The Design and Integrated Performance of SPT-3G

Abstract

SPT-3G is the third survey receiver operating on the South Pole Telescope dedicated to high-resolution observations of the cosmic microwave background (CMB). Sensitive measurements of the temperature and polarization anisotropies of the CMB provide a powerful data set for constraining cosmology. Additionally, CMB surveys with arcminute-scale resolution are capable of detecting galaxy clusters, millimeter-wave bright galaxies, and a variety of transient phenomena. The SPT-3G instrument provides a significant improvement in mapping speed over its predecessors, SPT-SZ and SPTpol. The broadband optics design of the instrument achieves a 430 mm diameter image plane across observing bands of 95, 150, and 220 GHz, with 1.2′ FWHM beam response at 150 GHz. In the receiver, this image plane is populated with 2690 dual-polarization, trichroic pixels (∼16,000 detectors) read out using a 68× digital frequency-domain multiplexing readout system. In 2018, SPT-3G began a multiyear survey of 1500 deg2 of the southern sky. We summarize the unique optical, cryogenic, detector, and readout technologies employed in SPT-3G, and we report on the integrated performance of the instrument.

Constraints on galaxy formation from the cosmic-infrared-background$\,-\,$optical-imaging cross-correlation using $\boldsymbol{Herschel}$ and UNIONS

“…CMB-type experiments have already mapped the millimetre sky over thousands of square degrees with beamsizes of around 1 arcmin (e.g. Mallaby-Kay et al 2021;Sobrin et al 2022) and the entire sky with Planck's 5-arcmin beam. In a few year's time, the Prime-Cam instrument on CCAT-prime/FYST (CCAT-Prime Collaboration 2021) will carry out a survey of 20,000 deg 2 of sky from Chile, over several millimetre-to-submillimetre bands, with a beamsize of 15 arcsec at 350 µm.…”

Improving Cosmological Constraints from Galaxy Cluster Number Counts with CMB-cluster-lensing Data: Results from the SPT-SZ Survey and Forecasts for the Future

“…Using the likelihood framework from Section 3, we forecast the results from two surveys: the ongoing SPT-3G survey, and the planned CMB-S4 survey. We assume that SPT-3G will survey 1500 deg 2 with a temperature map noise level of 2.5 mK arcmin -(polarization map noise level a factor of 2 higher) at 150 GHz (Sobrin et al 2022) and produce a catalog of ∼3600 clusters above an S/N of 4.5. After galactic cuts, we assume the CMB-S4 survey will cover 60% of the sky with a map noise level of 1.0 mK arcmin -(polarization map noise level a factor of 2 higher) at 150 GHz (CMB-S4 Collaboration 2019) and produce a catalog of ∼135,000 clusters above an S/N of 4.5.…”

Searching for axion-like time-dependent cosmic birefringence with SPT-3G

“…The SPT is a 10-meter millimeter-wavelength telescope located at the Amundsen-Scott South Pole Station in Antarctica [27]. The current camera installed on the telescope is SPT-3G, an array of ∼16, 000 polarizationsensitive transition-edge sensor (TES) bolometers [28].…”

“…As detailed in Sobrin et al [28], the bolometers are cooled to an operating temperature of 300 mK by a 3He/4He sorption cooler for ∼15 hours at a time, separated by a ∼4.5 hour interval when the cooler is re-cycled. SPT-3G is designed to observe the CMB in three bands, centered at approximately 95, 150, and 220 GHz, with an angular resolution of approximately 1.2 arcminutes at 150 GHz.…”

“…Each observation takes approximately two hours and generates a set of time-ordered data (TOD) for each bolometer that can later be turned into maps of the sky (Section III A). In addition to the survey field observations, SPT-3G also takes regular calibration observations, which are described in more detail in Sobrin et al [28] and Dutcher et al [29] (hereafter D21).…”