Development of Technologies for the Atacama Cosmology Telescope and Next Generation Cosmic Microwave Background Instruments

Jonathan Ward, University of Pennsylvania


A primary goal of modern cosmology is to obtain cosmological information and parameters from high-sensitivity measurements of the temperature and polarization of the Cosmic Microwave Background (CMB) radiation. These measurements will allow cosmologists to probe the many predictions made by the inflationary model of the Universe. To continue expanding the limits of CMB science, experimentalists need to develop novel technologies that will continue to improve our ability to observe the microwave sky. Paired with state of the art data analysis techniques, our understanding of the Universe will continue to grow now and for decades to come. The Atacama Cosmology Telescope (ACT) is a 6-meter diameter telescope located in the Andes Mountains of Northern Chile. Deployment of the Advanced ACTPol (AdvACT) receiver has vastly improved the capabilities of ACT. Next-generation detector arrays operating at 20, 40, 90, 150, and 240 GHz will provide the frequency coverage and detector count necessary to improve measurements of a wide range of cosmological parameters. Continuously rotating half-wave plates (HWPs) modulate the incoming polarized signal, resulting in a drastic suppression of the atmospheric 1/f noise that contaminates the ACT data at large angular scales. Finally, hardware and software upgrades to previous-generation ACTPol infrastructure have further improved the AdvACT instrument on the fronts of cryogenic performance, housekeeping data acquisition, assembly procedure, and site reliability. The design and deployment of AdvACT instrumentation is discussed in detail from Chapters 2-4, highlighting the key design changes and improvements over the ACTPol experiment. In addition to the instrumentation advances discussed above, data analysis and numerical modeling techniques provide the framework needed to extract the most information from the data gathered by the AdvACT experiment. Key efforts focused towards processing HWP data allows ACT to probe the inflationary gravitational wave signal that may lie in the low-frequency regime of the ACT data. Furthermore, simulations help predict the effects of various systematics on the raw data give a better understanding of what calibration strategies are needed to mitigate systematic effects. The software developed to accomplish these tasks is discussed in Chapters 5-6, along with the results obtained from the data when the code is implemented in the analysis pipeline. The technologies, instrumentation, and analysis techniques outlined in this paper and employed by the AdvACT experiment will continue to push ACT to the forefront of experimental cosmology research while also providing a template for future experimental efforts.

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Recommended Citation

Ward, Jonathan, "Development of Technologies for the Atacama Cosmology Telescope and Next Generation Cosmic Microwave Background Instruments" (2018). Dissertations available from ProQuest. AAI10827743.