  The Gas Electron Multiplier (GEM) detector is one of promising particle and
radiation detectors that has been improved greatly from previous gas detectors.
The improvement includes better spatial resolutions, higher detection rate
capabilities, and flexibilities in designs. In particular, the 10 cm x 10 cm
GEM prototype is designed and provided by the Gas Detectors Development group
(GDD) at CERN, Switzerland. With its simplicity in operations and designs,
while still maintaining high qualities, the GEM prototype is suitable for both
start-up and advanced researches. This article aims to report the
investigations on some important properties of the 10 cm x 10 cm GEM detector
using current measurement and signal counting. Results have shown that gains of
the GEM prototype exponentially increase as voltage supplied to the detector
increases, while the detector reaches full efficiency (plateau region) when the
voltage is greater than 4100 V. In terms of signal sharing between X and Y
strips of the readout, X strips, which is on the top layer of the readout,
collect ~57% of the total signal. For the uniformity test, the GEM prototype
has slightly higher efficiencies at the center of the detector and decreases as
positions are closer to edges.
