Validation of SiPMs for the DUNE Far detector photon detection system through the development and commissioning of a cryogenic facility

The Deep Underground Neutrino Experiment (DUNE) is a next generation long baseline neutrino experiment in preparation in the US. Its main scientific goals are the measurement of neutrino parameters such as the CP-violating phase, $\delta_{\textrm{CP}}$, determine the neutrino mass ordering, and precisely measure the oscillation angles $\theta_{23}$ and $\theta_{13}$. DUNE will be implemented with a Near Detector and a Far Detector, located at 500 m and 1300 km, respectively, along the neutrino beamline originating at Fermilab. The FD complex will consist of four detectors modules of Liquid Argon Time Projection Chambers, instrumented with a Photon Detection System (PDS) to detect the scintillation light produced inside the active volume. The PDS will be based on light collectors coupled to Silicon Photomultipliers (SiPMs) working in a Liquid Argon environment. This thesis is focused on the test activities and the validation of the photosensors for the experiment, along with the optimization of the PDS performance for its first module. %to verify the compatibility of the photosensors to the experiment requirements. This was necessary to ensure a uniform response of the system. The results of a selection process of SiPMs are reported, as well as the full characterization of these devices at room and cryogenic temperatures (77 K). Based on these results, the SiPMs for the first module prototype (ProtoDUNE, at CERN) were produced. A description of the semi-automated system used to validate these sensors is given along with the results obtained. A campaign of validation of all the SiPMs ($\sim$300000) which will be eventually installed in the first DUNE Far Detector module is currently undergoing using this system. The results for the samples tested up to now are here presented.