Study and optimization of the light-yield of a triple-GEM detector

The high-resolution tracking of low energy release particles had a remarkable development in recent years and will give a crucial contribution in different fields, from medical uses to those in dark matter search. Characteristics, such as high space and time resolution, low material budget, large volumes, low costs, make gas detectors ideal candidates for this type of devices. A very promising technique involves the optical reading of the light produced by the de-excitation of gas molecules during the processes of electron multiplication. This type of detector has been made possible thanks to the great progresses achieved in last years in the performance in micro pattern gas detector and in the evolution of the CMOS technology which led to the production of sensors able of offering high sensitivity and granularity combined with a very low noise level. In this thesis the performance of a prototype where the light is produced through the multiplication of electrons in a triple GEM structure and acquired by a camera equipped with CMOS sensor with 4 Mega Pixels were studied. Using a high light yield HeCF4 gas mixture, the tracks due to X-Rays emitted by a 55Fe radioactive source, had been revealed allowing to measure a resolution on energy measurement between 20% and 30%.