Partenaires
Menu
Rechercher
Navigation
Accueil > Thèses, Stages, Formation et Enseignement > Propositions de thèses 2023 > Development of the new silicon pixel tracker for the upgrade of the ATLAS detector at the High Luminosity LHC (HL-LHC), study of the performance of the new design, and application to the research of new physics and precision Higgs measurements at HL-LHC
Development of the new silicon pixel tracker for the upgrade of the ATLAS detector at the High Luminosity LHC (HL-LHC), study of the performance of the new design, and application to the research of new physics and precision Higgs measurements at HL-LHC
par Tristan Beau - 8 novembre 2022
Titre : Development of the new silicon pixel tracker for the upgrade of the ATLAS detector at the High Luminosity LHC (HL-LHC), study of the performance of the new design, and application to the research of new physics and precision Higgs measurements at HL-LHC.
Directrice/directeur de thèse : Giovanni Calderini
Co-encadrant.e : Francesco Crescioli
Groupe d’accueil :ATLAS
Webpage du projet : https://atlas.cern/
Collaboration : ATLAS ITk
Description :
ATLAS is one of the four large detectors installed at the LHC proton collider of CERN at Geneve. A large upgrade of the accelerator and the detectors is under way for the so-called high-luminosity phase of LHC, or HL-LHC which will start in 2028. During this phase, which will last for about ten years, an instantaneous luminosity between 5 and 7 times larger than the nominal LHC luminosity will be delivered, providing a dataset of 3-4 inverse attobarns of proton-proton collisions. Each bunch crossing will produce about 200 collisions, so more than 5 times the design LHC density, and the level of radiation in the interaction region will 20 times larger than the nominal one. Under these conditions, not only the design of the present detectors, in particular the trackers, but the technology itself which has been used to build them will be totally inadequate. For this reason, the conception and construction of totally new systems has been started, to be ready to put them on the LHC beamline in 2028.
The LPNHE group of ATLAS has a longstanding expertise in silicon detectors. After having contributed to the new innermost pixel layer added in 2014 to the present ATLAS tracker, the group has participated to the design and validation of the pixel sensors for the HL-LHC tracker upgrade (ITk). The new sensors are significantly thinner than the previous ones and feature a much smaller pixel size to master the high number of expected tracks and the increase in radiation.
Electrical characterization of the new sensors, which will be produced for the detector upgrade, will be done in the LPNHE cleanrooms and at CERN test beams after assembly with the front-end electronics into detector modules. Three laboratories of the Paris area, the LPNHE, IJCLab and IRFU will be involved in this activity working in close connection, which represents one of the largest module assembly and test clusters of all the ATLAS tracker upgrade project. Participation to test beams in which the new modules will be evaluated and analysis of test beam data will complete this part of the thesis work, which will be of primary importance for the characterization of the pixel technology which is being used.
In parallel, the extrapolation of the expected performance of the new system to the HL-LHC data-taking conditions will be studied, in particular in the field of the Higgs boson physics. The decay mode of Higgs to pairs of b-quarks (H->bb), which represents about 58% of all the Higgs decays, is one of the channels for which the detector tracking capability is more critical, given the need for a performant track jet reconstruction and b-quark tagging. The H -> bb cannot be reconstructed in inclusive way given the overwhelming QCD background. This mode has been studied exploiting more complex event topologies, such as the Higgs production associated with a Z of a W bosons decaying to leptons (electrons or muons), and more recently in hadronic decays of the vector boson.
Our LPNHE groups has been strongly involved in these analyses and also in the performance studies for b-jet tagging and for transverse missing energy reconstruction, which are essential ingredients in these measurements.
The present performance will be extrapolated to the new HL-LHC detector to study how the improved tracking capability will increase the sensitivity of the analysis and will pave the way also to new measurements such as the Higgs HH self-coupling, which are out of reach with the present statistics.
Working Place : LPNHE, with frequent travel to CERN for working group meetings, Collaboration meetings, data taking shifts, work for qualification task, test-beams.
A period of short-term or middle-term permanence at CERN can be organized.
Stage foreseen before the thesis, for a period of 4-5 months
Lieu(x) de travail : Paris
Déplacements éventuels : CERN for collaboration meetings and testbeams
Stage proposé avant la thèse : Oui
Dans la même rubrique :
- Etude de la production de di-Higgs pour la nouvelles physiques et amélioration du trajectographe de l’expérience ATLAS en vue de la phase à haute luminosité du LHC
- Mesure de l’élément Vub de la matrice CKM et recherche de nouvelle physique dans l’étude de l’universalité de la saveur leptonique avec l’expérience LHCb au CERN/Measurement of the Vub element of the CKM matrix and search for new physics in lepton flavour universality tests with the LHCb experiment at CERN
- Analyses en amplitudes des désintégrations
- Mesure de la masse du quark top avec des événements ttbar avec des mésons J/ψ et D dans l’état final. Études et réalisation du détecteur de temps hautement granulaire (HGTD) dans l’expérience ATLAS auprès du LHC. Measurement of the top quark mass using ttbar events with J/ψ and D mesons in the final state. Study and realization of a High Granularity Timing Detector (HGTD) for the ATLAS detector for the High Luminosity phase of the LHC.
- Variability from active galactic nuclei with the future Cherenkov Telescope Array and validation tests with the NectarCAM camera
- Joint supernovae and galaxy clustering analysis with ZTF and the DESI BGS
- First LSST dataset : toward the next generation of cosmological constrains.
- Towards precise measurement of neutrino oscillations parameters in T2K-II with new input from the upgraded Near Detector ND280
- Development of reconstruction algorithms for the Hyper-Kamiokande experiment – a unique observatory for rare events in the Universe
- Incertitudes pour les tâches de régression avec des réseaux de neurones sur graphe. Application à la détection de particules cosmiques.
- Prospectives pour une détection interférométrique de particules cosmiques dans le projet GRAND
- Quantifying ML uncertainties in searches for new physics at the LHC
