The Quiet Project: Phase I

University Of Chicago, Chicago IL

Investigators

Abstract

AST 0506648 Winstein This award will be used to implement Phase I of QUIET, a project to measure the polarization of the cosmic microwave background (CMB) with levels of precision approaching the limit of what is possible from the ground. The polarization is measured with coherent detectors at two frequencies over angular scales from a few arc-minutes to a few degrees. The QUIET Collaboration comprises scientists from CalTech; the University of Chicago; Columbia University; Jet Propulsion Laboratory; the University of Miami; Princeton University, and Stanford University. A group from Oxford University, UK is also participating but is separately funded; and individuals from Goddard Space Flight Center; and Harvard-Smithsonian Center for Astrophysics are playing advisory roles. The goal for Phase I is to field two sets of detectors on telescopes situated in the Atacama desert in Chile, and carry out two seasons of science operations. These data will: a) provide the demonstration that the new radiometer technology works; b) give two modes of linear polarization, particularly the B-mode, of CMB power spectra measurements that are at the state of the art; and c) provide the deepest maps of the CMB available at the two frequencies of the measurements. QUIET will make valuable measurements not only of the CMB itself, but also of the foreground signals, mostly from our Galaxy, in order to disentangle confusion due to one of the biggest obstacles to a clean measurement of CMB polarization. Results from QUIET will complement the continuing WMAP satellite observations, and the soon-to-be-launched European-US Planck mission, by consideration of different angular scales on the sky and different polarization modes , and by use of different frequencies, different receiver technologies, and different telescope structures. The technological breakthrough that makes these measurements possible comes from a detector laboratory at JPL. Through the application of low-cost, mass production techniques to cryogenic millimeter-wave circuits, very large arrays can now be made inexpensively, with state-of-the-art performance. An important and unique feature of these polarimeters is the systematic control arising from their ability to measure both of the polarization Stokes parameters simultaneously. The research carried out with this project leads to benefits beyond scientific discoveries. Collaboration members will continue strong programs of hands-on research for students. University students will go to JPL for invaluable technical training and hundreds more will be informed of the science during regularly scheduled class time. The work will contribute to increased public understanding of this most fascinating area of the physical sciences. Over the life of the project, some 100 more undergraduates will have contributed to the science and over forty public lectures will be delivered by QUIET scientists who will also help create radio and TV shows about science. The basic packaging technology developed for the compact cryogenic QUIET arrays finds application in a number of fields beyond the CMB, including arrays for use in atmospheric remote sensing, thermal mapping of extrasolar planets, and telecommunications.