A lightweight field cage for a large TPC prototype for the ILC

We have developed and constructed the field cage of a prototype Time Projection Chamber for research and development studies for a detector at the International Linear Collider. This prototype has an inner diameter of 72 cm and a length of 61 cm. The design of the field cage wall was optimized for a low material budget of 1.21% of a radiation length and a drift field homogeneity of ΔE/E∼<10-4. Since November 2008 the prototype has been part of a comprehensive test beam setup at DESY and used as a test chamber for the development of Micro Pattern Gas Detector based readout devices.