Space Sciences/Astrophysics Seminar Seminar with Ian Gullett on Cosmic Microwave Background Telescope

Far-sidelobe contamination from wide angle scattering is a potentially prominent source of systematic error in large aperture telescopes measuring cosmic microwave background (CMB) polarization on large angular scales.  Future instruments targeting more sensitive measurements need to develop better sidelobe mitigation strategies to realize their goals.  Here we present and use 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 the result of scattering at the detector-cryostat entrance interacting with the walls of the telescope cabin.  After comparing simulated sidelobe maps and power spectra for different cabin wall treatments, we propose a highly scattering cabin wall surface that would provide more than an order of magnitude reduction in the degree-scale far-sidelobe contrast compared to typical reflective cabin walls.  We then discuss the fabrication of and present measurements of a prototype scattering wall panel.