Performance of CMS Endcap Precision Timing Sensors

The Large Hadron Collider, a particle accelerator in Geneva, Switzerland, willenter its High Luminosity (HL) phase, whose upgrade has already started. Thisphase will include an increase in particle collisions, achieving instantaneousluminosities of 5 to 7 times the nominal luminosity, 1 × 10 34 cm −2 s −1. Thisincrease gives more opportunities for rare processes to come to light, howeverit also means that there is more overlapping particle interactions, calledpileup, in the detectors. To address this added pileup, the Compact MuonSolenoid (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. Thesensors comprising the endcap section of the MTD are silicon low gain avalanchedetectors (LGADs). From extensive tests at the Fermilab test beam facility, ithas been shown that prototypes of these sensors perform in accordance to ourexpectations and requirements for the MTD. Specifically, these sensors havedemonstrated a timing resolution within 30-40 picoseconds.