BICEP2/Keck Array. IV. Optical Characterization and Performance of the BICEP2 and Keck Array Experiments
bicep2 and the Keck Array are polarization-sensitive microwave telescopes that observe the cosmic microwave background (CMB) from the South Pole at degree angular scales in search of a signature of inflation imprinted as B-mode polarization in the CMB. bicep2 was deployed in late 2009, observed for three years until the end of 2012 at 150 GHz with 512 antenna-coupled transition edge sensor bolometers, and has reported a detection of B-mode polarization on degree angular scales. The Keck Array was first deployed in late 2010 and will observe through 2016 with five receivers at several frequencies (95, 150, and 220 GHz). bicep2 and the Keck Array share a common optical design and employ the field-proven bicep1 strategy of using small-aperture, 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. Here we describe the optical design of both instruments and report a full characterization of the optical performance and beams of bicep2 and the Keck Array at 150 GHz.
© 2015 American Astronomical Society. Received 2015 February 3; accepted 2015 April 24; published 2015 June 18. BICEP2 was supported by the National Science Foundation (NSF) under grants ANT-0742818 and ANT-1044978 (Caltech/Harvard) and ANT-0742592 and ANT-1110087 (Chicago/Minnesota). The Keck Array was supported by the NSF under grants ANT-1145172 (Harvard), ANT-1145143 (Minnesota), and ANT-1145248 (Stanford), and by the W. M. Keck Foundation (Caltech). The development of antenna-coupled detector technology was supported by the JPL Research and Technology Development Fund and grants 06-ARPA206-0040 and 10-SAT10-0017 from the NASA APRA and SAT programs. The development and testing of focal planes were supported by the Gordon and Betty Moore Foundation at Caltech. Readout electronics were supported by a Canada Foundation for Innovation grant to UBC. Computations presented in this paper were run on the Odyssey cluster supported by the FAS Science Division Research Computing Group at Harvard. The analysis effort at Stanford and SLAC was partially supported by the U.S. Department of Energy Office of Science. The receiver development was supported in part by a grant from the W. M. Keck Foundation. Tireless administrative support was provided by Irene Coyle and Kathy Deniston. We thank the staff of the US Antarctic Program and in particular the South Pole Station without whose help this research would not have been possible. Most special thanks go to our heroic winter-overs Robert Schwarz and Steffen Richter. We thank all those who have contributed past efforts to the BICEP/Keck Array series of experiments, including the BICEP1-team, as well as our colleagues on the SPIDER team with whom we coordinated receiver and detector development efforts at Caltech.
Published - 0004-637X_806_2_206.pdf
Submitted - 1502.00596v2.pdf