This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5). This proposal requests support for the development of a state-of-the-art polarization-sensitive receiver SPT-POL that will be used to conduct a program of cosmological research with the 10-meter South Pole Telescope (SPT). The SPT-POL will be installed on the SPT and used to measure the polarization anisotropy of the Cosmic Microwave Background (CMB) radiation from scales of an arcminute to degrees, starting in austral winter 2012. From the analysis of the resulting polarization maps, the project will determine the angular power spectrum of the CMB B-mode polarization (curl component) induced by the lensing of the intrinsic E-mode polarization (curl-free component) by large-scale structures. The lensing B-mode spectrum provides sensitivity to the neutrino masses through their impact on the growth of the large-scale, lensing structure. The project will also search for the large angular scale B-mode polarization signal imprinted on the CMB by inflationary gravitational waves generated in the first instants of the Universe. Detection of the inflationary B-mode spectrum would be a spectacular test of the Inflation theory of the origin of the Universe and will set the energy scale of the Inflationary epoch. In addition to the CMB temperature and polarization anisotropy data, the obtained datasets will include a wealth of information including catalogs of massive galaxy clusters and extragalactic millimeter and submillimeter sources. Continued reliance on students provides a broader impact of this proposed research and firmly grounds this effort in its educational mission. The project will contribute significantly to the training of the next generation of scientists by integrating graduate and undergraduate education with technology and instrumentation development, astronomical field observations, and scientific analysis. The sharing of forefront research with non-scientists will be extended beyond the university through a well-established and vibrant educational network that reaches a wide audience at all levels of the educational continuum.
The grant was used to build and deploy a new polarization sensitive camera for the 10-meter South Pole Telescope (SPT). The goal of the SPT polarization measurements is to learn more about the origin and evolution of our universe through detailed polarization studies of the cosmic microwave radiation, the fossil light from the big bang. The polarization sensitivity opens a new window into the physics of the first instant of the universe, when we believe the universe underwent a burst of inflation at extremely high energies. The polarization data will also allows us to set stringent contraints on the growth of structure in the universe and set tight limits on the masses of the elusive neutrinos, a goal of fundamental research in physics. The core of the camera is new superconducting detectors operating at 0.25 degrees above absolute zero, i.e., 0.25 degress Kelvin. Detectors technologies were built to operate in two bands. The 150 GHz detectors were built at NIST and the 90 GHz detectors were built at Argonne National Laboratory. The SPT collaboration was involved in the design, testing and integration of the detectors. The 150 GHz horns, which direct the radiation to the detectors were fabricated by a novel method using stacked etched silicon wafers. The 90 GHz horns were designed at Chicago and built using a single shaped tool. The cold and room temperature electronics use a new frequency multiplexed system, built at McGill University, to reduce the thermal loading on the detector assembly via the readout wires. The polarimeter was successfully deployed on the telescope in January 2012 and has been taking data since. The data quality is exceptional and the team expects to announce its first results in Summer 2013. The work of the SPT team is performed nearly exclusively by postdoctoral fellows, graduate students and undergraduate students. The award helped support a graduate student in the building of the camera, its deployment and the data analysis.
