Polarized Beam Patterns from a Multi-Moded Feed For Observations of the Cosmic Microwave Background

2018/01/26 by Kogut, A., Fixsen, D. J.
#FOS: Physical sciences #Instrumentation and Methods for Astrophysics (astro-ph.IM)

paper · doi:10.48550/arxiv.1801.08971

Abstract

We measure linearly polarized beam patterns for a multi-moded concentrator and compare the results to a simple model based on geometric optics. We convolve the measured co-polar and cross-polar beams with simulated maps of CMB polarization to estimate the amplitude of the systematic error resulting from the cross-polar beam response. The un-corrected error signal has typical amplitude of 3 nK, corresponding to inflationary B-mode amplitude r ~ 10^-3. Convolving the measured cross-polar beam pattern with maps of the CMB E-mode polarization provides a template for correcting the cross-polar response, reducing it to negligible levels.

Related

• Antenna Instrumental Polarization and its Effects on E- and B-Modes for CMBP Observations
• Systematic Effects in CMB Polarization Measurements
• Deprojecting beam systematics for next-generation CMB B-mode searches
• Polarization angle accuracy for future CMB experiments. The COSMOCal project and its prototype in the 1mm band
• Systematic error cancellation for a four-port interferometric polarimeter