Right-left ambiguity resolution in a time expansion chamber

Abstract In a Time Expansion Chamber two high resolution drift volumes on both sides of a small detection gap are separated from the gap by a fine grid wire plane. The charge asymmetry induced on the grid wires in the vicinity of an anode is used to resolve the right-left ambiguity. It is the only method which is fast enough for a first level trigger and which does not deteriorate the necessary field homogeneity.