On-Sky Performance of the SPT-3G Frequency-Domain Multiplexed Readout
Frequency-domain multiplexing (fMux) is an established technique for the readout of large arrays of transition-edge sensor (TES) bolometers. Each TES in a multiplexing module has a unique AC voltage bias that is selected by a resonant filter. This scheme provides for the operation and readout of multiple bolometers on a single pair of wires, reducing thermal loading onto sub-Kelvin stages. The current receiver on the South Pole Telescope, SPT-3G, uses a 68x fMux system to operate its large-format camera of ~16,000 TES bolometers. We present here the successful implementation and performance of the SPT-3G readout as measured on-sky. Characterization of the noise reveals a median pair-differenced 1/f knee frequency of 33 mHz, indicating that low-frequency noise in the readout will not limit SPT-3G’s measurements of sky power on large angular scales. Measurements further show that the median readout white noise level in each of the SPT-3G observing bands is below the expectation for photon noise, demonstrating that SPT-3G is operating in the photon-noise-dominated regime.
- Research Organization:
- SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States); Argonne National Laboratory (ANL), Argonne, IL (United States); Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States)
- Sponsoring Organization:
- National Science Foundation (NSF); Kavli Foundation; Gordon and Betty Moore Foundation; Natural Sciences and Engineering Research Council of Canada (NSERC); Canadian Institute for Advanced Research; Sloan Foundation; Canadian Institute for Advanced Research (CIFAR); Australian Research Council; Alfred P. Sloan Foundation; USDOE Office of Science (SC), High Energy Physics (HEP)
- Contributing Organization:
- SPT Collaboration
- Grant/Contract Number:
- AC02-76SF00515; PLR-1248097; PHY-1125897; GBMF#947; AC02-06CH11357; AC02-07CH11359; AST-0956135
- OSTI ID:
- 1616755
- Alternate ID(s):
- OSTI ID: 1632820
- Journal Information:
- Journal of Low Temperature Physics, Vol. 199, Issue 1-2; ISSN 0022-2291
- Publisher:
- SpringerCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
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