Murphy, James (2022) Optical Modelling and Instrument Calibration for QUBIC, the Q & U Bolometric Interferometer for Cosmology. PhD thesis, National University of Ireland Maynooth.

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Abstract

The current generation of cosmology experiments aims to detect the B-mode po- larisation of the cosmic microwave background. The B-modes are experimental proof for the Inflation theory of the early Universe. This thesis contributes to the development, integration, and deployment of one of those experiments, QUBIC. A detailed Physical Optics model of a technical demonstrator optical combiner was developed using the software package GRASP. This model included measured mir- ror surfaces and rims as well as the internal sources used for the inter-calibration of the detectors. The data produced by these models were used for validation and calibration of the instrument in the laboratory in Astroparticule et Cosmologie in Paris. The models were then expanded to encompass the full QUBIC instrument that will later be deployed in Argentina. A contribution was made to the bespoke QUBIC data analysis software and a project milestone was reached when the first multi-frequency synthesised beam maps were produced in July 2020, thereby demonstrating QUBIC’s spectro-imaging capability. Zemax ray-tracing was used to investigate possible optical causes for artefacts that were found in early beam maps. A study of the likely characteristics of the artefacts generated by opti- cal reflections and electronic cross-talk was produced for future reference. Lastly, the application to QUBIC of redundant baseline self-calibration was investigated. Originally developed for radio astronomy, aberrations due to the instrument’s off-axis optics have implications for QUBIC’s implementation of this calibration technique. At the time of writing, QUBIC has been tested and is being assembled and commissioned in Salta, Argentina, ready to begin observing in the coming months.

Item Type:	Thesis (PhD)
Keywords:	Optical Modelling; Instrument Calibration; QUBIC; Q & U Bolometric Interferometer; Cosmology;
Academic Unit:	Faculty of Science and Engineering > Experimental Physics
Item ID:	16544
Depositing User:	IR eTheses
Date Deposited:	20 Sep 2022 13:34
URI:
Use Licence:	This item is available under a Creative Commons Attribution Non Commercial Share Alike Licence (CC BY-NC-SA). Details of this licence are available here

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