ABSTRACT
This chapter presents the Low-Gain Avalanche Diode (LGAD) technology and how this technology has been optimized in the Ultra-Fast Silicon Detectors (UFSD) design to achieve excellent temporal resolution. It describes the UFSD segmentation technology required for the design of large-area sensors. An important parameter in the design of an LGAD is the depth of the gain implant. The low-gain avalanche design is a very powerful tool to increase the signal in silicon sensors. It can be applied to almost any geometry, improving the signal-to-noise ratio of the system. However, the characteristics needed to achieve a precise determination of the arrival time of an impinging particle are not limited to the signal amplitude. In sensor with gain, a second effect, the so-called excess noise, contributes to make the shot noise term larger. In sensor with gain, a second effect, the so-called excess noise, contributes to make the shot noise term larger.
