Energy and angular distributions of secondary electrons resulting from ionizing collisions of electrons with helium and krypton

Cross sections differential in angle and energy have been measured of secondary electrons resulting from ionizing collisions of electrons with helium at the primary energy E 0 =500 eV and 1 keV and with krypton at E 0 =1 keV. The total spectra, consisting of the continuum spectra due to direct ionizations and the sharp line spectra due to indirect ionizations (autoionizations or Auger processes), have been measured with an energy resolution of about 0.2 eV over the angular range from 10° to 130°. The continuum spectra are derived from the total spectra for electron energies from 25 eV to 45 eV for helium and from 24 eV to 52 eV for krypton and compared with the calculations by the binary encounter theory.