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We have developed superconducting Ti transition-edge sensors with Au protection layers on the top and bottom for the South Pole Telescope’s third-generation receiver (a cosmic microwave background polarimeter, due to be upgraded this austral summer of 2017/2018). The base Au layer (deposited on a thin Ti glue layer) isolates the Ti from any substrate effects; the top Au layer protects the Ti from oxidation during processing and subsequent use of the sensors. We control the transition temperature and normal resistance of the sensors by varying the sensor width and the relative thicknesses of the Ti and Au layers. The transition temperature is roughly six times more sensitive to the thickness of the base Au layer than to that of the top Au layer. The normal resistance is inversely proportional to sensor width for any given film configuration. For widths greater than five micrometers, the critical temperature is independent of width. [ABSTRACT FROM AUTHOR]

During the austral summer of 2016-2017, the third-generation camera, SPT-3G, was installed on the South Pole Telescope, increasing the detector count in the focal plane by an order of magnitude relative to the previous generation. Designed to map the polarization of the cosmic microwave background, SPT-3G contains ten 6′′-hexagonal modules of detectors, each with 269 trichroic and dual-polarization pixels, read out using 68× frequency-domain multiplexing. Here we discuss design, assembly, and layout of the modules, as well as early performance characterization of the first-year array, including yield and detector properties. [ABSTRACT FROM AUTHOR]

A new receiver for the South Pole Telescope, SPT-3G, was deployed in early 2017 to map the cosmic microwave background at 95, 150, and 220 GHz with ∼ 16,000 detectors, 10 times more than its predecessor SPTpol. The increase in detector count is made possible by lenslet-coupled trichroic polarization-sensitive pixels fabricated at Argonne National Laboratory, new 68× frequency-domain multiplexing readout electronics, and a higher-throughput optical design. The enhanced sensitivity of SPT-3G will enable a wide range of results including constraints on primordial B-mode polarization, measurements of gravitational lensing of the CMB, and a galaxy cluster survey. Here we present an overview of the instrument and its science objectives, highlighting its measured performance and plans for the upcoming 2018 observing season. [ABSTRACT FROM AUTHOR]

The South Pole Telescope third-generation (SPT-3G) receiver was installed during the austral summer of 2016-2017. It is designed to measure the cosmic microwave background across three frequency bands centered at 95, 150, and 220 GHz. The SPT-3G receiver has ten focal plane modules, each with 269 pixels. Each pixel features a broadband sinuous antenna coupled to a niobium microstrip transmission line. In-line filters define the desired band-passes before the signal is coupled to six bolometers with Ti/Au/Ti/Au transition edge sensors (three bands × two polarizations). In total, the SPT-3G receiver is composed of  16,000 detectors, which are read out using a 68× frequency-domain multiplexing scheme. In this paper, we present the process employed in fabricating the detector arrays. [ABSTRACT FROM AUTHOR]

In this work, we have measured the properties of membrane-suspended bolometer thermal links and microstrip transmission lines in the transition-edge sensor arrays for the third-generation camera for South Pole Telescope (SPT-3G). A promising technique for controlling the end point of the release etch that defines the thermal link has been developed. We have also evaluated the microstrip loss in our detectors by measuring the optical efficiency of detectors with different lengths of microstrip line. The loss tangent is sufficiently low for the use in multi-chronic pixels for cosmic microwave background instruments like SPT-3G. [ABSTRACT FROM AUTHOR]