BICEP2. II. Experiment and three-year Data Set

• Published in: The Astrophysical Journal
• Main Authors: Ade, P. A. R., Aikin, R. W., Bock, J. J., Brevik, J. A., Filippini, J. P., Golwala, S. R., Hildebrandt, S. R., Lueker, M., Staniszewski, Z. K., Teply, G. P.
• Format: Article in Journal/Newspaper
• Language: English
• Published: American Astronomical Society 2014
• Subjects: South Pole; South pole
• Online Access: https://authors.library.caltech.edu/50026/; https://authors.library.caltech.edu/50026/1/0004-637X_792_1_62.pdf; https://authors.library.caltech.edu/50026/7/1403.4302v3.pdf; https://resolver.caltech.edu/CaltechAUTHORS:20140925-103717168

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 µK√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 deg^2 within a 1000 deg^2 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.