Luminosity Measurement at the Compact Muon Solenoid Experiment of the LHC (Springer Theses)

This book describes the application of a novel technology for beam instrumentation and luminosity measurement and first results on a cutting edge technology potentially to be used after the upgrade of the Large Hadron Collider to higher luminosity. It presents a unique diamond-based luminometer with a detailed performance study. The online bunch-by-bunch luminosity measurements provide an invaluable feedback to the Collider for beam optimisation and for the understanding of beam dynamics. The precision of the luminosity measurement is crucial for all physics analyses. This book highlights the Van der Meer method, which is used for the calibration of the luminometers of the CMS (Compact Muon Solenoid) experiment, and describes the estimate of systematic uncertainties, e.g. due to radiation damage of sensors and electronics and uncertainties of beam parameters. For the future high-luminosity upgrade of the collider, sapphire sensors are investigated in a test beam. It is demonstrated for the first time that sapphire sensors can be used as single particle detectors. A model for the charge transport in sapphire is developed and successfully applied. Supervisor’s Foreword 6 Abstract 8 Acknowledgements 10 Contents 12 Abbreviations 15 1 Thesis Introduction 17 References 21 2 Introduction to Collider Physics 23 2.1 Large Hadron Collider 23 2.2 Experiments at the LHC 24 2.3 Physics Goals at LHC 26 2.4 The CMS Experiment 26 References 29 3 Measurement of the Luminosity at Colliders 30 3.1 Absolute Luminosity from Machine Parameters 31 3.2 Calibration of Luminometers 32 3.3 Luminosity Calculation Using Physics Cross Section 35 3.4 Beam Radiation, Instrumentation and Luminosity Project 35 3.4.1 New Pixel Luminosity Telescope 38 3.4.2 The Fast Beam Condition Monitor 39 3.4.3 The Beam Halo Monitor 40 3.5 Other Luminometers of the CMS 41 3.5.1 The Hadron Forward Calorimeter 41 3.5.2 Silicon Pixel Detector 42 3.6 Radiation Simulations 43 References 44 4 BCM1F Detector as Luminometer 46 4.1 The BCM1F 46 4.2 Diamond as a Solid State Detector 46 4.3 Sensor Characterization 48 4.4 Front-End Electronics 49 4.5 Signal Transmission and Back-End Electronics 49 4.5.1 Analogue Signal Processing Using VME ADC 51 4.5.2 Processing of the Data Using the Real-Time Histogramming Unit 52 4.5.3 The MicroTCA Based Back-End Electronics 53 4.6 Beam Splashes and BCM1F Timing Adjustment 53 4.6.1 ADC Data Analysis from Splashes 54 4.7 The BCM1F Response Studies Using the VME ADC 56 4.7.1 Baseline Position 57 4.7.2 Detector Response for Particle Hits and Test Pulses 58 4.7.3 Signal Amplitude and Signal Length Spectra 59 4.8 Detector Stability and Radiation Damage Monitoring 61 4.8.1 BCM1F Stability within Long LHC Fills and in the 50 ns Operation Period 61 4.8.2 BCM1F Performance as a Function of the Luminosity 64 4.8.3 Observations During Measurements 70 4.8.4 Web Monitoring Tool 73 References 74 5 Measurements of the Luminosity Using BCM1F 76 5.1 BCM1F Rate Measurements Using the Real-Time Histogramming Unit 76 5.1.1 Online Luminosity Calculation 77 5.1.2 Aggregated Channel Rate Histograms 77 5.2 VdM Scan in August 2015 78 5.2.1 Van der Meer Scan Analysis Framework 80 5.2.2 Fits of the Rate as a Function of the Relative Displacement of the Beams 81 5.2.3 Influence of the Beam Current Measurement on σvis 83 5.2.4 Contribution of Satellite Bunches and Ghosts to the Beam Current Measurement 85 5.2.5 Contributions from MIB and Albedo to the Rates Measured in the VdM Scan 86 5.2.6 Length Scale Scan 87 5.2.7 Orbit Drift 92 5.2.8 Correlations Between the Particle Densities in the x and y Planes 94 5.2.9 Beam-Beam Effects 95 5.3 Stability of BCM1F over the 50 ns Running Period and Systematic Uncertainties 97 5.3.1 Relative Channel-to-Channel Stability 97 5.3.2 Systematic Uncertainties of the Luminosity Measurements 98 5.4 Luminosity Measurements Using a Single Channel 99 5.4.1 Validation of the Aggregated Histogram 99 5.4.2 Visible Cross Section for Single Channel 101 5.5 Comparison of VdM Scans in 2015 and 2016 102 5.6 Comparison of the Luminometers 105 References 106 6 Upgrade of the Luminometers for High Luminosity LHC 108 6.1 Artificial Sapphire 108 6.1.1 Historical Excurs 109 6.1.2 Basic Features of Artificial Sapphire and Industrial Applications 112 6.1.3 Sapphire as a Solid State Detector 112 6.2 Sensor Characterization and Tests 114 6.2.1 Electrodes 114 6.2.2 Sensor Characterization in the Laboratory 114 6.2.3 The Response of Sapphire Sensor as a Function of the Dose 115 6.3 Detector Stack Design 116 6.4 Test Beam Setup 118 6.5 Data Synchronization and Analysis 118 6.5.1 Track Reconstruction 120 6.5.2 Selection of Data Samples 120 6.5.3 Sapphire Sensor Response 122 6.5.4 Common Mode Noise 122 6.5.5 Signal Spectrum 124 6.5.6 Systematic Errors 124 6.6 Charge Collection Efficiency 126 6.7 Study of the Sensor Response as a Function of the x Coordinate 129 6.8 CCE as a Function of Time 130 6.9 A Model to Describe the CCE of Sapphire Sensors 131 6.9.1 Dependence of Electric Field on Sensor Depth 132 6.9.2 Signal Size Estimate 133 6.9.3 CCE as a Function of Local y 135 References 137 7 Summary and Conclusions 139 Appendix AAdjustment of the BCM1F Signal Delaywith Respect to BPTX 142 Appendix BLinear Coordinate Transformationfor the Sapphire Stack 145 Curriculum Vitae 150 This book describes the application of a novel technology for beam instrumentation and luminosity measurement and first results on a cutting edge technology potentially to be used after the upgrade of the Large Hadron Collider to higher luminosity. It presents a unique diamond-based luminometer with a detailed performance study. The online bunch-by-bunch luminosity measurements made provide an invaluable feedback to the Collider for beam optimisation and the understanding of the beam dynamics. The precision of the luminosity measurement is crucial for all physics analyses. This book highlights the Van der Meer method, which is used for the calibration of the luminometers of the CMS (Compact Muon Solenoid) experiment, and describes the estimate of systematic uncertainties, e.g. due to radiation damage of sensors and electronics and uncertainties of beam parameters. For the future high-luminosity upgrade of the collider, sapphire sensors are investigated in a test beam. It is demonstrated for the first time that sapphire sensors can be used as single particle detectors. A model for the charge transport in sapphire is developed and successfully applied Front Matter ....Pages i-xvi Thesis Introduction (Olena Karacheban)....Pages 1-6 Introduction to Collider Physics (Olena Karacheban)....Pages 7-13 Measurement of the Luminosity at Colliders (Olena Karacheban)....Pages 15-30 BCM1F Detector as Luminometer (Olena Karacheban)....Pages 31-60 Measurements of the Luminosity Using BCM1F (Olena Karacheban)....Pages 61-92 Upgrade of the Luminometers for High Luminosity LHC (Olena Karacheban)....Pages 93-123 Summary and Conclusions (Olena Karacheban)....Pages 125-127 Back Matter ....Pages 129-142