Development of a GEM-based High Resolution TPC for the ILC

The physics goals and the expected environment at the ILC requires the development of a detector with unprecedented tracking capabilities. A high-resolution TPC with gas amplification based on micro-pattern gas detectors is a promising candidate for the main tracker at the ILC detector.Significant progress has been achieved in the development of a TPC concept with Gas Electron Multipliers (GEM [F. Sauli, Nucl. Instr. and Meth. A 386 (1997) 531]) used for gas amplification. Significant ion backdrift reduction was obtained using special settings of the GEM structures. To further study the spatial resolution of a GEM-based TPC, a prototype with low-mass fieldcages was constructed. It was operated within a high-resolution silicon hodoscope. Additionally, extensive effort is spent on the development of an accurate numerical simulation of the TPC properties, such as drift, diffusion and gas amplification.