A model-independent measurement of the charm mixing parameters xD and yD in the D0 -> KSπ+π− decay mode is presented. The method uses ratios of yields in symmetric bins of the Dalitz plot and is binned in decay time. This is an alternative approach that does not require the knowledge of the phase-space model of the decay. It also preserves good sensitivity to xD and to the relative sign between xD and yD. Charm mixing parameters are an important step to measuring CP violation in charm mixing. The measured values of the mixing parameters are xD = (1.89±0.43±0.21±0.51)% and yD = (−2.59±1.36±1.13±3.12)% where the uncertainties are statistical, systematic, and due to input parameters respectively.

The research presented in this thesis focuses on the relatively young field of direct electron cooling via semiconductor-superconductor tunnel junctions. These devices utilise the superconducting energy gap to form a high pass electron filter, capable of lowering the effective electron temperature in the semiconductor electrode. The presented research focuses on optimizing the performance of such junctions i.e. the minimum achieved electron temperature, primarily by modifying the electrical properties of the semiconductor/superconductor and influencing the quality of the semiconductor-superconductor interface. In the semiconducting electrode, the effect of carrier type on the thermal coupling of the system is studied, as is the effect of mechanical strain, induced via lattice mismatch. A study is made of alternative superconductors, modifying their properties through the use of thin films for the superconducting contact. Finally, a comprehensive investigation is presented into the importance of fabrication procedures on device characteristics, leading to the development of the first semiconductor-insulator-superconductor junction.

This thesis reports research on the characterisation of the structure of point defects in chemical vapour deposition (CVD) diamond. Electron paramagnetic resonance (EPR) has been used as a tool to determine the constituent nuclei and symmetry of previously unreported EPR active defects. Optical spectroscopy has been employed to track defect concentrations and correlate optical features with EPR active defects. Multi-frequency EPR has been used to identify and characterise a previously unreported EPR signal arising from N2VH0: a vacancy bounded by two substitutional nitrogen atoms and two carbon atoms wherein a hydrogen is bonded along one of the two carbon atoms and the unpaired electron of the system is bonded along the second carbon. This defect exhibits C2v symmetry in both X- and Q-band EPR, suggesting that the hydrogen rapidly reorientates between the two equivalent carbon atoms resulting in a time averaged C2v symmetry. The effects of annealing CVD diamond have been investigated. It has been shown that N2VH0 is produced consistently upon annealing at 1800 °C and continues to increase in intensity up to 2200 °C. The charge transfer behaviour of the N2VH0 defect is reported and the local vibrational mode (LVM) doublet at 1375 and 1378 cm-1 has been correlated with the intensity of the N2VH0 EPR signal. A calibration coefficient for the concentration of N3VH0 as calculated from the integrated intensity of the 3107 cm-1 LVM is proposed and a nitrogen assay of six samples in the as-grown and post-treated states suggest that this is a reasonable estimate. The annealing behaviour of theWAR5 EPR centre has been investigated and found to match density functional theory (DFT) predictions for the binding energy of the OsV defect. It has been reported that the WAR5 signal can be increased in intensity upon the irradiation and annealing at 800 °C of CVD diamond grown from a C:H:O chemistry, further supporting the assignment of this signal to the OV0 defect. A new EPR signal is reported and characterised as arising from a substitutional oxygen adjacent to a vacancy wherein a hydrogen atom rapidly reorientates between the three available carbon dangling bonds (OsVH0). The effect of irradiation and annealing on as-grown and pre-annealed CVD diamond has been investigated. It is shown that the 3324 cm-1 LVM (arising from the Ns:H-C0 defect) can be introduced into CVD diamond upon irradiation and further increased in intensity by annealing at 600 °C. The increase in 3324 cm-1 intensity has been correlated with a loss of NVH allowing a calibration correlation for this centre to be determined. Further, the reintroduction of the VnH- defect has been reported in a diamond sample which has been annealed prior to additional irradiation and annealing treatments.

In the past decade the field of extra-solar planetary science has moved beyond simple detections of planets outside of our Solar System into more detailed characterisations of these objects. One avenue that is at the forefront of current research is the study of extra-solar planet atmospheres. This work has focused on a subset of the current exoplanet population: transiting hot Jupiters. The large sizes, high temperatures and bright stellar hosts of these planets make them particularly amenable to atmospheric studies through techniques such as secondary eclipse observations, which can sample the planetary thermal and reflected light. Atmospheric detections have now been made for over 50 extra-solar planets. With such a population, we can begin to look for trends in the atmospheric properties of these planets, in order to shed more light on the physical processes that affect their atmospheres. It is in this context that I present the work in this thesis, which comprises secondary eclipse observations of five transiting hot Jupiter exoplanets. Secondary eclipses of WASP-3b were observed using the Spitzer Space Telescope, giving estimates of the planets thermally emitted flux at 3.6 μm, 4.5 μm and 8.0 μm. These estimates imply the planet is very hot (Teff = 2280+200−150 K) and that it may host an inverted vertical temperature profile. This system probes a cut-off in a proposed correlation between the vertical temperature structures of hot Jupiters and the chromospheric activity of their host stars. I find that my measurements for WASP-3b imply this cut-off is more complex than initial data has suggested. Secondary eclipses of the planets WASP-21b, WASP-28b and WASP-37b, all with low metallicity host stars, were also observed with the Spitzer Space Telescope, at 3.6 μm and 4.5 μm. These systems were studied to explore potential correlations between planetary spectral properties and host star metallicities. In existing data, a hint of a trend between the vertical temperature structures of planets and the metallicities of their host stars is found. However this trend is not supported by the planetary flux estimates derived for the three systems I have studied. Ground-based optical and near infra-red secondary eclipses were also observed for WASP-33b, using the ULTRACAM instrument on the William Herschel Telescope. The emission of WASP-33b, detected in the z’ band, confirms that the planet is extremely hot (Tz = 3170+90−190 K) and supports a trend found for highly irradiated planets to have systematically low albedos and poor heat redistribution properties.

The T2K (Tokai-to-Kamioka) experiment is a long baseline neutrino oscillation experiment built, primarily, to measure the neutrino mixing angle 13. To determine this parameter with minimal uncertainty requires a good understanding of the initial neutrino flux in the beam and precise measurements of neutrino interactions with matter. For this reason, T2K employs a near detector placed 280m downstream of the neutrino production point, the ND280. Using data taken by the ND280 between November 2010 and April 2013 (5:73x1020 protons on target), a flux-integrated muon antineutrino charged-current inclusive cross-section measurement per nucleon using the carbon target of the ND280 FGD1 is reported, including a description of the event selection and the systematic uncertainty evaluation. The final result is: [Result unable to be displayed] at a mean muon antineutrino energy of 1 GeV. The uncertainty on this measurement is dominated by neutrino flux uncertainties. A possible method of improving the precision with which the flux is known is presented, which indicates that at the end of the expected T2K data-taking period, this uncertainty can be reduced from 12:4% to 5:8%.

Segregation to crystalline interfaces has been considered in terms of its effect on the thermodynamic interfacial energies. The experimental evidence for segregation was reviewed and its effects on interfacial energies and mechanical properties discussed with particular reference to boron in iron and steels. The effects of boron concentration on the surface and grain boundary energies of iron and AISI.316 stainless steel were measured, Grain boundary to surface energy ratios were measured from the dihedral angles at the grooves (and ridges) formed during vacuum annealing where these boundaries intersect the surface. The effect of boron on the absolute grain boundary and surface energies was obtained by the assumption that twin boundary energy is independent of boron concentration. Measurements were made on 316 steels containing 0.001 and "'0.006 wt% boron at 950° to 1250° C, and on iron alloys containing up to 0.020 wt% boron at 950° and 1050°C. Reductions of up to ,30% in the surface energies and 40% in the grain I, boundary energies were found on increasing the boron concentration to 0.004-0.008 wt%. The results were interpreted in terms of segregation of boron~ the surfaces and grain boundaries and compared with literature data for other systems including nickel-boron alloys. The relevance of interfacial energy measurements to the effects of boron on mechanical properties was considered.

This thesis presents the work carried out on two types of nano-particle materials with the purpose of investigating their lithium ion storage properties. Several different types of morphologies of tin disul�de were grown hydrothermally, including several known and two novel morphologies. These have been extensively characterised using both electron microscopy and computational simulation, which led to a good understanding of the topology of the particles. In a further step, these were tested electrochemically in lithium ion test cells to elucidate their lithium ion storage properties. While it was possible to reversibly store a significant amount of lithium, the cells unfortunately could not yet compete with other available lithium ion cells. In addition, a hybrid material composed of lithium niobate and lithiated niobium sulfide was also investigated. For this, a lithium niobate precursor was created using either a hydrothermal synthesis or commercially available material. The synthesis route was shown to be able to produce lithium niobate, but unfortunately still contained other niobium oxide contaminants. Both were sul�dised using a novel approach and shown to exhibit layered shell growth as would be expected for lithiated niobium sulfide. Initial test cells were constructed and tested, but solid electrochemical results could not be gathered before the end of the project.

Energetic ion dynamics play an important role in magnetic confinement fusion (MCF) plasmas, as well as in the solar wind. In the former case, energetic ions such as neutral beam injection (NBI) ions and fusion-born alpha-particles, can interact with global modes in tokamak plasmas leading to instabilities that might result in loss of confinement and energy. In the latter case, ion dynamics must be taken into account in order to explain in situ and remote observations of heating of the solar wind, which show the occurrence of anisotropic heating of ions, as well as magnetohydrodynamics turbulence and intermittency all at the same time. In this thesis we address two scenarios in plasma physics where ion dynamics play a key role modifying the mass and energy transport in the plasma, specifically, ion cyclotron emission (ICE) in MCF plasmas, and preferential ion heating due to intermittent magnetic fields in the solar wind. ICE results from a radiative instability, probably the magnetoacoustic cyclotron instability (MCI), driven by energetic ions in MCF plasmas. Understanding the underlying physics of ICE is important for the exploitation of ICE as a non-perturbative diagnostic for confined and lost alpha-particles in deuterium-tritium (D-T) plasmas in future thermonuclear fusion reactors [McClements et al., Nucl. Fusion, 55, 043013 (2015); Dendy and McClements, Plasma Phys. Controlled Fusion, 57, 044002 (2015)]. On the other hand, preferential ion heating in the solar wind, observed as the occurrence of an ion beam which drifts along the background magnetic field with a velocity close to the local Alfven speed, is still an open problem. Despite the large amount of studies conducted in this issue, none of them included intermittency self-consistently. Therefore, the relationships between preferential ion heating and intermittency have remained unknown, until now. We study in detail the previously mentioned scenarios through numerical simulations using the hybrid approximation for the plasma, which treat ions as kinetic particles and electrons as a neutralizing massless fluid. Our hybrid simulations of the MCI confirm predictions of the analytical theory of the MCI, and recover some features of ICE as observed in D-T plasmas in JET. Furthermore, by going deep into the nonlinear stage of the MCI, we recover additional features of ICE which are not predicted by the linear theory of the MCI but are present in the measured ICE signal, resulting in a good match between our simulation results and the measured ICE intensity in JET. On the other hand, we present the first study of preferential ion heating in the fast solar wind including intermittent electromagnetic fields in a self-consistent way. We find that the temporal and spatial dynamics of the mechanisms driving preferential ion heating in our simulations (gyrobunching and ion trapping by the electric field), the ion temperature anisotropy T=T (perpendicular temperature/parallel temperature), and the degree of correlation between velocity and magnetic field fluctuations, show strong dependence on the level of intermittency in the electromagnetic fields.

T2K is a long-baseline neutrino oscillation experiment based in Japan. The experiment has already measured the appearance of ⌫e in a ⌫μ beam, and is hoping to measure the appearance of ⌫¯e in a ⌫¯μ beam, which would open the possibility of observing CP-violation in the lepton sector. The charged current quasi-elastic (CCQE) interaction (vμ + n -> μ− + p) is of great importance to T2K as it is expected to make up over 80% of the interactions at the oscillation peak (600 MeV). In recent years it has become clear that the most common model describing CCQE interactions on nuclei, the Relativistic Fermi Gas (RFG) model, is not able to describe low energy data on nuclear targets. An alternative model, the Spectral Function (SF) model, was implemented in the NEUT interaction generator. Relevant uncertainties in this model are identified and evaluated. The charged current quasi-elastic-like cross section is then measured using the T2K near detector, ND280, as a function of muon momentum and angle. This data is then critically compared to the predictions from two implementations of the RFG model, and also to the newly implemented SF model. The total integrated cross section is found to be (4.06 ± 0.757) x 10−39 cm2 nucleon−1. This value is currently in agreement with all three predictions.

Studies of charmless three-body decays of either B0(s) mesons or beauty baryons with a K0 meson in the final state are presented in this thesis. The analyses are performed using the 2011 and 2012 LHCb dataset, corresponding to an integrated luminosity of 1.0 fb−1 and 2.0 fb−1 recorded at a centre-of-mass energy of 7 TeV and 8 TeV, respectively. The decays B0s->K 0K±⇡⌥ and B0s -> K0⇡+⇡− are observed for the first time, and the decay mode B0 -> K 0K±⇡⌥, previously observed by the BaBar experiment, is confirmed. Moreover, the ⇤0b -> K0p⇡− channel is also observed for the first time and its phase-space integrated CP asymmetry measured, which shows no significant deviation from zero. No significant signals are seen for ⇤0b -> K0pK− decays, ⌅0 b decays to both the K0 S p⇡− and K0 SpK− final states, and the ⇤0b ! D−s (K0 SK−)p decay, and upper limits on their branching fractions are reported. Finally, the first untagged decay-time-integrated amplitude analysis of B0s -> K0 SK±⇡⌥ decays has been performed. All branching fraction results obtained from this analysis are either the most precise to date or are first measurements.