The (S)ilicon (A)nd (Ge)rmanium (sage) spectrometer has been employed, together with the ritu gas-filled separator and the great focal plane spectrometer with Total Data Readout (TDR) at the University of Jyv¨askyl¨a to analyse the heavy actinide nucleus 253No (Z=102). Initially, the neutron-deficient odd-A isotope 177Au (Z=79) is studied using the recoil-decay tagging technique, enabling testing and demonstration of γ ray and conversion electron coincidence analysis techniques using sage. This has allowed for conversion coefficient measurements on a number of low-lying states. The main focus of the study is on 253No with combined in-beam γ ray and electron spectroscopy through the recoil-tagging technique. Orbitals emanating from the next shell closure above 208Pb are sensitive to measurement in the deformed heavy midshell region. Thus probing the single-particle structure of regional midshell heavy nuclei allows for exploration of the island of enhanced stability toward the next closed nucleon shells. Using 253No data from sage has enabled γ-electron coincidences to be established for level scheme construction with transition energies determined. Recoil-tagged prompt γ ray and internal conversion electron spectra are compared to Monte Carlo simulations to confirm the rotational structure nature of the bands. Internal conversion coefficient measurements establish the multipolarity of transitions within the bands. Measurement of the B(M1+E2’)/B(E2) interband-intraband ratio confirms the assignment of the bandhead configuration, with results presented strongly supporting the 9/2−[734]ν observed in previous studies. An isomeric state is measured with T1/2=28.6±2.3 µs confirmed through a decay via a 167 keV M2 transition resulting from the 5/2+[622]ν configuration. A 608±20 µs slower isomer has also been tentatively measured, potentially with decay through a non-yrast structure. Excited 249Fm states following the α-decay of 253No are also measured through the recoil-decay tagging technique.

A combination of in-situ surface x-ray scattering (SXS) and cyclic voltammetry (CV) measurements have been performed to develop an increased understanding of supported metal multilayers on single crystal metal substrates. The formation of ordered metal structures and metal oxides are investigated together with the effect of the surface modification on processes such as OH adsorption and hydrogen evolution. A detailed in-situ study of the structure and behaviour of underpotentially deposited (UPD) monolayer and bilayer of Ag on the Au(111) surface is given both before and after transfer of the electrode to alkaline electrolyte. Analysis of the SXS data shows that while the bilayer is stable upon transfer, the Ag monolayer reorders to a partial bilayer. Sulphate anions in the UPD electrolyte stabilise the monolayer as it is formed, however upon transfer to the alkaline electrolyte these are replaced by more specifically adsorbed OH- ions causing the Ag to restructure to the more stable partial bilayer. The Ag modified electrodes show potential response for OH- adsorption similar to that of Ag single crystals. Detailed modelling of the SXS data at the positive potential limit in alkaline electrolyte shows evidence of an ordered OH- layer in the electrochemical double layer. Sub-surface OH indicated in the CV is confirmed in the SXS by a roughening of the topmost Ag layer. The atomic structure and properties of Co thin films electrodeposited onto Au(111) electrode is investigated using STM and SXS. Measurements confirm that the Co initially grows on the surface as a bilayer. Detailed characterisation of the thin film structure was obtained by analysis of the specular CTR. Results show a small outward expansion in the Co film which may be caused by the presence of adsorbed hydrogen on the Co surface. Changes induced by the presence of CO were investigated and it was found that CO has a dramatic effect on the magnetisation but only cause very small changes in the atomic structure of the Co film. The measurements indicate the changes in magnetic behaviour are driven by subtle changes in the electrolyte double layer region adjacent to the Co surface. Thin films of Co were deposited on a Au(111) electrode prior to transfer of the electrode to alkaline electrolyte. Ex-situ AFM imaging revealed that the Co is present on the Au(111) surface in the form of large islands which cover approximately 2.2% of the surface and are located at step edges. Their presence gives rise to a modified reconstruction of the topmost Au layer which was also investigated. Resonant SXS measurements revealed that Co is present both in its metallic state and charged state, most likely in the form Co(OH)2. The Co-modified Au(111) surface shifts the potential for hydrogen evolution positively by ~ 0.1 V compared with that of clean gold.

At the limits of nuclear stability, increasing proton-neutron asymmetry leads to a shifting of orbitals from nuclear shell model predictions. In turn this leads to a weakening of shell gaps such as at N = 20, and the emergence of new gaps at N = 14 and 16. To observe this evolution of the structure as the neutron dripline is approached, single-nucleon removal reactions have been employed for oxygen and fluorine isotopes. These reactions are an excellent way of probing the nuclear wavefunction to reveal information on the single-particle content in the wavefunction. Cross sections have been measured, both inclusive and exclusive, and partial production cross sections calculated. This has allowed spectroscopic factors to be extracted and compared to theoretical predictions from shell model calculations. Longitudinal momentum distributions, both inclusive and exclusive, have also been measured. The orbital angular momentum of the removed nucleon has a pronounced effect on the momentum distribution of the surviving core, which can be compared to theoretical predictions based on eikonal theory. This gives a valuable insight into the configuration mixing for the ground and excited states of the nuclei of interest.

The proof of concept of a fused radiometric and optical stereoscopic imaging device is presented. The project was in collaboration with the National Nuclear Laboratory and the Nuclear Decommissioning Authority with the aim of developing a sensor that can be deployed in a nuclear decommissioning environment. The radiometric system was a Compton camera comprised of two HPGe planar detectors and presents a significant improvement in efficiency and dynamic range over coded aperture systems currently used in industry. The optical stereoscopic camera is the proprietary Bumblebee XB3 system that provides 3D physical information of the surroundings. Two main experiments are presented; the first investigated the disparity between true source location and reconstructed image position. This disparity was proven and methods for accounting for and correcting it were developed, whereby the image position accuracy was improved by a factor of 26.7. The second experiment imaged 20 MBq $^{137}$Cs sources at distances of 80 - 150 cm with both radiometric and optical stereoscopic systems simultaneously. The first fused images were produced using this data, with the radiometric sources and surroundings clearly visible. A GUI was developed in Matlab to process and fuse the data. Alongside both experiments image optimisation techniques were investigated. Pulse shape analysis was implemented and shown to improve image resolution by 30\% on average at the expense of efficiency. Fold 2 event imaging was conversely shown to improve efficiency at the expense of image resolution. This work provides the basis to develop the project towards a complete system. The steps that must be taken to realise this are outlined and recommendations for overcoming potential challenges are discussed.

A search for non-prompt photons in diphoton events with large missing transverse energy at the ATLAS detector is presented in this thesis. This search was performed using data collected from proton-proton collisions provided by the Large Hadron Collider at CERN at two energies: 4.8 fb^-1 collected at a center of mass energy of 7 TeV in 2011 and 20.3 fb^-1 collected at a center of mass energy of 8 TeV in 2012. The theoretical motivation for this search lies in the Gauge Mediated Symmetry Breaking models in which the lightest neutralino can be long-lived and decay to a photon and a gravitino, which is stable and the source of missing transverse momentum in these models. The photons produced in these decays have two unique properties due to the finite lifetime of the neutralino: they will not point back to the primary collision vertex and they will arrive at the electromagnetic calorimeter delayed compared to promptly produced photons. These two signatures were used to search for non-prompt photons in a simplified model in which the only two free parameters are the lifetime of the neutralino and the effective supersymmetry breaking scale, corresponding to the mass of the neutralino. In the two datasets, no significant excess over the Standard Model predictions was observed. These results were used to set exclusion limits on the lifetime and mass of the lightest neutralinos at the 95% confidence level: neutralinos with lifetimes varying from 250 ps to 50 ns in the mass range of 95 GeV to 240 GeV were excluded by the 7 TeV analysis, neutralinos with lifetimes varying from 250 ps to 100 ns in the mass range of 120 GeV to 440 GeV were excluded by the 8 TeV analysis.

Scanning transmission electron microscopy is amongst the most valuable techniques for nanoscale structural characterization. It is capable of providing atomic resolution images with lesser sample damage than is typically incurred by other techniques of comparable resolution. Additionally, recent studies have found that the intensity in these images can be used to deduce the three dimensional structures of samples. The atomic resolution, three-dimensional characterization of gold nanoclusters is particularly desirable, as it is expected to provide significant insights into their surprising catalytic activity. Unfortunately, the image formation process in scanning transmission electron microscopy is not straightforward, with many microscope and sample parameters affecting image intensities. Recently, there has been a concerted effort in the electron microscopy community to achieve more quantitative analyses of images to maximise the information which can be extracted from them. This is typically achieved through the comparison of experimental and simulated images of model structures. To apply such methods to nanoscale structures, the simulations should account for the large inhomogeneities expected in these structures. In particular, both the static structural disordering induced by strain, and the dynamic disordering caused by thermal motion, should be included. These effects are frequently overlooked in reports in the literature, principally because there is currently no means by which they can be accurately measured. In the work presented here, molecular dynamics simulations are used to predict the structural relaxations and thermal motion in small gold nanoclusters, in order to produce more rigorous electron microscope simulations than any previously reported. This method is equally applicable to any system for which accurate molecular dynamics simulations can be performed. Images produced using this new method are compared with those produced using more conventional techniques and found to be sufficiently different to confirm the value of this approach. The results of the comparisons also prompt a systematic study into the effect of structural disorder on image intensities. It is found that electron channelling effects play a large role in image formation and cause a non-trivial relationship between thermal motion and image intensities. The results of this work show that the interrelated effects of the many factors affecting image formation in scanning transmission electron microscopy preclude parametrizations, so that the physical interpretation of images is expected to continue to rely upon rigorous computational simulations.

Organic photovoltaic (OPV) devices have been developed extensively and optimised due to the use of nanomaterials in their construction. More recently, the demand for such devices to be flexible and mechanically robust has been a major area of research. Presently, Indium Tin Oxide (ITO) is the material that is used almost exclusively for transparent electrode. However, it has several drawbacks such as brittleness, high refractive index and high processing temperature. Furthermore, the price of ITO has been highly volatile due to scarcity of indium resources and the increased consumption of the material. Therefore, cheap, flexible and solution-processed transparent conductors are required for emerging optoelectronic devices with flexible construction which can be promising for wearable or environmentally adaptable devices purposes such as flexible solar cells and displays. Therefore, over the past decade an alternative material has been sought intensively, particularly in the need for producing large area flexible transparent electrodes. Many materials have been investigated but most investigations have focused on carbon nanotube (CNT), graphene flakes and metallic nanowires. Silver nanowires (Ag NWs) networks have been proven to show a high electrical conductivity with high optical transmittance. This special characteristic is desirable in transparent conductive electrodes in optoelectronic applications such as solar cells, light emitting diodes, and touch screen. On the other hand, Polymeric substrates that act as a non-brittle scaffold as well as protective packaging of the OPV are an essential element for such an “All-plastic” device. However, for such applications where the coating should be relatively hard a bottleneck to fabricating large area homogeneous films is associated with the formation of cracks as a result of local mismatches in mechanical properties during film formation. In this work, the fabrication and characterization of flexible transparent electrodes of Ag NWs on flexible substrates by spray deposition technique have been described. Furthermore, a way to enhance the electrical and mechanical properties of the Ag NWs transparent electrodes by incorporating a low density ensemble of graphene on top of the metal electrode networks using the Langmuir-Schafer has been achieved. Interestingly, the electrical conductivity in these hybrid electrodes is stable over relatively large strains during mechanical agitation indicating that such electrodes may have important application in future applications. Finally, producing crack-free monolayer latex over large area has been fabricated and characterised. Therefore, the polymer latex thin film has promising applications as purposes of hard coatings.

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