurements at low energies by time-of-flight spectroscopy

Recent improvements to the authors' time-of-flight spectrometer are described in detail, in particular the redesign of the gas-target entrance and exit necessary for the essential elimination of a systematic error which affected the measurements near cross section minima. The modified spectrometer was used to measure the cross section of argon in the energy range of 0.08 to 20 eV. For the Ramsauer minimum of argon at 0.345 eV the authors obtain a cross section about twice as high as that of earlier experiments but in excellent agreement with another current experiment as well as with recent theoretical results and with cross sections derived from swarm experiments. At higher energies, the authors' results agree well with other experimental and theoretical data.