Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Design and characterization of a ground-based absolute polarization
  calibrator for use with polarization sensitive CMB experiments   We present the design and characterization of a ground-based absolute
polarization angle calibrator accurate to better than 0.1 degrees for use with
polarization sensitive cosmic microwave background (CMB) experiments. The
calibrator's accuracy requirement is driven by the need to reduce upper limits
on cosmic polarization rotation, which is expected to be zero in a large class
of cosmological models. Cosmic polarization effects such as cosmic
birefringence and primordial magnetic fields can generate spurious B-modes that
result in non-zero CMB TB and EB correlations that are degenerate with a
misalignment of detector orientation. Common polarized astrophysical sources
used for absolute polarization angle calibration have not been characterized to
better than 0.5 degrees. Higher accuracy can be achieved through
self-calibration methods, however these are subject to astrophysical foreground
contamination and inherently assume the absence of effects like cosmic
polarization rotation. The deficiencies in these two calibration methods
highlight the need for a well characterized polarized source. The calibrator we
present utilizes a 76 GHz Gunn oscillator coupled to a frequency doubler,
pyramidal horn antenna, and co-rotating wire-grid polarizer. We use an accurate
bubble level in combination with four precision-grade aluminum planes located
within the enclosure to calibrate the source's linear polarization plane with
respect to the local gravity vector to better than the 0.1 degree goal. In 2017
the calibrator was deployed for an engineering test run on the POLARBEAR CMB
experiment located in Chile's Atacama Desert and is being upgraded for
calibration of the POLARBEAR-2b receiver in 2018. In the following work we
present a detailed overview of the calibrator design, systematic control,
characterization, deployment, and plans for future CMB experiment absolute
polarization calibration.

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The categories of this paper are: stat
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The categories of this paper are: math-ph
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The categories of this paper are: comp-gas
9
The categories of this paper are: nlin
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The categories of this paper are: hep-lat
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The categories of this paper are: adap-org
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The categories of this paper are: ao-sci
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The categories of this paper are: acc-phys
3
The categories of this paper are: physics
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The categories of this paper are: eess
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The categories of this paper are: econ
4
The categories of this paper are: cond-mat
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The categories of this paper are: patt-sol
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The categories of this paper are: supr-con
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The categories of this paper are: cmp-lg
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The categories of this paper are: chao-dyn