2022 upgrade and improved low frequency camera sensitivity for cmb observation at the south pole

A. Soliman, P. A.R. Ade, Z. Ahmed, M. Amiri, D. Barkats, R. Basu Thakur, C. A. Bischoff, D. Beck, J. J. Bock, V. Buza, James R Cheshire, J. Connors, J. Cornelison, Mike Crumrine, A. J. Cukierman, E. V. Denison, M. I. Dierichx, L. Duband, M. Eiben, S. FatigoniJ. P. Filippini, C. Giannakopoulos, N. Goeckner-Wald, D. C. Goldfinger, J. Grayson, P. K. Grimes, G. Hall, G. Halal, M. Halpern, E. Hand, S. A. Harrison, S. Henderson, S. R. Hildebrandt, G. C. Hilton, J. Hubmayr, H. Hui, K. D. Irwin, J. Kang, K. S. Karkare, S. Kefeli, J. M. Kovac, C. L. Kuo, Kenny Lau, E. M. Leitch, A. Lennox, T. Liu, K. G. Megerian, L. Minutolo, L. Moncelsi, Y. Nakato, T. Namikawa, H. T. Nguyen, R. O'Brient, S. Palladino, M. A. Petroff, Nathan Precup, T. Prouve, C. Pryke, B. Racine, C. D. Reintsema, M. Salatino, A. Schillaci, B. L. Schmitt, B. Singari, T. St Germaine, B. Steinback, R. V. Sudiwala, K. L. Thompson, C. Tsai, C. Tucker, A. D. Turner, C. Umilta, C. Verges, A. G. Vieregg, A. Wandui, A. C. Weber, D. V. Wiebe, Justin B Willmert, W. L.K. Wu, H. Yang, K. W. Yoon, E. Young, C. Yu, L. Zeng, C. Zhang, S. Zhang

Research output: Chapter in Book/Report/Conference proceedingConference contribution


Constraining the Galactic foregrounds with multi-frequency Cosmic Microwave Background (CMB) observations is an essential step towards ultimately reaching the sensitivity to measure primordial gravitational waves (PGWs), the sign of inflation after the Big-Bang that would be imprinted on the CMB. The BICEP Array is a set of multi-frequency cameras designed to constrain the energy scale of inflation through CMB B-mode searches while also controlling the polarized galactic foregrounds. The lowest frequency BICEP Array receiver (BA1) has been observing from the South Pole since 2020 and provides 30 GHz and 40 GHz data to characterize galactic synchrotron in our CMB maps. In this paper, we present the design of the BA1 detectors and the full optical characterization of the camera including the on-sky performance at the South Pole. The paper also introduces the design challenges during the first observing season including the effect of out-of-band photons on detectors performance. It also describes the tests done to diagnose that effect and the new upgrade to minimize these photons, as well as installing more dichroic detectors during the 2022 deployment season to improve the BA1 sensitivity. We finally report background noise measurements of the detectors with the goal of having photon-noise dominated detectors in both optical channels. BA1 achieves an improvement in mapping speed compared to the previous deployment season.

Original languageEnglish (US)
Title of host publicationMillimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy XI
EditorsJonas Zmuidzinas, Jian-Rong Gao
ISBN (Electronic)9781510653610
StatePublished - 2022
EventMillimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy XI 2022 - Montreal, Canada
Duration: Jul 17 2022Jul 22 2022

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X


ConferenceMillimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy XI 2022

Bibliographical note

Funding Information:
The BICEP/Keck project (including BICEP2, BICEP3, and BICEP Array) have 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, 1726917, 1313010, 1313062, 1313158, 1313287, 0960243, 1836010, 1056465, & 1255358 and by the Keck Foundation. The development of antenna-coupled detector technology was supported by the JPL Research and Technology Development Fund and NASA Grants 06-ARPA206-0040, 10-SAT10-0017, 12-SAT12-0031, 14-SAT14-0009, 16-SAT16-0002, & 18-SAT18-0017. 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 Odyssey cluster supported by the FAS Science Division Research Computing Group at Harvard University. The analysis effort at Stanford and SLAC was partially supported by the Department of Energy, Contract DE-AC02-76SF00515. 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. Tireless administrative support was provided by Kathy Deniston, Sheri Stoll, Irene Coyle, Amy Dierker, Donna Hernandez, and Julie Shih.

Publisher Copyright:
© 2022 SPIE.


  • BICEP Array
  • Cosmic Microwave Background
  • Detectors
  • Inflation
  • Synchrotron
  • Telescopes


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