Optical and electrical performance of commercially manufactured large GEM foils

With interest in large area GEM foils increasing and CERN being the only main distributor, keeping up with the demand for GEM foils will be difficult. Thus the commercialization of GEMs is being established by Tech-Etch of Plymouth, MA, USA using single-mask techniques. We report here on the first of a two step quality verification of the commercially produced 10×10 cm² and 40×40 cm² GEM foils, which includes characterizing their electrical and geometrical properties. We have found that the Tech-Etch foils display excellent electrical properties, as well as uniform and consistent hole diameters comparable to established foils produced by CERN.