CERN-LHCC-2014-NNN CMS-TDR-MMM 2 ISBN 978-92-9083-396-3 1 23 June 2014; Draft V02-00 3 CMS TECHNICAL 4 DESIGN REPORT 5 FOR THE MUON 6 ENDCAP UPGRADE: 7 GE1/1 - THE STATION 1 8 GEM PROJECT 9 This report describes the technical design and outlines the expected performance of the Phase 2 Upgrade of the CMS Muon System with Gas Electron Multiplier (GEM) detectors to be installed in the first endcap station during the 2nd LHC Long Shutdown (LS2). After LS2, the LHC luminosity and pileup level will be double the design value. The upgrade is designed to improve the muon trigger and tracking performance at high luminosity, and to add redundancy to the muon system in the 1.6 < jhj < 2.4 region, where the number of muon hits is actually least, while the background rates are highest and the muon trajectory bending is reduced. GEM detectors have been identified as a suitable technology to sustain the specific high radiation environment in that region. The first muon endcap station will be instrumented in the aforementioned h region with a double layer of triple-GEM chambers. The chamber front-end elec- tronics is based on the digital VFAT3 chip and provides fast input for the level-1 muon trigger and full granularity information for offline muon reconstruction. The expected performance of the muon system after this upgrade is discussed, including a study of some benchmark physics channels. The planning for the detector construction, testing, integration into CMS is presented, including the project schedule, cost and organization. 10 Editors 11 M. Abbrescia, A. Sharma and M. Tytgat 12 Chapter Editors 13 P. Aspell, L. Benussi, S. Bianco, O. Bouhali, A. Cimmino, A. Colaleo, G. De Lentdecker, P. Gi- 14 acomelli, J. Hauser, K. Hoepfner, M. Hohlmann, H. Hoorani, P. Karchin, A. Lanaro, M. Maggi, 15 A. Marinov, A. Safonov, A. Sharma and M. Tytgat 16 Language Editors 17 M. Hohlmann and P. Karchin 18 Cover Design 19 S. Cittolin 20 Acknowledgments 21 We would like to thank the technical staff from the various institutions for the design, R&D 22 and testing of all components of this upgrade. 23 We thank G. Alverson for tireless technical assistance in the preparation of this document. 24 We acknowledge the warm support received from the CMS management team and the CMS 25 offline and computing projects. ii 26 Contents 27 1 Introduction 1 28 1.1 Motivation for Additional Detectors in the Muon Endcaps . .1 29 1.2 Overview of the upgrade project . .3 30 2 GE1/1 GEM Chambers 5 31 2.1 Technology Overview . .5 32 2.1.1 Requirements on GE1/1 chamber performances and design . .5 33 2.1.2 Gas Electron Multiplier principles . .7 34 2.1.3 Choice of GEM technology for GE1/1 as motivated by other experiments9 35 2.2 GE1/1 prototyping results . 11 36 2.2.1 R&D program on full-size GE1/1 prototypes . 11 37 2.2.2 Performance measurements and simulation studies . 12 38 2.2.3 Considerations for environmentally-friendly counting gas mixtures . 25 39 2.3 Technical Design of GE1/1 Chambers for CMS . 26 40 2.3.1 GEM foil design and production technology . 26 41 2.3.2 Validation of chamber materials . 26 42 2.3.3 Mechanical Design . 28 43 2.3.4 HV distribution to GEM foils . 29 44 2.3.5 Readout board design . 29 45 3 Electronics 37 46 3.1 Electronics system overview . 37 47 3.2 The VFAT3 front-end ASIC . 38 48 3.2.1 The Analog Front-end . 40 49 3.2.2 Variable Latency Data Path . 41 50 3.2.3 Fixed Latency Trigger Path . 44 51 3.2.4 Slow Control . 44 52 3.2.5 Programmability . 45 53 3.3 The GEB board . 45 54 3.4 The opto-hybrid and optical links . 47 55 3.4.1 The Gigabit Transceiver (GBT) and the Versatile Link . 47 56 3.5 The back-end electronics . 48 57 3.6 Trigger path to the CSC . 49 58 4 Data Acquisition and Trigger 51 59 4.1 DAQ data flow . 51 60 4.2 GEM-CSC trigger data flow . 53 61 4.3 DAQ firmware and Software . 53 62 4.3.1 MP7 and mTCA control . 53 63 4.3.2 Overview of the online software . 54 64 4.3.3 DAQ Prototype . 54 iii 65 5 Chamber Production and Quality Assurance 57 66 5.1 GEM Production and Assembly plan . 57 67 5.1.1 Production protocols and assembly workflow . 57 68 5.1.2 Production sites specification . 57 69 5.1.3 Production protocols and assembly workflow at sites . 58 70 5.1.4 Gain uniformity test and chamber facility . 59 71 5.1.5 Gain uniformity test and chamber facility . 60 72 5.1.6 Reception of chambers at CERN and validation protocols (OB, PK, MA) . 60 73 5.1.7 Cosmic ray tests (OB, PK, MA) . 61 74 5.2 Super Chamber production . 61 75 5.2.1 Mechanical assembly and QC . 61 76 5.2.2 Final electronics connectivity and integration . 61 77 5.2.3 Final QC procedure . 61 78 5.3 Database . 62 79 6 System Performance 63 80 6.1 LHC Conditions for the operation of GE1/1 . 63 81 6.2 Simulation: data samples and workflow (Ahmed and Yasser) . 63 82 6.3 Muon reconstruction (Anna) . 64 83 6.3.1 Local Reconstruction (Anna, Raffaella) . 64 84 6.3.2 Tracking of Charged Particles and Parameter Measurements in CMS . 64 85 6.3.3 Muon Reconstruction in the Muon Spectrometer . 66 86 6.3.4 Regional reconstruction: Standalone muon (Anna,Archie) . 67 87 6.3.5 Global Muon Reconstruction (Anna,Cesare) . 67 88 6.3.6 Muon identification . 68 89 6.4 Performance (Anna, Cesare, Raffaella, Archie) . 69 90 6.4.1 Local Muon Reconstruction: GEM spatial resolution . 70 91 6.4.2 Global Reconstruction: Efficiencies . 70 92 6.4.3 Global Reconstruction: Resolutions and Charge Misidentification . 72 93 6.5 Radiation background in the muon stations (Silvia Costantini) . 72 94 6.5.1 GEM sensitivities to neutrons and photons . 75 95 6.5.2 Energy spectra of neutrons and photons . 76 96 6.6 Particle fluxes in the muon chambers (KH, Archie Sharma) . 76 97 6.7 Muon performance measurements (Anna) . 76 98 6.8 Muon trigger performance (?) . 76 99 6.9 Performance for representative physics processes (Kerstin and Paolo) . 77 100 6.10 Track-based Detector Alignment Performance (?) . 80 101 7 Integration, Installation and Commissioning in CMS 81 102 7.1 Introduction . 81 103 7.2 Mechanical aspects and Alignment . 81 104 7.2.1 Description of the GE1/1 Location . 82 105 7.2.2 Installation Procedures and Tools . 83 106 7.2.3 Position Monitoring . 83 iv v 107 7.2.4 Alignment . 83 108 7.3 Power System . 86 109 7.3.1 HV Power System . 86 110 7.3.2 LV Power System . 87 111 7.4 Cabling . 87 112 7.4.1 HV Cabling . 87 113 7.4.2 LV Cabling . 87 114 7.5 Cable Routing . 87 115 7.6 Readout and Control . 91 116 7.6.1 Optical Links and Architecture . 91 117 7.6.2 Radhard Optical Lines YE1 . 91 118 7.6.3 Fibers from UXC to USC . 91 119 7.6.4 Commissioning . 91 120 7.7 Gas System . 91 121 7.8 Cooling System . 92 122 7.9 Database . 92 123 7.10 Commissioning . 94 124 8 Controls and Monitoring 95 125 8.1 Introduction . 95 126 8.2 Detector Control System . 95 127 8.2.1 GEM Detector Control System . 96 128 8.2.2 GEM Finite State Machine . 97 129 8.3 Data Quality Monitoring System . 97 130 8.3.1 Architecture of the GEM DQM System . 98 131 8.3.2 DQM Graphical User Interfaces . 99 132 9 Project Organization, Schedule and Costs 101 133 9.1 Participating institutes . ..