We report accurate measurements of excess electron mobility in high-density Ar gas at a temperature T≃163 K in the density range (4<N<70)×${10}^{20}$ ${\mathrm{cm}}^{\mathrm{-}3}$ as a function of the electric-field strength. The positive-density effect shown by the zero-field density-normalized mobility ${\mathrm{\mu }}_0$N can be explained within the same theoretical framework recently used for neon gas, where ${\mathrm{\mu }}_0$N shows a negative-density effect. Thus the analysis of our present measurements indicates that there is no need for two separate theories for both negative- and positive-scattering-length gases.

• Received 1 June 1992

DOI:https://doi.org/10.1103/PhysRevA.46.7902