Optical Characterization of the Keck Array Polarimeter at the South Pole

• 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, J. M., Kuo, C. L., Leitch, E., Lueker, M., Montroy, T., Netterfield, C. B., Nguyen, H. T., O'Brient, 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: Text
• Language: unknown
• Published: arXiv 2012
• Subjects: Instrumentation and Methods for Astrophysics astro-ph.IM; FOS Physical sciences; Austral; South Pole; South pole
• Online Access: https://dx.doi.org/10.48550/arxiv.1208.0844; https://arxiv.org/abs/1208.0844

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. : 13 pages, 11 figures, Proceedings of the SPIE, Vol 8452: Millimeter, Submillimeter and Far-Infrared Detectors and Instrumentation for Astronomy VI, July 2012