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 congruent-to 163 K in the density range (4 < N < 70) x 10(20) cm-3 as a function of the electric-field strength. The positive-density effect shown by the zero-field density-normalized mobility mu0N can be explained within the same theoretical framework recently used for neon gas, where mu0N 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.