Production and characterization of random electrode sectorization in GEM foils

In triple-GEM detectors, the segmentation of GEM foils in electrically independentsectors allows reducing the probability of discharge damage to the detector and improving thedetector rate capability. However, a segmented foil presents thin dead regions in the separationbetween two sectors and the segmentation pattern has to be manually aligned with the GEM holepattern during the foil manufacturing, a procedure potentially sensitive to errors.We describe the production and characterization of triple-GEM detectors obtained with aninnovative GEM foil segmentation technique, the “random hole segmentation”, that allows easiermanufacturing of segmented GEM foils. The electrical stability to high voltage and the gainuniformity of a random-hole segmented triple-GEM prototype are measured. The results of a testbeam on a prototype assembled for the Phase-2 GEM upgrade of the CMS experiment are alsopresented. A high statistics efficiency measurement shows that the random hole segmentation canlimit the efficiency loss of the detector in the areas between two sectors, making it a viablealternative to blank segmentation for the GEM foil manufacturing of large-area detector systems.