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Quantitative Raman spectroscopy of gases related to KATRIN. / Timothy M James

Swansea University Author: Timothy M James

Abstract

"The overall aim of this thesis was to improve the laser Raman system of the Karlsruhe Tritium Neutrino (KATRIN) experiment and enable the extracted Raman intensity data to be quantified. This was achieved by improving the signal-to-noise ratio of the system and accurately measuring the depolar...

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Published: 2013
Institution: Swansea University
Degree level: Doctoral
Degree name: Ph.D
URI: https://cronfa.swan.ac.uk/Record/cronfa42680
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Abstract: "The overall aim of this thesis was to improve the laser Raman system of the Karlsruhe Tritium Neutrino (KATRIN) experiment and enable the extracted Raman intensity data to be quantified. This was achieved by improving the signal-to-noise ratio of the system and accurately measuring the depolarisation ratios of all six hydrogen isotopologues. This measurement was required to verify whether the polarisability tensors, a and gamma, found in the literature can be inserted into the Raman intensity to produce a theoretical intensity curve, which is needed to extract compositions from the measured Raman intensity with a known accuracy. A procedure has been developed to accurately measure the depolarisation ratio of all six hydrogen isotopologues and the depolarisation ratios of the Q1-branch agree with the theoretical values, calculated by LeRoy, with a 1 confidence level. This procedure has also been applied to some of the atmospheric gases. In addition, a Raman system beyond the scope of the KATRIN experiment has been developed, to increase the signal-to-noise ratio of the system further. The selected setup makes use of a hollow metal-coated glass fibre as the Raman cell and is referred to as "capillary Raman spectroscopy". The initial test measurements have shown that capillary Raman spectroscopy produces Raman signals that are a factor of 170 higher than single-pass 90° Raman spectroscopy. Due to increased fluorescence, as a result of the observation of Raman light in the same direction as the laser excitation, the increase in the signal-to-noise ratio is between a factor of 9 and 24. As a result of these successful measurements the capillary Raman system will be tested with tritium in the near future."
Keywords: Applied physics.;Optics.
College: Faculty of Science and Engineering

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