Dale Li -- National Institute of Standards and Technology, Boulder, Colorado
A new class of observatories are currently poised to dramatically improve our understanding of the early universe. At the heart of these observatories are large scale polarimeter arrays read out with ultra sensitive superconducting power meters. The realization of these arrays requires a careful balance of microwave design, low temperature physics, and micro-fabrication. I will discuss how we navigated these challenges with experiments designed to investigate improvements in dielectric loss, Tc uniformity, engineered heat capacity, and structural stability of delicate membranes. These improvements were applied to the development of two separate polarimeter instruments one at the South Pole Telescope and the other at the Atacama Cosmology Telescope with different performance requirements and design parameters including transition edge sensor material, bath temperature, readout scheme, and on-sky power loading. I will also describe our progress in developing lumped-element microwave kinetic inductance polarimeters for the study of star formation in cold Galactic interstellar clouds at Terahertz frequencies for the next generation Balloon-borne Large-Aperture Submillimeter Telescope.