Excess electron mobility in high-density argon gas

We report accurate measurements of excess electron mobility in high-density Ar gas at a temperature T{}163 K in the density range (4N70)×{}10²⁰ cm^-3 as a function of the electric-field strength. The positive-density effect shown by the zero-field density-normalized mobility μ₀N can be explained within the same theoretical framework recently used for neon gas, where μ₀N 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.