title: Systematic effects from an ambient-temperature, continuously rotating half-wave plate.
abstract: We present an evaluation of systematic effects associated with a continuously rotating, ambient-temperature half-wave plate (HWP) based on two seasons of data from the Atacama B-Mode Search (ABS) experiment located in the Atacama Desert of Chile. The ABS experiment is a microwave telescope sensitive at 145 GHz. Here we present our in-field evaluation of celestial (Cosmic Microwave Background (CMB) plus galactic foreground) temperature-to-polarization leakage. We decompose the leakage into scalar, dipole, and quadrupole leakage terms. We report a scalar leakage of ∼0.01%, consistent with model expectations and an order of magnitude smaller than other CMB experiments have been reported. No significant dipole or quadrupole terms are detected; we constrain each to be <0.07% (95% confidence), limited by statistical uncertainty in our measurement. Dipole and quadrupole leakage at this level lead to systematic error on r ≲ 0.01 before any mitigation due to scan cross-linking or boresight rotation. The measured scalar leakage and the theoretical level of dipole and quadrupole leakage produce systematic error of r < 0.001 for the ABS survey and focal-plane layout before any data correction such as so-called deprojection. This demonstrates that ABS achieves significant beam systematic error mitigation from its HWP and shows the promise of continuously rotating HWPs for future experiments.
authors: Department of Physics, Princeton University, Princeton, New Jersey 08544, USA.
authors: T
authors: T
authors: Essinger-Hileman
authors: Department of Physics, Princeton University, Princeton, New Jersey 08544, USA.
authors: A
authors: A
authors: Kusaka
authors: Department of Physics, Princeton University, Princeton, New Jersey 08544, USA.
authors: J W
authors: JW
authors: Appel
authors: Department of Physics, Princeton University, Princeton, New Jersey 08544, USA.
authors: S K
authors: SK
authors: Choi
authors: Department of Physics, Princeton University, Princeton, New Jersey 08544, USA.
authors: K
authors: K
authors: Crowley
authors: Department of Physics, Princeton University, Princeton, New Jersey 08544, USA.
authors: S P
authors: SP
authors: Ho
authors: Department of Physics, Princeton University, Princeton, New Jersey 08544, USA.
authors: N
authors: N
authors: Jarosik
authors: Department of Physics, Princeton University, Princeton, New Jersey 08544, USA.
authors: L A
authors: LA
authors: Page
authors: Department of Physics, Princeton University, Princeton, New Jersey 08544, USA.
authors: L P
authors: LP
authors: Parker
authors: Department of Astronomy, Universidad de Chile, Santiago, Chile.
authors: S
authors: S
authors: Raghunathan
authors: Department of Physics, Princeton University, Princeton, New Jersey 08544, USA.
authors: S M
authors: SM
authors: Simon
authors: Department of Physics, Princeton University, Princeton, New Jersey 08544, USA.
authors: S T
authors: ST
authors: Staggs
authors: Department of Physics, Princeton University, Princeton, New Jersey 08544, USA.
authors: K
authors: K
authors: Visnjic