Caratterizzazione di rivelatori al silicio ad alta risoluzione temporale

High energy physics increasingly requires instruments with improved spatial and time resolution and for this reason there is a continuous research in innovative particle detectors in order to achieve better performances. This thesis focuses on the development and characterization of Low Gain Avalanche Detectors (LGAD), which represent an evolution of silicon detectors with internal charge multiplication. LGAD technology is at the basis of the development of Ultra-Fast Silicon Detectors (UFSD). They are innovative silicon detectors that use a gain layer in order to achieve charge multiplication, amplifying the signal produced by a particle crossing the detector. Thanks to this innovation, and to the use of thin sensors, UFSD can provide an excellent space and time measurements of the passage of a charged particle. This thesis presents the work I did during my internship at Laboratory for Innovative Silicon Sensors in Torino. I studied the response of the gain layer, verifying that is essential to achieve an excellent time resolution. Especially, I probed the uniformity of the internal gain among many hundreds of sensors and I measured for the first time the doping uniformity in the gain layer within a wafer and among wafers. In the second part of my activities, I measured the sensors response when they are exposed to a laser beam.