The cosmic microwave background (CMB) field has an almost sixty-year history of measurements and discoveries. Measurements of the temperature of the CMB are a cornerstone of our current model of the universe, the standard model of Big Bang cosmology. More precise measurements of the CMB and its polarization are motivated by outstanding questions in cosmology and particle physics, including seeking evidence of inflation and signatures of new particles and new physics.  In the past two decades, three generations of ground-based CMB polarization telescopes have made successive leaps in sensitivity, which led to the detection of the faint B-mode polarization of the CMB from gravitational lensing. The recent Astro2020 decadal survey has prioritized funding and building the next-generation CMB experiment, CMB-S4. CMB-S4 will characterize microwave polarization and the CMB over the majority of the sky, with excellent sensitivity at small and large angular scales, from 30 – 300 GHz. In this talk, I will discuss the techniques and technologies for these precision microwave measurements, along with recent progress and upcoming plans for CMB-S4.

Dr. Darcy Barron is an assistant professor in the Department of Physics and Astronomy at the University of New Mexico. Prior to joining the department at UNM, Dr. Barron was a National Science Foundation Astronomy and Astrophysics Postdoctoral Fellow and Charles H. Townes Postdoctoral Fellow at the Space Sciences Lab at the University of California, Berkeley. Dr. Barron received her Ph.D. in Physics from the University of California, San Diego in 2015, advised by Prof. Brian Keating.