Performance and on-sky optical characterization of the SPTpol instrument

• Main Authors: George, E. M., Lueker, M., Shirokoff, E., Vieira, J. D.
• Other Authors: Holland, Wayne S., Zmuidzinas, Jonas
• Format: Book Part
• Language: English
• Published: Society of Photo-Optical Instrumentation Engineers (SPIE) 2012
• Subjects: South Pole; South pole
• Online Access: https://authors.library.caltech.edu/71508/; https://authors.library.caltech.edu/71508/1/84521F.pdf; https://authors.library.caltech.edu/71508/2/1210.4971v1.pdf; https://resolver.caltech.edu/CaltechAUTHORS:20161026-141054723

In January 2012, the 10m South Pole Telescope (SPT) was equipped with a polarization-sensitive camera, SPTpol, in order to measure the polarization anisotropy of the cosmic microwave background (CMB). Measurements of the polarization of the CMB at small angular scales (~several arcminutes) can detect the gravitational lensing of the CMB by large scale structure and constrain the sum of the neutrino masses. At large angular scales (~few degrees) CMB measurements can constrain the energy scale of Inflation. SPTpol is a two-color mm-wave camera that consists of 180 polarimeters at 90 GHz and 588 polarimeters at 150 GHz, with each polarimeter consisting of a dual transition edge sensor (TES) bolometers. The full complement of 150 GHz detectors consists of 7 arrays of 84 ortho-mode transducers (OMTs) that are stripline coupled to two TES detectors per OMT, developed by the TRUCE collaboration and fabricated at NIST. Each 90 GHz pixel consists of two antenna-coupled absorbers coupled to two TES detectors, developed with Argonne National Labs. The 1536 total detectors are read out with digital frequency-domain multiplexing (DfMUX). The SPTpol deployment represents the first on-sky tests of both of these detector technologies, and is one of the first deployed instruments using DfMUX readout technology. We present the details of the design, commissioning, deployment, on-sky optical characterization and detector performance of the complete SPTpol focal plane.