Development of Superconducting Detectors for Millimeter-Wave Astronomy and Cosmology

Walker, Samantha

Graduate Thesis Or Dissertation

Development of Superconducting Detectors for Millimeter-Wave Astronomy and Cosmology Public Deposited

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Citeable URL: https://scholar.colorado.edu/concern/graduate_thesis_or_dissertations/2n49t321j

Abstract

Superconducting detectors have revolutionized the field of millimeter-wave (mm-wave) and submillimeter-wave astrophysics and cosmology over the past twenty years. These detectors work at very low temperatures, typically well below 1 K, and exploit phenomena in superconductivity, such as the superconducting phase transition, to enable photon-noise-limited performance. Large arrays of superconducting detectors are being more frequently used as the detector of choice for current and future (sub)mm-wave instruments on ground-based telescopes. For example, by using arrays numbering nearly 10⁵ detectors total, the upcoming ground-based experiment Simons Observatory (SO) will measure the very faint temperature and polarization anisotropies of the cosmic microwave background (CMB). Despite the prevalence of these detectors, challenges remain in operating large arrays of these detectors and optimizing their performance under dynamic loading conditions as seen when observing on-sky from ground-based observatories. My dissertation addresses the development and characterization of superconducting detectors, transition-edge sensor (TES) bolometers and microwave kinetic inductance detectors (MKIDs), at the National Institute of Standard and Technology (NIST) to study the mm-wave Universe. In this work, we discuss the optical characterization of TES bolometer pixels, consisting of four detectors, one for each passband and polarization, for the highest frequency passbands of SO. We describe our new MKID tuning method to optimize operation of MKID arrays, consisting of hundreds of resonators on the same feedline, for TolTEC, a mm-wave imaging polarimeter at the Large Millimeter Telescope. We also investigate the system noise of the TolTEC 1.1 mm array and comment on future steps towards improving its current readout configuration and noise.

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