Fabrication of a GEM detector and its signal readout with a homemade readout board

The gas electron multiplier (GEM) chamber fabricated in this experiment had a double GEM structure, and Ar and CO2 gases were used as the counting and the quencher gases, respectively, with a mixing ratio of Ar : CO2 = 80 : 20. A homemade readout board was used to read the electric signals from the GEM detector. The analog-to-digital converter (ADC) was synchronized with the trigger signal, and the converted digital values were fed to a personal computer (PC) by the data acquisition (DAQ) program. The whole detector system was tested with an Fe-55 radiation source (5.9 keV), and we calculated the mass attenuation coecients for a Cu and an Ar/CO 2 gas mixture under 5.9 keV X-ray irradiation. From the results, we found that the Cu film (cathode) played an important role in the signal generation.