The Interacting Resonant Level Model (IRLM) is studied by making use of different standard techniques common to the study strongly correlated quantum systems. Exact results are computed both analytically and numerically, in order to obtain a full consistent theory of the model in equilibrium thermodynamics, opening the path towards a future treatment of the model.

The constant bombardment of millimeter and submillimeter interplanetary dust and orbital debris particles on spacecraft and other space assets leads to long term degradation of exposed surfaces and systems. In the past, post-flight surface analysis on the Space Shuttle provided regular data on these small particles in low Earth orbit. The accumulation of data provided by the characterisation of these particles is required for the development, and updating, of orbital debris environment models, which are essential to predict the conditions in space that can significantly a↵ect the design, operation and cost of spacecraft. Since the retirement of the Space Shuttle program in 2011, there has been very little new data generated. Consequently, there is now an increasing need for additional information on the characteristics of interplanetary dust and orbital debris for both commercial and research purposes. Dedicated dust detectors, rather than post-flight data collection from collision damage, have successfully demonstrated the potential for characterising particles in the past, and provide the most likely method of analysis going forward. However, current versions have a number of limitations and there is an opportunity to make significant advancements in the next generation of detectors. Designing, testing and analyzing improved detector systems was the primary focus of this research. Interplanetary dust and orbital debris properties of specific interest include; flux, size, velocity, trajectory, kinetic energy, density and mass. Although previously flown detectors are capable of measuring a number of these parameters, no previous detector has integrated the capacity to measure all of them simultaneously. This thesis describes concepts for a detector capable of collecting, processing and transmitting back the data for all of the parameters listed above and in real time, which is a significant advancement on current state-of-the-art detectors. Prototypes were designed incorporating selected adaptations of previous detectors, utilising the basic principle of sequential detection gates. Proof-of-concept experiments were conducted on the prototypes using the light gas gun at the University of Kent in order to replicate orbital impacts with simulated space particles in the laboratory. Algorithms written in Python were developed for the five subsystems to analyse data collected by PVDF sensors on each of the three detection gates, and to directly calcu- late the flux, velocity, trajectory, diameter and kinetic energy of particles interacting with the prototypes. In turn, these results were used to derive mass and density. The characteristics of particles calculated by the subsystems during the experiments were compared with their known properties in order to quantify the accuracy of each mea- surement. The velocity, trajectory and diameter calculations had an average confidence within 6.5%, 0.5% and 10.0%, respectively. Measurement of the kinetic energy was accurate to ⇠26.0 %, which is regarded as a significant step forward. Additionally, the experiments provided evidence that flux models can be accurately measured for par- ticles larger than 50μm. The prototypes designed and validated in this research can be used as templates for future detectors capable of providing real-time data on the characteristics of interplanetary dust and orbital debris. These data will contribute directly to the design of future instrumentation and assist the development of more detailed environment models with both commercial and research applications.

Over recent years, in the field of nuclear medicine, advances in the development of small field of view (SFOV) gamma cameras have been increased. High resolution compact gamma cameras are designed to be used in intraoperative medical imaging procedures such as in head and neck sentinel node biopsies or for small organ imaging such as thyroid investigations. SFOV imaging can offer advantages over large field of view (LFOV) cameras in spatial resolution and sensitivity although, there is a trade-off between spatial resolution and sensitivity. Also SFOV cameras are highly favourable in terms of reduced size and weight in comparison to the standard gamma camera. Over the last two decades, advances in semiconductor detector technology have now reached the point where they are sufficiently sensitive to be the basis of SFOV cameras for nuclear medicine imaging systems. A new concept for a medical imaging system is presented, the Hybrid Gamma Camera (HGC). The performance characteristics of the HGC are evaluated following modified quality assurance protocols. The Cadmium-Telluride (CdTe) XRI-UNO and the HEXITEC semiconductor (CdTe) detector are also investigated. Their performance is compared to that of the scintillator-based Hybrid Gamma Camera (HGC). A novel dual gamma near infrared (NIR) fluorescence camera has been developed and is described. Preliminary in vivo and in vitro studies were undertaken to demonstrate the suitability of the system for fluorescent imaging. This dual modality gamma-NIR system has been proposed as one possibility for improving surgical utility.

Small field of view (SFOV) gamma detection and imaging technologies for monitoring in vivo tracer uptake are rapidly expanding and being introduced for bed-side imaging and image guided surgical procedures. The Hybrid Gamma Camera (HGC) has been developed, at the University of Leicester, to enhance the localisation of targeted radiopharmaceuticals during surgical procedures, for example in sentinel lymph node (SLN) biopsies, and for bed-side imaging in small organ gamma imaging procedures such as lacrimal scintigraphy and thyroid scintigraphy. In this thesis, prototype medical phantoms including anthropomorphic three-dimensional printed phantoms have been designed, constructed, and evaluated using representative modelled medical scenarios to study the capability of the HGC to detect SLNs and image small organs. Furthermore, the results of the first clinical feasibility study of the HGC has been discussed. The HGC was used to perform non-invasive hybrid gamma-optical imaging procedures on patients attending their routine scint32igraphic imaging appointments in a nuclear medicine clinic. Various quantitative and qualitative assessments have been conducted on different phantom configurations including simulating targeted tissues at several depths and using different radioactivity concentrations. Two generations of the HGC have been utilised, having two different thicknesses of columnar CsI(Tl) scintillator, and two pinhole collimator diameters (0.5 mm and 1.0 mm). Additionally, the behaviour of the HGC at a range of imaging distances and acquisition times has been examined. All of these factors were considered to judge the detection limitations of the HGC. The results demonstrate that the HGC was ideally suited for small organ imaging. The HGC capability to detect low activity uptake in small SLNs indicates its usefulness as an intraoperative imaging system during surgical SLN procedures. The ability of the HGC to utilise both pinhole collimators enhances its practicality and improves its ability to meet the needs of SFOV gamma imaging.

The European Space Agency’s (ESA’s) 241Am radioisotope power systems (RPSs) research and development programme is ongoing. The chemical form of the americium oxide ‘fuel’ has yet to be decided. The fuel powder will need to be sintered. The size and shape of the oxide powder particles are expected to influence sintering. The current chemical flow-sheet creates lath-shaped AmO2. Investigations with surrogates help to minimise the work with radioactive americium. This study has proposed that certain cubic Ce1-xNdxO2-(x/2) oxides (Ia-3 crystal structures with 0.5 < x < 0.7) could be potential surrogates for some cubic AmO2-(x/2) phases. A new wet-chemical-synthesis-based process for fabricating Ce1-xNdxO2-(x/2) with a targeted x-values has been demonstrated. It uses a continuous oxalate coprecipitation and calcination route. An x of 0.6 was nominally targeted. Powder X-ray diffraction (PXRD) and Raman spectroscopy confirmed its Ia-3 structure. An increase in precipitation temperature (25 °C to 60 °C) caused an increase in oxalate particle median size. Lath/plate-shaped particles were precipitated. Ce Nd oxide PXRD data was Rietveld refined to precisely determine its lattice parameter. The data will be essential for future sintering trials with the oxide where variations in its crystal structure during sintering will be investigated. Sintering investigations with micrometric CeO2 and Nd2O3 have been conducted to understand how AmO2 and Am2O3 may sinter. This is the first reported pure Nd2O3 spark plasma sintering (SPS) investigation. A comparative study on the SPS and the cold-press-and-sinter of CeO2 has been conducted. This is the first study to report sintering lath-shaped CeO2 particles. Differences in their sizes and specific surface areas affected powder cold-pressing and caused variations in cold-pressed-and-sintered CeO2 relative density and Vickers hardness. The targeted density range (85-90%) was met using both sintering techniques. The cold-press-and-sinter method created intact CeO2 discs with reproducible geometry and superior Vickers hardness to those made by SPS.

Two now X-ray curved crystal vacuum spectrometers are described. With the first of these the LX1,2 lines of Lanthnaum were remeasured, and with the second a study of the Mx,b emissons and the absorptions in the expected region of the and Miv and MV edges was undertaken, in addition the and Miv and Mv edges of Barium were remeasured. The Miv and Mv edges for the rare earth are not found and the absorption detected is of a line character and of the same Wavelength as the emission lines Mx and My. A discrepancy between previous measurements loading to the energy difference between the Miv and Mv levels of Lanthanum has been resolved. Assuggestion is made to account in part for the apparent absence of the normal absorption edges. As a direct result of the investigation of the Lanthanum emission and absorptions, it has been possible to give an explanation which accounts for the presence of the Mx and My lines in Lanthanum and also for the reciprocal nature of the absorption and emission processes, processes. Also described in a section dealing with ancillary equipment are a tapo-coupled, variable ratio micro-densitometer of new design, and an optical micrometer for the measurement of the microdensitometer traces.

An X-ray curved crystal vacuum spectrograph was made available for the investigation. This and the constructional alterations to the X-ray tube are described. The 'thin' and 'thick' target M emission spectra f and the Miv, v absorption spectra of the elements Europium, Gadolinium and Terbium (in the form of the oxide) have been photographed. Attempts to record the M i, ii, iii absorption edges of Gadolinium and Terbium are also described. The Miv, v absorption spectra of Europium and Terbium (in the form of the fluoride) and Samarium, Gadolinium, Terbium and Ytterbium (in the form of the metals) have been photographed. The observed duality of the Miv, v absorption spectrum of Europium has been explained. Prom the results obtained in the present investigation, it has been possible to complete observations on the M spectra of the rare earth elements. The correspondence between the spectral components of the M emission and absorption spectra has been demonstrated for the middle elements of the series though there are indications that additional transitions are taking place in the emission spectra. It has also been possible to establish the extent to which the Miv, v absorption spectra of these elements is due to transitions into the incomplete 4f shells. Finally, the wavelengths of the spectral components of the M emission and absorption spectra of the middle rare earth elements are quoted and their significance discussed.

No description available.

In Part I of this work the properties of H-, He, Li+ and Be++ calculated using a large series of wavefunctions are examined. Values Comparisons of the results obtained from explicitly correlated (EC) and configuration interaction (CI) wavefunctions with those obtained from independent particle functions enable us to discuss the correlation effects arising from specific terms within an EC wavefunction and from changes in the orbital basis set of a CI function. The relative performance of EC and CI wavefunctions with respect to one- and two-electron properties is also examined. In Part II electron correlation effects in the scattering of electrons, protons and hydrogen-like atoms from He and Li+ are examined. Both elastic scattering and the l'S → n'P (n = 2,3) excitation reactions axe considered. The first Born approximation is used throughout. Generalized oscillator strengths, total cross sections and atomic form factors are presented; all calculations were performed using both the "length" and "velocity" formulae for the scattering amplitude. The natural expansion of a 35-configuration CI wavefunction, truncated to include only the first X terms, was used for the ground state wavefunction of the target atom. For X = 1 this wavefunction closely resembles the Hartree Fock function. The influence of a systematic introduction of correlation is examined by taking X = 1, 2, 3 ... etc. In addition, results calculated from the complete CI function are compared with others obtained from an EC function of comparable energy. In Part III there is a change of emphasis. Here we investigate the usefulness of certain novel 'cusp orbitals' in one-centre calculations on molecules. Several calculations applied to the H2+ molecule as a test system are described.

A review of the chemistry of phospholene oxides is presented. The synthesis of 2,3-epoxyphospholane oxides is described, and the reactions of these compounds with Lewis acids were investigated. Four different attempts at forming the episulphide of 3-methyl-1- -phenyl-2-phospholene-l-oxide are reported, all of which were unsuccessful. The stereospecific synthesis of 3,4-epoxyphospholane oxides is discussed in terms of a directive effect from the phosphoryl group. The rearrangement of these epoxides with boron trifluoride etherate, to give vinyl ethers and phospholan-3-ones, was studied. Following a discussion of the alkaline hydrolysis of phosphonium salts, the hydrolyses of 1-methyl-1-phenyl-2- and 3-phospholenium iodides are described. The hydrolyses of 1-iodomethyl- phospholenium iodides were also investigated and found to proceed, in the majority of cases studied, to give ring-opened products and the phospholene oxide. Only with 1-iodomethyl-l,2-diphenyl-2-phospholenium iodide, where the incipient carbanion is relatively more stable, was ring expansion found to occur. Ring expansion of phospholenes was achieved using ethyl propiolate and dimethyl acetylenedicarboxylate. The hydrolysis of the products formed from phospholenes and acyl and aroyl chlorides is discussed in terms of nucleophilic attack either at phosphorus or at the carbonyl group, the former being favoured when substituted benzoyl chlorides are used (giving aldehydes), but the latter being favoured in the case of acyl chlorides to produce phospholenes and carboxylic acids. Ring expansion was found to occur when the product from benzoyl chloride and 1,2-diphenyl-2-phospholene was hydrolysed. Attempts to synthesise an epoxide of a cyclic unsaturated phosphonate are described. The breakdown in the mass spectrometer of 3,5,5-trimethyl-l,2-oxaphosphol-2-ene derivatives to give a metaphosphate analogue is discussed, and possible syntheses of the neutral compound are suggested. The hydrolyses of the methyl and phenyl esters derived from the 3,5,5-trimethyl-1,2-oxaphospholane system were studied. In all cases the ring-retained product with loss of the exocyclic ester group was isolated in greater than 60% yield. The mechanistic possibilities of this reaction are discussed. A short account of the synthesis of possible anti-inflammatory agents based on the acenaphthene system is presented in an appendix.