Bulk Micromegas detectors for large TPC applications

A large volume TPC will be used in the near future for a variety of experiments, including T2K and possibly the Linear Collider detector. The bulk Micromegas detector is a novel construction technique suited for building compact and robust low mass detectors. The ability to pave a large surface with a simple mechanical solution and negligible dead space between modules is of particular interest for these applications, offering a simple and low cost alternative to wire chambers. We have built and tested two large bulk   detectors (26×27cm2 with 8×8mm2 pads) in the former HARP field cage setup at CERN, with cosmic ray data in a magnetic field up to 0.4 T. We present the excellent detector performances, with gains in excess of 104104, space point resolution of 700μm at 1 m drift, and dE/dxdE/dx resolution of 12%12%. Improvement on the point resolution with the use of a resistive anode is also discussed.