Atacama B-Mode Search (ABS)
The Atacama B-Mode Search (ABS) is an experiment designed to measure cosmic microwave background (CMB) polarization. ABS mapped roughly 2,400 square degrees of the sky in a spectral band centered at 145 GHz between February 2012 and October 2014 from a high-altitude site at 5,190 m elevation in northern Chile. The ABS receiver housed 480 polarization-sensitive transition-edge-sensor (TES) bolometers along with a cryogenic 60-cm reflective telescope that provided 32 arcminute resolution. A continuously-rotating, ambient-temperature half-wave plate (HWP) modulated incoming polarization to provide improved system stability and control of systematic effects.