This proposal is for the study of gravitational physics and cosmology through measurements of the cosmic microwave background (CMB) radiation. The research has two main components that complement what we expect to find with the Planck satellite and other measurements. In the first component, we continue our support and leadership of the Atacama Cosmology Telescope (ACT). Specifically, working with the ACT team, we will test detectors for, build, deploy, observe with, and analyze data from ACTPol, a new polarization sensitive receiver. The scientific payoff from ACT, measuring the CMB at small angular scales, has been considerable thus far and we expect ACTPol to be as successful if not more so. In the second component, we will observe with, upgrade, and analyze data from the Atacama B-mode Survey (ABS). ABS is aimed at detecting the signature of primordial gravitational waves in the polarization of the CMB at large angular scales.
Measurements of the CMB have revolutionized our understanding of the universe. We now have a standard model of cosmology that is so well tested we may use it as a foundation. The current generation of measurements is aimed at such things as determining the mass sum of neutrinos, elusive sub-atomic particles, and finding primordial gravitation waves. Thus CMB observations are touching on and informing everything from particle physics to quantum gravity. The lure of this exciting science has led to the invention of new types of detectors and detecting systems as well as to new algorithms for analyzing the data. The research is done by undergraduates, graduate students, and postdocs who are active participants in international collaborations. These students and postdocs go on not only in astrophysics but in other branches of science and in research labs as well. For example, former students are working at NIST on advanced X-ray detectors, which are intimately related to our detectors, for threat assessment and other applications.
