Charge transport in liquid and solid argon.

Short pulses of electrons of 40 keV energy have been used to generate electron-hole pairs in solid and liquid argon. The drift velocity of electrons has been measured at applied fields of 100 V.cm-1 to 15 kV.cm-1 in the solid, and 40 V.cm-1 to 70 kV.cm-1 in the liquid. For both the solid and the liquid, the drift velocity is determined principally by acoustic mode scattering. The low field mobilities (?.) are: In the solid, the mobility has been measured as a function of temperature. The results are not inconsistent with ?. ? T-3/2, except near the triple point, where the variation of mobility is more rapid. In both liquid and solid there is a transition at intermediate fields to a region in which v (v = drift velocity, E = electric field). This behaviour is explained in terms of the Shockley hot electron theory; agreement with the theory is good. At high fields there is a further saturation; in the liquid, for E < 10 kV.cm-1, this is in good agreement with the theoretical drift velocities calculated by Lekner. (Lekner's theory has not yet been applied to the solid). At fields above 10 kV.cm-1, the experimental drift velocities are greater than those predicted by the theory. In the liquid, the drift of positive ions has been observed; their mobility is about 1.0 to 1.2.10-3 cm2.s-1.v-1, for fields of 4 kV.cm-1 to 60 kV.cm-1. In the solid, no drift of positive holes could be detected.