On-Sky Performance of New 90 GHz Detectors for the Cosmology Large Angular Scale Surveyor (CLASS)

• Published in: IEEE transactions on applied superconductivity Vol. 33; no. 5; pp. 1 - 4
• Main Authors: Nunez, Carolina, Appel, John W., Brewer, Michael K., Bruno, Sarah Marie, Datta, Rahul, Bennett, Charles L., Bustos, Ricardo, Chuss, David T., Dahal, Sumit, Denis, Kevin L., Eimer, Joseph, Essinger-Hileman, Thomas, Helson, Kyle, Marriage, Tobias, Perez, Carolina Morales, Padilla, Ivan L., Petroff, Matthew A., Rostem, Karwan, Watts, Duncan J., Wollack, Edward J., Xu, Zhilei
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.08.2023; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Arrays; Cosmic microwave background; Cosmology; Detectors; Focal plane; Frequencies; Jupiter; Microwave antenna arrays; microwave detectors; millimeter wave detectors; Modules; Optical detectors; Optical filters; Optical polarization; Optical variables measurement; superconducting bolometers; Telescopes; transition-edge sensors (TES) devices
• ISSN: 1051-8223; 1558-2515
• DOI: 10.1109/TASC.2023.3262497

The Cosmology Large Angular Scale Surveyor (CLASS) is a polarization-sensitive telescope array located at an altitude of 5,200 m in the Chilean Atacama Desert and designed to measure the polarized Cosmic Microwave Background (CMB) over large angular scales. The CLASS array is currently observing with three telescopes covering four frequency bands: one at 40 GHz (Q); one at 90 GHz (W1); and one dichroic system at 150/220 GHz (HF). During the austral winter of 2022, we upgraded the first 90 GHz telescope (W1) by replacing four of the seven focal plane modules. These new modules contain detector wafers with an updated design, aimed at improving the optical efficiency and detector stability. We present a description of the design changes and measurements of on-sky optical efficiencies derived from observations of Jupiter.