School of Physics - Theses

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End date: 2009 × Type: Masters Research thesis ×

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    On the one-dimensional bose gas
    Makin, Melissa I. ( 2007-02)
    The main work of this thesis involves the calculation, using the Bethe ansatz, of two of the signature quantities of the one-dimensional delta-function Bose gas. These are the density matrix and concomitantly its Fourier transform the occupation numbers, and the correlation function and concomitantly its Fourier transform the structure factor. The coefficient of the delta-function is called the coupling constant; these quantities are calculated in the finite-coupling regime, both expansions around zero coupling and infinite coupling are considered. Further to this, the density matrix in the infinite coupling limit, and its first order correction, is recast into Toeplitz determinant form. From this the occupation numbers are calculated up to 36 particles for the ground state and up to 26 particles for the first and second excited states. This data is used to fit the coefficients of an ansatz for the occupation numbers. The correlation function in the infinite coupling limit, and its first order correction, is recast into a form which is easy to calculate for any N, and is determined explicitly in the thermodynamic limit.
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    Characterisation of Optical Fibres Based on High Resolution Imaging
    Pace, Mr Peter ( 2004-12)
    This thesis presents a method for accurate characterisation of optical fibres using highspatial resolution imaging. Increasing demands in the application of optical fibres hasproduced a rapid advance in fibre fabrication and optical fibres are being createdexhibiting features that are beyond the optical resolution of current characterisationtechniques.High resolution imaging of optical fibres was performed using an atomic forcemicroscope (AFM). Germanium doped fibres were chemically etched in hydrofluoricacid solution (HF) and the wet etching characteristics of germanium were studied. Amethod of calculating the refractive index profile from an AFM depth profile isdemonstrated. The refractive index profile extracted from AFM data was compared withQuantitative Phase Microscopy (QPM) and nanometer Secondary Ion MassSpectrometry (nanoSIMS) measurement techniques.In addition, AFM was employed to study the diffusion of the dopant produced by thearc fusion splicing technique using a fluorine-doped fibre and a multiple-dopant fibre.Furthermore, the phase and the refractive index profiles of a thermally expanded core(TEC) fibre were performed using quantitative phase microscopy (QPM).The application of the AFM to the resolution problem provides a fundamentalenhancement on the optical resolution from of around 400 nm to 500 nm. This providesconsiderable new structural information about the fibre.
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    Cosmic ray measurement
    Norman, R. J. ( 1950)
    The following report embraces the work carried out by the author in the Physics Department of the University of Melbourne, from January 1948 to February 1950. It is divided into five sections: Section A. Theory and Design of Ionization Chambers. B. Continuous Recorder. C. Extensive Shower Apparatus. D. Polar Continuous Recording Rack. E. Design & Construction of the Electrodynamic Electrometer. The records and apparatus described in Section B , together with the first electrodynamic electrometer, were a total loss in the hut fire. The original version of the extensive shower apparatus, the project of J.R. Prescott, was also destroyed, ant the author assisted in its modification and rebuilding. (From Introduction)
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    The energy levels in atoms
    Webster, Hugh C. ( 1928)