BICEP/Keck. XIX. Extremely Thin Composite Polymer Vacuum Windows for BICEP and Other High-throughput Millimeter-wave Telescopes
Abstract Millimeter-wave refracting telescopes targeting the degree-scale structure of the cosmic microwave background (CMB) have recently grown to diffraction-limited apertures of over 0.5 m. These instruments are entirely housed in vacuum cryostats to support their subkelvin bolometric detectors and to minimize radiative loading from thermal emission due to absorption loss in their transmissive optical elements. The large vacuum window is the only optical element in the system at ambient temperature, and therefore minimizing loss in the window is crucial for maximizing detector sensitivity. This motivates the use of low-loss polymer materials and a window as thin as practicable. However, the window must simultaneously meet the requirement to keep a sufficient vacuum, and therefore must limit gas permeation and remain mechanically robust against catastrophic failure under pressure. We report on the development of extremely thin composite polyethylene window technology that meets these goals. Two windows have been deployed for two full observing seasons on the BICEP3 and the 150 GHz BICEP Array receiver CMB telescopes at the South Pole. On BICEP3, the window has demonstrated a 6% improvement in detector sensitivity.
Authors
- Jake Connors (ORCID: https://orcid.org/0000-0002-6094-2943)
- Mitchell D. Miller (ORCID: https://orcid.org/0000-0003-1626-4943)
- Kurt Sjoberg
- George Halal (ORCID: https://orcid.org/0000-0003-2221-3018)
- Christos Giannakopoulos (ORCID: https://orcid.org/0000-0003-1822-7716)
- Elaine Sheffield
- Keara Carter
- Lorenzo Moncelsi (ORCID: https://orcid.org/0000-0002-4242-3015)
- Scott Paine (ORCID: https://orcid.org/0000-0003-4622-5857)
- Sage Crystian (ORCID: https://orcid.org/0000-0002-1050-278X)
- Destiny Santalucia
- D. Beck (ORCID: https://orcid.org/0000-0003-0848-2756)
- Lorenzo Minutolo (ORCID: https://orcid.org/0000-0002-4876-112X)
- A. Schillaci (ORCID: https://orcid.org/0000-0002-0512-1042)
- Roger O’Brient
- Margaret Lautzenhiser
- Amy Greathouse
- E. Hand
- A. Steiger
- B. Singari
- S. Zhang
- K. G. Megerian
- A. D. Turner
- S. Henderson
- L. Duband
- C. Tsai
- M. A. Petroff
- J. A. Grayson
- T. Prouve
- C. Vergès
- J. Willmert
- C. A. Bischoff
- Y. Nakato
- A. Wandui
- M. Halpern
- W. L. K. Wu
- C. Kuo
- A. C. Weber
- L. Zeng
- T. Romand
- A. Soliman
- C. Pryke
- Z. Ahmed
- C. D. Reintsema
- H. Hui
- D. C. Goldfinger
- L. Corrigan
- A. Patel
- R. Sudiwala
- J. P. Filippini
- K. Lau
- J. M. Kovac
- H. Yang
- M. Crumrine
- T. Liu
- J. J. Bock
- D. Barkats
- S. A. Harrison
- N. Goeckner-Wald
- P. A. R. Ade
- S. Fatigoni
- C. Tucker
- C. Zhang
- E. Denison
- M. Gao
- J. R. Cheshire
- S. Kefeli
- K. S. Karkare
- B. Steinbach
- M. Eiben
- J. H. Kang
- A. Fortes
- A. J. Cukierman
- G. Hall
- M. Echter
- A. Lennox
- H. Boenish
- H. T. Nguyen
- B. D. Elwood
- R. Basu Thakur
- A. R. Polish
- J. Cornelison
- B. Schmitt
- A. G. Vieregg
- T. St Germaine
- M. Amiri
- J. Hubmayr
- K. L. Thompson
- C. Yu
- P. K. Grimes
- V. Buza
- K. D. Irwin
Institutions
- California Institute of Technology (US)
- University of Minnesota (US)
- National Institute of Standards and Technology (US)
- Jet Propulsion Laboratory (US)
- Harvard University (US)
- University of British Columbia (CA)
- University of Illinois Urbana-Champaign (US)
- Commissariat à l'Énergie Atomique et aux Énergies Alternatives (FR)
- SLAC National Accelerator Laboratory (US)
- University of Chicago (US)
- Kavli Institute for Particle Astrophysics and Cosmology (US)
- Center for Astrophysics Harvard & Smithsonian (US)
- University of Cincinnati (US)
- Cardiff University (GB)
- Stanford University (US)
Publication Details
- Journal
- The Astrophysical Journal
- Published
- 2026-03-26
- DOI
- https://doi.org/10.3847/1538-4357/ae486d
- Primary Topic
- Superconducting and THz Device Technology
- Type
- article
- Field-Weighted Citation Impact
- 0.00