Bicep/Keck XV: The B icep3 Cosmic Microwave Background Polarimeter and the First Three-year Data Set

Bicep/Keck collaboration

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Abstract

We report on the design and performance of the Bicep3 instrument and its first three-year data set collected from 2016 to 2018. Bicep3 is a 52 cm aperture refracting telescope designed to observe the polarization of the cosmic microwave background (CMB) on degree angular scales at 95 GHz. It started science observation at the South Pole in 2016 with 2400 antenna-coupled transition-edge sensor bolometers. The receiver first demonstrated new technologies such as large-diameter alumina optics, Zotefoam infrared filters, and flux-activated SQUIDs, allowing ∼10× higher optical throughput compared to the Keck design. Bicep3 achieved instrument noise equivalent temperatures of 9.2, 6.8, and 7.1 μKCMBs and reached Stokes Q and U map depths of 5.9, 4.4, and 4.4 μK arcmin in 2016, 2017, and 2018, respectively. The combined three-year data set achieved a polarization map depth of 2.8 μK arcmin over an effective area of 585 square degrees, which is the deepest CMB polarization map made to date at 95 GHz.

Original languageEnglish (US)
Article number77
JournalAstrophysical Journal
Volume927
Issue number1
DOIs
StatePublished - Mar 1 2022

Bibliographical note

Funding Information:
B icep / Keck has been made possible through a series of grants from the National Science Foundation including 0742818, 0742592, 1044978, 1110087, 1145172, 1145143, 1145248, 1639040, 1638957, 1638978, 1638970, and 1836010 and by the Keck Foundation. The construction of the B icep3 receiver was supported by the Department of Energy, Laboratory Directed Research and Development program at SLAC National Accelerator Laboratory, under contract DE-AC02-76SF00515. The development of antenna-coupled detector technology was supported by the JPL Research and Technology Development Fund and grant Nos. 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. The computations in this paper were run on the Cannon cluster supported by the FAS Science Division Research Computing Group at Harvard University. We thank the staff of the U.S. 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 Sam Harrison, Hans Boenish, Grantland Hall, Ta-Lee Shue, Paula Crock, and Calvin Tsai. We thank all those who have contributed past efforts to the B icep / Keck series of experiments, including the B icep 1 team. We would also like to thank Jonathon Hunacek at JPL/Caltech for exchange of information regarding detector readout and laboratory housekeeping design, and Aritoki Suzuki, Oliver Jeong, Yuki Inoue, and Tomotake Matsumura at Berkeley and in Japan for discussions regarding alumina optics and AR coatings.

Publisher Copyright:
© 2022. The Author(s). Published by the American Astronomical Society.

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