Optical characterization of the Keck array polarimeter at the South Pole

• Published in: SPIE Proceedings, Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy VI
• Main Authors: Vieregg, A. G., Ade, P. A. R., Aikin, R., Bischoff, C., Bock, J. J., Bonetti, J. A., Bradford, K. J., Brevik, J. A., Dowell, C. D., Duband, L., Filippini, J. P., Fliescher, S., Golwala, S. R., Gordon, M. S., Halpern, M., Hilton, G., Hristov, V. V., Irwin, K., Kernasovskiy, S., Kovac, John M, Kuo, C. L., Leitch, E., Lueker, M., Montroy, T., Netterfield, C. B., Nguyen, H. T., O, R., Ogburn, R. W., Pryke, C., Ruhl, J. E., Runyan, M., Schwarz, R., Sheehy, C., Staniszewski, Z., Sudiwala, R., Teply, G., Tolan, J., Turner, A. D., Wilson, P., Wong, C. L.
• Format: Conference Object
• Language: English
• Published: 2016
• Subjects: Cosmic Microwave Background; polarization; Inflation; The Keck Array; Austral; South Pole; South pole
• Online Access: http://nrs.harvard.edu/urn-3:HUL.InstRepos:25682777; https://doi.org/10.1117/12.926639

The Keck Array (Spud) is a set of microwave polarimeters that observes from the South Pole at degree angular scales in search of a signature of Inflation imprinted as B-mode polarization in the Cosmic Microwave Background (CMB). The first three Keck Array receivers were deployed during the 2010-2011 Austral summer, followed by two new receivers in the 2011-2012 summer season, completing the full five-receiver array. All five receivers are currently observing at 150 GHz. The Keck Array employs the field-proven Bicep/Bicep2 strategy of using small, cold, on-axis refractive optics, providing excellent control of systematics while maintaining a large field of view. This design allows for full characterization of far-field optical performance using microwave sources on the ground. We describe our efforts to characterize the main beam shape and beam shape mismatch between co-located orthogonally-polarized detector pairs, and discuss the implications of measured differential beam parameters on temperature to polarization leakage in CMB analysis. Astronomy Accepted Manuscript