The microdot gas avalanche chamber: an investigation of new geometries

The gains of the microstrip and microgap gas avalanche chambers are limited to below gains of 5 × 103 by geometrical and gas properties. In order to increase the maximum gain to greater than 2 × 104 a new detector geometry, the microdot, is proposed that can be produced at a standard silicon MOS microfabrication facility at similar cost to present microstrip gas detectors. In addition to charged particle tracking, the new geometry is also well suited to imaging applications. The operating characteristics of the new device have been investigated using a numerical simulation and a comparison with conventional strip geometries is presented. These results show that the microdot geometry reaches higher gas gains than the strip-like geometries, for the same set of electrode potentials, with a reduced cathode electric field enhancing operational stability.