Date of Award

8-19-2024

Author's School

Graduate School of Arts and Sciences

Author's Department

Physics

Degree Name

Doctor of Philosophy (PhD)

Degree Type

Dissertation

Abstract

Transition-edge sensor (TES) detectors have become increasingly common in X-ray and gamma-ray astrophysics due to their high resolving power and feasibility of fabricating thousands of pixels within a compact area. In the framework of my thesis, I have tested a 32-pixel microwave multiplexed TES detector array, a smaller version of the SLEDGEHAMMER (Spectrometer to Leverage Extensive Development of Gamma-ray TESs for Huge Arrays using Microwave Multiplexed Enabled Readout) gamma-ray detector developed by NIST to perform X-ray and gamma-ray observation on a balloon mission known as DR-TES. DR-TES is scheduled to be launched from Fort Sumner, New Mexico, in the fall of 2024. The detector has a total area of 1.50 x 0.7 cm^2, with a single pixel area of 0.15 x 0.15 cm^2. A portable miniature dilution refrigerator (mini-DR) developed by Chase Cryogenics will be used in the balloon flight to cool the detector to ~85 millikelvin with a cooling power of 1 uW at <100 mK. Our custom-designed cryostat will provide the mini-DR with a base temperature of 4 K with a 22 L liquid He bath. I contributed to the design of the experimental setup inside the cryostat and the readout electrics, the characterization of the TES gamma-ray detectors, and the estimating and calibrating of the performance and cooling power of the mini-DR in the flight cryostat for the DR-TES balloon flight. Low-temperature detectors show reduced thermal noise and the associated reduction in statistical fluctuations, which improves the signal-to-noise ratio. Furthermore, low-temperature material properties, such as the small heat capacity of the absorber pixels and the rapid change of the conductivity of a superconductor operated inside the normal to superconductor transition, can be used for "calorimetric" detectors. Technological breakthroughs now offer easier access to cryogenic temperatures. Dilution refrigerators achieving cryogenic temperatures can now be purchased off the shelves. In this thesis, I discuss the tests and results of a novel phonon-mediated distributed TES gamma-ray detector, which would be useful for astrophysical studies of phenomena such as magnetic reconnection in the solar corona, the warm-hot intergalactic and the intracluster medium of galaxy clusters. The detector uses large superconducting absorbers and TESs to read out the absorbed energy. Calorimetry is performed on individual photons, and the partitioning of the detector into many pixels can be used to obtain information about the location of the detected X-ray or gamma-ray. Equipped with thicker absorbers, the detectors can record 511 keV gamma-rays and decide between different possible hypotheses explaining their origin, either from dark matter or other astrophysical sources. I will also discuss the mini-DR's performance and a next-generation balloon mission. I will conclude with the results from the analysis of X-ray observations of the black hole binary Cygnus X-1 and present a new black hole spin estimate that accounts for recent polarimetric constraints about the inclination of the inner accretion disk.

Language

English (en)

Chair and Committee

Henric Krawczynski

Committee Members

Erik Henriksen; Fabian Kislat; Manel Errando; Ramanath Cowsik

Available for download on Friday, February 14, 2025

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