Microwave multiplexing on the Keck Array

• Published in: Journal of Low Temperature Physics
• Main Authors: Cukierman, A., Ahmed, Z., Henderson, S., Young, E., Yu, C., Barkats, D., Brown, D., Chaudhuri, S., Cornelison, J., D'Ewart, J. M., Dierickx, M., Dober, B. J., Dusatko, J., Fatigoni, S., Filippini, J. P., Frisch, J. C., Haller, G., Halpern, M., Hilton, G. C., Hubmayr, J., Irwin, K. D., Karkare, K. S., Karpel, E., Kernasovskiy, S. A., Kovac, J. M., Kovacs, A., Kuenstner, S. E., Kuo, C. L., Li, D., Mates, J. A. B., Smith, S., St. Germaine, T., Ullom, J. N., Vale, L. R., Van Winkle, D. D., Vasquez, J., Willmert, J., Zeng, L., Ade, P. A. R., Amiri, M., Basu Thakur, R., Bischoff, C. A., Bock, J. J., Boenish, H., Bullock, E., Buza, V., Cheshire, J., Connors, J., Crumrine, M., Duband, L.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Springer Verlag 2020
• Subjects: Austral; South Pole; South pole
• Online Access: https://orca.cardiff.ac.uk/id/eprint/128507/; https://doi.org/10.1007/s10909-019-02296-2; https://orca.cardiff.ac.uk/id/eprint/128507/1/1909.013051.pdf

We describe an on-sky demonstration of a microwave-multiplexing readout system in one of the receivers of the Keck Array, a polarimetry experiment observing the cosmic microwave background at the South Pole. During the austral summer of 2018–2019, we replaced the time-division multiplexing readout system with microwave-multiplexing components including superconducting microwave resonators coupled to radio frequency superconducting quantum interference devices at the sub-Kelvin focal plane, coaxial-cable plumbing and amplification between room temperature and the cold stages, and a SLAC Microresonator Radio Frequency system for the warm electronics. In the range 5–6 GHz, a single coaxial cable reads out 528 channels. The readout system is coupled to transition-edge sensors, which are in turn coupled to 150-GHz slot-dipole phased-array antennas. Observations began in April 2019, and we report here on an initial characterization of the system performance.