BICEP2. II. Experiment and three-year Data Set
Ade, P. A. R.; Bock, J. J.; Hildebrandt, S. R.; Netterfield, C. B.; Dowell, C. D.; Halpern, M.; Nguyen, H. T.; Leitch, E. M.; Lueker, M.; Pryke, C.; Story, K. T.; Hilton, G. C.; Richter, S.; Davis, G.; Barkats, D.; Schwarz, R.; Aikin, R. W.; Benton, S. J.; Bischoff, C. A.; Brevik, J. A.; Buder, I.; Bullock, E.; Duband, L.; Filippini, J. P.; Fliescher, S.; Golwala, S. R.; Hasselfield, M.; Irwin, K. D.; Karkare, K. S.; Kaufman, J. P.; Keating, B. G.; Kernasovskiy, S. A.; Kovac, J. M.; Kuo, C. L.; O'Brient, R.; Ogburn, R. W., IV; Orlando, A.; Sheehy, C. D.; Staniszewski, Z. K.; Sudiwala, R. V.; Teply, G. P.; Tolan, J. E.; Turner, A. D.; Vieregg, A. G.; Wong, C. L.; Yoon, K. W.; BICEP2 Collaboration; Wilson, P.; Amiri, M.; Day, P. K.; Llombart, N.; Reintsema, C. D.
United Kingdom, United States, Canada, Chile, France
Abstract
We report on the design and performance of the BICEP2 instrument and on its three-year data set. BICEP2 was designed to measure the polarization of the cosmic microwave background (CMB) on angular scales of 1°-5°(l = 40-200), near the expected peak of the B-mode polarization signature of primordial gravitational waves from cosmic inflation. Measuring B-modes requires dramatic improvements in sensitivity combined with exquisite control of systematics. The BICEP2 telescope observed from the South Pole with a 26 cm aperture and cold, on-axis, refractive optics. BICEP2 also adopted a new detector design in which beam-defining slot antenna arrays couple to transition-edge sensor (TES) bolometers, all fabricated on a common substrate. The antenna-coupled TES detectors supported scalable fabrication and multiplexed readout that allowed BICEP2 to achieve a high detector count of 500 bolometers at 150 GHz, giving unprecedented sensitivity to B-modes at degree angular scales. After optimization of detector and readout parameters, BICEP2 achieved an instrument noise-equivalent temperature of 15.8 μ {K}\sqrt{{s}}. The full data set reached Stokes Q and U map depths of 87.2 nK in square-degree pixels (5.'2 μK) over an effective area of 384 deg2 within a 1000 deg2 field. These are the deepest CMB polarization maps at degree angular scales to date. The power spectrum analysis presented in a companion paper has resulted in a significant detection of B-mode polarization at degree scales.