Speaker
Dr
Michael Niemack
(National Institute of Standards and Technology)
Description
We are building large arrays of feedhorn-coupled superconducting transition-edge sensor (TES) polarimeters to measure the polarization of the cosmic microwave background (CMB) radiation. These polarimeters will be deployed on three experiments in the coming year: the Atacama B-mode Search, the South Pole Telescope Polarimeter, and the Atacama Cosmology Telescope Polarimeter. The science goals of these instruments include probing the energy scale of inflation by searching for the signature of inflationary gravity waves and constraining the sum of the neutrino masses.
TES detectors are most sensitive when voltage biased at sub-Kelvin temperatures, which necessitates minimizing the number of wires connected to the cold stage. These constraints have driven the development of multiplexed superconducting quantum interference device (SQUID) readout technologies. Two SQUID multiplexing techniques (time-division and MHz frequency-division multiplexing) have recently been used for astrophysical observations, and two more techniques are under development (GHz frequency-division and code-division multiplexing).
I will describe the arrays of TES polarimeters we are building for upcoming measurements of the CMB polarization, then will review the four SQUID multiplexing techniques and some of the non-astrophysical applications our group works on, including x-ray, gamma-ray, and alpha particle detection.
Author
Dr
Michael Niemack
(National Institute of Standards and Technology)
