UC Santa Cruz

We report on the performance of 50m thick Ultra-Fast Silicon Detectors (UFSDs) made by Hamamatsu Photonics (HPK) and Centre Nacional de Microelectronica (CNM) Barcelona at test beams at Fermilab National Accelerator Laboratory (FNAL). Using the precision particle tracking available at FNAL, we measured the spatial dependence of parameters including the time resolution and gain of UFSDs. We observed and documented unexpected differences in signals due to a lack of metallization on the top of sensors. We measured the widths of inactive areas in 2x2 arrays of 9mm2 square pixel sensors, a limiting factor in particle detection. We also compared the timing performance of ~1mm2 single diode sensors with different digitizers. We measured time resolutions near 30ps for diodes at a gain near 15 with the CAEN V1742 digitizer board and Teledyne Lecroy WavePro 725Zi.