The White Mountain polarimeter telescope and an upper limit on cosmic microwave background polarization

Creators: Levy, Alan R.; Leonardi, Rodrigo; Ansmann, Markus; Bersanelli, Marco; Childers, Jeffery; Cole, Terrence D.; D'Arcangelo, Ocleto; Davis, G. Vietor; Lubin, Philip M.; Marvil, Joshua; Meinhold, Peter R.; Miller, Gerald; O'Neill, Hugh; Stavola, Fabrizio; Stebor, Nathan C.; Timbie, Peter T.; van der Heide, Maarten; Villa, Fabrizio; Villela, Thyrso; Williams, Brian D.; Wuensche, Carlos A.

Abstract

The White Mountain Polarimeter (WMPol) is a dedicated ground-based microwave telescope and receiver system for observing polarization of the cosmic microwave background. WMPol is located at an altitude of 3880 m on a plateau in the White Mountains of Eastern California, at the Barcroft Facility of the University of California White Mountain Research Station. Presented here is a description of the instrument and the data collected during 2004 April through October. We set an upper limit on E-mode polarization of 14 μK (95% confidence limit) in the multipole range 170 < l < 240. This result was obtained with 422 hr of observations of a 3 deg^2 sky area about the North Celestial Pole, using a 42 GHz polarimeter. This upper limit is consistent with EE polarization predicted from a standard ΛCDM concordance model.

Additional Information

© 2008 The American Astronomical Society. Received 2007 June 10; accepted 2008 March 16. This work would not have been possible without the support of Frank Powell, the Director of the White Mountain Research Station, and the dedicated WMRS staff including Associate Director John Smiley, Paul Addison, Dori Cann, Martin Freeman, Ryan Kitts, Matt Lokken, Richard McDade, Gary Milender, Donna Lisa Shinn, Valerie Thorp, Mike Virgin, and Denise Waterbury. We are also grateful for the many UCSB undergraduate students who contributed during the course of building, testing, and installing the telescope. The superb UCSB Machine Shop was instrumental in the success of this project. We thank Todd Gaier and Sandy Weinreb for providing the HEMT amplifiers. We also acknowledge the efforts of Chris O'Dell who did much of the initial work in designing the W-band polarimeter and Miikka Kangas who prepared some of the figures in this article. We thank Julian Borrill, Radek Stompor, and Chris Cantalupo for help with and providing resources to use MADCAP and we thank Eric Hivon and Ian O'Dwyer for help with and providing resources to use Pol Spice. This work was supported by NSF grants AST-9802851, 9813920, and 0118297 and the UCSB Office of Research. The development of the carbon fiber reflectors was supported by NASA grants NAG5-4078, NAG5-9073, and NAG5-4185.We are especially grateful to Thin Film Technology Inc., Buellton, CA, for coating the reflectors. The W-band feeds were developed at the Microwave Laboratory of Istituto di Fisica dei Plasmi-CNR, Milan, Italy. A. L. was supported by a California Space Grant Consortium Graduate Research Fellowship, and A. L., N. S., and B.W. were supported by the WMRS Graduate Student Research Fellowship. R. L. was supported by CAPES and the NASA Planck project under contract 1261740. T. V. and C. A. W. were partially supported by FAPESP grant 00/06770-2. In addition, T. V. acknowledges support from CNPq grant 305219/2004-9, and C. A. W. acknowledges support from CNPq grant 307433/2004-8-FA and FAPESP grant 96/06501-4. G. M. was supported by a UCSB Chancellor's Undergraduate Research Award, and M. v. d. H. was supported by a UCSB Undergraduate Research and Creative Activities Award. Some of the results in this paper have been derived using the HEAL Pix package (Gorski et al. 2005). The research described in this paper was performed in part at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.

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