This electronic thesis or dissertation has been downloaded from Explore Bristol Research, http://research-information.bristol.ac.uk Author: Bologna, Simone Title: Trigger design studies at future high-luminosity colliders General rights Access to the thesis is subject to the Creative Commons Attribution - NonCommercial-No Derivatives 4.0 International Public License. A copy of this may be found at https://creativecommons.org/licenses/by-nc-nd/4.0/legalcode This license sets out your rights and the restrictions that apply to your access to the thesis so it is important you read this before proceeding. Take down policy Some pages of this thesis may have been removed for copyright restrictions prior to having it been deposited in Explore Bristol Research. However, if you have discovered material within the thesis that you consider to be unlawful e.g. breaches of copyright (either yours or that of a third party) or any other law, including but not limited to those relating to patent, trademark, confidentiality, data protection, obscenity, defamation, libel, then please contact [email protected] and include the following information in your message: •Your contact details •Bibliographic details for the item, including a URL •An outline nature of the complaint Your claim will be investigated and, where appropriate, the item in question will be removed from public view as soon as possible. Trigger design studies at future high-luminosity colliders By SIMONE BOLOGNA School of Physics UNIVERSITY OF BRISTOL A dissertation submitted to the University of Bristol in ac- cordance with the requirements of the degree of DOCTOR OF PHILOSOPHY in the Faculty of Science. OCTOBER 2020 Word count: 31726 ABSTRACT he LHC will enter in 2026 its high-luminosity phase which will deliver a peak instanta- 34 2 1 neous luminosity of 7.5 10 cm¡ s¡ and produce events with an average pile-up of 200. £ TIn order to pursue its ambitious physics programme, the CMS experiment will undergo a major upgrade. The level-1 trigger will be replaced with a new system able to run the particle flow algorithm. An algorithm that reconstructs jets and computes energy sums from particles found by the particle flow algorithm is presented in this thesis. The algorithm is able to provide similar performance to offline reconstruction and keep the same pT threshold as in the previous CMS runs. The algorithm was implemented in firmware and tested on Xilinx FPGA. An agreement rate of 96% was obtained in a small-scale demonstrator setup running on a Xilinx FPGA. The full-scale algorithm is expected to use around 41.5% of LUTs, 11.6% of flip-flops, and 2.9% of DSPs of a Xilinx VU9P FPGA running at the frequency of 360 MHz. The FCC-hh project studies the feasibility of a hadron collider operating at the centre-of-mass energy of 100 TeV after the LHC operations have ended. The collider is expected to operate at a 34 2 1 34 2 1 base instantaneous luminosity of 5 10 cm¡ s¡ , and reach a peak value of 30 10 cm¡ s¡ £ £ corresponding to an average pile-up of 200 and 1000, respectively. Rates of a trigger system of a detector at FCC-hh were estimated by scaling rates of the Phase-2 CMS level-1 trigger and by developing a parameterised simulation of the Phase-1 trigger system. The results showed that 34 2 1 at the instantaneous luminosity of 5 10 cm¡ s¡ the 100-kHz pT threshold is expected at £ 85 GeV, 170 GeV, and 350 GeV for single muon, e/γ , and jet triggers, respectively. i ACKNOWLEDGEMENTS would like to thank the people I had the pleasure to work and share this experience with. First of all, I am grateful to my supervisor Jim Brooke for helping me with his wise advice Ithroughout my PhD research, Paris Sphicas for his supervision at CERN, Dave Newbold and Joel Goldstein. I would like to thank Aaron Bundock, Emyr Clement, and Katie for their help in testing and demonstrating my firmware on hardware. A special thanks goes to Alessandro Thea, without him I would probably have not started this project in the first place (although I think he now regrets this!). I thank Yingpu, who I have shared a significant part of my PhD troubles with. I would like to thank my colleagues Joe, fellow hiker, and Esh, the author of innumerable memes, for the fun times in and outside the office. I met amazing people at CERN that I would like to include in these acknowledgements: Glenn, dino-fanatic and software guru; Stefan, host of memorable Stefanfests; Amy, my favourite hiking partner; Simone, my theatre boss and owner of a Beethoven bust; and Federica, who introduced me to the joy of half marathons. Thanks to them, my staying at CERN was an amazing and unique experience. Finally, a big grazie to my parents and brothers, who supported me all the time. Grazie to the zagatori della valmorea that have been together with me since ever. A special grazie to Bobbi, who patiently listened to my stressed rants, and to Erika and Federico. iii AUTHOR’S DECLARATION declare that the work in this dissertation was carried out in accordance with the requirements of the University’s Regulations and Code of Practice for Research IDegree Programmes and that it has not been submitted for any other academic award. Except where indicated by specific reference in the text, the work is the candidate’s own work. Work done in collaboration with, or with the assistance of, others, is indicated as such. Any views expressed in the dissertation are those of the author. SIGNED: .................................................... DATE: .......................................... v TABLE OF CONTENTS Page List of Tables xi List of Figures xiii 1 Introduction 1 1.1 Triggering at hadron and lepton colliders......................... 1 1.2 Historical background and present status of triggers.................. 3 1.3 Overview of the thesis .................................... 5 2 Physics at hadron colliders7 2.1 The standard model...................................... 7 2.2 The strong force........................................ 9 2.2.1 The parton model................................... 10 2.2.2 General properties of proton-proton collisions.................. 10 2.3 The signals........................................... 16 2.3.1 Electroweak physics................................. 16 2.3.2 Higgs sector...................................... 17 2.3.3 New physics...................................... 20 2.4 Summary............................................ 21 3 The LHC and CMS experiments 23 3.1 The Large Hadron Collider ................................. 23 3.1.1 The high-luminosity upgrade............................ 24 3.2 The CMS experiment..................................... 25 3.2.1 Silicon tracker .................................... 26 3.2.2 Electromagnetic and hadron calorimeters.................... 27 3.2.3 Muon chambers.................................... 28 3.3 The Level-1 Trigger...................................... 29 3.3.1 Overview of the CMS trigger system....................... 29 3.3.2 The Phase-1 Level-1 Trigger............................ 30 vii TABLE OF CONTENTS 3.3.3 The Phase-2 Level-1 trigger ............................ 33 3.4 Summary............................................ 38 4 Design and study of a jet and sum trigger algorithm 41 4.1 Overview of the development of a trigger algorithm................... 41 4.2 The Phase-1 jet and sum algorithms............................ 42 4.3 The Phase-2 jet and sum algorithms............................ 44 4.3.1 Jet calibration..................................... 45 4.4 Performance of the jet and sum trigger algorithm.................... 46 4.4.1 Jet energy corrections................................ 47 4.4.2 Jet area study..................................... 48 4.4.3 Performance of the histogrammed jet algorithm ................ 51 4.4.4 Performance of the energy sum algorithms ................... 57 4.4.5 Trigger efficiency and rates............................. 59 4.5 Conclusions........................................... 62 5 Implementation of the Phase-2 jet and sum trigger algorithm 65 5.1 High-Level Synthesis workflow............................... 65 5.2 The inputs ........................................... 67 5.3 Design of the algorithm.................................... 68 5.3.1 The histogrammer.................................. 69 5.3.2 The jet and sum finder ............................... 70 5.4 The jet trigger demonstrator ................................ 73 5.4.1 Inputs ......................................... 73 5.4.2 Implementing the jet trigger demonstrator ................... 74 5.4.3 Validation of the jet trigger algorithm demonstrator.............. 77 5.5 Scaling to the final design.................................. 79 5.6 Future work .......................................... 81 5.7 Conclusions........................................... 82 6 Triggers at the Future Circular Collider hadron collider 83 6.1 The FCC-ee and FCC-eh projects.............................. 83 6.1.1 FCC-ee......................................... 83 6.1.2 FCC-eh......................................... 85 6.2 FCC-hh experiment...................................... 85 6.2.1 QCD physics at FCC-hh............................... 85 6.2.2 Goals.......................................... 86 6.2.3 FCC-hh detector ................................... 86 6.3 Triggering at FCC-hh..................................... 88 viii TABLE OF CONTENTS 6.3.1 Trigger architectures at FCC-hh.......................... 88 6.3.2 Trigger inputs..................................... 89 6.4 Estimation