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Intensity-coupled polarization in instruments with a continuously rotating half-wave plate

Didier, Joy, Miller, Amber D., Araujo, Derek, Aubin, François, Geach, Christopher, Johnson, Bradley, Korotkov, Andrei, Raach, Kate, Westbrook, Benjamin, Young, Karl, Aboobaker, Asad M., Ade, Peter, Baccigalupi, Carlo, Bao, Chaoyun, Chapman, Daniel, Dobbs, Matt, Grainger, Will, Hanany, Shaul, Helson, Kyle, Hillbrand, Seth, Hubmayr, Johannes, Jaffe, Andrew, Jones, Terry J., Klein, Jeff, Lee, Adrian, Limon, Michele, MacDermid, Kevin, Milligan, Michael, Pascale, Enzo, Reichborn-Kjennerud, Britt, Sagiv, Ilan, Tucker, Carole, Tucker, Gregory S. and Zilic, Kyle 2019. Intensity-coupled polarization in instruments with a continuously rotating half-wave plate. Astrophysical Journal 876 (1) , 54. 10.3847/1538-4357/ab0f36

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We discuss a systematic effect associated with measuring polarization with a continuously rotating half-wave plate (HWP). The effect was identified with the data from the E and B Experiment, which was a balloon-borne instrument designed to measure the polarization of the cosmic microwave background (CMB) as well as that from Galactic dust. The data show polarization fractions larger than 10%, while less than 3% were expected from instrumental polarization. We give evidence that the excess polarization is due to detector nonlinearity in the presence of a continuously rotating HWP. The nonlinearity couples intensity signals to polarization. We develop a map-based method to remove the excess polarization. Applying this method to the 150 (250) GHz band data, we find that 81% (92%) of the excess polarization was removed. Characterization and mitigation of this effect are important for future experiments aiming to measure the CMB B-modes with a continuously rotating HWP

Item Type: Article
Date Type: Published Online
Status: Published
Schools: Physics and Astronomy
Publisher: American Astronomical Society
ISSN: 1538-4357
Date of First Compliant Deposit: 4 June 2019
Date of Acceptance: 11 March 2019
Last Modified: 28 Jun 2019 02:02

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