Special Astrophysics Seminar

Development of instrumentation for Cosmic Microwave Background (CMB) measurements with the SPT-3G and CMB Stage-4 experiments

Ritoban Basu Thakur

University of Chicago

The 3rd Generation South Pole Telescope (SPT 3G) will measure the CMB in three frequency bands with over 15000 polarization sensitive superconducting bolometers. With SPT-3G we will probe essential Physics of the early universe, perhaps the most important ones being: B-modes from inflationary gravitational waves, total mass of neutrinos and the neutrino mass hierarchy. Partnerships with experiments like BICEP/KECK, DES etc. will enhance our understanding of topics beyond the recombination epoch as well. In this talk I will discuss the design of SPT-3G, provide an overview of ongoing work and highlight the science cases. I will further discuss some offshoots of the SPT-3G efforts, which are aimed at the even more ambitious Stage-4 CMB experiments currently under planning and recommended by the P5 & NRC Antarctic report panels. These new projects include: (a) Development of Kinetic Inductance Devices (KIDs) for CMB measurement which will be essential when Stage 4 telescopes must operate ~500,000 detectors. Reading out this vast number of detectors is not trivial and KIDs have the potential for vastly simplifying the instrumentation. (b) Additionally precise measurement of the CMB frequency spectrum can enlighten us about the energetics of the early universe prior to recombination. One of the most interesting cases for this is characterizing dark matter decay at early times. The Fourier Transform Spectrometer (FTS) being developed for SPT-3G will pave the path for future high precision FTSs experiments like PIXIE.