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Proceedings Paper

BICEP2 and Keck array: upgrades and improved beam characterization
Author(s): I. Buder; P. A. R. Ade; Z. Ahmed; R. W. Aikin; K. D. Alexander; M. Amiri; D. Barkats; S. J. Benton; C. A. Bischoff; J. J. Bock; J. A. Bonetti; J. A. Brevik; E. Bullock; B. Burger; B. P. Crill; G. Davis; C. D. Dowell; L. Duband; J. P. Filippini; S. Fliescher; S. R. Golwala; M. S. Gordon; M. Halpern; M. Hasselfield; S. R. Hildebrandt; G. C. Hilton; V. V. Hristov; H. Hui; K. D. Irwin; K. S. Karkare; J. P. Kaufman; B. G. Keating; S. Kefeli; S. A. Kernasovskiy; J. M. Kovac; C. L. Kuo; E. M. Leitch; M. Lueker; P. Mason; K. G. Megerian; C. B. Netterfield; H. T. Nguyen; R. O’Brient; R. W. Ogburn; A. Orlando; C. Pryke; C. D. Reintsema; S. Richter; R. Schwarz; C. D. Sheehy; Z. K. Staniszewski; R. V. Sudiwala; G. P. Teply; K. L. Thompson; J. E. Tolan; A. D. Turner; A. G. Vieregg; A. C. Weber; D. V. Wiebe; P. Wilson; C. L. Wong; K. W. Yoon
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Paper Abstract

Searching for evidence of inflation by measuring B-modes in the cosmic microwave background (CMB) polarization at degree angular scales remains one of the most compelling experimental challenges in cosmology. BICEP2 and the Keck Array are part of a program of experiments at the South Pole whose main goal is to achieve the sensitivity and systematic control necessary for measurements of the tensor-to-scalar ratio at σ(r) ~0:01. Beam imperfections that are not sufficiently accounted for are a potential source of spurious polarization that could interfere with that goal. The strategy of BICEP2 and the Keck Array is to completely characterize their telescopes' polarized beam response with a combination of in-lab, pre-deployment, and on-site calibrations. We Sereport the status of these experiments, focusing on continued improved understanding of their beams. Far-field measurements of the BICEP2 beam with a chopped thermal source, combined with analysis improvements, show that the level of residual beam-induced systematic errors is acceptable for the goal of σ(r) ~ 0:01 measurements. Beam measurements of the Keck Array side lobes helped identify a way to reduce optical loading with interior cold baffles, which we installed in late 2013. These baffles reduced total optical loading, leading to a ~ 10% increase in mapping speed for the 2014 observing season. The sensitivity of the Keck Array continues to improve: for the 2013 season it was 9:5 μK _/s noise equivalent temperature (NET). In 2014 we converted two of the 150-GHz cameras to 100 GHz for foreground separation capability. We have shown that the BICEP2 and the Keck Array telescope technology is sufficient for the goal of σ(r) ~ 0:01 measurements. Furthermore, the program is continuing with BICEP3, a 100-GHz telescope with 2560 detectors.

Paper Details

Date Published: 19 August 2014
PDF: 10 pages
Proc. SPIE 9153, Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy VII, 915312 (19 August 2014); doi: 10.1117/12.2055713
Show Author Affiliations
I. Buder, Harvard-Smithsonian Ctr. for Astrophysics (United States)
P. A. R. Ade, Cardiff Univ. (United Kingdom)
Z. Ahmed, Stanford Univ. (United States)
SLAC National Accelerator Lab., Kavli Institute for Particle Astrophysics and Cosmology (United States)
R. W. Aikin, California Institute of Technology (United States)
K. D. Alexander, Harvard-Smithsonian Ctr. for Astrophysics (United States)
M. Amiri, The Univ. of British Columbia (Canada)
D. Barkats, Joint ALMA Observatory (Chile)
S. J. Benton, Univ. of Toronto (Canada)
C. A. Bischoff, Harvard-Smithsonian Ctr. for Astrophysics (United States)
J. J. Bock, California Institute of Technology (United States)
Jet Propulsion Lab. (United States)
J. A. Bonetti, Jet Propulsion Lab. (United States)
J. A. Brevik, California Institute of Technology (United States)
E. Bullock, Univ. of Minnesota (United States)
B. Burger, The Univ. of British Columbia (Canada)
B. P. Crill, California Institute of Technology (United States)
Jet Propulsion Lab. (United States)
G. Davis, The Univ. of British Columbia (Canada)
C. D. Dowell, Jet Propulsion Lab. (United States)
L. Duband, Service des Basses Températures, CEA (France)
J. P. Filippini, California Institute of Technology (United States)
S. Fliescher, Univ. of Minnesota (United States)
S. R. Golwala, California Institute of Technology (United States)
M. S. Gordon, Harvard-Smithsonian Ctr. for Astrophysics (United States)
M. Halpern, The Univ. of British Columbia (Canada)
M. Hasselfield, The Univ. of British Columbia (Canada)
S. R. Hildebrandt, California Institute of Technology (United States)
Jet Propulsion Lab. (United States)
G. C. Hilton, National Institute of Standards and Technology (United States)
V. V. Hristov, California Institute of Technology (United States)
H. Hui, California Institute of Technology (United States)
K. D. Irwin, Stanford Univ. (United States)
SLAC National Accelerator Lab., Kavli Institute for Particle Astrophysics and Cosmology (United States)
National Institute of Standards and Technology (United States)
K. S. Karkare, Harvard-Smithsonian Ctr. for Astrophysics (United States)
J. P. Kaufman, Univ. of California, San Diego (United States)
B. G. Keating, Univ. of California, San Diego (United States)
S. Kefeli, California Institute of Technology (United States)
S. A. Kernasovskiy, Stanford Univ. (United States)
J. M. Kovac, Harvard-Smithsonian Ctr. for Astrophysic (United States)
C. L. Kuo, Stanford Univ. (United States)
SLAC National Accelerator Lab., Kavli Institute for Particle Astrophysics and Cosmology (United States)
E. M. Leitch, Univ. of Chicago (United States)
M. Lueker, California Institute of Technology (United States)
P. Mason, California Institute of Technology (United States)
K. G. Megerian, Jet Propulsion Lab. (United States)
C. B. Netterfield, Univ. of Toronto (Canada)
Canadian Institute for Advanced Research (Canada)
H. T. Nguyen, Jet Propulsion Lab. (United States)
R. O’Brient, Jet Propulsion Lab. (United States)
R. W. Ogburn, Stanford Univ. (United States)
SLAC National Accelerator Lab., Kavli Institute for Particle Astrophysics and Cosmology (United States)
A. Orlando, Univ. of California, San Diego (United States)
C. Pryke, Univ. of Minnesota (United States)
Minnesota Institute for Astrophysics, Univ. of Minnesota (United States)
C. D. Reintsema, National Institute of Standards and Technology (United States)
S. Richter, Harvard-Smithsonian Ctr. for Astrophysics (United States)
R. Schwarz, Univ. of Minnesota, Twin Cities (United States)
C. D. Sheehy, Univ. of Minnesota (United States)
Univ. of Chicago (United States)
Z. K. Staniszewski, California Institute of Technology (United States)
Jet Propulsion Lab. (United States)
R. V. Sudiwala, Cardiff Univ. (United Kingdom)
G. P. Teply, California Institute of Technology (United States)
K. L. Thompson, Stanford Univ. (United States)
SLAC National Accelerator Lab., Kavli Institute for Particle Astrophysics and Cosmology (United States)
J. E. Tolan, Stanford Univ. (United States)
A. D. Turner, Jet Propulsion Lab. (United States)
A. G. Vieregg, Harvard-Smithsonian Ctr. for Astrophysics (United States)
Univ. of Chicago (United States)
A. C. Weber, Jet Propulsion Lab. (United States)
California Institute of Technology (United States)
D. V. Wiebe, The Univ. of British Columbia (Canada)
P. Wilson, Jet Propulsion Lab. (United States)
C. L. Wong, Harvard-Smithsonian Ctr. for Astrophysics (United States)
K. W. Yoon, Stanford Univ. (United States)
SLAC National Accelerator Lab., Kavli Institute for Particle Astrophysics and Cosmology (United States)


Published in SPIE Proceedings Vol. 9153:
Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy VII
Wayne S. Holland; Jonas Zmuidzinas, Editor(s)

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