Published online by Cambridge University Press: 05 January 2006
We present a new, fully-funded ground-based instrument designed to measurethe B-mode polarization of the Cosmic Microwave Background (CMB). The conceptis based on three independent sub-systems operating at 90, 150 and 220 GHz,each comprising a telescope and a focal plane of horn-coupled background-limited bolometers. This highly-sensitive experiment, planned to be based at Dome C station in Antarctica, is optimised to produce very low systematiceffects. It will allow the detection of the CMB polarization over angular multipoles 20<l<1000accurately enough to measure the B-mode signature from gravitationalwaves to a lensing-confusion-limited tensor-to-scalar ratio r ~ 0.005.