On-sky performance of the SPT-3G frequency-domain multiplexed readout

Abstract

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 enables 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 $\sim$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 also 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.

arXiv comment9 pages, 5 figures submitted to the Journal of Low Temperature Physics: LTD18 Special Edition

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Cited by in corpus (10)

• A Review of X-ray Microcalorimeters Based on Superconducting Transition Edge Sensors for Astrophysics and Particle Physics
• Simons Observatory Microwave SQUID Multiplexing Readout -- Cryogenic RF Amplifier and Coaxial Chain Design
• Instrumental systematics biases in CMB lensing reconstruction: a simulation-based assessment
• Performance and characterization of the SPT-3G digital frequency-domain multiplexed readout system using an improved noise and crosstalk model
• Characterization of MKIDs for CMB observation at 220 GHz with the South Pole Telescope
• Demonstration of a 1820 channel multiplexer for transition-edge sensor bolometers
• Light Dark Matter Detection with Hydrogen-rich Crystals and Low-Tc TES Detectors
• Performance of a low-parasitic frequency-domain multiplexing readout
• Correlating Visual Characteristics and Cryogenic Performance of Superconducting Detectors
• The Design and Integrated Performance of SPT-3G