Published May 2020 | Version Accepted Version
Journal Article Open

Optical Design and Characterization of 40-GHz Detector and Module for the BICEP Array

Abstract

Families of cosmic inflation models predict a primordial gravitational-wave background that imprints B-mode polarization pattern in the cosmic microwave background (CMB). High-sensitivity instruments with wide frequency coverage and well-controlled systematic errors are needed to constrain the faint B-mode amplitude. We have developed antenna-coupled transition edge sensor arrays for high-sensitivity polarized CMB observations over a wide range of millimeter-wave bands. BICEP array, the latest phase of the BICEP/Keck experiment series, is a multi-receiver experiment designed to search for inflationary B-mode polarization to a precision σ(r) between 0.002 and 0.004 after 3 full years of observations, depending on foreground complexity and the degree of lensing removal. We describe the electromagnetic design and measured performance of BICEP array's low-frequency 40-GHz detector, their packaging in focal plane modules, and optical characterization including efficiency and beam matching between polarization pairs. We summarize the design and simulated optical performance, including an approach to improve the optical efficiency due to mismatch losses. We report the measured beam maps for a new broadband corrugation design to minimize beam differential ellipticity between polarization pairs caused by interactions with the module housing frame, which helps minimize polarized beam mismatch that converts CMB temperature to polarization (T→P) anisotropy in CMB maps.

Additional Information

© 2020 Springer Nature Switzerland AG. Received 05 September 2019; Accepted 03 December 2019; Published 24 February 2020. The BICEP/Keck project 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, & 1726917 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. 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 is partially supported by the US DoE Office of Science. We thank the staff of the US 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, Donna Hernandez, and Dana Volponi.

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Additional details

Identifiers

Eprint ID
101517
Resolver ID
CaltechAUTHORS:20200225-072133380

Related works

Funding

NSF
OPP-0742818
NSF
OPP-0742592
NSF
OPP-1044978
NSF
PLR-1110087
NSF
OPP-1145172
NSF
OPP-1145143
NSF
OPP-1145248
NSF
OPP-1639040
NSF
OPP-1638957
NSF
OPP-1638978
NSF
OPP-1638970
NSF
OPP-1726917
W. M. Keck Foundation
JPL Research and Technology Development Fund
NASA
06-ARPA206-0040
NASA
10-SAT10-0017
NASA
12-SAT12-0031
NASA
14-SAT14-0009
NASA
16-SAT16-0002
Gordon and Betty Moore Foundation
Canada Foundation for Innovation
Harvard University
Department of Energy (DOE)

Dates

Created
2020-02-25
Created from EPrint's datestamp field
Updated
2023-03-16
Created from EPrint's last_modified field

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Caltech groups
Astronomy Department