Toward the Pixel-TPC: Construction and Operation of a Large Area GridPix Detector

We report on the construction of the largest GridPix detector to date and its successful operation as readout of a time projection chamber (TPC). By combining a charge sensitive pixelized readout chip with a micropattern gaseous detector, the GridPix features a high granularity with single electron detection and integrated signal processing. The readout structure consists of 160 GridPixes with a total of 10.5 million pixels, each of a size of $55 \times 55~\mu \text{m}^{ {2}}$ . With a sensitive area of 320 cm $^{ {2}}$ , it is a factor 20 larger than previously operated systems. We report on the integration of such a large number of GridPixes into a single compact detector, including cooling, readout electronics, and low-voltage and high-voltage power supply, and on the performance during a two weeks test beam campaign at DESY. The large area pixelated readout for gaseous detectors can be applied for different detectors. In our developments, we focused on an application for a TPC.