Performance of CMS Endcap Precision Timing Sensors

The Large Hadron Collider, a particle accelerator in Geneva, Switzerland, will enter its High Luminosity (HL) phase, whose upgrade has already started. This phase will include an increase in particle collisions, achieving instantaneous luminosities of 5 to 7 times the nominal luminosity, $1~\times~10^{34}$~cm$^{-2}$s$^{-1}$. This increase gives more opportunities for rare processes to come to light, however it also means that there is more overlapping particle interactions, called pileup, in the detectors. To address this added pileup, the Compact Muon Solenoid (CMS) detector at the LHC will install a new precision timing detector, the MIP Timing Detector (MTD), as part of the upgrades for the HL-LHC. The sensors comprising the endcap section of the MTD are silicon low gain avalanche detectors (LGADs). From extensive tests at the Fermilab test beam facility, it has been shown that prototypes of these sensors perform in accordance to our expectations and requirements for the MTD. Specifically, these sensors have demonstrated a timing resolution within 30-40 picoseconds.