Intensity-Coupled-Polarization in Instruments with a Continuously Rotating Half-Wave Plate

Abstract

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

arXiv comment43 pages, 12 figures, submitted to the Astrophysical Journal

References in corpus (12)

• Seven-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Cosmological Interpretation
• HEALPix -- a Framework for High Resolution Discretization, and Fast Analysis of Data Distributed on the Sphere
• BICEP2 I: Detection Of B-mode Polarization at Degree Angular Scales
• CMB Polarization Systematics Due to Beam Asymmetry: Impact on Inflationary Science
• Modulation of CMB polarization with a warm rapidly-rotating half-wave plate on the Atacama B-Mode Search (ABS) instrument
• MAXIPOL: Cosmic Microwave Background Polarimetry Using a Rotating Half-Wave Plate
• Performance of a continuously rotating half-wave plate on the POLARBEAR telescope
• Systematic effects from an ambient-temperature, continuously-rotating half-wave plate
• The EBEX Balloon-Borne Experiment - Gondola, Attitude Control, and Control Software
• The EBEX Balloon Borne Experiment - Optics, Receiver, and Polarimetry
• The EBEX Balloon Borne Experiment - Detectors and Readout
• Polarization Dependence of Emissivity

Cited by in corpus (3)

• Studies of Systematic Uncertainties for Simons Observatory: Detector Array Effects
• Modelling TES non-linearity induced by a rotating HWP in a CMB polarimeter
• The Simons Observatory: Quantifying the impact of beam chromaticity on large-scale B-mode science