“ACTPol: An instrument for small-scale CMB polarization observations” Speaker: Emily Grace, Princeton University ACTPol is a polarization sensitive upgrade to the Atacama Cosmology Telescope which aims to probe the small scale polarization anisotropy of the CMB, a signal which promises to constrain the sum of the neutrino masses and the dark energy equation of state. I will present the design and development of the ACTPol instrumentation. The new receiver will contain three optics tubes each consisting of three large cryogenic silicon lenses. The three arrays, two at 150 GHz and one at 90 GHz, are each composed of ~1000 feedhorn-coupled transition-edge sensor bolometer detectors. The focal plane will be cooled to an operating temperature of ~100 mK using a pulse-tube backed dilution refrigerator. The first 150 GHz array is scheduled to deploy in 2012.

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