Precision timing in high pile-up and time-based vertex reconstruction

Abstract

For the High Luminosity upgrade of the Large Hadron Collider (HL-LHC), the Com- pact Muon Solenoid Experiment (CMS) is currently studying various upgrade options (CMS Phase II Upgrade). HL-LHC involves raising the rate of collisions (luminosity) by a factor of 10 beyond the LHC’s original design value, posing the challenge of an in- creased rate of collisions per bunch-crossing (pile-up). In high pile-up conditions, it is difficult to assign final state particles to individual collisions, and complicated to separate jets. Studies have been conducted on the use of time of flight measurements in the elec- tromagnetic calorimeter (ECAL) of CMS in regards to time cleaning of pile-up jets and vertexing through triangulation of rechits. This project verifies a few applications of ECAL timing within the recently updated timing portion of the CMSSW framework.