The Atacama Cosmology Telescope (ACT) is designed to make high angular resolution measurements of anisotropies in the Cosmic Microwave Background (CMB) at millimeter wavelengths. We describe ACTPol, an upgraded receiver for ACT, which uses feedhorn-coupled, polarization-sensitive detector arrays, a 3 degree field of view, 100 mK cryogenics with continuous cooling, and meta material anti-reflection coatings. ACTPol comprises three arrays with separate cryogenic optics: two arrays at a central frequency of 148 GHz and one array operating simultaneously at both 97 GHz and 148 GHz. The combined instrument sensitivity, angular resolution, and sky coverage are optimized for measuring angular power spectra, clusters via the thermal Sunyaev-Zel'dovich and kinetic Sunyaev-Zel'dovich signals, and CMB lensing due to large scale structure. The receiver was commissioned with its first 148 GHz array in 2013, observed with both 148 GHz arrays in 2014, and has recently completed its first full season of operations with the full suite of three arrays. This paper provides an overview of the design and initial performance of the receiver and related systems.
@article{arxiv.1605.06569,
title = {The Atacama Cosmology Telescope: The polarization-sensitive ACTPol instrument},
author = {R. J. Thornton and P. A. R. Ade and S. Aiola and F. E. Angile and M. Amiri and J. A. Beall and D. T. Becker and H-M. Cho and S. K. Choi and P. Corlies and K. P. Coughlin and R. Datta and M. J. Devlin and S. R. Dicker and R. Dunner and J. W. Fowler and A. E. Fox and P. A. Gallardo and J. Gao and E. Grace and M. Halpern and M. Hasselfield and S. W. Henderson and G. C. Hilton and A. D. Hincks and S. P. Ho and J. Hubmayr and K. D. Irwin and J. Klein and B. Koopman and Dale Li and T. Louis and M. Lungu and L. Maurin and J. McMahon and C. D. Munson and S. Naess and F. Nati and L. Newburgh and J. Nibarger and M. D. Niemack and P. Niraula and M. R. Nolta and L. A. Page and C. G. Pappas and A. Schillaci and B. L. Schmitt and N. Sehgal and J. L. Sievers and S. M. Simon and S. T. Staggs and C. Tucker and M. Uehara and J. van Lanen and J. T. Ward and E. J. Wollack},
journal= {arXiv preprint arXiv:1605.06569},
year = {2016}
}