Development of the GridPix detector for dual phase noble gas time projection chambers

GridPix is a gas-filled detector with an aluminum mesh stretched 50 μm above the Timepix CMOS pixel chip. This defines a high electric field where gas amplification occurs. A feasibility study is currently ongoing at Nikhef for the application of the GridPix technology as a charge sensitive device in a dual phase noble gas Time Projection Chamber (TPC), within the framework of the DARWIN dark matter design study. The application in dual phase argon or xenon TPCs implies several technological challenges, such as the survival of the device at cryogenic temperature as well as the operation in a pure noble gas atmosphere without discharges. The equipment for tests at liquid nitrogen temperature and a gain measurement station have been built at Nikhef and the results are reported. Moreover, the first test of the device in a dual phase argon TPC has been performed in collaboration with ETH Zurich.