CMS Level-1 Trigger Upgrade & BSM Physics
29 Nov 2022







Supervisors: Tom Williams (RAL PPD) + Sudan Paramesvaran (Bristol University)

The Large Hadron Collider (LHC) at CERN will be upgraded to become the High-Luminosity LHC (HL-LHC), significantly increasing the rate of proton-proton collisions. The CMS experiment will be upgraded at the same time in order to ensure that we will get more precise physics measurements and greater sensitivity to new physics in the intense HL-LHC environment. The CMS level-1 trigger system plays a critical role in the experiment's data aquisition chain: Within a few microseconds it decides which collisions are sufficiently interesting to store for later analysis. As part of the HL-LHC upgrades, the level-1 trigger system will be replaced using cutting-edge technologies. It will consist of hundreds of FPGA-based custom electronics boards, connected by several thousand optical links with a total bandwidth of roughly 200 000 Gbit/s. For the first time the CMS level-1 trigger system will have access to information from the tracker, enabling a paradigm shift in the types of particle reconstruction and identification algorithms that can be run in the level-1 trigger. 

As part of the CMS collaboration, the student will play a key role in developing algorithms for the HL-LHC trigger system, working on all stages of the process: conceptual design of the algorithms, measuring their performance in simulated p-p collisions; implementing these algorithms in firmware; and testing these algorithms on the electronics boards. The student will also be involved in setting up test systems at CERN, and performing integration tests with connected components. The student will gain skills in computer programming and FPGA firmware development. In addition to learning classic hardware description languages for firmware development, the student will also use modern tools like Vivado HLS for expressing key components of algorithms in higher-level abstractions. ​

The LHC has just started Run 3 and the CMS experiment will be collecting its largest ever dataset. In addition to the HL-LHC level-1 trigger studies, the student will also work on searches for evidence of BSM physics in the context of extended Higgs sector models or dark sector models. The final states that will be exploited will include light higgs bosons or semi-visible jets, which will be reconstructed using techniques that make extensive use of neural nets such as Graph NNs and autoencoders. We work closely with theorists within the NExT Institute when developing new searches and interpreting results.

 For more details please contact Dr. Tom Williams (