Student: Walter Golay, Undergraduate Student in Astronomy and Physics, University of Iowa
Research Mentor: Dr. Robert Mutel
Beam Me Up, Scotty! New Algorithms for Characterizing the Beams of Next-Generation CMB Experiments
The latest cosmologies predict inflation in the early universe to have imprinted a signature polarization pattern in the cosmic microwave background (CMB). The BICEP/Keck Array is a collection of telescopes that aim to detect this unique pattern and constrain inflationary models. Precision measurements of the CMB require a thorough understanding of instrumental systematics. Determining the differential beam between pairs of orthogonal detectors is essential to mitigating the effects of temperature-to-polarization leakage, a significant source of systematic error. The first step in characterizing the beams is the demodulation of a signal from observing a chopped source. Here we summarize previously implemented demodulation techniques and propose new methodologies. We will further benchmark and compare the performance of each demodulator on simulated calibration time-streams and the latest data from the BICEP/Keck Array experiments. We find that a Fourier-space deconvolutional approach was most successful at accurately characterizing the beam, improving our understanding of the instrument to mitigate the effects of temperature-to-polarization leakage. With this information, we intend to continue developing this new approach for eventual implementation into the final science analysis pipeline.