The Simons Observatory 220 and 280 GHz Focal-Plane Module: Design and Initial Characterization

Erin Healy, Daniel Dutcher, Zachary Atkins, Jason Austermann, Steve K. Choi, Cody J. Duell, Shannon Duff, Nicholas Galitzki, Zachary B. Huber, Johannes Hubmayr, Bradley R. Johnson, Heather McCarrick, Michael D. Niemack, Rita Sonka, Suzanne T. Staggs, Eve Vavagiakis, Yuhan Wang, Zhilei Xu, Kaiwen Zheng

Research output: Contribution to journalArticlepeer-review

5 Scopus citations


The Simons Observatory (SO) will detect and map the temperature and polarization of the millimeter-wavelength sky from Cerro Toco, Chile, across a range of angular scales, providing rich data sets for cosmological and astrophysical analysis. The SO focal planes will be tiled with compact hexagonal packages, called universal focal-plane modules (UFMs), in which the transition-edge sensor (TES) detectors are coupled to 100 mK microwave-multiplexing electronics. Three different types of dichroic TES detector arrays with bands centered at 30/40, 90/150, and 220/280 GHz will be implemented across the 49 planned UFMs. The 90/150 GHz and 220/280 GHz arrays each contain 1764 TESes, which are read out with two 910x multiplexer circuits. The modules contain a series of routed silicon chips, which are packaged together in a controlled electromagnetic environment and operated at 100 mK. Following an overview of the module design, we report on early results from the first 220/280 GHz UFM, including detector yield, as well as readout and detector noise levels.

Original languageEnglish (US)
Pages (from-to)815-823
Number of pages9
JournalJournal of Low Temperature Physics
Issue number5-6
StatePublished - Dec 2022

All Science Journal Classification (ASJC) codes

  • Atomic and Molecular Physics, and Optics
  • General Materials Science
  • Condensed Matter Physics


  • Cosmic microwave background
  • Microwave SQUID multiplexing
  • Transition-edge sensor detectors


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