Cool Timepix – Electronic noise of the Timepix readout chip down to −125 °C

The Timepix readout chip with its 65k pixels on a sensitive area of 14 mm×14 mm provides a fine spatial resolution for particle tracking or medical imaging. We explore the operation of Timepix in a dual-phase xenon environment (around −110 °C). Used in dual-phase xenon time projection chambers, e.g. for dark matter search experiments, the readout must have a sufficiently low detection limit for small energy deposits. We measured the electronic pixel noise of three bare Timepix chips. For the first time Timepix readout chips were cooled to temperatures as low as −125 °C. In this work, we present the results of analysing noise transition curves recorded while applying a well-defined charge to the pixel׳s input. The electronic noise reduces to an average of 99e−, a reduction of 23% compared to operation at room temperature.