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The work presented in this thesis has focused on the development of a low dose Compton camera for nuclear medicine. A Compton camera composed of two high-purity planar germanium orthogonal-strip detectors has been constructed. Fast digital data acquisition has been utilised for the application of pulse shape analysis techniques. A simple back projection imaging code has been developed and validated with a Geant4 radiation transport simulation of the Compton camera configuration. L A 137CS isotropic source and a 22Na anisotropic source have been experimentally reconstructed. Parametric pulse shape analysis was applied to both data sets and has been shown to increase the detector spatial resolution from a raw granularity of 5x5x20mm to a spatial resolution that can be represented by a Gaussian distribution with a standard deviation of 1.5mm < u < 2mm in all dimensions; this result was in-part derived from Geant4 simulations. Qualitatively poor images have been shown to result - based wholly on simulation - from Gaussian spatial-resolution distributions that have a standard deviation of greater than 4mm. A partial experimental basis-data-set has been developed and proved capable of providing 1.9mm FWHM average spatial resolution through the depth axis of a single detector crystal. A novel technique to identify gamma ray scattering within single detector c1osed-face-pixels - hitherto unrecognised - has also been introduced in this thesis. This technique, henceforth known as Digital Compton Suppression (DieS), is based on spectral analysis and has demonstrated the ability of identifying events in which the Compton scattering and photoelectric absorption sites are separated by 13mm in the direction ofthe electric field. Supplied by The British Library - 'The world's knowledge'

The aim of this work was to produce an ion source with a high brightness and low energy spread. Two approaches were taken, an existing high brightness ion source (the liquid metal ion source) was monochromated to reduce its energy spread; this work was carried out at the University of York. The second approach was to develop a novel high brightness ion source with an intrinsically low energy spread. This approach was carried out at the University of Warwick. Several potential monochromators were simulated and the concentric hemispherical analyser was found to be the most suitable. Liquid metal ion sources were fabricated for monochromation by the author. However, these sources did not prove to be sufficiently stable for energy spread measurements and electron sources were used to try to demonstrate the principal. Ultimately this approach did not prove successful and the alternative ofdeveloping a novel source was pursued. This second approach utilises a novel emission process discovered at Warwick: surface enhanced field emission. Alkali metal vapours incident on a hot, chemically etched molybdenum wire are ionised at fields much lower than those normally required for field emission. Emission currents of several microamps have been obtained from the source and the sample current found to extremely stable with r.m.s noise of just 0.65%. The axial angular intensity of the source is 23 ~A sfl at 1 ~A emission. SIMS depth profiling has been carried out and the dynamic range at 1 keY was 3 orders of magnitude. Spot sizes of 20 ~m have been measured at 1 keY. The dynamic range and spot size do not represent the ultimate performance of the source, both are expected to improve in an ion column designed for a high brightness source.

Hydrogen bonding plays a key role in determining the molecular-level structure and dynamics of most organic systems. To fully understand this interaction and potentially exploit it for the design of new materials, the development and implementation of suitable analytical techniques is essential. The highly localised nature of solid-state NMR makes it a powerful probe of structure and dynamics. In particular, the IH chemical shift is a sensitive indicator of local environment, thereby providing a direct insight into hydrogen-bonding interactions. However, in comparison to other solid-state NMR techniques, IH solid-state NMR is very challenging due to the extensive spectral line broadening that results from strongly dipolar-coupled proton networks. Nevertheless, recent advances in solid-state NMR technology and methodology allow high-resolution IH NMR spectra to be obtained for these challenging systems. In this thesis, advanced solid-state NMR techniques and methodology are implemented in order to gain structural insight into a range of biologically and pharmaceutically relevant systems. A combined approach incorporating IH doublequantum (DQ) magic-angle spinning (MAS) NMR and single-crystal diffraction data is used to characterise supramolecular self-assembly in a group of novel nucleoside derivatives. High-resolution IH DQ combined rotation and multiple pulse spectroscopy (CRAMPS) NMR experiments are implemented to .provide a detailed insight into pseudo-polymorphic forms of an active pharmaceutical ingredient in a tablet formulation. This work constitutes a new tool for pseudo-polymorphic characterisation, with important implications for industry. The· concept of solid-state NMR crystallography is demonstrated for a challenging but biologically important disaccharide, for which a full IH resonance assignment is presented for the first time through a combined experimental and computational approach incorporating ab initio chemical shift calculations. This method is extended to the study ofthree polymorphs of paracetamol, where the hydrogen-bonding arrangement is characterised for a polymorph with an as-yet unsolved crystal structure. Additionally, experimental and numerically simulated results are presented for a low-load IH heteronuclear spin decoupling technique; this new approach shows good potential for use in MAS spin-echo experiments which can quantify hydrogen-bonding strength through the measurement of hydrogen-bond mediated J-couplings.