Charge protection characterisation and drift time resolution improvement for GridPix

A GridPix detector is a gaseous detector capable of detecting single primary electrons from ionising particles. Such a detector consists of a pixel chip as active anode covered with a thin layer of silicon rich silicon nitride (SiRN) for protection against discharges. A layer of 8 μm SiRN, and according recent tests even 4 μm, is sufficient to protect against discharges. The effect of the thickness of the SiRN layer on the operation of a detector has been determined.