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Measuring Inflation with CLASS

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Measuring Inflation with CLASS Measuring Inflation with CLASS by Dominik Gothe A dissertation submitted to Johns Hopkins University in conformity with the requirements for the degree of Doctor of Philosophy. July 2015 Baltimore, Maryland c Dominik Gothe All rights reserved Abstract Using the Cosmology Large Angular Scale Surveyor (CLASS), we will measure the po- larization of the Cosmic Microwave Background (CMB) to constrain inflationary theory. The gravitational waves generated during the inflationary epoch imprinted specific polar- ization patterns – quantifiable by tensor-to-scalar ratio r – onto the CMB, which CLASS is designed to detect. Furthermore, we will be able to make assertions about the energy scale during inflation by discovering the features of the polarization power spectrum, providing a probe into physics of energy scales not conceivable in particle-accelerator physics. CLASS is a unique ground based experiment with extensive consideration given to mitigating sys- tematic uncertainties. A brief introduction into inflationary cosmology and review of current scientific results will be presented in the light of the upcoming measurements with the newly built CLASS de- tector. I will detail some of my technical contribution to the construction of this telescope. I have conducted my research under the advise of Prof. Bennett. Additionally the thesis was reviewed by Prof. Marriage, Prof. Kamionkowski, Prof. Chuss, and Prof. Strobel. ii Acknowledgments I would like to thank my wife, friends, members of the Johns Hopkins community, my mentors, teachers, supervisors, and dissertation committee. The CLASS project receives support from the National Science Foundation Division of Astronomical Sciences under Grant Numbers 0959349 and 1429236. iii Contents I Physics of the Origin of the Universe 1 1 Introduction to the Big Bang Framework . 2 1.1 The Big-Bang Theory . 3 1.2 Cosmic Microwave Background . 4 1.3 The CMB in Detail . 5 1.4 The Horizon Problem . 8 1.5 The Flatness Problem . 10 2 The Theory of Inflation . 14 2.1 Introduction to the Theory of Inflation . 15 2.1.1 Solving the Flatness Problem . 16 2.1.2 Solving the Horizon Problem . 17 2.2 Physics of Inflation . 20 2.2.1 Simple Lagrangian Analysis . 21 2.2.2 Quantum Fluctuations . 23 2.2.3 Primordial Seeds . 24 2.2.4 Scalar and Tensor perturbations . 25 2.2.5 Constraining inflation . 27 3 Connecting Theory with Observation . 30 iv 3.1 The Power Spectrum of the CMB . 31 3.1.1 Cosmic Variance and Gaussianity . 31 3.1.2 Key Features of the Angular Power Spectrum . 33 3.1.3 Evolution of a Single Component Universe . 34 3.1.4 Acoustic Oscillations and their Damping Tail . 35 3.1.5 The Sachs-Wolfe Plateau . 38 3.2 The Need to Measure . 38 4 Observing Inflation through the CMB . 39 4.1 Polarization Review . 39 4.1.1 Scalar . 41 4.1.2 Tensor . 42 4.2 The E and B Mode Decomposition . 42 4.2.1 Planck Data . 44 v II Measuring Inflation with CLASS 46 5 Review . 47 5.1 Predictions . 49 5.2 Measuring the Tensor-to-Scalar Ratio . 49 6 CLASS Approach . 52 6.1 Designing for Low-` Sensitivity . 52 6.1.1 Location . 52 6.1.2 Scan Strategy . 54 6.2 Foregrounds . 56 7 Instrument Design . 58 7.0.1 Stokes Parameters . 59 7.0.2 The Variable Delay Polarization Modulator . 59 7.1 Modulator Implementation . 61 7.2 CLASS Optical Design . 62 III Instrument Development 64 8 Cryogenics . 65 8.1 The Dilution Refigerator . 65 8.2 Cryogenic Housekeeping . 67 vi 8.3 Details of the Cryogenic Signal Path . 70 8.3.1 300 K Interface . 70 8.3.2 Hermetic Feedthrough . 70 8.3.3 Cold Breakouts . 72 8.3.4 SRS Break-Out-Box . 74 8.4 Custom Diode Circuit . 88 8.4.1 Hardware . 90 8.4.2 Consistent Overhead Byte Stuffing Encoding . 95 8.4.3 Software . 97 8.4.4 Interface Isolation . 97 8.5 The G Measurements . 100 8.5.1 HP6643 Control Code . 100 8.5.2 60K Load Test . 102 8.5.3 4 K Load Test . 104 8.5.4 1K Load Test . 111 8.6 SRS Mainframe . 114 8.6.1 SRS Temperature Monitoring . 114 8.6.2 SRS PID . 115 8.6.3 SRS Voltage Source . 115 8.6.4 SRS Software . 115 9 Site Software . 118 vii 9.1 Pyro in the CLASS Infrastructure . 119 9.2 Network Considerations . 120 9.2.1 WiFi Link . 120 9.2.2 Switch Gear . 122 9.2.3 Overview of the Mount Networks . 122 9.2.4 Overview of the Control Room Network . 123 9.3 Beefy Miracle . 123 9.4 Data Structure . 126 9.4.1 Overview . 127 9.4.2 Science Data . 128 9.4.3 Additional Mount Data . 129 9.4.4 Cryogenics . 129 9.5 Data Storage and Handling . 130 9.5.1 Storage . 130 9.5.2 Bürgermeister RAID Configuration . 131 9.6 Low-Level Mount Control . 132 9.6.1 Start Up . 133 9.6.2 General Notes . 134 9.6.3 The Screen Program . 134 9.6.4 The Telescope Object . 136 9.6.5 The Sky Object . 137 viii 9.6.6 The Source Object . 139 9.6.7 Axis Objects . 140 9.6.8 Sync Box . 142 9.6.9 Shut Down . 143 9.7 Scan Commanding . 143 9.7.1 General Notes . 143 9.7.2 FivePoint Scan . 144 9.7.3 DriftScan Routine . 145 9.7.4 SkyDip Routine . 146 9.7.5 AzScan Routine . 147 9.7.6 DecScan Routine . 148 9.7.7 ProfileScan Routine . 149 9.8 Mount Control Scripting Language . 150 9.8.1 Submitting Scripts . 151 9.8.2 Precise Timing of Execution Function . 151 9.8.3 Loops within a Script . 153 9.8.4 Closing Thoughts . 153 IV CLASS Simulation 156 10 Software Overview . 158 10.1 Beam Shape . ..
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