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Measuring the Polarization of the Cosmic Microwave Background with BICEP3


Hui, Howard (2018) Measuring the Polarization of the Cosmic Microwave Background with BICEP3. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/G8ET-FD62.


Inflation, a period of accelerated expansion in the early Universe, is postulated to answer the horizon, flatness and monopole problems in the standard model of the Universe. This inflationary scenario generically predicts the existence of primordial gravitational waves, which would leave an unique B-mode polarization pattern in the Cosmic Microwave Background. Detection of the primordial B modes at degree angular scales would be a direct evidence for inflation; and the amplitude, parametrized by the tensor-to-scalar ratio r, would allow us to probe the energy scale at 10-35 second after the Big Bang.

The Bicep/Keck Array experiment is a series of telescopes located at the Amundsen-Scott South Pole Station designed to measure the CMB polarization at degree angular scales. The latest result in Bicep/Keck Array, using data collected up to 2015, and combined with other external data, set upper limits on r < 0.06 at 95% confidence. Bicep3 is the latest addition in the experiment, deployed to South Pole in 2015, and started science observation in 2016. It is a 520 mm aperture, compact two-lens refracting telescope at 95 GHz. With 2500 detectors, it achieved instantaneous sensitivity of 9.1μK√s and 7.3μK√s for 2016 and 2017, respectively. After two year of observations, Bicep3 is estimated to reach a map depth of 3.8μK-arcmin. This is the most sensitive polarization measurement at 95 GHz to date.

This dissertation provides an overview of the Bicep3 instrument design. In particular, the performance of the sub-Kelvin focal plane structure, antenna-coupled transition edge sensor and time domain multiplexing SQUID readout system. We discuss various calibration methods used to probe instrument sensitivity and systematics. Finally, we review the analysis pipeline, and some preliminary results from Bicep3.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Cosmic Microwave Background; cosmology: observations; gravitational waves; inflation; instrumentation: polarimeters; telescopes
Degree Grantor:California Institute of Technology
Division:Physics, Mathematics and Astronomy
Major Option:Physics
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Bock, James J.
Group:Astronomy Department
Thesis Committee:
  • Bock, James J. (chair)
  • Golwala, Sunil
  • Dore, Olivier P.
  • Fuller, James
Defense Date:25 May 2018
Non-Caltech Author Email:howard.h.hui (AT)
Record Number:CaltechTHESIS:06042018-002455152
Persistent URL:
Related URLs:
URLURL TypeDescription and Keck Array operational overview and status of observations TES bolometers for the Keck Array, Spider, and Polar-1 array and BICEP3: spectral characterization of 5000+ detectors a 95 GHz refracting telescope for degree-scale CMB polarization Performance of Bicep3: A Degree Angular Scale 95 GHz Band Polarimeter focal plane design and detector performance Characterization of the BICEP3 CMB Polarimeter at the South Pole performance overview and planned Keck Array upgrade TES bolometers used in BICEP2, Keck array, and SPIDER Joint Analysis of BICEP2/Keck Array and Planck Data Array IV: Optical Characterization and Performance of the BICEP2 and Keck Array Experiments / Keck Array V: Measurements of B-mode Polarization at Degree Angular Scales and 150 GHz by the Keck Array / Keck Array VI: Improved Constraints On Cosmology and Foregrounds When Adding 95 GHz Data From Keck Array / Keck Array VII: Matrix based E/B Separation applied to BICEP2 and the Keck Array
Hui, Howard0000-0001-5812-1903
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:11014
Deposited By: Howard Hui
Deposited On:09 Jun 2018 00:04
Last Modified:04 Mar 2020 22:00

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