Optimization of overhanging-metal microstrip detectors: test and simulation

The adoption of overhanging-metal contacts has been suggested as an effective means to limit breakdown risks in heavy-damaged high-voltage biased microstrip detectors. In this paper, the influence of the overhang on device noise parameters is analyzed, with particular reference to the interstrip capacitance. Data have been collected on a set of detectors featuring variable overhang extensions and different width/pitch ratios, and numerical simulation has been exploited to provide physical interpretation of the experimental findings. In particular, the nontrivial dependence of interstrip capacitance over geometrical parameters is discussed. By looking at leakage currents and charge collection as well, it is shown that limited-extension overhangs still have highly beneficial effects on the breakdown properties while having no practical drawbacks on the detector performance.