The Keck Array is a system of cosmic microwave background (CMB) polarimeters, each similar to the BICEP2 experiment. In this paper we report results from the 2012 and 2013 observing seasons, during which the Keck Array consisted of five receivers all operating in the same (150 GHz) frequency band and observing field as BICEP2. We again find an excess of B-mode power over the lensed-ΛCDM expectation of >5σ in the range 30<ℓ<150 and confirm that this is not due to systematics using jackknife tests and simulations based on detailed calibration measurements. In map difference and spectral difference tests these new data are shown to be consistent with BICEP2. Finally, we combine the maps from the two experiments to produce final Q and U maps which have a depth of 57 nK deg (3.4 μK arcmin) over an effective area of 400 deg2 for an equivalent survey weight of 250,000 μK−2. The final BB band powers have noise uncertainty a factor of 2.3 times better than the previous results, and a significance of detection of excess power of >6σ.
@article{arxiv.1502.00643,
title = {BICEP2 / Keck Array V: Measurements of B-mode Polarization at Degree Angular Scales and 150 GHz by the Keck Array},
author = {The BICEP2 and Keck Array Collaborations and : and P. A. R. Ade and Z. Ahmed and R. W. Aikin and K. D. Alexander and D. Barkats and S. J. Benton and C. A. Bischoff and J. J. Bock and J. A. Brevik and I. Buder and E. Bullock and V. Buza and J. Connors and B. P. Crill and C. D. Dowell and C. Dvorkin and L. Duband and J. P. Filippini and S. Fliescher and S. R. Golwala and M. Halpern and M. Hasselfield and S. R. Hildebrandt and G. C. Hilton and V. V. Hristov and H. Hui and K. D. Irwin and K. S. Karkare and J. P. Kaufman and B. G. Keating and S. Kefeli and S. A. Kernasovskiy and J. M. Kovac and C. L. Kuo and E. M. Leitch and M. Lueker and P. Mason and K. G. Megerian and C. B. Netterfield and H. T. Nguyen and R. O'Brient and R. W. Ogburn and A. Orlando and C. Pryke and C. D. Reintsema and S. Richter and R. Schwarz and C. D. Sheehy and Z. K. Staniszewski and R. V. Sudiwala and G. P. Teply and K. L. Thompson and J. E. Tolan and A. D. Turner and A. G. Vieregg and A. C. Weber and J. Willmert and C. L. Wong and K. W. Yoon},
journal= {arXiv preprint arXiv:1502.00643},
year = {2015}
}