A large TPC prototype for a linear collider detector

A Time Projection Chamber (TPC), operated in a detector at a future linear e +e − collider, will require a significantly advanced readout concept compared to the traditional pad-wire-based systems used previously. The LCTPC collaboration studies the prospects of TPC readout systems based on Micro-Pattern Gas Detectors, namely GEMs and Micromegas, in combination with pads or a CMOS on the underlying anode plane. In small TPC prototype chambers, resolutions of better than σ ⊥ = 100 μ m were demonstrated for drift distances of up to 66 cm. In the future, the R&D efforts will focus on the technical realization of large-surface readout systems with the aim to develop a technical concept for a readout module of a future TPC. A large TPC prototype with a diameter of 77 cm has been constructed for the planned studies. It is part of a test beam infrastructure at the electron test beam at DESY. First test beam operations with Micromegas and GEM based prototype modules in December 2008 and during 2009 gave promising results.