Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Empirical modelling of the BLASTPol achromatic half-wave plate for
  precision submillimetre polarimetry   A cryogenic achromatic half-wave plate (HWP) for submillimetre astronomical
polarimetry has been designed, manufactured, tested, and deployed in the
Balloon-borne Large-Aperture Submillimeter Telescope for Polarimetry
(BLASTPol). The design is based on the five-slab Pancharatnam recipe and it
works in the wavelength range 200-600 micron, making it the broadest-band HWP
built to date at (sub)millimetre wavelengths. The frequency behaviour of the
HWP has been fully characterised at room and cryogenic temperatures with
incoherent radiation from a polarising Fourier transform spectrometer. We
develop a novel empirical model, complementary to the physical and analytical
ones available in the literature, that allows us to recover the HWP Mueller
matrix and phase shift as a function of frequency and extrapolated to 4K. We
show that most of the HWP non-idealities can be modelled by quantifying one
wavelength-dependent parameter, the position of the HWP equivalent axes, which
is then readily implemented in a map-making algorithm. We derive this parameter
for a range of spectral signatures of input astronomical sources relevant to
BLASTPol, and provide a benchmark example of how our method can yield improved
accuracy on measurements of the polarisation angle on the sky at submillimetre
wavelengths.

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The categories of this paper are: funct-an
11
The categories of this paper are: hep-lat
8
The categories of this paper are: hep-ex
23
The categories of this paper are: solv-int
14
The categories of this paper are: math-ph
22
The categories of this paper are: chao-dyn
5
The categories of this paper are: gr-qc
18
The categories of this paper are: econ
35
The categories of this paper are: mtrl-th
25
The categories of this paper are: patt-sol
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The categories of this paper are: supr-con
7
The categories of this paper are: hep-th
36
The categories of this paper are: cmp-lg
26
The categories of this paper are: bayes-an
24
The categories of this paper are: dg-ga
31
The categories of this paper are: ao-sci