BICEP3: a 95GHz refracting telescope for degree-scale CMB polarization

Abstract

BICEP3 is a 550 mm-aperture refracting telescope for polarimetry of radiation\nin the cosmic microwave background at 95 GHz. It adopts the methodology of\nBICEP1, BICEP2 and the Keck Array experiments - it possesses sufficient\nresolution to search for signatures of the inflation-induced cosmic\ngravitational-wave background while utilizing a compact design for ease of\nconstruction and to facilitate the characterization and mitigation of\nsystematics. However, BICEP3 represents a significant breakthrough in\nper-receiver sensitivity, with a focal plane area 5$\\times$ larger than a\nBICEP2/Keck Array receiver and faster optics ($f/1.6$ vs. $f/2.4$).\nLarge-aperture infrared-reflective metal-mesh filters and infrared-absorptive\ncold alumina filters and lenses were developed and implemented for its optics.\nThe camera consists of 1280 dual-polarization pixels; each is a pair of\northogonal antenna arrays coupled to transition-edge sensor bolometers and read\nout by multiplexed SQUIDs. Upon deployment at the South Pole during the 2014-15\nseason, BICEP3 will have survey speed comparable to Keck Array 150 GHz (2013),\nand will significantly enhance spectral separation of primordial B-mode power\nfrom that of possible galactic dust contamination in the BICEP2 observation\npatch.\n