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MICROMEGAS Chambers for Hadronic Calorimetry, Search for New Physics in the Field of the Top Quark Ambroise Espargilière

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MICROMEGAS Chambers for Hadronic Calorimetry, Search for New Physics in the Field of the Top Quark Ambroise Espargilière MICROMEGAS Chambers for Hadronic Calorimetry, Search for New Physics in the Field of the Top Quark Ambroise Espargilière To cite this version: Ambroise Espargilière. MICROMEGAS Chambers for Hadronic Calorimetry, Search for New Physics in the Field of the Top Quark. High Energy Physics - Experiment [hep-ex]. Université de Grenoble, 2011. English. tel-00657129v1 HAL Id: tel-00657129 https://tel.archives-ouvertes.fr/tel-00657129v1 Submitted on 5 Jan 2012 (v1), last revised 17 Mar 2012 (v2) HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. THESE` Pour obtenir le diplomeˆ de DOCTEUR DE L’UNIVERSITE´ DE GRENOBLE Specialit´ e´ : Physique/Physique Subatomique & Astroparticules Arretˆ e´ ministerial´ : 7 aoutˆ 2006 Present´ ee´ par AMBROISE ESPARGILIERE` These` dirigee´ par Catherine ADLOFF et codirigee´ par Yannis KARYOTAKIS prepar´ ee´ au Laboratoire d'Annecy-le-vieux de Physique des Particules et de l’Ecole´ Doctorale de Physique de Grenoble Chambres MICROMEGAS pour la Calorimetrie´ Hadronique, Recherche d’une Nouvelle Physique dans le Domaine du Quark Top R&D pour un futur collisionneur lineaire´ These` soutenue publiquement le 21 septembre 2011, devant le jury compose´ de : Dr. Jean-Jacques BLAISING Directeur de Recherche au LAPP, Annecy-le-Vieux, President´ Dr. Felix SEFKOW Directeur de Recherche a` DESY, Hambourg, Rapporteur Dr. Paul COLAS Directeur de Recherche au CEA, Saclay, Rapporteur Dr. Yorgos TSIPOLITIS Professeur associe´ au N.T.U.A., Athenes,` Examinateur Dr. Lucie LINSSEN Directeur de Recherche au CERN, Geneve,` Examinateur Dr. Yannis KARYOTAKIS Directeur du LAPP, Annecy-le-Vieux, Examinateur Dr. Catherine ADLOFF Maitre de Conference´ a` l’Universite´ de Savoie, Chambery,´ Directeur de these` Thesis of Ambroise Espargiliere` Under the direction of Dr. Catherine Adloff and Dr. Yannis Karyotakis. MICROMEGAS Chambers for Hadronic Calorimetry, Search for New Physics in the Field of the Top Quark R&D towards a future linear collider A` ma famille, mes amis et mes professeurs qui m’ont construit et me permettent aujourd’hui d’´ecrire ces quelques lignes. Et `aDoroth´ee et C´elestin, pour qui j’´ecris toutes les autres ... i Complete document v1.7 31/08/2011 ii Complete document v1.7 31/08/2011 Contents Introduction 1 I Introductory Topics 3 1 Fundamental particles 5 1.1 GlimpseofParticlePhysics . 5 1.1.1 Particlesandtheirinteractions . ... 5 1.1.2 Thequarks ............................... 7 1.1.3 StandardModel ............................ 9 1.2 Today’squestionsandexperiments . .... 9 1.3 NewPhysics................................... 11 1.3.1 SuperSymmetry ............................ 12 1.3.2 Kaluza-Kleinmodels . 13 1.3.3 Theexpectedroleofthetopquark . 14 R´esum´educhapitre ................................. 15 2 Particle colliders and detectors 17 2.1 Acceleratingparticles . 17 2.2 Collidingparticles .............................. 17 2.3 Futurecolliders................................. 18 2.3.1 The International Linear Collider . 19 2.3.2 TheCompactLinearCollider . 20 2.4 Recordingcollisions. 21 2.5 Calorimetry................................... 23 2.5.1 Particleshowers ............................ 24 2.5.2 Energy measurement and resolution . 27 2.6 ParticleFlowAlgorithm . 31 R´esum´educhapitre ................................. 34 iii CONTENTS II Characterisation and Development of MICROMEGAS Cham- bers for Hadronic Calorimetry at a Future Linear Collider 37 3 MICROMEGAS chambers for hadronic calorimetry 39 3.1 Abriefoverviewofgaseousdetectors . ..... 39 3.1.1 MWPC ................................. 40 3.1.2 Some electron amplifying gaseous detectors . ..... 41 3.2 MICROMEGAStechnology . 43 3.2.1 Descriptionandbasicprinciple . 43 3.2.2 The MICROMEGAS signal . 44 3.2.3 BulkMICROMEGAS ......................... 45 3.3 ContextoftheR&Dproject. 46 3.4 R&Dprojectoutline .............................. 47 3.5 Descriptionoftheprototypes . 48 3.5.1 Commonfeatures............................ 48 3.5.2 Analogueprototypes . 48 3.5.3 Digitalprototypes ........................... 48 R´esum´educhapitre ................................. 49 4 X-ray tests 53 4.1 Experimentalsetup............................... 53 4.2 Electroncollectionefficiency. 54 4.3 Gasgain..................................... 54 4.4 Method for pressure and temperature correction . ....... 56 4.4.1 GasGainModel ............................ 56 4.4.2 Application to Ar/iC4H10 and Ar/CO2 ............... 57 4.5 Environmental study in Ar/CO2 (80/20)................... 57 4.5.1 Experimentalconditions . 57 4.5.2 Pressurecorrections . 57 4.5.3 Temperaturecorrections . 58 4.5.4 Corrections using the ratio of pressure over temperature...... 59 4.5.5 Conclusionofthestudy . 59 R´esum´educhapitre ................................. 60 5 Tests in particle beams 63 5.1 Experimentallayout .............................. 63 5.1.1 Detectorstack ............................. 63 5.1.2 Readoutsystem............................. 63 5.1.3 Calibration ............................... 64 5.1.4 Particlesources............................. 65 5.2 Dataquality................................... 66 5.2.1 Environmental and noise conditions . 66 5.2.2 Eventtags................................ 67 5.2.3 Chambersalignment . 67 5.2.4 Noisecontamination . 68 5.3 Gaindistributionmeasurement . 70 iv Complete document v1.7 31/08/2011 CONTENTS 5.4 Efficiencymeasurement ............................ 71 5.5 Multiplicitymeasurement . 75 5.6 MICROMEGAS in high energy hadronic showers . 75 5.7 Calorimetrymeasurements. 78 5.7.1 Experimentalsetup. 78 5.7.2 Eventselection ............................. 79 5.7.3 Electronshowerprofile. 80 5.7.4 Interpretation in terms of electromagnetic calorimetry ....... 81 5.7.5 Hadronshowerprofile . 83 5.7.6 Interpretation in terms of hadronic calorimetry . ....... 84 5.7.7 Predictions for 4 GeV/c data...................... 86 5.7.8 Conclusionofthestudy . 87 R´esum´educhapitre ................................. 87 6 Development of the project 89 6.1 Embeddedreadoutchip ............................ 89 6.1.1 Readoutchipscatalog . 89 6.1.2 Performance of the DIRAC1 prototype . 90 6.1.3 DIRAC2performance . 90 6.2 LargeareaMICROMEGASforaDHCAL . 91 6.2.1 Square meter prototype design and assembly process . ...... 92 6.2.2 Mechanicalprototype . 94 6.2.3 Physicalprototype . 94 6.2.4 Powerpulsing.............................. 97 6.2.5 Preliminary results on the second square meter prototype ..... 98 6.3 Expected performance of a MICROMEGAS DHCAL prototype . 99 6.3.1 Cubicmeterproject . 99 6.3.2 Mini-calorimeteralternative . 100 6.4 Layout studies towards the SiD DHCAL . 101 6.4.1 Globalgeometry ............................101 6.4.2 AlternativeDHCALlayout . .101 R´esum´educhapitre ................................. 102 7 Conclusion 105 III Search for New Physics in the Field of the Top Quark at CLIC109 8 The top quark at CLIC 111 + 8.1 e e− collisionsat3TeV ............................111 8.1.1 InitialStateRadiation . 111 8.1.2 Beamstrahlung .............................112 8.1.3 Machine induced background . 113 8.2 tt¯ eventsatCLIC................................114 8.2.1 Total cross section as a function of the centre of mass energy . 115 8.2.2 tt¯ pairenergyspectrum . .116 v Complete document v1.7 31/08/2011 CONTENTS 8.3 Top-tagging...................................118 8.3.1 Backgroundchannels. .119 8.3.2 Discriminativevariables . 119 8.3.3 WW backgroundrejection. .121 8.3.4 tt¯ eventselectionperformance. .122 R´esum´educhapitre ................................. 122 9 Search for a light Z′ in 3 TeV tt¯ events 127 9.1 TheRightHandedNeutrinoModel . 127 9.2 Crosssectionstudy............................... 128 9.2.1 Channel e+e ννZ¯ .........................129 − → ′ 9.2.2 Channel e+e HZ .........................129 − → ′ 9.2.3 Channel e+e τ +τ Z .......................130 − → − ′ 9.2.4 Choiceofthechannel . .131 9.2.5 Choiceofthedecaymode . .132 9.3 Eventselection .................................132 9.3.1 Background...............................133 9.3.2 Eventgeneration . .134 9.3.3 Discriminativevariables . 134 9.3.4 Classifier training and testing . 135 9.4 Measurements..................................136 9.4.1 Z′ mass measurement method . 136 9.4.2 Z′ massmeasurementresults . .137 9.4.3 Crosssectionmeasurement . .142 9.5 Performance estimation with full detector simulation . ...........143 R´esum´educhapitre ................................. 144 10 Conclusion 147 Appendices and back matter 151 A MICROMEGAS signal computation 151 B tt¯ production in the SM together with neutrinos 155 B.1 Productiondiagrams .............................. 155 B.1.1 e+e ttν¯ ν¯ .............................155 − → e e B.1.2 e+e ttν¯ ν¯ .............................156 − → µ µ B.1.3 e+e ttν¯ ν¯ .............................157 − → τ τ B.2 Crosssection ..................................158 C Toy Model of tt¯ event energy spectrum 159 D Appendix to the RHNM generator level study 163 D.1 Dark matter relic density and detection rate . .......163 D.2 Summary of the cross sections and statistics for the signal.. .163 D.3 Indexofthefinalstatevariables
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