Detection and Removal of Short-circuits on GEM-foils

High resolution scanning system was used to locate the areas on GEM-foils that might contain short-circuit. These areas were analyzed by threshold method for fast identification. Different methods to remove short-circuits on GEM-foils were studied. Since using the standard procedure of “burning” shorts with high current might incur additional damage to the foil, we have also studied several non-destructive methods. These methods were for example washing with high power ultrasonic, manual extirpation and by using resonance frequencies. We will show results on locating and removing the GEM-shorts from standard bi-conical 10 cm ¥ 10 cm foils.