Characterization of an optically readout gaseous time projection chamber with a $^{55}$Fe source

The nature of dark matter (DM) is currently one of the most intriguing questions of fundamental physics. Even if the question of dark matter finds its roots in astrophysics and cosmology, it is also actively searched for in particle physics experiments, at colliders as well as in dark matter detection experiments, which aim at discovering dark matter particles. The main experimental challenge comes of course from the elusive nature of DM. One of the most important observables connecting dark matter, cosmology and particle physics is the cosmological density of DM, which is called in this context the relic density. In the last years, several experiments were performed to detect DM particles and some of these experiments use a direct directional detection of WIMP particles. This thesis is an experimental thesis about the development of a new type of detector, called CYGNO. This detector is composed by a Time Projection Chamber filled with a gas mixture at atmospheric pressure. A triple GEM-system is used to produce the light in the detector. By using an optical readout the light is collected.