Discharge Protection and Ageing of Micromegas Pixel Detectors

GridPix is a gas-filled detector in which a Micromegas is combined with a CMOS pixel chip. The GridPix detector, originally developed for the readout of TPCs, can be applied as X-ray imaging device. With a drift gap of only one mm, GridPix could be well applied as radiation hard, low power, (and therefore) low-mass vertex (track) detector. A procedure to construct a Micromegas onto a Si wafer, using chip production technology ('wafer post processing'), has been developed. A method to protect the CMOS anode pixel chip against discharges has been studied. An ageing test of a Micromegas chamber has been carried out, after verifying the chamber's proportionality at a very high dose rate.