Initial performance of the BICEP2 antenna-coupled superconducting bolometers at the South Pole
We report on the preliminary detector performance of the Bicep2 mm-wave polarimeter, deployed in 2009 to the South Pole. Bicep2 is currently imaging the polarization of the cosmic microwave background at 150 GHz using an array of 512 antenna-coupled superconducting bolometers. The antennas, band-defining filters and transition edge sensor (TES) bolometers are photolithographically fabricated on 4 silicon tiles. Each tile consists of an 8×8 grid of ~7 mm spatial pixels, for a total of 256 detector pairs. A patial pixel contains 2 sets of orthogonal antenna slots summed in-phase, with each set coupled to a TES by a filtered microstrip. The detectors are read out using time-domain multiplexed SQUIDs. The detector pair of each spatial pixel is differenced to measure polarization. We report on the performance of the Bicep2 detectors in the field, including the focal plane yield, detector and multiplexer optimization, detector noise and stability, and a preliminary estimate of the improvement in mapping speed compared to Bicep1.
Additional Information© 2010 SPIE. Bicep2 has been made possible by support from the National Science Foundation, Grant No. ANT-0742818. Detector development has been made possible by the generous support of the Gordon and Betty Moore Foundation. We are grateful to have Steffen Richter as our 2010 South Pole winterover. The Bicep2 team would also like to thank the South Pole Station staff for logistical support. We thank our Bicep1, Keck Array, and Spider colleagues for useful discussions and shared expertise. Finally we wish to thank Barbara Wertz and Kathy Deniston for their tireless logistical and administrative support.