  Study of the stability of gain and energy resolution for a triple GEM
detector has been performed under continuous radiation of X-ray with high rate,
using premixed gas of Argon and CO$_2$ in 70/30 ratio and conventional NIM
electronics. A strong Fe$^{55}$ X-ray source is used for this study. The
novelty of this study is that for the stability test same source is used to
irradiate the GEM chamber and to monitor the spectrum. The radiation is not
collimated to a point but exposed to a larger area. Effect of temperature and
pressure on these parameters are also studied. The detail method of measurement
and the first test results are presented in this article.
