Studies of the CMS Level 1 Trigger and Tracker Upgrade

  • Yi Liu

Student thesis: Master's ThesisMaster of Science (MSc)


The Large Hadron Collider (LHC) is the world’s largest and most powerful particle accelerator. It found the Higgs particle in 2012. In order to fully exploit the potential of the LHC, it is planned to upgrade to the High-Luminosity LHC (HL-LHC), reaching a peak luminosity of 5−7.5×1034 cm−2s−1. The Compact Muon Solenoid (CMS) detector, as one of four detectors at the LHC, will be upgraded to operate at the HL-LHC. One of the most important aspects of this upgrade will be the addition of track information in the Level-1 trigger system.

In this thesis, we will present the concept of the CMS tracker and trigger system upgrade including the limitations of the current trigger system. The implementation ofthetracktriggerviaaHoughtransformwillbediscussed. Simulationsofthetrack trigger system show that more than 90% of tracking particles can be reconstructed over the full acceptance. We also discuss the relationship between the tracker layout and the number of reconstructed tracks. The performance of the track trigger for tracks generated at different positions in the z-direction is shown. By changing the cell size of the Hough transform, the performance of the track trigger system changes. The best performance is obtained with a granularity of 32x64 cells per sector. The effect in the performance of the Hough transform due to dense track environments will be discussed last.
Date of Award25 Jun 2019
Original languageEnglish
Awarding Institution
  • The University of Bristol
SupervisorJoel Goldstein (Supervisor)

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