Abstract:

QUIET (the Q/U Imaging ExperimenT) is a dedicated experiment to observe the Cosmic Microwave Background polarization on large angular scales using sensitive HEMT-based polarimeters. This measurement targets the signature on the CMB of gravitational waves generated during inflation, known as B-mode polarization. The first observing season was from October 2008 through May 2009 using a 19-element 40 GHz instrument coupled to a 1.4 meter telescope located at the Chajnantor Observatory in Chile. In June 2009, the detector was replaced with a 90-element 90 GHz instrument which is currently operating. I will describe the status of analysis of the 40 GHz data as well as the current 90 GHZ observations. At both frequencies, we target four patches totaling ~1000 square degrees and chosen to have low foreground contamination. The current phase of QUIET will provide precise measurements of the E-mode polarization power spectrum and improve upper limits on B-modes for angular scales up to ell=1000. Meanwhile, planning is underway for the second phase of QUIET, which will increase the number of detector by an order of magnitude to reach the level of sensitivity necessary to detect B-mode polarization.