UC San Diego

Ground-based Cosmic Microwave Background (CMB) experiments have significantly advanced our understanding of the universe. Theories of cosmic inflation predict a period of rapid expansion after the Big Bang, explaining the isotropy and flatness observed in our universe. This proposed inflationary period is expected to have generated gravitational waves, manifesting as primordial B-modes observable in the CMB polarization signal at large angular scales. Maps of CMB are the most straightforward method to search for primordial gravitation waves. Moreover, the CMB temperature and polarization maps offer insights into fundamental questions about neutrino mass, dark matter, and dark energy. This information holds the potential to significantly narrow down the theoretical framework governing the origin and evolution of our universe.

This dissertation outlines my work on two ground-based CMB experiments: the Simons Observatory (SO) and the Simons Array (SA). SO, an upcoming experiment in Chile, aims to measure the temperature and polarization of CMB in six frequency bands from 27 to 280 GHz. It will deploy three 0.5-meter Small Aperture Telescopes (SATs) and one 6-meter Large Aperture Telescope (LAT), housing over 60,000 cryogenic bolometers. The dissertation primarily focuses on the integration of the first 90/150 GHz SAT, encompassing cryogenic testing of subsystems, mechanical design & testing, RF and DC performance, and finally on-site deployment. Next, I present my work on the gain calibration analysis for SA, a neighboring current CMB experiment. Utilizing data from the second receiver, this analysis aims to characterize the instrument beams and calibrate the raw observation data to CMB temperature. Lastly, I provide a brief outlook on the future of the experiment.