SiAl Composite Feedhorn Arrays for Astrophysical Applications: Cryogenic Material Properties

A study investigating the physical properties and use of the SiAl composite Controlled Expansion 7 (CE7) for the packaging of silicon bolometric detectors for millimeter-wave astrophysical applications at cryogenic temperatures is presented. The existing interfaces to such detectors are typically ma...

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Bibliographic Details
Published in:Review of scientific instruments 2022-02, Vol.93 (2), p.024503-024503
Main Authors: Ali, Aamir M., Essinger-Hileman, Thomas, Marriage, Tobias, Appel, John W., Bennett, Charles L., Berkeley, Matthew R., Bulcha, Berhanu, Chuss, David T., Dahal, Sumit, Denis, Kevin L., Rostem, Karwan, U-Yen, Kongpop, Wollack, Edward J., Zeng, Lingzhen
Format: Article
Language:English
Subjects:
Aluminum
Arrays
Chemistry And Materials (General)
Cosmology
Cryogenic temperature
Detectors
Focal plane
Gold
Machining
Material properties
Micromachining
Millimeter waves
Physical properties
Scientific apparatus & instruments
Silicon substrates
Superconductivity
Thermal conductivity
Thermal contraction
Tolerances
Transition temperature
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Summary:A study investigating the physical properties and use of the SiAl composite Controlled Expansion 7 (CE7) for the packaging of silicon bolometric detectors for millimeter-wave astrophysical applications at cryogenic temperatures is presented. The existing interfaces to such detectors are typically made of either ductile metals or micro-machined silicon. As a composite of Si and Al, we find that CE7 exhibits properties of both in ways that may be advantageous for this application. This exploration of the physical properties of CE7 reveals: (a) superconductivity below a critical transition temperature, T_c ∼ 1.2 K; (b) a thermal contraction profile much closer to Si than metal substrates; (c) the relatively low thermal conductivity anticipated for a superconductor, which can be improved by Au-plating; and (d) the feasibility of machining mechanical features with tolerances of ∼25 µm. We further discuss the use of CE7 in the cosmology large angular scale surveyor telescope array, which deployed CE7 in several of its detector focal planes.
ISSN:0034-6748
1089-7623
DOI:10.1063/5.0049526