The work described in this PhD thesis is a study of a real implementation of a track-finder system which could provide reconstructed high transverse momentum tracks to the first-level trigger of the High Luminosity LHC upgrade of the CMS experiment. This is vital for the future success of CMS, since otherwise it will be impossible to achieve the trigger selectivity needed to contain the very high event rates. The unique and extremely challenging requirement of the system is to utilise the enormous volume of tracker data within a few microseconds to arrive at a trigger decision. The track-finder demonstrator described proved unequivocally, using existing hardware, that a real-time track-finder could be built using present-generation FPGA-based technology which would meet the latency and performance requirements of the future tracker. This means that more advanced hardware customised for the new CMS tracker should be even more capable, and will deliver very significant gains for the future physics returns from the LHC.
This second open access volume of the handbook series deals with detectors, large experimental facilities and data handling, both for accelerator and non-accelerator based experiments. It also covers applications in medicine and life sciences. A joint CERN-Springer initiative, the "Particle Physics Reference Library" provides revised and updated contributions based on previously published material in the well-known Landolt-Boernstein series on particle physics, accelerators and detectors (volumes 21A, B1,B2,C), which took stock of the field approximately one decade ago. Central to this new initiative is publication under full open access
This informative monograph describes the technological evolution of silicon detectors and their impact on high energy particle physics. The author here marshals his own first-hand experience in the development and also the realization of the DELPHI, CDF II and the CMS tracking detector. The basic principles of small strip- and pixel-detectors are presented and also the final large-scale applications. The Evolution of Silicon Detector Technology acquaints readers with the manifold challenges involving the design of sensors and pushing this technology to the limits. The expert will find critical information that is so far only available in various slide presentation scattered over the world wide web. This practical introduction of silicon sensor technology and its day to day life in the lab also offers many examples to illustrate problems and their solutions over several detector generations. The new edition gives a detailed overview of the silicon sensor technology used at the LHC, from basic principles to actual implementation to lessons learned.
These two volumes present the proceedings of the International Conference on Technology and Instrumentation in Particle Physics 2017 (TIPP2017), which was held in Beijing, China from 22 to 26 May 2017. Gathering selected articles on the basis of their quality and originality, it highlights the latest developments and research trends in detectors and instrumentation for all branches of particle physics, particle astrophysics and closely related fields. This is the first volume, and focuses on the main themes Gaseous detectors, Semiconductor detectors, Experimental detector systems, Calorimeters, Particle identification, Photon detectors, Dark Matter Detectors and Neutrino Detectors. The TIPP2017 is the fourth in a series of international conferences on detectors and instrumentation, held under the auspices of the International Union of Pure and Applied Physics (IUPAP). The event brings together experts from the scientific and industrial communities to discuss their current efforts and plan for the future. The conference’s aim is to provide a stimulating atmosphere for scientists and engineers from around the world.
In this work, the interaction between the Higgs boson and the top quark is studied with the proton-proton collisions at 13 TeV provided by the LHC at the CMS detector at CERN (Geneva). At the LHC, these particles are produced simultaneously via the associate production of the Higgs boson with one top quark (tH process) or two top quarks (ttH process). Compared to many other possible outcomes of the proton-proton interactions, these processes are very rare, as the top quark and the Higgs boson are the heaviest elementary particles known. Hence, identifying them constitutes a significant experimental challenge. A high particle selection efficiency in the CMS detector is therefore crucial. At the core of this selection stands the Level-1 (L1) trigger system, a system that filters collision events to retain only those with potential interest for physics analysis. The selection of hadronically decaying τ leptons, expected from the Higgs boson decays, is especially demanding due to the large background arising from the QCD interactions. The first part of this thesis presents the optimization of the L1 τ algorithm in Run 2 (2016-2018) and Run 3 (2022-2024) of the LHC. It includes the development of a novel trigger concept for the High-Luminosity LHC, foreseen to start in 2027 and to deliver 5 times the current instantaneous luminosity. To this end, sophisticated algorithms based on machine learning approaches are used, facilitated by the increasingly modern technology and powerful computation of the trigger system. The second part of the work presents the search of the tH and ttH processes with the subsequent decays of the Higgs boson to pairs of τ lepton, W bosons or Z bosons, making use of the data recorded during Run 2. The presence of multiple particles in the final state, along with the low cross section of the processes, makes the search an ideal use case for multivariant discriminants that enhance the selectivity of the signals and reject the overwhelming background contributions. The discriminants presented are built using state-of-the-art machine learning techniques, able to capture the correlations amongst the processes involved, as well as the so-called Matrix Element Method (MEM), which combines the theoretical description of the processes with the detector resolution effects. The level of sophistication of the methods used, along with the unprecedented amount of collision data analyzed, result in the most stringent measurements of the tH and ttH cross sections up to date.
This open access book is a comprehensive review of the methods and algorithms that are used in the reconstruction of events recorded by past, running and planned experiments at particle accelerators such as the LHC, SuperKEKB and FAIR. The main topics are pattern recognition for track and vertex finding, solving the equations of motion by analytical or numerical methods, treatment of material effects such as multiple Coulomb scattering and energy loss, and the estimation of track and vertex parameters by statistical algorithms. The material covers both established methods and recent developments in these fields and illustrates them by outlining exemplary solutions developed by selected experiments. The clear presentation enables readers to easily implement the material in a high-level programming language. It also highlights software solutions that are in the public domain whenever possible. It is a valuable resource for PhD students and researchers working on online or offline reconstruction for their experiments.
The standard model of particle physics provides a coherent description of highenergy physics processes and has been hugely successful in providing experimental predictions. Among its long list of achievements, the most significant is arguably that of the discovery of the Higgs boson half a century after being theorised, providing the last cornerstone needed for the standard model to become fully consistent. Despite huge successes, the standard model still suffers from major shortcomings. On the path leading towards a better understanding of particle physics, an in-depth study of the Higgs boson is key. This relentless work of characterising the properties of the Higgs boson is currently being undertaken at the Large Hadron Collider, where high-energy proton collisions are being recorded by dedicated detectors, providing a continuous improvement to the understanding of the standard model. Amid tremendous achievements, some processes, remain too weak to be detected with the current installations. One such measurement is the combined production of two Higgs bosons allowing for a direct handle on the Higgs self-coupling parameter of the standard model. To maximise the physics reach of the collider, it will be subjected to a major upgrade, allowing for a strong increase in luminosity. Such a dramatic change will bring major challenges to the experiments recording these collisions and upgrades are required if they are to maintain their outstanding performance. This thesis explores the upgrade of the CMS silicon strip detector, centred around the in-beam characterisation of detector module prototypes and discusses the physics reach of the upgraded machine, with an emphasis on Higgs boson pair production in the bbWW(l) final state.
The exploration of the subnuclear world is done through increasingly complex experiments covering a wide range of energies and in a large variety of environments OCo from particle accelerators and underground detectors to satellites and space laboratories. For these research programs to succeed, novel techniques, new materials and new instrumentation need to be used in detectors, often on a large scale. Hence, particle physics is at the forefront of technological advancement and leads to numerous applications. Among these, medical applications have a particular importance due to the health and social benefits they bring. This volume reviews the advances made in all technological aspects of current experiments in the field."
