The thesis here presented is the result of a PhD research, with the aim to build a program able to solve the non-relativistic eigenvalue problem for the so-called cluster and nuclei (in particular the Beryllium-9 nucleus), in order to study them through the use of Effective Field Theory (EFT) potentials. After a brief introduction, that will show why this type of nuclei are important in the study of stellar nucleosynthesis, I introduce the Hyperspherical Harmonics basis with which the calculations were carried out. The following chapter has the momentum space as the main subject, ending with some results from the program. EFT and cluster nuclei are then introduced in the next chapter, together with the interaction I used for the cluster systems. The second to last chapter shows the results of the code, able to calculate the ground state of Carbon-12 and Beryllium-9 nuclei, two important nuclei in the process of stellar nucleosynthesis. The last chapter contains a brief summary and the future outlook on this research.

The subject of this thesis is the use of BECs for atom interferometry. The standard way atom interferometry is today performed is by interrogating free falling samples of atoms. The employed samples are cold (but not condensed) to have high coherence, and dilute, not to interact significantly with each other. This technique represents nowadays an almost mature field of research in which the achievable interferometric sensitivity is bounded by the atomic shot noise. Until a few years ago the employment of BECs in such devices was strongly limited by the effect of the interactions between the condensed atoms. This obstacle is today removable exploiting interaction tuning techniques. The use of BECs would be advantageous for atom interferometry inasmuch they represents the matter analogue of the optical laser providing the maximum coherence allowed by quantum mechanics. Moreover, non-linear dynamic can be exploited in order to prepare entangled states of the system. The realization of entangled samples can lead to sub-shot noise sensitivity of the interferometers. At today very nice proof-of-principle experiments have been realized in this direction but a competitive device is still missing. This thesis work is inserted in a long term project whose goal is the realization of such a device. The basic operational idea of the project starts with the preparation of a BEC in a double well potential. By the effect of strong interactions the atomic system can be driven into an entangled state. Once the entangled state is prepared, interactions can be †switched off†and the interferometric sequence performed. This thesis begins with the description of the apparatus for the production of tunable BECs to be used in the interferometer. We chose to work with 39K atoms because this atomic species presents many convenient Feshabch resonances at easily accessible magnetic field values. The cooling of this particular atomic species presents many difficulties, both for the laser and evaporative cooling processes. For this reason, this was the last alkaline atom to be condensed. Its condensation up to now was only possible by employing sympathetic cooling with another species. In this thesis our solutions to the various cooling issues is reported. In particular we realized sub-Doppler cooling for the first time for this species and we achieved condensation via evaporation in an optical dipole trap taking advantage of a Feshbach resonance. In the last part of this work, are presented original calculations for the effects of thermal fluctuations on the coherence of a BEC in a double well, discussing the interplay between thermal fluctuations and interactions in this system. Estimations and feasibility studies regarding the double well trap to be realized are also reported.

In this work we will face the problem of the vibrational properties of glasses focusing on the origin and nature of the boson peak (BP). This feature is an universal characteristic of glasses and a fingerprint of the presence of disorder. Two samples have been chosen for this study. The first is permanently densified vitreous SiO$_2$. Permanent densification has been exploited to tune the glassy properties focusing on their evolution. The second sample is a silicon-selenium glass whose low sound velocity allows a detailed study of its dynamics by means of neutron inelastic scattering.

In this thesis we address relevant problems of the physics of quantum disordered systems from a numerical and theoretical point of view, with specific attention to the connection of our findings with ultracold atomic gases experiments. We concentrate on two main issues: the interplay between localization and interaction in disordered systems and the problem of localization in correlated random potentials. The first problem is investigated considering the expansion of a weakly interacting Bose gas in a bichromtic optical lattice. We observe that interaction has a destructive effect on the disorder-induced localization and leads to a subdiffusive expansion of the atomic gas. By comparing three characteristic energy scales of the system one can identify three different spreading regimes: weak chaos, strong chaos and self-trapping. The spreading behaviour in these regimes is predicted theoretically and verified numerically. We also interpreted existing experimental data on the basis of our findings and showed that there is a qualitative agreement between our numerical simulations and experiments. The second problem is investigated proposing a new model of correlated disorder that can be implemented experimentally using ultracold dipolar gases. We show that this model is characterized by the presence of both short and long range correlations. We study the localization properties of the model and highlight the role played by short and long range correlations in the determination of those properties. In particular we show that when short-range correlations are dominant, extended states can appear in the spectrum. The effect of long-range correlations is instead to restore localization over the whole spectrum and lead to counterintuitive behaviours of the localization length. More precisely, depending on the localization regime they can enhance or reduce the localization length at the centre of the band.

In this Thesis we will theoretically address some issues concerning the Physics of ultracold Fermi gases, all of them with experimental relevance. The field of ultracold gases, and more recently of ultracold Fermi gases, is gathering a lot of experimental and theoretical interest for two main reasons: the great control on the relevant parameters of the problem and the relative simplicity of the minimal theory which is able to correctly describe the system. Building upon this solid background, ultracold gases provided an ideal laboratory for testing more refined theories and also for addressing fundamental issues of quantum mechanics as well as for simulating more complex physical systems such as those encountered in condensed matter. Even if the effective hamiltonian of ultracold gases can be simple, due to the diluteness of the system and the low temperature, which imply low energy physics, the solution of the quantum mechanic equations governing the state of these systems is not always simple. For the static properties usually mean-field solutions exist or perturbative expansions can be produced in some regimes. However Quantum Monte Carlo (QMC) techniques provide more accurate results especially in the strongly interacting regimes. For confined systems it is possible to use QMC only for a few particles, so that, for large number of particles, a fruitful combined use of Density Functional Theory (DFT) and QMC is necessary. The study of the dynamics of ultracold gases has received little attention with QMC techniques, due to the intrinsic computational difficulty of the many-body problem, so that general hydrodynamic equations are often used for studying the propagation of smoothly varying perturbations. In this Thesis we use QMC techniques for studying the problem of ferromagnetism in repulsive or effectively repulsive ultracold gases without a lattice and the problem of the Bardeen-Cooper-Schrieffer to Bose-Einstein-Condensation (BCS-BEC) crossover in two dimensions. We use DFT in the Local Density Approximation (LDA) for calculating the density profiles of ultracold Fermi gases in harmonic magneto-optical traps, starting from QMC equations of state. We study the propagation of first and second sound in ultracold Fermi gases in cylindrical geometry, using the hydrodynamic equations of superfluids.

Si presenta in questa tesi una serie di progetti didattici e divulgativi a tema energetica svolti nel corso del dottorato dal candidato. Trova spazio la presentazione di un'indagine originale che ha coinvolto 730 cittadini e volta alla comprensione di quale sia la percezione comune circa alcune tematiche di carattere energetico di estrema attualità. Sono, in seguito, presentati dei progetti didattici che hanno coinvolto scolaresche di scuole primarie e secondarie di primo e secondo grado. Lo scritto, infine, termina con la presentazione di un progetto di start Up accedemica volto alla divulgazione scientifica.

GIXRF (Grazing incidence X-Ray Fluorescence) is an analytical technique with high potential in the study of depth profiles and in the characterization of thin layered structures. To extract information from a GIXRF measurement and determine the layer composition it is necessary to compare the experimental data with simulation. However at the moment this thesis has been written, there is no software widely recognized from the scientific community as the reference software for the analysis. For this reason this work of thesis deals with the development of an analytical software and its application to several case studies. A program called GIMPy is presented. The program is capable to perform simulations of the expected GIXRF signal from a given model, but also of the expected fluorescence signal at high angle of incidence and the reflectivity (XRR). The use of a programming language like Python makes the library extremely portable, easily extendible and flexible thanks to its object oriented syntax and scripting capabilities. GIMPy bases the modelling of the electric field propagation inside the sample and the expected fluorescence from the theoretical description found in literature. Moreover a series of methods were developed to account for the effect of the instrumental set-up geometry, the detector response, indirect excitation and primary beam shape and energy composition. A round-robin related to GIXRF comparison with several institutes developing an analytical software has been organised. The comparison showed a good agreement between the results obtained with GIMPy and the other programs. GIXRF has then been applied to the characterisation of several systems. A combined XRR and GIXRF analysis of multi-layered transparent and conductive oxide films (TCO) of technological interest resulted in a nondestructive and precise characterization of their structures. Measurements were performed at the ESRF synchrotron facility and in the laboratory using a Cu tube as source. Combining the measurements performed with dif- ferent instrumental set-ups the effectiveness of the combined XRR-GIXRFapproach, that has proved already effective in the past, has been further shown. It has been possible to evidence the existence of a thin inter dif- fusion profile induced by annealing the samples, showing a sensitivity to structural changes in the depth of 0.5-1 nm. GIXRF measurements performed on Sn implants in Ge provided information about the total dose retained by the sample after an implantation process. Synchrotron tunable excitation energy was extremely valuable for the fluorescence analysis.The two different modelling strategies used for data fitting, one using a SIMS profile as an input the other an analytical description of the depth profile, and returned values close to the one obtained with other techniques. A new technology based on the deposition of ALD coatings for the preservation of cultural heritage object has been characterised with XRR and GIXRF. The XRR measurements were effective in revealing the deterioration of the coatings after the effect of an accelerated ageing process. Moreover the analysis of GIXRF also revealed the formation of nano-particles at the top of the surface, and allowed the characterisation of their size and composition. The last chapter shows some theoretical calculations investigating GIXRF potential in the size and chemical characterisation of nano-particles. It is shown how the experimental setup and the sample preparation can influ- ence the outcome of the measurement. The theoretical calculations are also reinforced by the result obtained on some preliminary experiments on Gold nano-particles.

A study of methods in few-body nuclear physics is presented, in particular for the study of the photodisintegration cross section of 3He at low energies, and for the determination of phase shifts in low-energy three-body scattering. A possible extension of the methods considered to the study of a five-body problem is investigated.

Abstract There is a growing concern related to increasing energy requirement and greenhouse gas emissions. Hydrogen gas is recognised as a desirable clean fuel and may be a sustainable solution. Hydrogen gas can be directly used as an anodic fuel for Proton Exchange Membrane Fuel Cell that converts chemical energy of hydrogen into electrical energy with no environmentally harmful by-products. Chemical hydrides with high hydrogen storage capacity in terms of gravimetric and volumetric efficiencies are the most promising candidates to supply pure hydrogen at room temperature. Among them, Sodium borohydride (SBH) and Ammonia borane (AB) have drawn a lot of interest as they are stable, non-flammable, nontoxic, and have a high hydrogen storage capability. Large amount of pure hydrogen gas is released during the hydrolysis of these chemical hydrides in presence of certain catalysts. The by-products are non-toxic, environmentally safe and can be recycled. Noble catalysts like Pt and Pd, used in the past to enhance the hydrogen production rate, do not seem to be viable for industrial application considering their cost and availability. Co and Ni borides are considered as good candidates for catalyzed hydrolysis owing to their good catalytic activity, low cost and effortlessly synthesis. Transition metals with varying (metal)/(Co + metal) molar ratio were doped in Co-B catalyst and the effect of metal doping on surface morphology, electronic interaction, and catalytic efficiency of the alloy catalyst powder on hydrogen production by hydrolysis of SBH and AB were studied. On the basis of characterization results, the role of each metal species, involved in hydrolysis and enhanced catalytic performance is discussed. The stability, reusability, and durability of these catalysts have also been investigated. Nanoparticle-assembled Co-B-P thin films on Ni foam (by electroless deposition), along with supported and unsupported Co-B nanoparticles over carbon films were synthesized by Pulsed Laser Deposition and studied for catalytic hydrolysis.

Oxide-based transparent conductors constitute a novel class of materials, which finds applications in many technological fields such as photovoltaics and organic light emitting devices. They can be employed in the new generation solar cells as transparent charge collectors. The transparent and conductive oxide mostly used nowadays is indium tin oxide (ITO), however due to the high cost and scarcity of indium, other materials are under research and development as potential substitutes. Many candidates are currently under study, mainly doped-ZnO, doped-CdO, doped-SnO2, doped-TiO2. The work undertaken in this thesis is a study of the doping processes of thin films of TiO2 and ZnO, two cheap, chemically stable and non-toxic materials. Two main objectives were pursued in this work: (i) the optimization of the film deposition and doping conditions for a potential replacement of ITO and (ii) the understanding of the factors dominating the doping process as well as its limitations. The approach was to explore three doping methods of the films: intrinsic doping, extrinsic doping and, with the aim to combine the benefits of both, intrinsic-extrinsic co-doping. Since the structural defects (such as oxygen vacancies) are at the basis of the intrinsic doping, a control of their formation was searched through the variation of the growth process conditions of the ZnO and TiO2 films. Niobium was selected for the extrinsic doping of the TiO2 films. The films were grown by RF plasma sputtering in different atmospheres (Argon, Ar-O2 and Ar-H2 gas mixtures) and under different plasma power conditions and substrate temperature, onto silicon and quartz substrate. The Nb-containing films were obtained by co-sputtering of either a single composite TiO2 -Nb target or two distinct niobium and TiO2 targets. Many characterization techniques were applied to define the film structural, electronic, electrical and optical properties obtained upon doping. For chemical analysis, X-ray Photoelectron Spectroscopy (XPS) was used. The structure and morphology of the films were analyzed by X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). The chemical species present in various plasmas used in deposition process were investigated by Optical Emission Spectroscopy (OES). Further, the defect structure and properties of the obtained films were studied by Positron Annihilation Spectroscopy. Analysis by this technique shed more light on the nature of the vacancies/open volume and on the effect of the latter on the electrical and structural properties of the films. A study based on a joint use of XPS and optical measurements allowed to define the electronic properties of the films (valence band edge, Fermi level position, work function, ionization potential and electron affinity). Structural analysis results revealed the formation of both anatase and rutile nanocrystalline phases for intrinsic and extrinsic doping of TiO2, while with the co-doping method only anatase phase was obtained, a phase known to be favorable for Nb incorporation in TiO2 lattice. The intrinsic doping of TiO2 films showed high transparency in the visible range, but resulted in still high resistivity values (101-103 ï —xcm). The latter could be lowered by using Ar-H2 gas mixtures during film deposition. The same trend was observed in the case of intrinsically-doped ZnO films, an increase in the electrical conductivity was observed when the concentration of defects was increased. The lowest resistivity was achieved with niobium doping of TiO2, 5x10-3 ï —xcm, with an optical absorption coefficient in the visible range of ~1x104 cm-1, however the combination of the internal defects and Nb, in co-doping, did not improve the conductivity. Nonetheless, it was found that co-doping method strongly modified the electronic properties of the TiO2 films, allowing a control of the work function, an important parameter for transparent electrodes. Low cost transparent conductive oxides were obtained when niobium was successfully incorporated in TiO2 lattice. By optimization of the deposition process of the films (dopant concentration, RF power, atmosphere, and annealing temperature) the electronic, electrical and optical properties of doped- TiO2 films can be improved. The obtained results can contribute to the development of transparent electrodes and charge collectors by RF sputtering, a suitable technique for coating on large area substrates.