Abstract
The polarization of the cosmic microwave background (CMB) provides complementary information to its primary anisotropy and is the frontier of ongoing and future CMB experiments. In particular, the large-scale CMB polarization encodes unique insights into inflationary modes and cosmic reionization. Despite significant advances in telescope design and detector technology, measuring the largest angular scales of the CMB remains challenging for ground-based experiments. In this talk, I will present the design and technological innovations of the Cosmology Large Angular Scale Surveyor (CLASS), showcasing its strategic approach and success in overcoming these challenges. I will discuss initial results from the 40 and 90 GHz surveys and highlight its first detection of the reionization signal from the ground.
