  The planned tracking upgrade of the STAR experiment at RHIC includes a
large-area GEM tracker used to determine the charge sign of electrons and
positrons produced from W+(-) decays. For such a large-scale project commercial
availability of GEM foils is necessary. We report first results obtained with a
triple GEM detector using GEM foils produced by Tech-Etch Inc. of Plymouth, MA,
USA. Measurements of gain uniformity, long-term stability as well as
measurements of the energy resolution for X-Rays are compared to results
obtained with an identical detector using GEM foils produced at CERN. A quality
assurance procedure based on optical tests using an automated high-resolution
scanner has been established, allowing a study of the correlation of the
observed behavior of the detector and the geometrical properties of the GEM
foils. Detectors based on Tech-Etch and CERN produced foils both show good
uniformity of the gain over the active area and stable gain after an initial
charge-up period, making them well suited for precision tracking applications.
