Investigation of GEM space point resolution for a TPC tracker

The Gas Electron Multiplier (GEM) is a leading candidate for the readout of the Time Projection Chamber (TPC) at a future linear collider detector. This presentation describes measurements of the space point resolution of a GEM with relatively large hexagonal pads. Resolution of approximately 50 μm is achieved for 4.5 keV x-rays with two independent methods, using charge sharing and using induction signals.