Gravitational waves from cosmic inflation may have left a signature in the parity-odd, B-mode polarization of the Cosmic Microwave Background (CMB). Detecting B-modes would probe some of the highest-energy physics in the known universe, but upper limits constrain the signal to be extremely faint and dominated by polarized Galactic foreground emission. The Canadian Galactic Emission Mapper (CGEM) is a new radio telescope that will map polarized Galactic synchrotron emission from 8-10GHz over the Northern sky. CGEM will improve models of polarized foregrounds and will be an important aid to current and future B-mode experiments. In this thesis, I outline work that I have done to help enable CGEM. I describe an instrument simulations pipeline that I helped develop to simulate realistic time-ordered CGEM data. The pipeline was crucial to the CGEM optical design, will be used to help analyze CGEM data, and can be used by other experiments. I then describe the CGEM optical design process in its entirety. I chose a hat feed optical design that exhibits excellent polarization purity. I developed a framework to optimize the optics to directly minimize polarization systematics in simulated survey maps. This framework was used to further enhance the polarization purity of the hat feed and can be used to design the optics of future instruments. I also describe the mechanical design and deployment of the CGEM optics. Finally, I outline several analyses to characterize the optics with on-sky data. I use Solar observations, a suite of physical measurements, and comparisons with electromagnetic simulations to determine small optical misalignments. The misalignments were simulated, found to minimally affect the polarization purity, and can be corrected in future. I then use satellites in the data to probe the beam and sidelobes down to 0.01% of the maximum and to probe polarization leakage out to ~4° off boresight. The simulated beam model is in striking agreement with the data. The thesis culminates in a preliminary measurement of the Moon's disk-averaged brightness temperature spectrum, the first of its kind in the X-band, which is a strong demonstration of CGEM's capabilities at this early stage.
Joshua MacEachern (Fri,) studied this question.