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 ![]() ![]() ![]() |
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Abstract
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 |
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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: | 17 Nov 2024 15:15 |
URI: | https://orca.cardiff.ac.uk/id/eprint/123155 |
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