The role of shallow traps on the mobility of electrons in liquid Ar, Kr, and Xe

It is shown that the saturation of the drift mobility observed in liquid Ar, Kr, Xe and other insulating liquids is not a hot electron effect but can instead be understood as an effect due to shallow traps. Estimates of the binding energy (B.E.) of such traps in Ar indicate a value ∼90 meV. The effect of the addition of impurities can be understood as enhancing a Schottky ionization process.