Intensity-coupled Polarization in Instruments with a Continuously Rotating Half-wave Plate

Joy Didier, Amber D. Miller, Derek Araujo, François Aubin, Christopher Geach, Bradley Johnson, Andrei Korotkov, Kate Raach, Benjamin Westbrook, Karl Young, Asad M. Aboobaker, Peter Ade, Carlo Baccigalupi, Chaoyun Bao, Daniel Chapman, Matt Dobbs, Will Grainger, Shaul Hanany, Kyle Helson, Seth HillbrandJohannes Hubmayr, Andrew Jaffe, Terry J. Jones, Jeff Klein, Adrian Lee, Michele Limon, Kevin Macdermid, Michael Milligan, Enzo Pascale, Britt Reichborn-Kjennerud, Ilan Sagiv, Carole Tucker, Gregory S. Tucker, Kyle Zilic

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


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.

Original languageEnglish (US)
Article number54
JournalAstrophysical Journal
Issue number1
StatePublished - May 1 2019

Bibliographical note

Publisher Copyright:
© 2019. The American Astronomical Society. All rights reserved.


  • balloons
  • cosmic background radiation
  • instrumentation: polarimeters
  • methods: data analysis
  • polarization
  • techniques: polarimetric


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