The Q/U Imaging ExperimenT (QUIET): The Q-band Receiver Array Instrument and Observations by Laura Newburgh Advisor: Professor Amber Miller Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Graduate School of Arts and Sciences COLUMBIA UNIVERSITY 2010 c 2010 Laura Newburgh All Rights Reserved Abstract The Q/U Imaging ExperimenT (QUIET): The Q-band Receiver Array Instrument and Observations by Laura Newburgh Phase I of the Q/U Imaging ExperimenT (QUIET) measures the Cosmic Microwave Background polarization anisotropy spectrum at angular scales 25 1000. QUIET has deployed two independent receiver arrays. The 40-GHz array took data between October 2008 and June 2009 in the Atacama Desert in northern Chile. The 90-GHz array was deployed in June 2009 and observations are ongoing. Both receivers observe four 15◦ 15◦ regions of the sky in the southern hemisphere that are expected × to have low or negligible levels of polarized foreground contamination. This thesis will describe the 40 GHz (Q-band) QUIET Phase I instrument, instrument testing, observations, analysis procedures, and preliminary power spectra. Contents 1 Cosmology with the Cosmic Microwave Background 1 1.1 The Cosmic Microwave Background . 1 1.2 Inflation . 2 1.2.1 Single Field Slow Roll Inflation . 3 1.2.2 Observables . 4 1.3 CMB Anisotropies . 6 1.3.1 Temperature . 6 1.3.2 Polarization . 7 1.3.3 Angular Power Spectrum Decomposition . 8 1.4 Foregrounds . 14 1.5 CMB Science with QUIET . 15 2 The Q/U Imaging ExperimenT Q-band Instrument 19 2.1 QUIET Q-band Instrument Overview . 19 2.2 Optics . 23 2.2.1 Introduction . 23 2.2.2 Telescope Optics . 23 2.2.3 Feedhorns and Interface Plate . 27 2.2.4 Ortho-mode Transducer Assemblies . 28 2.2.5 Hybrid-Tee Assembly . 33 2.2.6 Optics Performance . 34 2.3 Polarimeter Modules . 49 2.3.1 Introduction . 49 i 2.3.2 Polarimeter Module Components . 51 2.3.3 Module Bias Optimization . 60 2.3.4 Compression . 61 2.3.5 Signal Processing by the QUIET Module . 62 2.4 Single Module Testing at the Jet Propulsion Laboratory and Columbia University . 77 2.5 Electronics . 79 2.5.1 Introduction . 79 2.5.2 Electronics Overview . 80 2.5.3 Protection Circuitry . 84 2.5.4 Bias Boards . 88 2.5.5 Monitor and Data Acquisition Boards . 90 2.5.6 Timing cards . 94 2.5.7 External-Temperature Monitor Boards . 94 2.5.8 Software . 94 2.6 Cryostat . 96 2.6.1 Introduction . 96 2.6.2 Description of W- and Q- band Cryostats . 96 2.6.3 Mechanical Simulations . 99 2.6.4 Expected and Measured Cryostat Temperatures . 100 2.6.5 The Cryostat Window . 106 3 Q-band Array Integration, Characterization, and Testing 119 3.1 Introduction . 119 3.2 Bandpasses . 119 3.2.1 Columbia Laboratory Data . 121 3.2.2 Site Data . 122 3.2.3 Receiver Bandwidths and Central Frequencies . 124 3.2.4 Amplifier Bias . 128 ii 3.2.5 Central Frequencies and Bandwidths: Weighted by Source Spec- trum . 131 3.3 Noise Temperature Measurements . 133 3.4 Responsivity . 135 3.4.1 Total Power . 135 3.4.2 Polarized Response . 137 3.5 Compression . 140 3.6 Noise . 142 3.7 Instrument Sensitivity . 144 4 Observations and Data Reduction 148 4.1 QUIET Observing Site . 148 4.1.1 Observing Conditions . 148 4.2 Patch Selection . 151 4.3 Scan Strategy . 151 4.4 Data Selection and Reduction . 151 4.4.1 Nomenclature . 152 4.4.2 Standard and Static Cuts . 152 4.4.3 Scan Duration . 153 4.4.4 Glitching Cut . 153 4.4.5 Phase Switch Cut . 154 4.4.6 Weather Cut . 155 4.4.7 Fourier-Transform Based Cuts and Filtering . 166 4.4.8 Side-lobe Cut . 171 4.4.9 Coordinate System . 171 4.4.10 Cut Development . 172 4.4.11 Ground Map . 173 4.4.12 Max-Min Removal . 177 4.4.13 Source Removal and Edge-Masking . 179 4.4.14 Data Selected . 179 iii 5 Instrument Calibration and Characterization 180 5.1 Introduction . 180 5.1.1 Nomenclature . 180 5.2 Calibration Overview . 181 5.2.1 Calibration Sources . 181 5.3 Responsivity . 183 5.3.1 Total Power Responsivity . 184 5.3.2 Polarization Responsivity . 185 5.3.3 Systematic Error Assessment . 185 5.4 Sensitivity . 187 5.5 Pointing . 188 5.5.1 Systematic Error Assessment . 193 5.6 Timing . 194 5.7 Polarized Detector Angles . 196 5.7.1 Systematic Error Assessment . 198 5.8 Leakage . 198 5.8.1 Systematic Error Assessment . 199 5.9 Beams . 201 5.9.1 Polarized Beams . 201 5.9.2 Total Power Beams . 204 5.9.3 Ghosting . 205 5.9.4 Systematic Error Assessment for the Beams . 206 5.10 Summary of Calibration and Systematics . 207 5.10.1 Summary of Calibration Accuracy and Precision . 207 5.10.2 Systematics Summary . 208 6 CMB Power Spectrum Analysis and Results With a Maximum Like- lihood Pipeline 209 6.1 Introduction . 209 6.2 Maximum-Likelihood Method Background . 209 iv 6.3 Optimal Map Making . 210 6.4 Maximum Likelihood Power Spectrum Estimation . 212 6.4.1 Overview . 212 6.4.2 Gibbs Sampling . 214 6.4.3 Null Spectrum Testing . 215 6.5 Foreground Estimation . 221 6.6 Preliminary Results . 224 6.6.1 Galactic Center . 224 6.6.2 Null Tests . 224 A Module Signal Processing 242 A.1 Phase Switch Transmission Imbalance . 242 A.2 Module Systematics . 246 A.3 Signal Processing including systematics . 246 A.3.1 No Systematics: OMT input . 246 A.3.2 No Systematics: hybrid-Tee input . 246 A.3.3 Complex gain: OMT input . 246 A.3.4 Complex gain: Hybrid-Tee input . 248 A.3.5 Imperfect coupling within the Hybrid-Tee . 250 A.3.6 Phase lag in 180◦ coupler at input: OMT input . 252 A.3.7 Phase lag in 180◦ coupler at input: Hybrid-Tee input . 253 A.3.8 Phase lag.