Feedhorn development and scalability for Simons Observatory and beyond

The Simons Observatory (SO) will measure the cosmic microwave background (CMB) in both temperature and polarization over a wide range of angular scales and frequencies from 27-270 GHz with unprecedented sensitivity. One technology for coupling light onto the ~50 detector wafers that SO will field is spline-profiled feedhorns, which offer tunability between coupling efficiency and control of beam polarization leakage effects. We will present efforts to scale up feedhorn production for SO and their viability for future CMB experiments, including direct-machining metal feedhorn arrays and laser machining stacked Si arrays.

[1]  Ghassan Yassin,et al.  Multiple flare-angle horn feeds for sub-mm astronomy and cosmic microwave background experiments , 2011 .

[2]  Edward J. Wollack,et al.  The Advanced ACTPol 27/39 GHz Array , 2018 .

[3]  Ki Won Yoon,et al.  An 84 Pixel All-Silicon Corrugated Feedhorn for CMB Measurements , 2011, Journal of Low Temperature Physics.

[4]  Adrian T. Lee,et al.  CMB-S4 Science Book, First Edition , 2016, 1610.02743.

[5]  J. Leech,et al.  Experimental Investigation of a Low-Cost, High Performance Focal-Plane Horn Array , 2012, IEEE Transactions on Terahertz Science and Technology.

[6]  Shaul Hanany,et al.  CMB-S4 Technology Book, First Edition , 2017, 1706.02464.

[7]  Edward J. Wollack,et al.  A Low Cross-Polarization Smooth-walled Dorn with Improved Bandwidth , 2009 .

[8]  Michele Limon,et al.  CLASS: the cosmology large angular scale surveyor , 2014, Astronomical Telescopes and Instrumentation.

[9]  G. K. White,et al.  Thermal expansion of Cr, Mo and W at low temperatures , 1978 .

[10]  Johannes Hubmayr,et al.  The design and characterization of wideband spline-profiled feedhorns for Advanced ACTPol , 2016, Astronomical Telescopes + Instrumentation.

[11]  Edward J. Wollack,et al.  SiAl alloy feedhorn arrays: material properties, feedhorn design, and astrophysical applications , 2018, Astronomical Telescopes + Instrumentation.

[12]  C. Granet,et al.  A smooth-walled spline-profile horn as an alternative to the corrugated horn for wide band millimeter-wave applications , 2004, IEEE Transactions on Antennas and Propagation.

[13]  J. Leech,et al.  A High Performance Horn for Large Format Focal Plane Arrays , 2007 .