  Three Gas-Electron-Multiplier tracking detectors with an active area of 10 cm
x 10 cm and a two-dimensional, laser-etched orthogonal strip readout have been
tested extensively in particle beams at the Meson Test Beam Facility at
Fermilab. These detectors used GEM foils produced by Tech-Etch, Inc. They
showed an efficiency in excess of 95% and spatial resolution better than 70 um.
The influence of the angle of incidence of particles on efficiency and spatial
resolution was studied in detail.
