  The characteristics of triple GEM detectors have been studied systematically
by using cosmic ray muons. The minimum ionizing particle (MIP) spectra has been
taken for different GEM voltage setting. Efficiency of GEM detector has been
measured for cosmic ray. At high rate operation of GEMs the value of the
protection resistor influences the gain and the stability. This feature has
been investigated varying both the rate and the value of the protection
resistor. This measurement has been performed using both X-ray generator and
Fe55 source. The ageing and long-term stability of GEM based detectors has been
studied employing both X-ray generator and Fe55 source. The ageing study of one
GEM module is performed by using a 8 keV Cu X-ray generator to verify the
stability and integrity of the GEM detectors over a longer period of time. The
accumulated charge on the detector is calculated from the rate of the X-ray and
the average gain of the detector. The details of the measurement and results
has been described in this article.
