Cosmology Large Angular Scale Surveyor

Abstract

The Cosmology Large Angular Scale Surveyor (CLASS) is an experiment to measure the imprint of gravitational waves from inflation in the polarization of the cosmic microwave background. CLASS is a multi-frequency array of four telescopes to be deployed in the Atacama Desert in Chile. From this site, CLASS will observe 70% of the sky at four frequency bands centered at 38, 93, 148, and 217 GHz - designed to straddle the full-sky galactic foreground minimum. The large survey area enables CLASS to characterize the B-mode and E-mode power spectra on both the reionization and recombination scales. Simulations including the presence of foregrounds suggest the CLASS strategy of combining large sky coverage, control of systematic errors, signal stability, and high sensitivity will allow detection of the tensor-to-scalar ratio down to the level of r=0.01 and enable cosmic-variance-limited measurements of the optical depth to reionization. In this talk, I present an overview of the CLASS strategy for measuring the E-modes and B-modes at the largest angular scales and give an update on the project status.