The most successful model of the universe involves a period of immense expansion during the first small fraction of a second following the Big Bang. This "phase-change" in the early universe explains a number of key observations, including the extreme flatness of the universe, the very similar properties of causally unrelated regions of the observable universe, and the lack of magnetic monopoles. An important prediction of inflation is the "handedness" of polarization imprinted by gravitational waves that are thought to have existed at the time of the last photon scattering. Searching for this "B-mode" polarization signal is a fundamental test of inflation, diagnostic of the energy scale over which the phase change operated, and one of the key science themes identified for the next decade by the ASTRO2010 survey New Worlds, New Horizons in Astronomy and Astrophysics.
Dr. Adrian Lee of the University of California Berkeley and collaborators elsewhere within the U.S. as well as in Canada, United Kingdom, and Japan plan an experiment to detect and explore for the first time the B-mode polarization using a dedicated radio antenna high on the Atacama Plateau in Chile and a state-of-the-art 7,588 pixel bolometer array to map the sky at the dual frequencies of 150 and 220 GHz with higher sensitivity and an order of magnitude faster than current experiments. The project, POLARBEAR-2, is very well motivated scientifically and equally well justified on a technical and management footing by the pilot project POLARBEAR-1, now complete and obtaining initial data at the Chilean site. Technical developments made through the project will be important at other wavelength regions of astronomical detection, including the sub-mm. Postdoctoral and student involvement is included in important elements of the development and testing, continuing the strong tradition of training in the hardware and techniques of radio astronomy at U.C. Berkeley.
Funding for the development of the POLARBEAR-2 project is being provided by NSF's Division of Astronomical Sciences through its Advanced Technologies and Instrumentation program.
