Feedhorn-Coupled TES Polarimeter Camera Modules at 150 GHz for CMB Polarization Measurements with SPTpol

• Published in: SPIE Proceedings, Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy VI
• Main Authors: Henning, J. W., Lueker, M., Shirokoff, E., Vieira, J. D.
• Other Authors: Holland, Wayne S., Zmuidzinas, J.
• Format: Book Part
• Language: unknown
• Published: Society of Photo-Optical Instrumentation Engineers (SPIE) 2012
• Subjects: cosmology; CMB; polarization; TES bolometer; Canada; South Pole; Kavli; South pole
• Online Access: https://doi.org/10.1117/12.927172

The SPTpol camera is a dichroic polarimetric receiver at 90 and 150 GHz. Deployed in January 2012 on the South Pole Telescope (SPT), SPTpol is looking for faint polarization signals in the Cosmic Microwave Background (CMB). The camera consists of 180 individual Transition Edge Sensor (TES) polarimeters at 90 GHz and seven 84-polarimeter camera modules (a total of 588 polarimeters) at 150 GHz. We present the design, dark characterization, and in-lab optical properties of the 150 GHz camera modules. The modules consist of photolithographed arrays of TES polarimeters coupled to silicon platelet arrays of corrugated feedhorns, both of which are fabricated at NIST-Boulder. In addition to mounting hardware and RF shielding, each module also contains a set of passive readout electronics for digital frequency-domain multiplexing. A single module, therefore, is fully functional as a miniature focal plane and can be tested independently. Across the modules tested before deployment, the detectors average a critical temperature of 478 mK, normal resistance R_N of 1.2 Ω, unloaded saturation power of 22.5 pW, (detector-only) optical efficiency of ~ 90%, and have electrothermal time constants < 1 ms in transition. © 2012 Society of Photo-Optical Instrumentation Engineers (SPIE). Work at the University of Colorado - Boulder, Case Western Reserve University, the University of California - Berkeley, and the University of Chicago is supported by grants from the NSF (awards ANT-0638937, AST-0956135, and PHY-0114422), the Kavli Foundation, and the Gordon and Betty Moore Foundation. Work at NIST is supported by the NIST Innovations in Measurement Science program. The McGill authors acknowledge funding from the Natural Sciences and Engineering Research Council, Canadian Institute for Advanced Research, and Canada Research Chairs program. MD acknowledges support from an Alfred P. Sloan Research Fellowship. Work at Argonne National Lab is supported by UChicago Argonne, LLC, Operator of Argonne National Laboratory (\Argonne"). ...