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1
Perrin, Océane. "Étude de l'autocouplage du boson de Higgs avec le détecteur ATLAS au LHC. Performance d'un détecteur en temps pour la phase de Haute luminosité du LHC". Electronic Thesis or Diss., Université Clermont Auvergne (2021-...), 2023. http://www.theses.fr/2023UCFA0164.
Abstract (sommario):
Une particule ayant une masse de 125 GeV a été observée en 2012 grâce au grand collisionneur de hadrons (Large Hadron Collider - LHC) par les collaborations ATLAS et CMS. Cette particule fut associée au boson de Higgs ou boson BEH, dont l'existence fut prédite en 1964 par François Englert, Robert Brout et Peter Higgs. Cette particule permit de valider l'existence du mécanisme BEH, expliquant l'origine de la masse des particules découverte dès lors et de la brisure de symétrie électrofaible.Depuis sa découverte, il est devenu crucial de sonder les différentes propriétés que l'on confère au boson de Higgs. En particulier, l'auto-couplage du boson de Higgs est une des propriétés les plus attendues et une mesure de ce paramètre permettrait d'obtenir une mesure directe du potentiel de Higgs dans le vide. Cette mesure se réalise grâce à la production de di-Higgs au LHC, en exploitant différents canaux de désintégrations.Cette thèse porte sur l'étude de la désintégration de la paire de boson de Higgs en deux leptons légers de même charge (appelé signature ou 2lSS), dans le cadre du Run2 du LHC correspondant à une luminosité intégrée de 139 fb⁻¹ et une énergie de centre de masse de √s = 13TeV. L'étude utilise des simulations Monte-Carlo et vise à développer une stratégie basée sur le machine Learning afin de maximiser la distinction entre le signal (2lSS issues de la désintégration de la paire de Higgs) et les bruits de fond (ensemble des processus produisant la signature). Une étude sur l'estimation des bruits de fond ainsi que sur l'estimation des incertitudes systématiques y sont aussi présentées.Enfin, bien que la mesure de l'auto-couplage puisse être contrainte par le Run2, sa mesure directe est attendue pour la phase de haute luminosité du LHC (HL-LHC). Cette phase implique une augmentation de la luminosité instantanée par un facteur 5, nécessitant une actualisation du détecteur ATLAS afin de garantir des performances comparables à celles du Run2, malgré l'augmentation des radiations et de l'effet d'empilement. De ce fait, un nouveau détecteur en temps à haute granularité (HGTD) sera ajouté. Une étude portant sur l'électronique de lecture de ce futur détecteur est présentée dans cette thèse, déterminant les performances en banc de tests ou lors de tests d'irradiationsA bosonic particle with a mass equal to 125GeV was observed in 2012, by ATLAS and CMS collaborations at the Large Hadron Collider (LHC). This particle was associated with the Higgs Boson or BEH boson, predicted fifty years before its discovery by François Englert, Robert Brout and Peter Higgs. This particle validates the BEH mechanism, explaining the origin of the mass of known particles and the electroweak symmetry breaking.Since its discovery, it has become crucial to probe the various properties of the Higgs boson such as the Higgs self-coupling. The success in probing Higgs self-coupling will bring another probe of the standard model and will provide a direct measurement of the Higgs field potential in the vacuum. This measure is performed through a global analysis of the di-Higgs (HH) production at LHC, decaying into various channels.This thesis focuses on the study of the decay of the Higgs boson pair into two light leptons with the same charge (referred to as 2lSS) within the context of the Run2 at LHC, providing an integrated luminosity of 139 fb⁻¹ and a centre of mass energy of √s = 13 TeV. The study based on Monte-Carlo simulations aims to develop a machine learning-based strategy to discriminate the signal (2lSS originating from the decay of the Higgs boson pair ) from the background (all other processes producing 2lSS events). An analysis of background noise estimation and systematic uncertainty estimation is also presented in this work.Finally, although the measurement of the self-coupling can be constrained by Run2, its direct measurement is expected in the High-Luminosity phase of the LHC (HL-LHC). This phase involves a five-fold increase in instantaneous luminosity, requiring an upgrade of the ATLAS detector to ensure performance comparable to Run2 performances, despite the increase of radiation and pile-up effects. As a result, a new high-granularity timing detector (HGTD) will be added. A study on the readout electronics of this future detector is presented in this thesis, determining its performance in the test bench and during irradiation tests
2
Köhler, Michael [Verfasser], e Karl [Akademischer Betreuer] Jakobs. "Double-sided 3D silicon detectors for the high-luminosity LHC = Doppelseitige 3D-Siliziumdetektoren für den High-Luminosity LHC". Freiburg : Universität, 2011. http://d-nb.info/1123462038/34.
3
White, S. "Determination of the absolute luminosity at the LHC". Phd thesis, Université Paris Sud - Paris XI, 2010. http://tel.archives-ouvertes.fr/tel-00537325.
Abstract (sommario):
Les paramètres les plus importants décrivant les performances d'un collisionneur de particules sont l'énergie et la luminosité. Les hautes énergies permettent aux expériences de physique des particules d' étudier de nouveaux effets. La luminosité décrit la capacité du collisionneur à produire le nombre requis d'interactions utiles ou événements. Le Large Hadron Collider (Grand Collisionneur de Hadron) ou LHC a été conçu pour produire des collisions proton proton à une énergie dans le centre de masse de 14 TeV. Cette énergie est la plus haute jamais atteinte jusqu'alors dans un accélérateur de particules. Les connaissances et la compréhension de la physique des particules à de telles énergies sont basées sur des simulations et des prédictions théoriques. Contrairement aux collisionneurs électron positron pour lesquels la section efficace de diffusion de Bhabba peut être précisément calculée et utilisée pour calibrer la luminosité, il n'existe pas de processus ayant une section efficace bien connu et un taux de production suffisant pour être utilisé afin de calibrer la luminosité durant les premières années d'opération du LHC. La luminosité peut aussi être exprimée en fonction du nombre de charges par faisceau et leur taille au point d'interaction. Il est donc possible d'utiliser cette propriété afin de déterminer la luminosité à partir des paramètres machine. La détermination de la luminosité absolue a partir des paramètres machine est une méthode alternative à celle utilisant les sections efficaces et offre des informations complémentaires au modèle de fragmentation. Pour le LHC, il a été proposé d'utiliser la méthode développée par S. Van Der Meer à ISR afin d'offrir une calibration de la luminosité aux expériences de physique des particules durant les premières années d'opération. Cette thèse décrit comment cette méthodea été implémentée et utilisée pour la première fois au LHC afin d'optimiser et de calibrer la luminosité. Des études complémentaires d'optique linéaire et de dynamique faisceau ainsi que des mesures faites pour le collisionneur RHIC sont aussi décrites. Cette étude commence par un chapitre introductif qui reprend les notions de physique des accélérateurs nécessaire à la compréhension des chapitres suivants. Les équations décrivant les mouvements des particules dans un accélérateur circulaire sont rappelées ainsi que les principes de base d'optique linéaire. Des grandeurs caractéristiques du faisceau et de la machine telles que l'émittance ou le tune sont définies. Une brève introduction aux effets faisceau-faisceau est aussi présentée ces derniers étant inhérent aux collisionneurs de particules. Une description plus détaillée du concept de luminosité est donnée. Les équations générales de luminosité en présence d'effets tel qu'un angle de croisement sont dérivées. Enfin différentes méthodes permettant de déterminer la luminosité absolue sont présentées et le choix de la méthode de Van Der Meer pour les premiéres années d'opérations du LHC est expliqué. Le second chapitre se concentre sur la méthode de Van Der Meer. Le principe développé par S. Van Der Meer est décrit et plus particulièrement comment cette méthode offre une mesure directe de l'intégrale de recouvrement, décrivant la région d'interaction des deux faisceaux, sans avoir besoin de connaître les distributions initiales des faisceaux. L'impact des différents effets présentés dans le chapitre1 sur la précision de la mesure sont étudiés analytiquement afin de déterminer les paramètres faisceau optimaux pour une mesure de la luminosité absolue. Enfin une estimation de l'erreur sur la détermination de la luminosité basée sur des études numériques et les spécifications des instruments utilisés durant cette mesure est donnée. Le chapitre 3 présente le LHC et comment les principaux paramètres faisceau ont été choisis afin de délivrer une luminosité de 1034 cm−2 s−1 aux expériences ATLAS et CMS. Quelques dates clé de la mise en route du LHC sont rappelées afin de justifier l'orientation de certaines études présentées dans cette thèse et comment il a été nécessaire de s'adapter au changement de programme de mise en marche du LHC. Les différentes étapes permettant d'accélérer et de mettre les faisceaux en collision à partir de l'injection sont brièvement décrites. Dans le cadre de cette thèse des études concernant plus particulièrement la mise en collision des faisceaux dans le LHC. Des simulations de l'impact sur l'orbite des effets d'hystérésis présents dans les aimants permettant de déplacer les faisceaux au point d'interaction ainsi que la manière dont ceux-ci sont utilisés pour générer l'angle de croisement, la séparation ou l'optimisation des collisions sont décrites. Lors de la mise en collision des faisceaux de nombreux effets liés à la dynamique faisceau et plus particulièrement aux effets faisceau-faisceau entrent en jeux. Des simulations permettant de modéliser ces effets et de comprendre leur impact sur l' émittance ont été réalisées et seront aussi décrites dans ce chapitre. Le chapitre 4 donne une description des divers instruments utilisés lors de l'analyse des données permettant de déterminer la luminosité absolue. En principe, seules les mesures de courant sont nécessaires pour déterminer la luminosité. Des informations complémentaires et qui se sont révélées très utiles par la suite ont été données par d'autre instruments tel que les wire-scanner permettant de mesurer l' émittance ou les BPM permettant déterminer la trajectoire des faisceaux le long de l'anneau. Ces instruments sont donc aussi décrits dans ce chapitre. Enfin, le LHC est équipé de moniteurs de luminosité donc le but est de fournir des signaux robustes grâce auxquels il est possible d'optimiser la luminosité. Ce chapitre se termine donc sur une description détaillée de ces moniteur de luminosité et les simulations qui ont été faites a l'aide du logiciel FLUKA afin de déterminer les performances et l'efficacité de ces moniteurs à haute énergie. Le chapitre 5 présente les résultats des mesures effectuées sur le collisionneur RHIC (relativistic ion collider). Ces mesures ont été effectuées en 2009 alors que le LHC était stoppé suite à l'incident de Septembre 2008. RHIC présente certaines caractéristiques communes au LHC et représente donc un excellent test pour les futures mesures au LHC. La calibration de la luminosité par la méthode de Van Der Meer est aussi utilisée à RHIC, une collaboration avec ce laboratoire a donc été mise en place afin de profiter de l'expérience acquise par le passé dans ce laboratoire. Malgré certains paramètres faisceaux non optimisées pour une mesure de précision de la luminosité absolue il a été possible de déterminer celle-ci avec une précision de 7% dominée par l'erreur sur les mesures de courant et la détermination du déplacement des faisceaux. Une étude détaillée des différentes sources d'erreur ainsi que des propositions pour les réduire lors de futures mesures sont présentées. Les faisceaux du collisionneur RHIC ont un courant élevé ce qui n'est pas optimal pour la détermination de la luminosité absolue mais a permis d'observer certains effets faisceau-faisceau qui n'avaient pas été observé par le passé à RHIC et présentent donc un résultat très intéressant de ce chapitre. Le chapitre 7 présente les résultats obtenus en 2010 au LHC. L'année 2010 a été une année de beaucoup de premères pour le LHC auxquelles j'ai eu la chance de participer. J'ai notamment été impliqué dans l'établissement des premères collisions, les premières optimisations de luminosité. Ces trois contributions sont décrites dans ce chapitre ainsi que les outils développés afin de réaliser ces mesures et plus particulièrement le logiciel d'optimisation et de calibration de la luminosité qui est décrit plus en d étail dans les annexes. Enfin l'année 2010 a aussi vu la première calibration de la luminosité utilisant la méthode de Van Der Meer à 3.5TeV. Le protocole de la méthode est présenté ainsi qu'une étude détaillée des erreurs systématiques associées a cette méhode. Ces premières mesures ont permis de déterminer la luminosité avec une précision de 11% largement dominée par les mesures de courant des faisceaux. Pour terminer, des propositions pour améliorer la précision des futures mesures sont présentées. Le dernier chapitre de cette thèse présente des travaux effectués sur les optiques de beta élevés. Ces optiques ont été développées pour les expériences TOTEM et ATLAS et permettront de mesurer précisément les angles de diffusion élastiques des interactions proton-proton et ainsi déterminer leur section efficace. Cette méthode présente un alternative a la méthode de Van Der Meer et devrait en principe donner une mesure de section efficace avec une précision de quelques pour cents. Ces optiques étant très difficiles ils ne pourront pas être mis en place avant que le LHC atteigne son énergie nominale de 7TeV par faisceau. Des optiques intermédiaires ont donc aussi été développées et sont présentées brièvement dans ce dernier chapitre.
4
Laface, Emanuele. "Selected issues for the LHC luminosity upgrade". Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2008. http://tel.archives-ouvertes.fr/tel-00377619.
Abstract (sommario):
Le grand collisionneur d'hadrons (LHC) a commencé les opérations de faisceau de protons le 10 septembre 2008. Respectant le programme prévu pour les prochaines années, le LHC devrait démontrer ou réfuter l'existence du boson de Higgs de façon réaliste d'ici 2014. Après cette date il est raisonnable de prévoir l'amélioration de la luminosité de la machine pour explorer en détail la physique des événements rares.Le présent travail de thèse propose différentes idées pour augmenter la luminosité des expériences ATLAS et CMS, les deux principales expériences du programme scientifique du LHC. Une idée pour l'amélioration de l'acceptance de l'expérience TOTEM est aussi présentée.
L'ensemble des aimants qui réalisent la focalisation finale du faisceau avant la collision ont été pris en considération pour augmenter la luminosité dans les zones expérimentales. Les nouvelles configurations ont été étudiées en utilisant des méthodes d'optique des accélérateurs et de dynamique des faisceaux. L'intégration des solutions a été aussi explorée en analysant les énergies déposées dans les différents éléments et les tolérances des alignements.
Un nouveau schéma optique pour augmenter l'acceptance de l'expérience TOTEM utilisant les cristaux de silicium est aussi présenté. Les résultats attendus sont comparés avec les résultats actuels.
Les études ont été menées en utilisant des méthodes analytiques pour les considérations générales et des méthodes numériques pour l'optimisation des paramètres.
Les résultats présentés dans cette thèse ont été publiés et présentés dans différentes conférences et workshops internationaux.
5
Vázquez, Furelos David. "3D pixel sensors for the high luminosity LHC ATLAS detector upgrade". Doctoral thesis, Universitat Autònoma de Barcelona, 2019. http://hdl.handle.net/10803/669548.
6
James, Tom. "A hardware track-trigger for CMS at the High Luminosity LHC". Thesis, Imperial College London, 2018. http://hdl.handle.net/10044/1/60593.
Abstract (sommario):
The Compact Muon Solenoid (CMS) experiment at the Large Hadron Collider (LHC) is designed to study a wide range of high energy physics phenomena. It employs a large all-silicon tracker within a 3.8 T magnetic solenoid, which allows precise measurements of transverse momentum (pT) and vertex position. This tracking detector will be upgraded to coincide with the installation of the High-Luminosity LHC, which will provide up to about 10^35 / cm^2 / s to CMS, or 200 collisions per 25 ns bunch crossing. This new tracker must maintain the nominal physics performance in this more challenging environment. Novel tracking modules that utilise closely spaced silicon sensors to discriminate on track pT have been developed that would allow the readout of only hits compatible with pT > 2−3 GeV tracks to off-detector trigger electronics. This would allow the use of tracking information at the Level-1 trigger of the experiment, a requirement to keep the Level-1 triggering rate below the 750 kHz target, while maintaining physics sensitivity. This thesis presents a concept for an all Field Programmable Gate Array (FPGA) based track finder using a fully time-multiplexed architecture. A hardware demonstrator has been assembled to prove the feasibility and capability of such a system. The track finding demonstrator uses a projective binning algorithm called a Hough Transform to form track-candidates, which are then cleaned and fitted by a combinatorial Kalman Filter. Both of these algorithms are implemented in FPGA firmware. This demonstrator system, composed of eight Master Processor Virtex-7 (MP7) processing boards, is able to successfully find tracks in one eighth of the tracker solid angle at a time, within the expected 4 μs latency constraint. The performance for a variety of physics scenarios is studied, as well as the proposed scaling of the demonstrator to the final system and new technologies.
7
POULIOS, STAMATIOS. "Data compression for the CMS pixel detector at High-Luminosity LHC". Doctoral thesis, Università di Siena, 2017. http://hdl.handle.net/11365/1013403.
Abstract (sommario):
The High Luminosity run of the Large Hadron Collider (HL-LHC), foreseen to start in ~2026, will increase the delivered luminosity by roughly an order of magnitude compared to its original design, allowing to collect a statistics of about 3000 fb^(-1) . This large amount of data will consent a deeper study of the Standard Model of particle physics, searching for physics beyond it. In order to sustain the high collision rate and higher radiation doses, as well as to increase the precise reconstruction of the charged track trajectories, a new Silicon Pixel detector will be installed in the CMS experiment. This will guarantee better impact parameter measurements to detect b-quarks and tau-leptons from the top-quark and Higgs-boson decays, which are believed to offer the best opportunities to investigate physics beyond the Standard Model. Such an improved Silicon Pixel detector will require unprecedented radiation tolerance (up to 1 Grad) and should offer "intelligent" data processing in the front-end chip, while keeping low power and low material budget. The readout chip will be developed in planar 65 nm technology. This is the first time that this technology will be used in High-Energy physics experiments, due to the complexity of the rules for designing the analogue and digital circuitries: it is more radiation tolerant and less power hungry with respect to technologies used so far and allows to develop more logic in the
device area. This thesis describes the impact of the foreseen upgraded Silicon Pixel detector on the physics of CMS at HL-LHC through the precise measurement of charged track trajectories, by the reduction of the material budget using less readout cables through lossless data compression algorithms embedded in the pixel readout chip. The outcome is not only the reduction of the material budget due to the reduction of the number of cables, but also the further transmission stages can be reduced improving the power consumption of the silicon detector. Two lossless data compression techniques are studied, based on Huffman and arithmetic coding. The selection of these encoding methods was established by the implementation requirements. The data compression should be as simple as possible to avoid complex designs that lead to big and power consuming circuitry. In addition the compression should be very fast due to the very high readout rate of 750 MHz. The results give various
solutions with compression ratios ranging between 1.2 and 2.9 depending on the implementation complexity. This activity has been developed within the projects INFIERI (FP7-PEOPLE-2012-ITN, project number 317446), CHIPIX65 and RD53, respectively funded by EU, INFN and CERN.
8
Gkougkousis, Evangelos. "Etudes de bruit du fond dans le canal H→ZZ*→4l pour le Run 1 du LHC. Perspectives du mode bbH(→γγ) et études d'un système de détecteur pixel amélioré pour la mise à niveau de l'expérience ATLAS pour la phase HL-LHC". Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLS063/document.
Abstract (sommario):
La première prise des données du LHC (2010-2012) a été marquée par la découverte du boson scalaire, dit boson de Higgs. Sa masse a été mesurée avec une précision de 0.2% en utilisant ses désintégrations en deux photons et celles en deux bosons Z donnant quatre leptons dans l’état final. Les couplages ont été estimés en combinant plusieurs états finaux, tandis que la précision sur leur mesure pourra bénéficier énormément de la grande statistique qui sera accumulée pendant les prochaines périodes de prise des données au LHC (Run 2, Phase 2).Le canal H→ZZ*→4 leptons, a un rapport d'embranchement réduit mais présente un faible bruit de fond, ce qui le rend attractif pour la détermination des propriétés du nouveau boson. Dans cette thèse, l’analyse conduite pour la mise en évidence de ce mode dans l’expérience ATLAS est détaillée, avec un poids particulier porté à la mesure et au contrôle du bruit de fond réductible en présence d’électrons.Dans le cadre de la préparation de futures prises de données à très haute luminosité, prévues à partir de 2025, deux études sont menées:La première concerne l’observabilité du mode de production du boson de Higgs en association avec des quarks b. Une analyse multivariée, basée sur des données simulées, confirme un très faible signal dans le canal H→2 photons.La seconde concerne la conception et le développement d’un détecteur interne en silicium, adapté à l’environnement hostile, de haute irradiation et de taux d’occupation élevée, attendues pendant la Phase 2 du LHC. Des études concernant l’optimisation de la géométrie, l’amélioration de l’efficacité ainsi que la résistance à l’irradiation ont été menées. A travers des mesures SiMS et des simulations des procédés de fabrication, les profiles de dopage et les caractéristiques électriques attendues pour des technologies innovantes sont explorés. Des prototypes ont été testés sous faisceau et soumis à des irradiations, afin d’évaluer les performances du détecteur et celles de son électronique associéeThe discovery of a scalar boson, known as the Higgs boson, marked the first LHC data period (2010-2012). Using mainly di-photon and di-Z decays, with the latest leading to a four leptons final state, the mass of the boson was measured with a precision of <0.2%. Relevant couplings were estimated by combining several final states, while corresponding uncertainties would largely benefit from the increased statistics expected during the next LHC data periods (Run 2, Phase 2).The H→ZZ*→4l channel, in spite of its suppressed brunching ratio, benefits from a weak background, making it a prime choice for the investigation of the new boson’s properties. In this thesis, the analysis aimed to the observation of this mode with the ALTAS detector is presented, with a focus on the measurement and control of the reducible electron background.In the context of preparation for future high luminosity data periods, foreseen from 2025 onwards, two distinct studies are conducted:The first concerns the observability potential of the Higgs associated production mode in conjunction with two b-quarks. A multivariate analysis based on simulated data confirms a very weak expected signal in the H→di-photon channel.The second revolves around the conception and development of an inner silicon detector capable of operating in the hostile environment of high radiation and increased occupancy, expected during LHC Phase 2. Main studies were concentrated on improving radiation hardness, geometrical and detection efficiency. Through fabrication process simulation and SiMS measurements, doping profiles and electrical characteristics, expected for innovative technologies, are explored. Prototypes were designed and evaluated in test beams and irradiation experiments in order to asses their performances and that of associated read-out electronics
9
Gasperini, Simone. "Performance of the CMS barrel muon trigger algorithms for high luminosity LHC". Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amslaurea.unibo.it/17740/.
Abstract (sommario):
In questa tesi sono state misurate le prestazioni di un nuovo algoritmo per il trigger muonico locale delle camere a deriva di CMS
(Compact Muon Solenoid).
L'algoritmo è stato sviluppato e proposto da un gruppo di ricercatori dell'INFN di Padova, in vista del futuro upgrade sull'acceleratore di particelle LHC (Large Hadron Collider), che diventerà High Luminosity LHC, ed il rispettivo upgrade di CMS.
In particolare, sono stati svolti studi sulle efficienze e sulle risoluzioni spaziali del nuovo algoritmo comparandole con quelle del
sistema di trigger attualmente in uso.
Questo lavoro è stato realizzato sviluppando uno strumento di analisi che sfrutta il pacchetto software di ROOT.
Le misure di efficienza e risoluzione sono state ottenute con il metodo del Tag & Probe, utilizzando un campione di dati raccolti durante il run di collisioni protone-protone nel settembre 2018.
10
Succi, Giovanni. "Analysis of impregnated Niobium-Tin coils for the High-luminosity LHC magnets". Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amslaurea.unibo.it/17800/.
Abstract (sommario):
The High-luminosity project of the LHC calls for the employment of a new technology of superconducting magnets, which will make use of a material never used before, Nb3Sn. Some of the dipole magnets will be replaced inside the accelerator to enhance the collimating system of the beams and will be capable of producing magnetic fields in the order of 12 T, against the 8 T of the present machine.
Experimental tests were conducted at the cryogenic laboratory at CERN to study the thermal behavior of a sample of the 11 T dipole under AC losses, with typical values of the input power density in the order of the mW/cmᵌ. The sample was inserted into an open box of insulator, to get closer to real operation.
This thesis, which was carried out at the MSC (Magnets, Superconductors and Cryostats) Group at CERN, regards the development of a 1-D model of a radial line crossing the middle plane of a quadrant of the magnet. It is also representative of the materials in the section and it was used with the aim to study the temperature evolution and steady-state profiles in response to heat injections in the conductors, similar to those provided in the experiment.
The same model was adapted to reproduce results of quench tests carried out at the SM-18 facility on short models of the 11 T dipole. In such tests, inductive heaters were energized to release heat in the magnet, in order to trigger the quench phenomenon, starting from given operating conditions of current and field. Using magnetic field maps together with the parametrization of the superconducting material, it was possible to derive local values of the T_cs, thus employing the magnet as a temperature probe.
This work presents a detailed description of the model and of the hypothesis made to run the simulations, together with its validation obtained through the comparison with experimental tests cited above.
11
Hall, Ben. "Designing the four rod crab cavity for the high-luminosity LHC upgrade". Thesis, Lancaster University, 2012. http://eprints.lancs.ac.uk/76341/.
Abstract (sommario):
This thesis presents the design for a novel compact crab cavity for the HL-LHC upgrade at CERN, Geneva. The LHC requires 400MHz RF cavities that can provide up to 10MV transverse gradient across two to three cavities with suitably low surface fields for continual operation. As a result, a cavity design was required that would be optimised to these new parameters. From initial design studies based on Jefferson Laboratory’s CEBAF deflector, extensive optimization was carried out to design a superconducting crab cavity, dubbed the Four Rod Crab Cavity (4RCC). The design underwent several iterations throughout the course of the project due to changing requirements from CERN, particularly space requirements inside the LHC. In addition, it was decided that a focus on field flatness was required. An aluminium prototype was then constructed from the finalised and computer-simulated design to confirm the designed field flatness. Additional computer simulation studies using CST were performed to ensure that multipacting and higher order modes were at tolerable levels. Design considerations were made to ensure a niobium prototype could be constructed for cold testing, the results of which are presented along with discussion of future plans for continuing to further the design of the cavity.
12
Gradin, Joakim. "Design and performance studies of a track trigger for the high luminosity LHC". Thesis, Uppsala universitet, Högenergifysik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-208691.
Abstract (sommario):
At the high luminosity LHC the current L1 trigger of ATLAS will not be able to reduce the number of events to a level accepted by the higher level triggers. It is therefore of importance to implement new strategies of triggering to be able to continue successful operation. This study examined an RoI-seeded muon track trigger in the Higgs to tau-tau to mu-mu channel and found that the ability to select signal events was very good, even at five times rejection of soft minimum bias events compared to the current trigger. The overall trigger efficiency for selected signal muons is decreased by less than 4% with smearing of track transverse momenta up to ten times coarser than the current offline resolution.
13
Gonella, Laura [Verfasser]. "Low mass hybrid pixel detectors for the high luminosity LHC upgrade / Laura Gonella". Bonn : Universitäts- und Landesbibliothek Bonn, 2013. http://d-nb.info/1045276553/34.
14
Da, Ros Bryan. "Automatizzazione dei controlli di qualità per i sensori dei moduli dell'Inner Tracker dell'esperimento ATLAS per HL-LHC". Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amslaurea.unibo.it/17813/.
Abstract (sommario):
Il lavoro della mia tesi consiste nell'automatizzazione dei controlli di qualità dei moduli che andranno installati nel nuovo rivelatore interno di ATLAS, l'Inner Tracker, per la Fase II di LHC, High Luminosity - LHC.
Per questa fase è previsto un incremento sostanziale della luminosità integrata e del pile-up delle collisioni.
Pertanto, alcuni dei rivelatori che LHC ospita subiranno importanti modifiche.
Il ruolo dell' INFN, nell'ambito della costruzione di ITk, è di progettare uno dei suoi end-cap. La realizzazione dei moduli che vi saranno installati comprende fasi di costruzione e assemblaggio, alcune delle quali effettuate dall'industria, e fasi di controllo di qualità dei componenti, di cui se ne occupano i laboratori.
In particolare, la Sezione di Bologna ha il compito di testare e qualificare i moduli che dovranno essere installati nel nuovo detector. I test di qualità comprendono test ai sensori, ai chip e al loro collegamento.
Il mio contributo è stato quello di automatizzare le scansioni che verranno effettuate sui sensori dei 2000 moduli che l'INFN riceverà: trattandosi di rivelatori a semiconduttore che funzionano come diodi, il test più importante è la misura della caratteristica IV. Grazie al lavoro svolto per questa tesi, sarà possibile effettuare la misura su quattro moduli, collegati simultaneamente ad un unico power supply, in maniera sequenziale.
Il mio lavoro ha contribuito a velocizzare i tempi di misura delle curve IV e a minimizzare l'intervento manuale da parte di chi effettuerà le misure.
15
Mereghetti, Alessio. "Performance evaluation of the SPS scraping system in view of the high luminosity LHC". Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/performance-evaluation-of-the-sps-scraping-system-in-view-of-the-high-luminosity-lhc(600579c0-0877-415d-bf8d-32896497b5ff).html.
Abstract (sommario):
Injection in the LHC is a delicate moment, since the LHC collimation system cannot offer adequate protection during beam transfer. For this reason, a complex chain of injection protection devices has been put in place. Among them, the SPS scrapers are the multi-turn cleaning system installed in the SPS aimed at halo removal immediately before injection in the LHC. The upgrade in luminosity of the LHC foresees beams brighter than those currently available in machine, posing serious problems to the performance of the existing injection protection systems. In particular, the integrity of beam-intercepting devices is challenged by unprecedented beam parameters, leading to interactions potentially destructive. In this context, a new design of scrapers has been proposed, aimed at improved robustness and performance. This thesis compares the two scraping systems, i.e. the existing one and the one proposed for upgrade. Unlike any other collimation system for regular halo cleaning, both are "fast" systems, characterised by the variation of the relative distance between the beam and the absorbing medium during cleaning, which enhances the challenge on energy deposition values. Assets/liabilities of the two systems are highlighted by means of numerical simulations and discussed, with particular emphasis on energy deposition in the absorbing medium, time evolution of the beam current during scraping and losses in the machine. Advantages of the system proposed for upgrade over the existing one are highlighted. The analysis of the existing system takes into account present operational conditions and addresses the sensitivity to settings previously not considered, updating and extending past studies. The work carried out on the upgraded system represents the first extensive characterisation of a multi-turn cleaning system based on a magnetic bump. Results have been obtained with the Fluka-SixTrack coupling, developed during this PhD activity from its initial version to being a state-of-art tracking tool for cleaning studies in circular machines. Relevant contributions to the development involve the handling of time-varying impact conditions. An extensive benchmark against a test of the scraper blades with beam has been carried out, to verify the reliability of results. Effcts induced in the tested blades confirm the high values of energy deposition predicted by the simulation. Moreover, the comparison with the time profile of the beam intensity measured during scraping allowed the reconstruction of the actual settings of the blades during the test. Finally, the good agreement of the quantitative benchmark against readouts of beam loss monitors finally proves the quality of the analyses and the maturity of the coupling.
16
Eichhorn, Thomas [Verfasser], e Peter [Akademischer Betreuer] Schleper. "Development of Silicon Detectors for the High-Luminosity LHC / Thomas Eichhorn. Betreuer: Peter Schleper". Hamburg : Staats- und Universitätsbibliothek Hamburg, 2015. http://d-nb.info/1074642643/34.
17
Roff, Daniel. "The development of CVD diamond tracking detectors for high luminosity experiments at the LHC". Thesis, University of Bristol, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.266908.
18
Eichhorn, Thomas Valentin [Verfasser], e Peter [Akademischer Betreuer] Schleper. "Development of Silicon Detectors for the High-Luminosity LHC / Thomas Eichhorn. Betreuer: Peter Schleper". Hamburg : Staats- und Universitätsbibliothek Hamburg, 2015. http://nbn-resolving.de/urn:nbn:de:gbv:18-74550.
19
Abdel, khalek Samah. "Mesure de la section efficace totale proton-proton avec le détecteur ATLAS au LHC". Phd thesis, Université Paris Sud - Paris XI, 2013. http://tel.archives-ouvertes.fr/tel-00962261.
Abstract (sommario):
Celà fait maintenant presque 50 ans qu'on a découvert que la section efficace totale proton-proton augmentait avec l'énergie, alors qu'on pensait précédemment qu'elle deviendrait asymptotiquement constante. Les incertitudes des mesures sur les rayons cosmiques effectuées à haute énergie ne permettent pas de déterminer la forme exacte de l'augmentation de la section efficace avec l'énergie.Le LHC au CERN à Genève fournit des collisions avec une énergie jamais atteinte dans un accélérateur de particule. L'énergie dans le centre de masse était 7 TeV en 2010 - 2011, 8 TeV en 2012 et atteindra 14 TeV dans un futur proche. Le détecteur ATLAS installé sur un des quatre points d'interaction du LHC, est utilisé pour collecter le résultat des collisions proton-proton. Son sous-détecteur ALFA, situé à 240 m du point d'interaction, est utilisé pour détecter les proton résultant des collisions élastiques. ALFA est donc capable, dans certaines conditions particulières de l'optique, de mesurer la section efficace totale et la pente nucléaire.Le travail effectué durant cette thèse a permit de mesurer σtot = 94.88 ± 0.12 stat ± 1.56syst mb et b = 19.45 ± 0.05stat ± 0.31syst GeV-2 à 7 TeV.
20
LUCCHINI, MARCO TOLIMAN. "Evolution of the CMS ECAL performance and R&D Studies for Calorimetry Options at High Luminosity LHC". Doctoral thesis, Università degli Studi di Milano-Bicocca, 2014. http://hdl.handle.net/10281/54816.
Abstract (sommario):
In this thesis the evolution of the CMS ECAL Calorimeter performance during the HL-LHC operating condition is estimated.
A detailed picture of radiation damage in lead tungstate crystals is obtained with the analysis of beam test data.
Given the necessity of the upgrade of the CMS endcap calorimeters, new scintillators which can withstand high levels of radiation have been study as candidates for calorimetry application under HL-LHC conditions.
In particular, results obtained in test beam with calorimetric module made of brass and LuAG:Ce single crystalline fibers are presented.
21
Heller, M. "Mesure de la luminosité absolue et de la section efficace totale proton-proton dans l'expérience ATLAS au LHC". Phd thesis, Université Paris Sud - Paris XI, 2010. http://tel.archives-ouvertes.fr/tel-00491316.
Abstract (sommario):
Le Large Hadron Collider (LHC) au CERN à Genève délivrera bientôt des collisions avec une énergie jamais atteinte jusqu'alors dans un accélérateur de particules. Une énergie dans le centre de masse entre 10 et 14 TeV permettra de dépasser les frontières de la physique actuelle. Le détecteur ATLAS fera la chasse au boson de Higgs et recherchera une nouvelle physique au delà du modèle standard. Tout processus physique est décrit par sa section section efficace. Les détecteurs positionnés aux différents points de collision du LHC déterminerons les taux de comptage associés aux divers processus. Cependant, pour en déduire la section efficace associée, il faut connaître la luminosité. Pour l'expérience ATLAS, une mesure relative de la luminosité peut être fournie par quelques uns de ses sous-détecteurs. Cependant, pour calibrer ces détecteurs, une mesure absolue doit être effectuée. Le détecteur ALFA a été conçu pour mesurer le spectre de diffusion élastique qui permettra de déterminer la luminosité absolue et par la même occasion, la section efficace totale proton-proton fournissant ainsi un outils de calibration très précis, de l'ordre du %. Ces détecteurs, installés à 240 m de part et d'autre du point d'interaction sont appelés pots romains. Il s'agit d'un système mécanique permettant d'approcher un trajectographe à fibres scintillantes à une distance de l'ordre du millimètre du cœur du faisceau. La simulation de la mesure nécessite l'utilisation d'un logiciel de transport de particules chargées. Ce logiciel doit être soigneusement choisi car il sert à la détermination des protons perdus dans la séquence de l'accélérateur, entre le point d'interaction jusqu'aux détecteurs. L'impact des incertitudes systématiques qui affectent la mesure de la luminosité et de la section efficace totale est également déterminé en utilisant la simulation. Les détecteur ALFA opère dans un environnement complexe et en conséquence sa conception requiert une grande attention. Une large campagne de tests sur l'électronique front-end a été effectuée. L'analyses des données résultant de ces tests a permis de démontrer que toutes les exigences étaient remplies. A chaque avancement majeur dans la conception du détecteur, celui-ci doit être soumis à des tests en faisceau. Durant ces périodes, tous les aspects du détecteur sont étudiés. L'algorithme de reconstruction des traces, les méthodes pour extraire des données l'efficacité de détection ou encore le niveau de diaphonie sont autant de paramètres qu'il a fallu déterminer. Les conclusions de ces tests ont permis de valider les différents choix techniques effectués permettant ainsi le lancement de la fabrication en série des huit détecteurs utiles à la mesure. L'installation prévue courant 2011 permettra de mesurer la luminosité et la section efficace totale proton-proton courant 2012.
22
Beyer, Julien-Christopher [Verfasser], e Richard [Akademischer Betreuer] Nisius. "Optimisation of pixel modules for the ATLAS inner tracker at the high-luminosity LHC / Julien-Christopher Beyer ; Betreuer: Richard Nisius". München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2019. http://d-nb.info/118357228X/34.
23
GEROSA, RAFFAELE ANGELO. "Search for new particles decaying into vector boson pairs at LHC with the CMS detector and prospects for the vector boson scattering at the future High Luminosity LHC". Doctoral thesis, Università degli Studi di Milano-Bicocca, 2015. http://hdl.handle.net/10281/94351.
Abstract (sommario):
This thesis presents a three year work inside the Compact Muon Solenoid (CMS) collaboration, mainly focused on data analysis from proton-proton collisions collected by the Large Hadron Collider (LHC) at a centre of mass energy of 8 TeV (LHC Run-I).
My efforts were dedicated to searches for heavy particles decaying into di-boson pairs exploring boosted topologies, where the fragmentation products of hadronically decaying vector bosons overlap in the detector, preventing their identification as resolved jets.
Several benchmark scenarios for new physics have been considered, from heavy Standard Model (SM) like Higgs boson to beyond the SM (BSM) extensions of the Higgs sector and massive gravitons predicted by Warped Extra Dimension (WED) models.
In order to explore these boosted signatures, I developed specific algorithms to identify boosted vector bosons decaying hadronically (V-jets), which are also applied in other searches for new physics characterized high p_{T} jets originating from W/Z-boson, Higgs boson or top quark decays. These algorithms have been improved and new methods have been tested on detailed simulation, reproducing the conditions of the present data taking (LHC Run-II), and finally commissioned with first 13 TeV collisions.
In particular, I performed a semi-leptonic WW search for heavy resonances with 8 TeV data, as well as the combination with other exclusive searches in di-boson final states.
With no significant excess observed above the predicted background yield, upper limits have been produced in the context of massive gravitons predicted by Bulk and Randall-Sundrum WED models. Eventually, a model independent re-interpretation of the analysis is also performed.
In addition, I developed also a search for SM-like Higgs boson at high mass, in the boosted semi-leptonic WW final state. The analysis is categorised in exclusive jet bins to disentangle the gluon fusion production from the vector boson fusion mode. The result is also interpreted in the context of a BSM heavy Higgs scenario, called electroweak singlet model, which predicts the existence of two Higgs scalars with the mass of the lighter one being around 125 GeV. Upper limits on these models are set through an unbinned fit to the di-boson invariant mass spectrum, where a deviation with a local significance of about 2.5 $\sigma$ has been observed in the VBF category.
Eventually, I performed feasibility studies for the Vector Boson Scattering (VBS) in view of the CMS detector upgrade, foreseen for the high luminosity LHC (HL-LHC) data taking. If no evidence for new physics will be observed with Run-II collisions, this rare process would become crucial to search for BSM physics via precision electroweak measurements.
Two scattering topologies have been considered: the scattering of same sign W-boson pairs and the fully leptonic WZ boson one.
The ultimate goal is to assess the future CMS sensitivity to the longitudinal electroweak scattering, to partial unitarized scenarios and to new physics in the EWSB sector, which is parametrized through anomalies in the vector boson self couplings.
In addition, the difference in the performance between the proposed upgraded CMS detector and the present one, which will undergo a strong degradation due to radiation damage, is investigated showing how the upgraded technology allows better performances in all the considered benchmark measurements.
24
Calandri, Alessandro. "Propriétés du Boson de Higgs se désintégrant en 4 leptons au LHC dans l’expérience ATLAS : masse, limite sur la contribution à haute masse et sur la largeur". Thesis, Paris 11, 2015. http://www.theses.fr/2015PA112115/document.
Abstract (sommario):
Le thème des analyses présentées dans ce document est la mesure des propriétés du boson de Higgs se désintégrant dans le mode H→ZZ→4l dans l'expérience ATLAS au CERN. Le document commence par un résumé détaillé concernant la procédure d'étalonnage des électrons: l'algorithme de combinaison trace-cluster améliore la résolution en énergie (surtout pour les électrons ayant une faible énergie transverse) en exploitant les informations du cluster et de la trace dans un ajustement par maximum de vraisemblance. L'amélioration en résolution est approximativement de 18-20% pour les désintégrations du J/Ψ en di-électrons, et 3% pour Z→ee. Par la suite, la combinaison E-p est appliquée au canal H→ZZ→4l avec électrons dans l'état final permettant d’obtenir un gain modéré sur la distribution de la masse invariante (4-5%). En deuxième lieu, la masse du boson de Higgs et sa largeur sont estimées, en particulier afin de comprendre les effets apportés par l'utilisation de l'algorithme de combinaison trace-cluster. La masse a été calculée en se servant d'un ajustement à deux dimensions appliqué sur la masse invariante m4l et un score de discrimination du signal contre le bruit de fond ZZ*. Cette discrimination est obtenue en exploitant les corrélations angulaires dont les distributions sont sensibles au spin et à la parité du boson de Higgs. L’étude sur la largeur du boson est ensuite détaillée : les résultats sont basés sur une approche qui vise à contraindre cette largeur en analysant la région de haute masse m4l où le boson de Higgs se comporte comme un propagateur. La section efficace au pic de la résonance (« on-shell ») dépend de la largeur totale du boson de Higgs, ce qui n’est pas le cas pour la production dans la région de haute masse (« off-shell »). Par conséquent, des limites indirectes sur la largeur peuvent être déterminées en combinant les régions « on-shell » et « off-shell ». Une limite à 6.7 fois la largeur Higgs ΓSMH est obtenue via le canal 4l. En combinant la mesure « on-shell » avec tous les canaux de désintégration étudiés (notamment ZZ→4l, ZZ→2l2ν and WW→lνlν), les résultats aboutissent à une limite observée (attendue) sur la largeur totale de 22.7 (33.0) MeV. La dernière partie de ce travail de thèse est consacrée à l'analyse sur la largeur du boson de Higgs en quatre leptons à haute (High-Luminosity LHC) luminosité intégrée (respectivement 300 fb⁻¹ et 3000 fb⁻¹) : il s’agit d’une étude extrapolant à √s =14 TeV les techniques utilisées pour l’analyse à 8 TeV (Run 1)The theme of the analyses presented in this Thesis is the measurement of the Higgs boson properties in the H→ZZ→4l decay channel with the ATLAS experiment at the LHC. A detailed overview on the electron calibration process is first presented. In this regard, the track-cluster combination algorithm is found to improve the energy resolution of low ET electrons by exploiting both track and cluster information into a maximum likelihood fit. The improvement in resolution is approximately 18-20% for J/Ψ dielectron decays, and of the order of 3% for Z→ee events. In addition, the E-p combination algorithm has also been applied to the H→ZZ→4l channel with electrons in the final state resulting in a non-negligible gain on the invariant mass distribution (4-5%). Secondly, the Higgs mass and its total width are evaluated in the H→ZZ→4l channel. The Higgs mass is measured in the 4l decay channel with particular interest on the beneficial effects brought by the improved electron calibration and the track-cluster combination. The mass on the full 2011 and 2012 datasets is worked out with a 2-dimensional fit on the invariant mass of the 4 lepton final state, m4l, and on a boosted decision tree (BDT)-based output conceived against the main ZZ irreducible background and constructed on variables that are sensitive to the Higgs boson spin-parity state. Regarding the Higgs width, results are based on a relatively recent approach aimed at indirectly constraining the Higgs boson width by exploiting the m4l high-mass region where the Higgs boson acts as a propagator. The Higgs production cross section in the on-shell m4l region, where the Higgs boson is a resonance, depends on the total Higgs width, whereas this is not the case for the high mass m4l (off-shell). Limits on the Higgs width can be therefore set when merging the off-shell results with the on-shell ones. A limit of ∼ 6.7 times ΓSMH is obtained in the four lepton channel. Secondly, by combining with the on-shell measurement and using all the decay channels in the analysis, i.e. ZZ→4l, ZZ→2l2ν and WW→lνlν, the results lead to an observed (expected) 95% C.L. upper limit on the Higgs boson total width of 22.7 (33.0) MeV (4.2 MeV is the Standard Model predicted Higgs width at mH=125 GeV).The last section of the thesis is devoted to the evaluation of the Higgs width at √s=14 TeV in the high luminosity scenario (High Luminosity LHC), 300 fb⁻¹ and 3000 fb⁻¹, by employing the same techniques exploited in the previous Run 1 analysis at √s=8 TeV
25
Herkert, Adrian [Verfasser], e André [Akademischer Betreuer] Schöning. "Characterization of a Monolithic Pixel Sensor Prototype in HV-CMOS Technology for the High-Luminosity LHC / Adrian Herkert ; Betreuer: André Schöning". Heidelberg : Universitätsbibliothek Heidelberg, 2020. http://d-nb.info/1205002774/34.
26
Cavalier, Sophie. "Détermination des paramètres optiques nécessaires pour la mesure de la luminosité absolue et de la section efficace totale dans ATLAS". Phd thesis, Université Paris Sud - Paris XI, 2013. http://tel.archives-ouvertes.fr/tel-00870367.
Abstract (sommario):
ALFA (Absolute Luminosity for ATLAS) vise à mesurer la luminosité absolue pour l'expérience ATLAS avec une incertitude de 2 - 3\% et la section efficace totale. La luminosité est reliée au nombre d'événements. Plus la luminosité est élevée, plus le nombre d'événements est élevé. C'est donc une quantité importante pour les collisionneurs en général et notamment pour le LHC (Large Hadron Collider). LHC est constitué de deux faisceaux circulant dans deux chambres à vide différentes et collisionnant aux quatre points d'interaction où les principales expériences de physique sont positionnées (ATLAS, CMS, ALICE et LHCb). Les détecteurs constituant ALFA insérés dans des Pots Romains sont positionnés à 240 m de distance du point d'intéraction d'ATLAS après six quadrîpoles et deux dipôles qui constituent la partie de ligne faisceau utile à ALFA et localisée sur le LHC.Les détecteurs sont constitués de fibres scintillantes pour détecter les protons élastiques issus du Point d'Interaction. Ces protons sont transportés au travers des différents aimants qui constituent la ligne de faisceau considérée et qui nécessite une optimisation des paramètres optiques pour les besoins de la mesure. Nous appellerons les optiques fort β, les optiques utilisées durant les périodes expérimentales dédiées à ALFA. Les paramètres des optiques fort β ont été simulés afin de remplir le cahier des charges demandé pour ALFA et elles ont été testées sur le LHC en 2011 et 2012 pendant un certain nombre de périodes expérimentales spécifiques aux optiques fort β sur le LHC.Ces périodes expérimentales se sont terminées en 2013 avant l'arrêt du LHC. Les paramètres optiques ont été mesurés et comparés aux simulations.Certains paramètres ayant des valeurs bien meilleures que celles attendues. Cela a aussi permis de regardes quelques incertitudes sur les paramètres optiques et d'évaluer l'impact de certains de ces paramètres sur la mesure de section efficace totale.
27
Ali, Babar. "Study of the performance of the Level-1 track trigger in the H→ττ→ee channel in ATLAS at high luminosity LHC". Thesis, Uppsala universitet, Högenergifysik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-208333.
28
Hallsjö, Sven-Patrik. "Search for Dark Matter in the Upgraded High Luminosity LHC at CERN : Sensitivity of ATLAS phase II upgrade to dark matter production". Thesis, Linköpings universitet, Institutionen för fysik, kemi och biologi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-107583.
Abstract (sommario):
The LHC at CERN is now undergoing a set of upgrades to increase the center of mass energy for the colliding particles to be able to explore new physical processes. The focus of this thesis lies on the so called phase II upgrade which will preliminarily be completed in 2023. After the upgrade the LHC will be able to accelerate proton beams to such a velocity thateach proton has a center of mass energy of 14 TeV. One disadvantage of the upgrade is that it will be harder for the atlas detector to isolate unique particle collisions since more and more collisions will occur simultaneously, so called pile-up. For 14 TeV there does not exist a full simulation of the atlas detector. This thesis instead uses data from Monte Carlo simulations for the particle collisions and then uses so called smearing functions to emulate the detector responses. This thesis focuses on how a mono-jet analysis looking for different wimp models of dark matter will be affected by this increase in pile-up rate. The signal models which are in focus are those which try to explain dark matter without adding new theories to the standard model or QFT, such as the effective theory D5 operator and light vector mediator models. The exclusion limits set for the D5 operators mass suppression scale at 14 TeV and 1000 fb-1are 2-3 times better than previous results at 8 TeV and 10 fb-1. For the first time limits have been set on which vector mediator mass models can be excluded at 14 TeV.
29
Paggi, Giulia. "Sviluppo di un algoritmo di trigger per la ricerca di particelle esotiche a lunga vita media a High Luminosity LHC con il rivelatore di muoni di CMS". Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amslaurea.unibo.it/21605/.
Abstract (sommario):
In questa tesi si è sviluppato un nuovo algoritmo di trigger per la selezione di particelle esotiche, che fa uso delle DT di CMS, nel contesto dell'upgrade di rivelatore e sistema di trigger, in preparazione per HL-LHC. Si fa uso dell'algoritmo Analytical Method (AM) che genera i segmenti di trigger nelle camere DT, con una risoluzione temporale di alcuni ns, migliorando quasi di un ordine di grandezza le prestazioni rispetto al sistema attuale. Questo permette di aumentare l'accettanza di selezione per HSCP, che attraversano il rivelatore con una velocità significativamente minore di quella della luce. È stato sviluppato un algoritmo in grado di stimare, tramite un fit a due parametri, sia il valore di β = v/c di una particella, sia il tempo della collisione a cui è stata prodotta.
Per migliorare ulteriormente i risultati ottenuti, è stato sviluppato un metodo di correzione della misura di tempo nelle camere, considerando il tempo necessario a propagare il segnale attraverso il filo anodico fino all'elettronica di Front End. In questo modo è migliorata la risoluzione temporale dei segmenti di trigger e di conseguenza la stima sia del valore di β sia del tempo al momento della collisione. Per migliorare la stima
di β, si è vincolato il parametro temporale al valore nominale del bunch crossing ed è stato eseguito di nuovo il fit con un solo parametro libero. Combinando il prompt muon trigger e l'algoritmo proposto per HSCP, applicando a quest’ultimo un taglio in β ≤ 0.7 in modo da minimizzarne la sovrapposizione, si riesce a ottenere un'efficienza pari o maggiore del ≈ 90% fino a β ≈ 0.35. Per il campione usato si misura un incremento di accettanza che va dal 67.4% al 93.4%. Infine, con un campione di muoni, si è studiata la frequenza con cui vengono associati ad un BX precedente a quello corretto. Il risultato è il 4% del campione: buono, ma da ridurre migliorando ulteriormente l'algoritmo.
30
Morrone, Marco. "Thermomechanical study of complex structures in the aperture of superconducting magnets : application to the design of the High-Luminosity LHC shielded beam screen". Thesis, Imperial College London, 2018. http://hdl.handle.net/10044/1/60584.
Abstract (sommario):
In the framework of the High-Luminosity Large Hadron Collider (HL-LHC) project, a complex structure, known as the beam screen, will be installed by 2024 in the aperture of the inner triplet superconducting magnets nearby the ATLAS and CMS experiments. The beam screen is an octagonal shaped pipe that shields the 1.9 K magnet cryogenic system from the heat loads and damage to the magnet coils that would be otherwise induced by the highly penetrating collision debris. It also ensures that the vacuum conditions, required for the stability of the beam, are met. This thesis describes the design of the beam screen and proposes extensions to important components and features. The unknown physical properties of the beam screen materials have been characterised. The thermal behaviour of the beam screen during normal working conditions has been optimised by simulations and validated by measurements. The behaviour of the beam screen during a magnet quench, a resistive transition of the superconducting magnet, has been studied. Two magnet quench protection systems have been considered: the Quench Heaters (QH) by themselves and in conjunction with the Coupling Loss Induced Quench (CLIQ) device. To this purpose two innovative coupled multiphysic models have been developed, which have been verified by comparison with a closed form expression showing the advantages of considering self-inductance phenomena. In the case of the QH the force distribution per quadrant gives rise to forces up 330 N/mm in the beam screen closest to the interaction point, while in the case of the CLIQ a torque load-type is induced, whose maximum intensity is around 2 N m/mm. With the new multiphysic models an unprecedented level of accuracy has been achieved, which has permitted to demonstrate the mechanical integrity of the proposed beam screen design during a quench.
31
Bassalat, Ahmed. "Contribution to the construction of the Insertable B-Layer of ATLAS for high luminosity upgrade and Research for invisible Higgs". Thesis, Université Paris-Saclay (ComUE), 2015. http://www.theses.fr/2015SACLS245.
Abstract (sommario):
Pour la deuxième période de prise des données du LHC (Run 2) de 2015 - 2022, une quatrième couche de senseurs pixels a été installée dans le détecteur de l’existence ATLAS sur un tube de faisceau de plus petit diamètre afin d’ajouter de la redondance pour améliorer la reconstruction des trajectoires des particules chargées. Ce détecteur du pixel permettra d’assurer un suivi de la qualité de l’étiquetage des mesons b haute luminosité (b-tagging). Au cours des deux dernières années plusieurs composants ont été produits et assemblés sur des structures de soutien appelées échelles. Au total, 20 échelles ont été construites et qualifiées en cardere d’un procédé d’assurance qualité définie par ATLAS au CERN. Quatorze échelles ont été intégrées sur le tube de faisceau. Ceci constitue la première partie de la thèse dédiée à la partie construction du détecteur. La deuxième partie est consacrée à la recherche de boson de Higgs issu de collisions proton proton l’énergie du 8 TeV centre de masse de, se désintégrant en particules invisibles une luminosité integrée de 20.3 fb−1 enregistrées par le détecteur ATLAS au LHC. Les résultats sont interprétés dans les modèles de matière noire Higgs portail(Higgs portal Dark Matter)For Run 2 of the LHC a fourth, innermost Pixel Detector layer on a smaller radius beampipe has been installed in the ATLAS Detector to add redundancy against radiation damage ofthe current Pixel Detector and to ensure a high quality tracking and b-tagging performance ofthe Inner Detector over the coming years until the High Luminosity Upgrade. State of the artcomponents have been produced and assembled onto support structures known as staves overthe last two years. In total, 20 staves have been built and qualified in a designated QualityAssurance setup at CERN of which 14 have been integrated onto the beam pipe. In the secondpart, A search for a Higgs boson produced via vector-boson fusion and decaying into invisibleparticles is discussed, using 20.3 fb−1 of proton proton collision data at the centre of massenergy of 8 TeV recorded by the ATLAS detector at the LHC. For a Higgs boson with a massof 125 GeV, assuming the Standard Model production cross section, an upper bound of 0.28is set on the branching fraction of H →invisible at 90% confidence level, where the expectedupper limit is 0.31. The results are interpreted in model of Higgs portal dark matter where thebranching fraction limit is converted into upper bounds on the dark matter nucleon scatteringcross section as a function of the dark matter particle mass, and compared to results from thedirect dark matter detection experiments
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ZUOLO, DAVIDE. "Development of silicon pixel sensors for the High Luminosity upgrade of the CMS experiment at LHC and search for Higgs boson pair production in the $bar b au^+ au^- :$ final state at $sqrt{s}$ = 13 TeV". Doctoral thesis, Università degli Studi di Milano-Bicocca, 2021. http://hdl.handle.net/10281/308715.
Abstract (sommario):
Durante il mio percorso di dottorato mi sono occupato principalmente dello sviluppo di nuovi sensori a pixel in Silicio per l’upgrade dell’esperimento CMS in vista della fase ad alta luminosità del collisionatore LHC (HL – LHC o LHC fase 2) al CERN, un’attività che avevo già intrapreso per il mio lavoro di tesi magistrale. Questi sensori devono tollerare fluenze di radiazione di alcuni 10^16 neq/cm^2 ad una distanza di circa 3 cm dal punto di interazione. Il programma di R&D portato avanti da un gruppo INFN ATLAS-CMS, in collaborazione con Fondazione Bruno Kessler, riguarda lo sviluppo di sensori planari sottili e 3D su substrati prodotti con la tecnica del Direct Wafer Bonding. L'impiego di questa tecnica permette di attuare tutti i processi di fabbricazione su una sola superficie del wafer, riducendo notevolmente i costi del processo. Lo spessore attivo dei prototipi è di 100 o 130 um per i sensori planari e 130 um per quelli 3D. I primi sensori prodotti hanno pixel delle stesse dimensioni di quelli attualmente in uso in CMS, 100 x 150 um^2. Le dimensioni sono state poi ridotte a 25 x 100 um^2 e 50 x 50 um^2 in modo da aumentare il numero di canali di lettura in vista della maggiore molteplicità di tracce attesa ad HL-LHC. Sono state effettuate numerose campagne di prova su fascio per caratterizzare i sensori planari e quelli 3D, prima e dopo l’irraggiamento a fluenze fino a 1 x 10^16 neq/cm^2. I miei contributi alla caratterizzazione dei prototipi sono riportati in questa tesi e includono anche lo sviluppo di algoritmi dedicati. Dopo circa due anni di lavoro sulla caratterizzazione dei nuovi prototipi ho sviluppato un interesse anche per l’impatto del rivelatore a pixel sul programma di fisica dell’esperimento. All’inizio del mio secondo anno di dottorato mi sono messo in cerca di un’analisi in cui le informazioni del rivelatore a pixel fossero largamente sfruttate. Ho scelto di lavorare alla ricerca della produzione di coppie di bosoni di Higgs nello stato finale con 2 b-jets e 2 leptoni tau. Ho scelto questa analisi sia perchè la ricostruzione delle particelle nello stato finale fa ampio uso delle informazioni di tracce e vertici sia perchè l’analisi trarrà grande benificio dell'incremento della statistica previsto ad HL-LHC, che potrebbe portare ad avere la prima evidenza sperimentale di produzione HH. La ricerca di coppie di bosoni di Higgs ha un ruolo fondamentale nella caratterizzazione di questa particella in quanto rappresenta il canale migliore per la misura della costante di accoppiamento trilineare. Ogni deviazione dalle previsioni teoriche del Modello Standard porterebbe a cambiamenti importanti nella cinematica e nel rateo di produzione di coppie di bosoni di Higgs, il che rende queste ricerche sensibili a effetti di nuova fisica. Lo stato finale bbtau^+tau^- rappresenta uno dei canali più interessanti in questo studio visti il branching ratio elevato e la piccola contaminazione di eventi di fondo. In questa tesi viene descritta la strategia sviluppata per l'analisi dei dati raccolti dall’esperimento CMS durante il Run 2 di LHC (2016 + 2017 + 2018), corrispondenti ad una luminosità integrata di 137 fb^-1. Viene inoltre riportata la sensitività attesa dell'analisi, che include lo studio di due meccanismi di produzione di coppie di bosoni di Higgs: Gluon-Gluon Fusion (GGF) e Vector Boson Fusion (VBF).My research activity during the PhD has focused mainly on the development of new silicon pixel sensors for the upgrade of the CMS experiment inner tracker in view of the CERN LHC High Luminosity phase (HL-LHC), an activity I started to work on during my master thesis. These sensors must be capable of surviving irradiation fluences up to a few 10^16 neq/cm^2 at ~ 3 cm from the interaction point. The R&D program carried out by an INFN ATLAS-CMS group, in collaboration with Fondazione Bruno Kessler, covers both planar and 3D pixel devices made on substrates obtained by the Direct Wafer Bonding technique. Using this technology, every fabrication process takes place on one side only of the wafer, with consequent cost savings. The active thickness of the planar sensors studied in this thesis is 100 um or 130 um, that of 3D sensors 130 um. Sensors belonging to the first batches have pixel cells with dimensions of 100 x 150 um^2, same as the sensors currently installed in CMS. These dimensions have been reduced to 25 x 100 um^2 and 50 x 50 um^2 in order to cope with the higher track multiplicity expected at HL-LHC. Prototypes of hybrid modules, bump-bonded to different readout chips, have been characterized in beam tests. Results on their performance before and after irradiation up to maximum fluence of ∼ 1 x 10^16 neq/cm^2 are reported in this thesis. After a couple of years working on the characterization of the new prototypes I became interested also on the impact of the pixel detector on the physics program of the experiment. At the beginning of my second year of PhD I started to look for a physics analysis where the information of the pixel detector is largely exploited. I chose to work on the search for double Higgs boson production in final states with 2 b-jets and 2 tau leptons since the reconstruction of the b-jets and tau leptons makes large use of vertexes and tracks information. Another reason why I chose this analysis is that it will benefit from the incremented statistics foreseen at HL-LHC, possibly leading to the first experimental evidence of HH production. Double Higgs searches play a fundamental role in the characterization of the Higgs boson as they represent the favorite channel to measure the Higgs boson trilinear self coupling. Any deviation from the theoretical predictions of the Standard Model would lead to sizable changes in both the kinematics and production rate of HH events, thus making double Higgs searches sensitive to new physics effects. The bbtau^+tau^-final state represents one of the most interesting channels to explore double Higgs production, because of the high branching ratio and the relatively small background contamination. The strategy developed to analyze data collected by the CMS experiment during the LHC Run 2 (2016 + 2017 + 2018), corresponding to an integrated luminosity of 137 fb^-1, is described in this thesis. The expected sensitivity of the analysis, targeting both the Gluon Fusion (GGF) and Vector Boson Fusion (VBF) production channels, is also reported.
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Brahimi, Nihal. "Search for the Higgs boson in the ttH(H->bb) channel and measurement of the production cross-section of ttbb with the ATLAS detector at the LHC". Thesis, Aix-Marseille, 2019. http://www.theses.fr/2019AIXM0337.
Abstract (sommario):
Depuis la découverte du boson de Higgs par les expériences ATLAS et CMS en juillet 2012, il est devenu crucial de mesurer ses propriétés, tel que son couplage aux fermions, pour établir sa nature et déceler toute déviation possible par rapport aux prédictions du Modèle Standard. Le couplage Yukawa du quark top est le plus fort et ainsi joue un rôle majeur dans la découverte de nouvelle physique. La production du boson de Higgs en association avec une paire de quark top et sa désintégration en deux quarks b, ttH(H->bb), donne accès à ce couplage. Bien que la production ttH a été récemment établie par ATLAS et CMS en combinant plusieurs canaux dont ttH(H->bb), ce dernier n'a jamais était observé directement. La complexité de l'état final de ttH(H->bb) impliquant un grand nombre de b-jets, ainsi que la présence du bruit de fond dominant de la production de paire de quark top avec des jets additionnels (tt+jets), en particulier avec des b-jets (ttbb), sont les principaux défis de ce canal. Par conséquent, l'étiquetage des b-jets, appelé b-tagging, et le contrôle du bruit de fond ttbb sont des ingrédients clés pour cette analyse. Cette thèse présente la recherche de ttH(H->bb) avec 36.1 /fb de données LHC recueillies par le détecteur ATLAS en 2015 et 2016. Des techniques novatrices pour améliorer la sensibilité de l'analyse, exploitant les données complètes du Run 2, sont aussi développées. En particulier, des études détaillées sont présentées dont la mesure de la section efficace différentielle du bruit de fond ttbb. L'optimisation des algorithmes de b-tagging en vue du projet LHC à haute luminosité, après l'amélioration du trajectographe d'ATLAS, est également présentéeSince the discovery of the Higgs boson at a mass around 125 GeV by both ATLAS and CMS collaborations in July 2012, it became crucial to measure its properties, such as its couplings to fermions, and unravel any deviations from the Standard Model (SM) predictions. The top quark Yukawa coupling is the strongest in the fermionic sector and one of the best probes to shed light on phenomena beyond the SM. The Higgs boson production in association with a pair of top quarks and its subsequent decay into a pair of bottom quarks, ttH(H->bb), grants direct access to this coupling in addition to the bottom quark Yukawa coupling. Although the ttH production was recently established by both ATLAS and CMS combining several channels including ttH(H->bb), the latter has never been observed directly. The complexity of the ttH(H->bb) final state with a large number of b-jets, and the overwhelming background of the top pair production with additional jets (tt+jets), especially b-jets (ttbb), are the major challenges of this channel. Thus, b-jet identification referred to as b-tagging, and the control of the ttbb background are key ingredients for this analysis. This thesis presents the search for ttH(H->bb) performed with 36.1 /fb of LHC data collected by the ATLAS detector in 2015 and 2016. Novel techniques to improve the search sensitivity with full Run 2 data are also developed. Particularly, detailed studies are presented including a differential cross-section measurement of the main ttbb background. The optimization of the b-tagging algorithms in view of the High Luminosity LHC upgrade, after the replacement of the ATLAS inner detector, is also presented
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Navarro, Jose Luis La Rosa. "Measurement of Z boson production in association with b-jets in proton-proton collisions at 13 TeV and studies of an electron trigger system for high luminosity in the ATLAS experiment". Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/43/43134/tde-09112017-024133/.
Abstract (sommario):
This thesis will present results on the measurement of Z boson production in the electron channel associated with b-jets in proton-proton collision at 13 TeV, a measurement of fundamental interest in precision measurements and physics searches. This measurement represents important precision tests of perturbative QCD and provides information related to the b-quark inside of the proton. This measurement also represents one of the main sources of background in top quark production studies, Higgs precision measurements and the search for supersymmetric particles. The results on cross section measurements and kinematic distributions presented in this work have been unfolded to particle level and are compared to the four and five flavor schemes in Monte Carlo generators, showing that the predictions are consistent within the experimental uncertainties. In this thesis it will be also shown results of the development of the new event selection system proposed for high luminosity measurements. This system will be implemented during the second LHC long shutdown (2019-2020), which involves studies on the reconstruction of electrons using the concept of supercells, where the fine granularity of the cells of the ATLAS Liquid Argon detector is exploited to mitigate the problems to be found in high luminosity conditions. One of the problems is the increase of pile-up, caused by secondary collisions of protons in the same event, generating a large number of low pT jets that can be erroneously identified as electrons. The studies in this work introduce new discriminants based on the electromagnetic shower shape, showing that is possible to further reduce the rate of low pT jets maintaining a good performance on electron reconstruction.Esta tese apresentará resultados da medida da produção de bósons Z no canal de elétrons associado com jatos b em colisões próton-próton a 13 TeV, uma medida de fundamental interesse em medidas de precisão e buscas por nova física. Essa medida representa importantes testes de precisão da QCD perturbativa e prove informações relacionadas ao quark b dentro do próton. Essa medida também representa uma das principais fontes de background na produção do quark top, medidas de precisão do Higgs e na busca de partículas supersimétricas. Os resultados na medida da seção de choque e distribuições cinemáticas apresentadas neste trabalho são comparados com os esquemas de quatro e cinco sabores nos geradores Monte Carlo, mostrando que as predições são consistentes dentro das incertezas experimentais. Nesta tese também serão apresentados estudos do desenvolvimento de um sistema de seleção de eventos proposto para medidas em alta luminosidade. Esse sistema será implementado durante o segundo LHC long shutdown (2019-2020), envolvendo estudos na reconstrução de elétrons usando o conceito de supercélulas, onde a fina granularidade das células do detector de Argônio Líquido do ATLAS será aproveitada para mitigar as dificuldades que se terão em condições de alta luminosidade. Um dos problemas é o aumento do empilhamento (pile-up), causado por colisões secundárias de prótons no mesmo evento, gerando uma grande quantidade de jatos de baixo pT que podem ser erroneamente identificados como elétrons. Os estudos neste trabalho apresentam novos discriminantes com base na forma da cascata eletromagnética, mostrando que é possível reduzir ainda mais a taxa de jatos de baixo pT mantendo uma boa reconstrução de elétrons.
35
Haughton, Iain William Philip. "3D detectors for the High Luminosity LHC, with a feasibility study into the observation of ZZ production in the Z → ee/μμ, Z → ττ channel with the ATLAS detector". Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/3d-detectors-for-the-high-luminosity-lhc-with-a-feasibility-study-into-the-observation-of-zz-production-in-the-z--ee-z---channel-with-the-atlas-detector(822c2a2f-d051-4f7b-b3a5-1bc890883d29).html.
Abstract (sommario):
This thesis presents three bodies of work related to the ATLAS detector and physics measurements at the high luminosity frontier. The first investigates the use of 3D silicon detectors at the High Luminosity LHC. Several sensors are irradiated up to a fluence equal to that expected in the ATLAS pixel detector layers, and tests into their radiation tolerance performed. The second continues along a similar theme and pertains to the application of the 3D principle in an intrinsically more radiation tolerant material – diamond. The fabrication and testing of the first prototype 3D diamond detector for the purpose of particle tracking is described. The final body of work moves away from the imperative technical work required with increased luminosity, to the potential gains in physics analysis. The feasibility of observing rare di-boson ZZ events in which one Z → ee/μμ and the other Z → ττ, in data taken by the ATLAS detector is detailed. In addition to an increased luminosity, this analysis is likely to benefit from future upgrades to the pixel detector.
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Chen, Zongde. "Depleted CMOS sensor development for pixel particle detectors under high intensity and high radiative dose". Thesis, Aix-Marseille, 2019. http://www.theses.fr/2019AIXM0430.
Abstract (sommario):
Le trajectographe interne (ITk) de l'expérience ATLAS sera amélioré pour la nouvelle phase de prise de données du grand collisionneur de hadrons du CERN à haute luminosité (HL-LHC) en 2026. Le HL-LHC fonctionnera avec l’énergie nominale de collision est de 14 TeV et la luminosité instantanée maximale de 7,5 x (10)34 cm(−2) s(−1), cinq fois plus élevée qu’à présent. La luminosité accrue se traduira par des niveaux de rayonnement et des débits de données environ dix fois plus élevés. Afin de faire face aux exigences d’ATLAS en termes d’intensite du rayonnement, de vitesse de lecture et de granularité au HL-LHC, le remplacement de l’actuel ATLAS Inner Tracker (ITk) est nécessaire. Deux capteurs CMOS épuisés à grande échelle dans la technologie LF de 150 nm, appelés LF-CPIX et LF-MONOPIX, ont été développés dans le cadre de la mise à niveau ATLAS Inner Tracker (ITK) pour le LHC à haute luminosité. Le travail présenté ici montre la caractérisation de ces trois prototypes, avec des contributions concernant le développement de la configuration, le calibrage source 55 Fe et 90 Sr, les modifications du microprogramme FPGA et le développement de programmes de test. L’enquête sur la dureté du rayonnement pour l’électronique et les composants du capteur a été une préoccupation majeure. Nous montrerons les résultats concernant les caractérisations de ces prototypes dans les performances de laboratoire du CPPM, ainsi que les résultats de multiples campagnes de rayonnement conduites à l’installation de protons IRRAD de 24 GeV du CERN, afin d’étudier les effets de la perte d’énergie non ionisante (NIEL) et du Dose ionisante (TID) sur les prototypesThe Inner Tracker (ITk) system of the ATLAS experiment will be upgraded for the 2026 High Luminosity Large Hadron Collider (HL-LHC) run. The HL-LHC will operate with a center of mass energy of 14 TeV and a peak instantaneous luminosity five times higher than at present. The increased luminosity will result in roughly ten times higher radiation levels and data rates. To cope with the ATLAS requirements in terms of radiation hardness, readout speed and granularity at the HL-LHC, the replacement of the present ATLAS Inner Tracker (ITk) is needed. Two large-scale depleted CMOS sensors in the 150 nm LF-technology called LF-CPIX and LF-MONOPIX, developed in the framework of the ATLAS Inner Tracker (ITK) upgrade for High Luminosity LHC. The work presented here shows the characterization for these three prototypes, with contributions concerning the setup development, 55Fe and 90Sr source calibration, modifications of the FPGA firmware and development of test programs. A main concern was the investigation on the radiation hardness for both the electronics and the sensor parts. We will show results concerning characterizations for these prototypes in the laboratory performance at CPPM, as well as results in multiple radiation campaigns performed at the 24 GeV IRRAD proton facility at CERN, to study the effects of Non-Ionizing Energy Loss (NIEL) and Total Ionizing Dose (TID) on the prototypes
37
Madysa, Nico [Verfasser], Arno [Akademischer Betreuer] Straessner e Peter [Gutachter] Krieger. "Simulation Studies of Digital Filters for the Phase-II Upgrade of the Liquid-Argon Calorimeters of the ATLAS Detector at the High-Luminosity LHC / Nico Madysa ; Gutachter: Peter Krieger ; Betreuer: Arno Straessner". Dresden : Technische Universität Dresden, 2021. http://d-nb.info/1236383737/34.
38
Bhatt, Heeral. "Design and Development of the Beam Position Monitor Calibration Test Bench : For testing the electrical parameters of the new High Luminosity Large Hadron Collider (HL-LHC) Beam Position Monitors using the Concurrent Engineering Approach". Thesis, Luleå tekniska universitet, Rymdteknik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-81200.
39
Wiik-Fuchs, Liv [Verfasser], Karl [Akademischer Betreuer] Jakobs e Jochen [Akademischer Betreuer] Dingfelder. "Search for heavy lepton resonances decaying to a Z Boson and a lepton in proton-proton at [radical]s = 8 TeV with the ATLAS detector and investigations of radiation tolerant silicon strip detectors for the high-luminosity LHC upgrade of the ATLAS inner detector". Freiburg : Universität, 2016. http://d-nb.info/1134884028/34.
40
Mårtensson, Oskar. "LHCb Upstream Tracker box : Thermal studies and conceptual design". Thesis, Umeå universitet, Institutionen för fysik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-116163.
Abstract (sommario):
The LHC (Large Hadron Collider) will have a long shut down in the years of 2019 and 2020, referred to as LS2. During this stop the LHC injector complex will be upgraded to increase the luminosities, which will be the first step of the high luminosity LHC program (which will be realized during LS3 that takes place in 2024-2026). The LHCb experiment, whose main purpose is to study the CP-violation, will during this long stop be upgraded in order to withstand a higher radiation dose, and to be able to read out the detector at a rate of 40MHz,compared to 1MHz at present. This change will improve the trigger efficiency significantly. One of the LHCb sub-detectors the Trigger Tracker (TT), will be replaced by a new sub-detector called UT. This report presents the early stage design (preparation for mock-up building) of the box that will be isolating the new UT detector from the surroundings and to ensure optimal detector operation. Methods to fulfill requirements such as light and gas tightness, Faraday-cage behavior and condensation free temperatures, without breaking the fragile beryllium beam pipe, are established.LHC (Large Hadron Collider) kommer under åren 2019-2020 att ha ett längre driftstopp. Under detta driftstopp så kommer LHC's injektionsanordningar att uppgraderas för att kunna sätta fler protoner i circulation i LHC, och därmed öka antalet partikelkollisioner per tidsenhet. Denna uppgradering kommer att vara första steget i "High Luminocity LHC"-programmet som kommer att realiseras år 2024-2026. LHCb-experimentet, vars främsta syfte är att studera CP-brott, kommer också att uppgraderas under stoppet 2019-2020. Framför allt så ska avläsningsfrekvensen ökas från dagens 1MHz till 40MHz, och experimentet ska förberedas för de högre strålningsdoser som kommer att bli aktuella efter stoppet 2024-2026. En av LHCb's deldetektorer, TT detektorn, kommer att bytas ut mot en ny deldetektor som kallas UT. Den här rapporten presenterar den förberedande designen av den låda som ska isolera UT från dess omgivning och försäkra optimala förhållanden för detektorn. Kraven på den isolerande lådan och tillvägagångssätt för att uppfylla dessa krav presenteras.
LHCb, LS2 and LS3 Upgrade
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Schmitt, Sebastian [Verfasser], e André [Akademischer Betreuer] Schöning. "Measurement of the Inclusive pp->Z/gamma*->e+e- Cross Section at sqrt(s) = 7 TeV with the ATLAS Experiment and Design Studies for a First Level Track Trigger for the ATLAS Trigger Upgrade at the future High Luminosity LHC / Sebastian Schmitt ; Betreuer: André Schöning". Heidelberg : Universitätsbibliothek Heidelberg, 2013. http://d-nb.info/1177382881/34.
42
RICCI, ALESSANDRO MARIA. "Superconducting magnets for future accelerators". Doctoral thesis, Università degli studi di Genova, 2020. http://hdl.handle.net/11567/1002038.
Abstract (sommario):
The Large Hadron Collider (LHC) at CERN, which is now in operation for ten years, is not only the largest and more powerful particle accelerator in the world, but also constitutes one of the greatest applications of the superconducting magnet technology. Nevertheless, the need to increase both the luminosity in the next future and the energy in more far future is demanding for the developments of new and more challenging superconducting magnets generating higher magnetic fields. Presently all laboratories worldwide involved in the superconducting magnet technology for accelerators are performing R&D activities aimed to the development of a high field superconducting magnet (16 T) for the Future Circular Collider, an accelerator for 50-TeV energy protons (7 times higher than the energy of the LHC beams). The needed technology demands for the use of superconducting material (Niobium Tin) well-known but of difficult application requiring a considerable development before it can be used for 16-T magnet. It is also under study the possible use of cables based on high critical temperature superconductors (HTS), which are even more difficult and have never been used in accelerators.
The design of the superconducting magnets for accelerators is closely related to the physics of the accelerator. In particular, the optics of the beams is determined by the quality of the magnetic field controlled by dipoles, quadrupoles and higher-order correctors. To a greater extent than existing magnets, the optimization of a magnetic design for the dipoles of the Future Circular Collider, for energies of 100 TeV in the center of mass, has many critical aspects partly related to the intrinsic limitations of superconducting cables (critical fields and currents) and partly to the need to develop stable geometric layouts with respect to geometric variations (mechanical deformation or manufacturing tolerances).
This thesis is focused on the optimization of the field quality for the magnets in the twin-coil configuration (for FCC as for LHC the two openings of the dipoles that curve the proton beams circulating in the opposite direction are assembled in a single cold mass). For this class of magnets, the magnetic cross-talk between the apertures presents considerable complications considering that in a dipole the components of higher-order multipoles must be at the most of the order of 10^-4 with respect to the main dipole field. We have developed analytical methodologies, complemented with numerical analyzes, to minimize magnetic cross-talk through suitable asymmetrical configurations. We have applied these methodologies in the various studies carried out for the development of magnets for the Future Circular Collider contributing to finalize a design, which has been presented as the baseline of an European project funded within H2020 framework, named EuroCirCol. We have also applied the developed methods for studying possible improvements to the present design of the recombination dipoles (called D2) for the high luminosity upgrade of LHC. These are NbTi magnets with a strong cross-talk between the two apertures and are under construction at ASG Superconductors in Genova with a design developed at INFN Genova. At the same time, we have developed the 3D electromagnetic models of both magnet classes. In particular, we have been responsible for the 3D electromagnetic simulations of the EuroCirCol magnet. Finally, we have helped to develop a preliminary design of the FCC recombination dipoles (called DARD), which have required a completely different approach with respect to the D2 magnets for LHC.
The thesis is structured in two main sections with five chapters. The first section (including three chapters) reports the theoretical background and the developed methods. The second section (two further chapters) reports the design activities of the magnets for the high luminosity upgrade of LHC and for FCC.
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Asbah, Nedaa. "LHC luminosity measurement with the ATLAS-MPX detectors". Thèse, 2013. http://hdl.handle.net/1866/10714.
Abstract (sommario):
En opération depuis 2008, l’expérience ATLAS est la plus grande de toutes les expériences au LHC. Les détecteurs ATLAS- MPX (MPX) installés dans ATLAS sont
basés sur le détecteur au silicium à pixels Medipix2 qui a été développé par la collaboration Medipix au CERN pour faire de l’imagerie en temps réel. Les détecteurs MPX peuvent être utilisés pour mesurer la luminosité. Ils ont été installés à seize différents endroits dans les zones expérimentale et technique d’ATLAS en 2008. Le réseau MPX a recueilli avec succès des données indépendamment de la chaîne d’enregistrement des données ATLAS de 2008 à 2013. Chaque détecteur MPX fournit des mesures de la luminosité intégrée du LHC. Ce mémoire décrit la méthode d’étalonnage de la luminosité
absolue mesurée avec les détectors MPX et la performance des détecteurs MPX pour les données de luminosité en 2012. Une constante d’étalonnage de la luminosité a été déterminée. L’étalonnage est basé sur technique de van der Meer (vdM). Cette technique permet la mesure de la taille des deux faisceaux en recouvrement dans le plan vertical et horizontal au point d’interaction d’ATLAS (IP1). La détermination de la luminosité absolue nécessite la connaissance précise de l’intensité des faisceaux et du nombre de
trains de particules. Les trois balayages d’étalonnage ont été analysés et les résultats obtenus par les détecteurs MPX ont été comparés aux autres détecteurs d’ATLAS dédiés spécifiquement à la mesure de la luminosité. La luminosité obtenue à partir des balayages vdM a été comparée à la luminosité des collisions proton- proton avant et après les balayages vdM. Le réseau des détecteurs MPX donne des informations fiables pour la détermination de la luminosité de l’expérience ATLAS sur un large intervalle (luminosité de 5 × 10^29 cm−2 s−1 jusqu’à 7 × 10^33 cm−2 s−1 .In operation since 2008, the ATLAS experiment is the largest of all the experiments at the LHC. The ATLAS-MPX (MPX) detectors installed in ATLAS are based on the Medipix2 silicon pixelated detector which has been developed by the Medipix Collaboration at CERN to perform real-time imaging. They can be used for luminosity measurements. They were installed at sixteen different positions in the ATLAS cavern at the LHC in 2008. The MPX network successfully collected data independently of the ATLAS data recording chain from 2008 to 2013. Each MPX detector provides measurements of the integrated LHC luminosity. This thesis describes the technique for calibrating the luminosity data and performance of MPX detectors for measuring the luminosity in 2012. The calibration was performed via the van der Meer (vdM) scans technique which allows the measurement of the convolved beam sizes in the vertical and the horizontal planes at the ATLAS interaction point (IP1). The determination of the absolute luminosity requires a precise knowledge of the beam intensities and the number of beam bunches. A luminosity calibration constant was determined. The three calibration scans were analyzed and the results were cross-checked among the MPX detectors and other ATLAS sub-detectors specifically dedicated to luminosity measurement. The luminosity determined from the calibration scans was compared to the luminosity of regular runs before and after the vdM scans. The MPX network gives reliable information for the overall ATLAS luminosity determination over a wide dynamic range (luminosity from 5 × 10^29 cm−2 s−1 up to 7 × 10^33 cm−2 s−1).
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(9385172), Simran Sunil Gurdasani. "Pixel Sensor Module Assembly Procedures for The CMS High Luminosity LHC Upgrade". Thesis, 2020.
Abstract (sommario):
The high luminosity phase of the LHC, poised to start taking data in 2027, aims to increase the instantaneous luminosity of the machine to 7.5 x 1034 cm-2 s-1. This will make it possible for experiments at CERN to make higher precision measurements on known physics phenomenon as well as to search for “new physics”. However, this motivates the need for hardware upgrades at the various experiments in order to ensure compatibility with the HL-LHC. This thesis describes some of the efforts to upgrade the inner-most layers of the Compact Muon Solenoid, namely the CMS silicon pixel tracking detector.
Silicon sensors used to track particles are installed in the detector as part of a pixel sensor module. Modules consist of a silicon sensor-readout chip assembly that is wire-bonded to an HDI, or High Density Interconnects to provide power and signals.
As part of the upgrade, 2,541 modules need to be assembled delicately and identically with alignment error margins as low as 10 microns. Assembly will be across three production sites in clean rooms to avoid dust and humidity contamination.
In addition, the modules need to survive high magnetic fields and extended close-range radiation as part of the HL-LHC.
In line with this effort, new materials and assembly procedures able to sustain such damage are investigated. Techniques to assemble modules are explored, specifically precision placing of parts with a robotic gantry and techniques to protect wirebonds. This is followed by a discussion of the accuracy and repeatability.
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Shroff, Maheyer Jamshed. "A data injector for the High Luminosity LHC ATLAS Liquid Argon Signal Processor". Thesis, 2020. http://hdl.handle.net/1828/12082.
Abstract (sommario):
A test-bench is created that injects digital pulses that emulate ATLAS LAr Front End Board electronic signal pulses in order to test prototypes. The prototypes are for new electronics for an upgrade to the CERN Large Hadron Collider that increases the rate of proton-proton collisions by an order of magnitude. This High-Luminosity Large Hadron Collider requires a completely new Trigger and Data Acquisition system to deal with information from detectors.
One such system that is currently being developed is the Liquid Argon Signal Processor (LASP) whose architecture is based on Field Programmable Gate Arrays (FPGA). Validation of individual modules of the LASP are of key importance in the development cycle. Additionally, verification of module behaviour with real ATLAS pulses will not be available until much later in the project timeline.
The injector project is implemented on an Intel Stratix 10 FPGA, using a soft-core NIOS II processor for TCP/IP communication with a workstation in order to transfer Monte Carlo simulation pulses to the FPGA, where it is then stored in a 2 GB DDR3 external memory. The pulses are then retrieved into internal memory buffers and are transmitted to the LASP at 40 MHz. The user is in complete control of the data pulses injected which is a vital property that would test LASP behaviour for different cases and possible failure modes.Graduate
46
Rieger, Julia. "Detector Development for the High Luminosity Large Hadron Collider". Doctoral thesis, 2016. http://hdl.handle.net/11858/00-1735-0000-0028-8802-8.
Abstract (sommario):
Um das Entdeckungspotential des Large Hadron Colliders auszunutzen, wird er beginnend 2024 zum High Luminosity Large Hadron Collider ausgebaut. Neue Detektorherausforderungen entstehen durch die höhere instantane Luminosität und den höheren Teilchenfluss. Der neue ATLAS Inner Tracker wird den aktuellen Spurdetektor ersetzen, um mit diesen Herausforderungen umzugehen. Es gibt viele Pixeldetektortechnologien zur Teilchenspurerkennung, jedoch muss ihre Eignung für den ATLAS Inner Tracker untersucht werden. Aktive Hochspannungs-CMOS-Sensoren, die in industriellen Prozessen produziert werden, bieten eine schnelle Auslese und Strahlenhärte. In dieser Arbeit wird der HV2FEI4v2-Sensor, der kapazitiv mit dem ATLAS-FE-I4-Auslesechip gekoppelt ist, dahingehend charakterisiert, ob er für eine Verwendung in einer der äußeren Lagen des ATLAS Inner Tracker geeignet ist. Schlüsselgrößen des Prototypens, wie die Treffereffizienz und die Subpixelentschlüsselung, werden untersucht. Der frühe HV2FEI4v2-Prototyp zeigt vielversprechende Ergebnisse, die als Ausgangspunkt für weitere Entwicklungen dienen. Aktive CMOS-Sensoren stellen einen möglichen Kandidaten für einen kosteneffizienten Detektor für den High Luminosity Large Hadron Collider.
47
Buschmann, Eric. "The Readout System for the ITk Pixel Demonstrator for the ATLAS High-Luminosity Upgrade". Doctoral thesis, 2020. http://hdl.handle.net/21.11130/00-1735-0000-0005-13B5-9.
48
Nguyen, Thong Quang. "Searches for Nonresonant Higgs Boson Pair Production and Long-Lived Particles at the LHC and Machine-Learning Solutions for the High-Luminosity LHC Era". Thesis, 2022.
Abstract (sommario):
This thesis presents two physics analyses using 137 fb−1 proton-proton collision data collected by the CMS experiment at √s = 13 TeV, along with a series of machine-learning solutions to extend the physics program at the LHC and to address the computational challenges in the High-Luminosity LHC era. The first analysis searches for nonresonant Higgs boson pair production in final states with two photons and two bottom quarks, with no significant deviation from the background-only hypothesis observed. The observed (expected) upper limit on the product of the Higgs boson pair production cross section and branching fraction into bb̅γγ is 0.67 (0.45) fb, corresponding to 7.7 (5.2) times the Standard Model prediction. The modifier of the Higgs trilinear self-coupling is constrained within the range -3.3 < κλ < 8.5. The modifier for coupling between a pair of Higgs bosons and a pair of vector bosons, along with the 2-dimensional constraint of the modifiers of Higgs self-coupling and Yukawa coupling, are also reported. A graph-based algorithm to identify boosted H → bb̅ jets to improve future Higgs search is presented. The second analysis searches for long-lived supersymmetry particles decaying to photons and gravitinos in the context of gauge-mediated supersymmetry breaking model. Results are presented in terms of 95% confidence level expected exclusion limits on the masses and proper decay lengths of the neutralino, which exceed the limits from the previous searches by up to 100 GeV for the neutralino mass and by five times for the neutralino proper decay length. A strategy for model-independent new physics searches is presented with an anomaly trigger based on unsupervised learning algorithms that can be deployed in both the high-level trigger and the Level-1 trigger in CMS. Three other machine-learning solutions are presented to address the computational challenges in the HL-LHC era: a layer based on multi-modal deep neural networks that can reduce the false-positive events selected by the trigger by over one order of magnitude while retaining 99% of signal events, a full-event simulation algorithm based on recurrent generative adversarial networks that has potential to replace traditional simulation method while being five orders of magnitude faster, and a fast simulation algorithm for specific analyses based on encoder-decoder architecture that would result in about an order-of-magnitude reduction in computing and storage requirements for the collision simulation workflow.
49
Madysa, Nico. "Simulation Studies of Digital Filters for the Phase-II Upgrade of the Liquid-Argon Calorimeters of the ATLAS Detector at the High-Luminosity LHC". 2020. https://tud.qucosa.de/id/qucosa%3A75152.
Abstract (sommario):
Am Large Hadron Collider und am ATLAS-Detektor werden umfangreiche Aufrüstungsarbeiten vorgenommen. Diese Arbeiten sind in mehrere Phasen gegliedert und umfassen unter Anderem Änderungen an der Ausleseelektronik der Flüssigargonkalorimeter; insbesondere ist es geplant, während der letzten Phase ihren Primärpfad vollständig auszutauschen. Die Elektronik besteht aus einem analogen und einem digitalen Teil: während ersterer die Signalpulse verstärkt und sie zur leichteren Abtastung verformt, führt letzterer einen Algorithmus zur Energierekonstruktion aus. Beide Teile müssen während der Aufrüstung verbessert werden, damit der Detektor interessante Kollisionsereignisse präzise rekonstruieren und uninteressante effizient verwerfen kann.
In dieser Dissertation werden Simulationsstudien präsentiert, die sowohl die analoge als auch die digitale Auslese der Flüssigargonkalorimeter optimieren. Die Korrektheit der Simulation wird mithilfe von Kalibrationsdaten geprüft, die im sog. Run 2 des ATLAS-Detektors aufgenommen worden sind. Der Einfluss verschiedener Parameter der Signalverformung auf die Energieauflösung wird analysiert und die Nützlichkeit einer erhöhten Abtastrate von 80 MHz untersucht. Des Weiteren gibt diese Arbeit eine Übersicht über lineare und nichtlineare Energierekonstruktionsalgorithmen. Schließlich wird eine Auswahl von ihnen hinsichtlich ihrer Leistungsfähigkeit miteinander verglichen.
Es wird gezeigt, dass ein Erhöhen der Ordnung des Optimalfilters, der gegenwärtig verwendete Algorithmus, die Energieauflösung um 2 bis 3 % verbessern kann, und zwar in allen Regionen des Detektors. Der Wiener Filter mit Vorwärtskorrektur, ein nichtlinearer Algorithmus, verbessert sie um bis zu 10 % in einigen Regionen, verschlechtert sie aber in anderen. Ein Zusammenhang dieses Verhaltens mit der Wahrscheinlichkeit fälschlich detektierter Kalorimetertreffer wird aufgezeigt und mögliche Lösungen werden diskutiert.:1 Introduction
2 An Overview of High-Energy Particle Physics
2.1 The Standard Model of Particle Physics
2.2 Verification of the Standard Model
2.3 Beyond the Standard Model
3 LHC, ATLAS, and the Liquid-Argon Calorimeters
3.1 The Large Hadron Collider
3.2 The ATLAS Detector
3.3 The ATLAS Liquid-Argon Calorimeters
4 Upgrades to the ATLAS Liquid-Argon Calorimeters
4.1 Physics Goals
4.2 Phase-I Upgrade
4.3 Phase-II Upgrade
5 Noise Suppression With Digital Filters
5.1 Terminology
5.2 Digital Filters
5.3 Wiener Filter
5.4 Matched Wiener Filter
5.5 Matched Wiener Filter Without Bias
5.6 Timing Reconstruction, Optimal Filtering, and Selection Criteria
5.7 Forward Correction
5.8 Sparse Signal Restoration
5.9 Artificial Neural Networks
6 Simulation of the ATLAS Liquid-Argon Calorimeter Readout Electronics
6.1 AREUS
6.2 Hit Generation and Sampling
6.3 Pulse Shapes
6.4 Thermal Noise
6.5 Quantization
6.6 Digital Filters
6.7 Statistical Analysis
7 Results of the Readout Electronics Simulation Studies
7.1 Statistical Treatment
7.2 Simulation Verification Using Run-2 Data
7.3 Dependence of the Noise on the Shaping Time
7.4 The Analog Readout Electronics and the ADC
7.5 The Optimal Filter (OF)
7.6 The Wiener Filter
7.7 The Wiener Filter with Forward Correction (WFFC)
7.8 Final Comparison and Conclusions
8 Conclusions and Outlook
AppendicesThe Large Hadron Collider and the ATLAS detector are undergoing a comprehensive upgrade split into multiple phases. This effort also affects the liquid-argon calorimeters, whose main readout electronics will be replaced completely during the final phase. The electronics consist of an analog and a digital portion: the former amplifies the signal and shapes it to facilitate sampling, the latter executes an energy reconstruction algorithm. Both must be improved during the upgrade so that the detector may accurately reconstruct interesting collision events and efficiently suppress uninteresting ones. In this thesis, simulation studies are presented that optimize both the analog and the digital readout of the liquid-argon calorimeters. The simulation is verified using calibration data that has been measured during Run 2 of the ATLAS detector. The influence of several parameters of the analog shaping stage on the energy resolution is analyzed and the utility of an increased signal sampling rate of 80 MHz is investigated. Furthermore, a number of linear and non-linear energy reconstruction algorithms is reviewed and the performance of a selection of them is compared. It is demonstrated that increasing the order of the Optimal Filter, the algorithm currently in use, improves energy resolution by 2 to 3 % in all detector regions. The Wiener filter with forward correction, a non-linear algorithm, gives an improvement of up to 10 % in some regions, but degrades the resolution in others. A link between this behavior and the probability of falsely detected calorimeter hits is shown and possible solutions are discussed.:1 Introduction 2 An Overview of High-Energy Particle Physics 2.1 The Standard Model of Particle Physics 2.2 Verification of the Standard Model 2.3 Beyond the Standard Model 3 LHC, ATLAS, and the Liquid-Argon Calorimeters 3.1 The Large Hadron Collider 3.2 The ATLAS Detector 3.3 The ATLAS Liquid-Argon Calorimeters 4 Upgrades to the ATLAS Liquid-Argon Calorimeters 4.1 Physics Goals 4.2 Phase-I Upgrade 4.3 Phase-II Upgrade 5 Noise Suppression With Digital Filters 5.1 Terminology 5.2 Digital Filters 5.3 Wiener Filter 5.4 Matched Wiener Filter 5.5 Matched Wiener Filter Without Bias 5.6 Timing Reconstruction, Optimal Filtering, and Selection Criteria 5.7 Forward Correction 5.8 Sparse Signal Restoration 5.9 Artificial Neural Networks 6 Simulation of the ATLAS Liquid-Argon Calorimeter Readout Electronics 6.1 AREUS 6.2 Hit Generation and Sampling 6.3 Pulse Shapes 6.4 Thermal Noise 6.5 Quantization 6.6 Digital Filters 6.7 Statistical Analysis 7 Results of the Readout Electronics Simulation Studies 7.1 Statistical Treatment 7.2 Simulation Verification Using Run-2 Data 7.3 Dependence of the Noise on the Shaping Time 7.4 The Analog Readout Electronics and the ADC 7.5 The Optimal Filter (OF) 7.6 The Wiener Filter 7.7 The Wiener Filter with Forward Correction (WFFC) 7.8 Final Comparison and Conclusions 8 Conclusions and Outlook Appendices
50
"Topics in particle physics: 1) Sensitivity of W H --> lvbb for high luminosity LHC and 2) Study of surface cosmic rays". Thesis, 2014. http://repository.lib.cuhk.edu.hk/en/item/cuhk-1292108.
Abstract (sommario):
Kwok, Ka Hei Martin = 粒子物理專題 : 1) 在高亮度LHC中的W H --> lvbb的靈敏度及2) 地表宇宙射線研究 / 郭家希.Thesis M.Phil. Chinese University of Hong Kong 2014.
Abstracts also in Chinese.
Title from PDF title page (viewed on 20, December, 2016).
Kwok, Ka Hei Martin = Li zi wu li zhuan ti : 1) Zai gao liang du LHC zhong de W H --> lvbb de ling min du ji 2) di biao yu zhou she xian yan jiu / Guo Jiaxi.