Two-dimensional microgap gas chambers on silicon

We are manufacturing microgap chambers (MGC) on silicon with two-dimensional read-out. They have an anode pitch of 100 μm and a cathode pitch of 400 μm. We obtained a maximum gas gain of 2500 and the avalanche charge collection takes place within 15 ns. The stability of the gas gain is very good. We have tested the position resolution for the detection of X-rays. It appears that the gas composition and the strength of the drift field are important parameters. A high concentration of dimethylether and a rather small drift field provide the smallest size of the total avalanche.