Low-energy electron drift and scattering in krypton and xenon

The drift velocity of electrons in Ar, Kr, and Xe has been measured at a gas temperature T=301 K using gas pressures of 300 and 600 kPa over the E/N range 2×${10}^{\mathrm{-}20}$≤E/N≤3×${10}^{\mathrm{-}17}$ V ${\mathrm{cm}}^2$. The measurements have been used to derive the low-energy momentum-transfer cross section ${\sigma }_m$(ɛ) in Kr and Xe at electron energies up to 8 eV using a Boltzmann-equation analysis along with a four-parameter modified-effective-range-theory procedure. Particular attention has been paid to the effects of impurities on the measured electron drift velocities and the uniqueness of the derived momentum-transfer cross sections. The present measurements and calculated cross sections are compared with published values from experiments and calculations.