Drift velocity of free electrons in liquid argon

A measurement of the drift velocity of free electrons in liquid argon has been performed. Free electrons have been produced by photoelectric effect using laser light in a so-called “laser chamber”. The results on the drift velocity vd are given as a function of the electric field strength in the range 0.5 kV/cm⩽|E|⩽12.6 kV/cm and the temperature in the range 87 K⩽T⩽94 K. A global parametrization of vd(|E|,T) has been fitted to the data. A temperature dependence of the electron drift velocity is observed, with a mean value of Δvd/(ΔT vd)=(−1.72±0.08)%/K in the range of 87–94 K.