Performance and on-sky optical characterization of the SPTpol instrument

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.

E.M. George, P. Ade, K.A. Aird, J.E. Austermann, J.A. Beall, D. Becker, A. Bender, B.A. Benson, L.E. Bleem, J. Britton, J.E. Carlstrom, C.L. Chang, H.C. Chiang, H-M. Cho, T.M. Crawford, A.T. Crites, A. Datesman, T. de Haan, M.A. Dobbs, W. Everett, A. Ewall-Wice, N.W. Halverson, N. Harrington, J.W. Henning, G.C. Hilton, W.L. Holzapfel, S. Hoover, N. Huang, J. Hubmayr, K.D. Irwin, M. Karfunkle, R. Keisler, J. Kennedy, A.T. Lee, E. Leitch, D. Li, M. Lueker, D.P. Marrone, J.J. McMahon, J. Mehl, S.S. Meyer, J. Montgomery, T.E. Montroy, J. Nagy, T. Natoli, J.P. Nibarger, M.D. Niemack, V. Novosad, S. Padin, C. Pryke, C.L. Reichardt, J.E. Ruhl, B.R. Saliwanchik, J.T. Sayre, K.K. Schaffer, E. Shirokoff, K. Story, C. Tucker, K. Vanderlinde, J.D. Vieira, G. Wang, R. Williamson, V. Yefremenko, K.W. Yoon, E. Young · 2012