SiD Letter of Intent v0.94 25 February 2009 Editors: H. Aihara, P. Burrows, M. Oreglia Figure 1: The SiD detector concept. 2 SiD Letter of Intent Contents 1 Introduction 3 1.1 The ILC Physics Menu ............................... 3 1.2 Detector Overview ................................. 4 1.3 Polarimeters and Energy Spectrometers ..................... 7 1.4 SiD Detector Optimization ............................ 8 1.5 ILC Environmental Concerns ........................... 10 1.5.1 Expected Backgrounds at the ILC .................... 12 1.5.2 Vertex Detector ............................... 13 1.5.3 Forward Tracker .............................. 14 1.5.4 Barrel Tracker ............................... 16 1.5.5 Electromagnetic Calorimeter ....................... 16 1.5.6 Beamcal and Lumcal. ........................... 16 References ......................................... 19 2 Subsystems 21 2.1 Vertex and Tracking System ............................ 22 2.1.1 Introduction ................................ 22 2.1.2 Beam Environment ............................. 23 2.1.3 Vertex Detector Design .......................... 25 2.1.4 Tracker Design ............................... 31 SiD Letter of Intent 3 CONTENTS 2.1.5 Tracker Module Design .......................... 33 2.1.6 Simulation Infrastructure ......................... 36 2.1.7 Vertex Detector Hit Digitization ..................... 37 2.1.8 Tracker Hit Digitization .......................... 39 2.1.9 Track Reconstruction ........................... 39 2.1.10 Tracking Performance ........................... 42 2.1.11 Tracker Alignment ............................. 43 References ......................................... 44 2.2 Calorimeters .................................... 55 2.2.1 Introduction to Calorimeters ....................... 55 2.2.2 Electromagnetic Calorimeter ....................... 55 2.2.3 Hadronic Calorimeter ........................... 65 2.3 Homogeneous Dual Readout Option ....................... 80 2.3.1 Principles of Operation: Energy Resolution ............... 80 2.3.2 Enabling Technological Developments .................. 84 2.3.3 Conceptual Design of High Resolution Calorimeter (HRC) ....... 84 2.3.4 Principal Challenges of the HRC ..................... 85 2.3.5 R&D Program ............................... 85 References ......................................... 88 2.4 SiD MAGNET SUBSYSTEM ........................... 89 2.4.1 Superconducting Solenoid ......................... 89 2.4.2 Cryostat and Magnet Iron ......................... 94 2.4.3 Detector Integrated Dipole (DID) .................... 95 2.5 Muon System .................................... 97 2.5.1 Overview .................................. 97 2.5.2 Design ................................... 97 2.5.3 Function ................................... 97 4 SiD Letter of Intent CONTENTS 2.5.4 Requirements ................................ 98 2.5.5 Detector Design .............................. 98 2.5.6 Backgrounds ................................ 98 2.5.7 Resistive Plate Chambers ......................... 99 2.5.8 R&D ..................................... 100 2.5.9 Milestones .................................. 106 References ......................................... 108 2.6 Forward Detector .................................. 109 2.6.1 Design criteria ............................... 109 2.6.2 Baseline Design ............................... 112 2.6.3 Expected Performance ........................... 114 2.6.4 High energy electron detection in BeamCal ............... 117 2.6.5 R&D ..................................... 119 References ......................................... 121 3 Machine-Detector Interface and Global Issues 123 3.1 SiD Assembly .................................... 123 3.2 Push Pull ...................................... 124 4 Physics Performance and Benchmarking 129 4.1 Simulation of SiD. ................................. 129 4.1.1 Beampipe: .................................. 131 4.1.2 Vertex Detector: .............................. 131 4.1.3 Tracker: ................................... 132 4.1.4 Calorimeters: ................................ 133 4.1.5 Solenoid: .................................. 134 4.1.6 Muon System: ............................... 134 4.1.7 Masks and Far Forward Detectors .................... 135 SiD Letter of Intent 5 CONTENTS 4.2 Benchmark Reactions ............................... 135 p 4.2.1 e+e¡ ! e+e¡H ; ¹+¹¡H , s=250 GeV ................ 136 p 4.2.2 e+e¡ ! ZH;H ! cc¹ ; Z ! ºº¹ ; qq¹, s=250 GeV .......... 136 p 4.2.3 e+e¡ ! ZH;H ! ¹+¹¡ ;Z ! ºº¹ ; qq¹, s=250 GeV ........ 144 p 4.2.4 e+e¡ ! ¿ +¿ ¡ , s=500 GeV ...................... 147 p 4.2.5 e+e¡ ! tt¹ ; t ! bW + ;W + ! qq¹0 , s=500 GeV ........... 150 + ¡ + ¡ 0 0 p 4.2.6 e e ! Â~1 Â~1 /~Â2Â~2 , s=500 GeV ................... 153 p 4.2.7 e+e¡ ! ZHH;H ! b¹b , s=500 GeV ................ 156 + ¡ ~¹~ ~ 0 4.2.8 Sbottom Quark Production: e e ! bb ; b ! bÂ~1 ........... 159 p 4.2.9 e+e¡ ! e+e¡(γ) ; ¹+¹¡(γ), s=500 GeV .............. 163 References ......................................... 165 5 Cost Estimate 167 6 Research and Development Issues 175 6 SiD Letter of Intent List of Figures 1 The SiD detector concept. ............................. 1 1.1 Illustration of a quadrant of SiD. ......................... 5 1.2 Fractional error in the triple Higgs coupling, ghhh, as a function of the jet energy resolution, ¢E/E [%], from the measurement of the cross section for e+e¡ ! ZHH at 500 GeV with an integrated luminosity of 2000 fb¡1. .... 10 1.3 Physics backgrounds from γγ produced e+e¡ pairs, muon pairs, and hadronic events integrated over 150 bunch crossings (left) and a single bunch crossing (right). ........................................ 11 1.4 VXD Hits/mm2/train for Barrel Layer 1 for the various ILC beam parameter sets. ......................................... 15 1.5 The number of charged particles / BX which reach a maximum radius between R and R + 2 cm, as a function of radius R, for nominal 500 GeV beam parameters. The e+e¡ pairs are shown in red; hadrons and muon pairs in green. 15 1.6 The density of electron and positron tracks / cm2/ BX in Layer #1 of the forward tracker, as a function of the radius of the hit. ............. 17 2.1 Maximum envelope of the e+e¡-pair backgrounds in a 5 Tesla ¯eld. Indicated is the 12 mm radius beampine. .......................... 24 2.2 R-z view of the vertex detector and its support structure. ........... 25 2.3 Barrel end view of the vertex detector (left) and layer arrangment of the silicon sensors only (right). ................................ 27 2.4 Tracker in the open position for servicing of the vertex detector. ....... 31 2.5 Hit pattern and material summary of the vertex detector as function of polar angle. ........................................ 45 2.6 R-z view of the whole tracking system. ..................... 46 SiD Letter of Intent 7 LIST OF FIGURES 2.7 Detail of the sensor overlap in the barrel region in the z and R' projection. 46 2.8 R' projection view of the tracker barrels and disks. .............. 47 2.9 Detail of the sensor overlap and cable routing for the tracker disks. ..... 48 2.10 Material budget of the tracking system. ..................... 49 2.11 Photograph of a prototype SiD tracker sensor. ................. 49 2.12 Detail of the double-metal routing of the traces to the readout chip and the connections to the readout cable, visible to the right of the bump-bond array. 50 2.13 Sketch of a module to the tracker barrel. This ¯gure should be replaced. .. 50 2.14 R-z view of the simpli¯ed tracking system as implemented in sid02. ..... 51 2.15 The central vertex detector showing the layout of the silicon pixel sensor mod- ules. ......................................... 51 2.16 The central tracker showing support barrels tiled with overlapping readout modules. ...................................... 52 2.17 Track ¯nding e±ciency as function of cos #. .................. 52 2.18 Track ¯nding e±ciency as function of pT . .................... 53 2.19 Number of mis-assigned hits on a track. ..................... 53 2.20 Resolution in momentum (right) and DCA (left) as function of momentum for tracks at various angles. ............................. 54 2.21 Sketch of the IR alignment method. ....................... 54 2.22 Simulated ½+ ! ¼+¼± in SiD. ........................... 56 2.23 Energy resolution for two longitudinal con¯gurations. ............. 58 2.24 Overall mechanical layout of the ECAL. ..................... 59 2.25 Drawing of a silicon sensor for the ECAL. .................... 61 2.26 Readout gap in the vicinity of the KPiX readout chip. ............. 62 2.27 Paul's Digital ECAL plot and a nice MAPS Shower picture .......... 62 2.28 Drawing of initial ECAL test module. ...................... 63 2.29 Cross-section of the HCAL barrel. ........................ 65 2.30 Face and top views of the forward HCAL. .................... 66 8 SiD Letter of Intent LIST OF FIGURES 2.31 Schematic of the RPC design with two glass plates. ............... 67 2.32 Schematic of the RPC design with one glass plate. ............... 67 2.33 MIP detection e±ciency .............................. 68 2.34 Longitudinal shower shape ............................. 69 2.35 MIP detection e±ciency as function of time ................... 69 2.36 Schematic layout of GEM-based DHCAL .................... 71 2.37 GEM results from FNAL beam test. ....................... 71 2.38 Signal from KPiX chip - anode pad under source ................ 72 2.39 MicroMegas 12x32 cm2 prototype. .......................