Kavli Affiliate: John Carlstrom
| First 5 Authors: Ian Gullett, Bradford Benson, Robert Besuner, Richard Bihary, John Carlstrom
| Summary:
Telescopes measuring cosmic microwave background (CMB) polarization on large
angular scales require exquisite control of systematic errors to ensure the
fidelity of the cosmological results. In particular, far-sidelobe contamination
from wide angle scattering is a potentially prominent source of systematic
error for large aperture microwave telescopes. Here we describe and demonstrate
a ray-tracing-based modeling technique to predict far sidelobes for a Three
Mirror Anistigmat (TMA) telescope designed to observe the CMB from the South
Pole. Those sidelobes are produced by light scattered in the receiver optics
subsequently interacting with the walls of the surrounding telescope enclosure.
After comparing simulated sidelobe maps and angular power spectra for different
enclosure wall treatments, we propose a highly scattering surface that would
provide more than an order of magnitude reduction in the degree-scale
far-sidelobe contrast compared to a typical reflective surface. We conclude by
discussing the fabrication of a prototype scattering wall panel and presenting
measurements of its angular scattering profile.
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