Online luminosity monitoring with liquid Argon calorimeters at ATLAS and D0

This note discuss a luminosity monitoring method for the high energy hadron colliders Tevatron and LHC, based on the measurement of the high voltage current of liquid Argon calorimeters. \\ This method gives a precise relative luminosity measurement, which could be used as an online monitoring. \\ Ionisation chamber theory with simplified detector models is used in this note to determine the expected current values and to investigate some of the systematic effects which might show up at high luminosity. \\ Other systematic effects, whose understanding needs more detector-specific studies, are discussed for the ATLAS detectors. \\ It is shown that, for the ATLAS detectors, a 1$\%$ precision, both from statistics and systematics point of view, can be achieved.