Signal processing for picosecond resolution timing measurements

The development of large-area homogeneous photo-detectors with sub-millimeter path-lengths for direct Cherenkov light and for secondary electrons opens the possibility of large time-of-flight systems for relativistic particles with resolutions in the picosecond range. Modern ASIC techniques allow fast multi-channel front-end electronics capable of sub-picosecond resolution directly integrated with the photo-detectors. However, achieving resolution in the picosecond range requires a precise knowledge of the signal generation process in order to understand the pulse waveform, the signal dynamics, and the noise induced by the detector itself, as well as the noise added by the processing electronics. Using the parameters measured for fast photo-detectors such as micro-channel plates photo-multipliers, we have simulated and compared the time resolutions for four signal processing techniques: leading edge discriminators, constant fraction discriminators, multiple-threshold discriminators and pulse waveform sampling.