Prototype Development and Simulation Studies for a GEM Based TPC

We report on the development of a large time projection chamber (TPC) for the e+ e− International Linear Collider. Our studies concentrate on the use of Gas Electron Multiplier (GEM [1]) foils for the gas amplification in the TPC. A TPC prototype has been designed and constructed for operation in a 5 T magnet at DESY Hamburg and for test beam measurements. To obtain an independent reference measurement of the particle tracks, a hodoscope made up of silicon strip sensors has been integrated into the test stand. To study the single and double track resolution in the z-coordinate (time coordinate), new fast readout electronics is under development. To gain a better understanding of the influence of the GEM structure and the readout geometry on the spatial resolution, a modular simulation of a TPC has been developed.