BICEP Array Detectors and Instrumentation at 30/40 GHz: Design, Performance, and Deployment to the South Pole for Constraining Primordial Gravitational Waves

• Main Author: Mohamed Soliman, Ahmed Mohamed
• Format: Thesis
• Language: English
• Published: 2023
• Subjects: South Pole; Amundsen-Scott; Amundsen Scott South Pole Station; Amundsen-Scott South Pole Station; South pole
• Online Access: https://thesis.library.caltech.edu/15203/; https://thesis.library.caltech.edu/15203/1/AhmedSoliman_Thesis_Final.pdf; https://resolver.caltech.edu/CaltechTHESIS:05232023-174453276

The discovery of the Cosmic Microwave Background (CMB) in the 1960s has provided strong observational evidence for the Big Bang cosmological model to describe the origin and evolution of the universe. The theory of cosmic inflation was developed in the 1980s to account for the initial density perturbations by a period of exponential expansion in the early Universe to solve the horizon, flatness and monopole problems. Many inflation models predict potentially detectable primordial gravitational-waves (PGWs) background that imprint a B-mode polarization pattern in the CMB. The amplitude of the inflationary B-mode polarization depends on the energy scale of inflation and is parameterized by the tensor-to-scalar ratio r . The detection of a B-mode pattern would open a new window to probe the energy scale at the beginning of time when the universe was a mere fraction of a second old after the Big Bang. The BICEP/Keck collaboration is building a series of experiments located at the Amundsen-Scott South Pole Station to map the polarization of the CMB at degree angular scales using small-aperture telescopes. Our latest BICEP/Keck publications use data collected through 2018 and report the strongest constraints r 0.05 < 0.036 at 95% confidence. The current sensitivity on r is limited by the variance from the gravitational lensing. BICEP/Keck is starting a collaboration with the South Pole Telescope (SPT) team to develop delensing techniques to improve future constraints on r . Characterizing Galactic foregrounds, especially synchrotron emission, remains a priority in order to improve constraints as statistical sensitivity continues to improve. The motivation for this thesis is to develop a highly sensitive receiver at 30 and 40 GHz, at frequencies where the synchrotron foreground dominates. BICEP Array represents the latest phase in the BICEP/Keck experiments, and will map the polarization of the CMB at 30/40, 95, 150, and 220/270 GHz. BICEP Array will search for PGWs with unprecedented sensitivity levels on r by ...