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École doctorale physique (Grenoble)

Overview
Works: 874 works in 916 publications in 2 languages and 1,690 library holdings
Roles: Other, 996
Publication Timeline
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Most widely held works by École doctorale physique (Grenoble)
Simulations numériques de collisions de vents dans les systèmes binaires by Astrid Lamberts-Marcade( )

2 editions published in 2012 in French and held by 3 WorldCat member libraries worldwide

The aim of this thesis is to understand the structure of colliding wind binaries composed of a massive star and a young pulsar, called gamma-ray binaries. They are expected to display a similar structure to colliding wind binaries composed of massive stars, with some particularities due to the relativistic nature of the pulsar wind. The interaction of the supersonic winds from massive stars creates a shocked structure with observational signatures from the radio domain to the X-rays. The structure is affected by various instabilities and by the orbital motion of the stars. To understand their impact, I carried out high resolution simulations of colliding wind binaries with the hydrodynamical code RAMSES. They are computationally demanding, especially when one of the winds strongly dominates the other one. Small scale simulations highlight the importance of the Non-linear Thin Shell Instability in isothermal collisions while the Kelvin-Helmholtz instability may strongly impact the dynamics of adiabatic collisions. I found that, at larger scales, this instability can destroy the expected large scale spiral structure when there is an important velocity gradient between the winds. WR 104 is a system that displays a spiral structure with important dust emission. The simulation of this system shows a good agreement with the observed structure and indicates cooling processes are necessary to enable dust formation. To model the pulsar wind in gamma-ray binaries, an extension of RAMSES has been developed, that incorporates relativistic hydrodynamics. I used this new relativistic code to perform preliminary simulations of gamma-ray binaries. They display a similar structure to colliding wind binaries with small relativistic corrections. We expect to use this code to perform large scale simulations of gamma-ray binaries. It will be part of the next public release of RAMSES and is suited for the study of many astrophysical problems such as relativistic jets, pulsar wind nebulae or gamma-ray bursts
La problématique de l'évolution des moments d'une densité de particules soumises à des forces non linéaires by Christophe Peaucelle( Book )

2 editions published in 2001 in French and held by 3 WorldCat member libraries worldwide

L'utilisation des accélérateurs linéaires de forte puissance dans différents projets (production de neutrons par spallation, réacteurs hybrides) nous a amené à se pencher sur les problèmes de la dynamique de faisceaux de haute intensité. Dans le cas de faisceaux intenses, les particules sont soumises à des forces non linéaires, principalement dues à l'effet de charge d'espace. Afin de disposer d'outils à la fois moins lourds et plus réalistes que les méthodes classiques de simulation (interaction particule-particule, modèle coeur-particule), la description de l'évolution d'une distribution de particules à partir de ses paramètres statistiques, ses moments, a donc été envisagée. Nous présentons donc dans une première partie une analyse détaillée de la problématique, menée dans un cadre simplifié mais non limitatif : tout d'abord, nous développons un formalisme original basé sur les propriétés fines des polygones orthogonaux permettant l'étude des moments d'une densité en une dimension. De cette analyse, nous voyons que l'on peut extraire, d'un nombre fini de moments, un certain nombre d'informations concernant la densité. En particulier, il en découle la notion fondamentale d'enveloppe convexe définissant le domaine d'existence de cette densité. Ceci permet de mieux comprendre la signification des moments. La généralisation de cette description en deux dimensions permet d'estimer avec une bonne précision où sont localisées les particules dans cet espace des phases. Enfin, nous abordons les difficultés rencontrées au cours de cette étude, fixant ainsi les limites de cette méthode. La deuxième partie de cette thèse, plus expérimentale, présente les mesures de faisceaulogie effectuées sur l'accélérateur GENEPI (GEnérateur de NEutrons Pulsé Intense) dans le cadre de l'étude des systèmes hybrides. Elles permettent, entre autres, la calibration du faisceau et la validation des codes de calculs nécessaires à la conception de la machine
Étude du dopage extrinsèque dans CdHgTe pour la réalisation de photodiodes infrarouges by Bruno Delacourt( )

1 edition published in 2017 in French and held by 2 WorldCat member libraries worldwide

La photodiode infrarouge, basée sur des semi-conducteurs à petit gap, permet de collecter des porteurs générés par l'impact de photons mais aussi par agitation thermique. Cette dernière crée un courant parasite dit d'obscurité qui détériore la performance du composant. Afin de minimiser le courant d'obscurité, le paramètre clef à maximiser est la durée de vie des porteurs minoritaires. Dans le contexte HOT, ceci ouvre la possibilité d'augmenter la température de fonctionnement des dispositifs de détection infrarouge quantique. Pour la fenêtre spectrale du MWIR, l'objectif à moyen terme est de fonctionner à 150-180 K au lieu de 80-120 K actuellement. Ceci permettrai un progrès significatif en termes de consommation, de puissance et donc d'autonomie et de fiabilité des systèmes. L'objectif de ces travaux de thèse est de déterminer expérimentalement les limites théoriques de la durée de vie des porteurs minoritaires dans le CdHgTe et dans un matériau III-V. Pour cela un banc de mesure de décroissance de photoluminescence ainsi qu'une méthode d'extraction des données permettant de discriminer les mécanismes de recombinaisons à partir de l'évolution du signal en fonction du niveau d'injection de porteurs dans l'échantillon ont été développés. En parallèle, un ensemble de caractérisations a été effectué pour assister le développement de technologies adressant le contexte HOT
Développement et validation de schémas de calcul dédiés à l'interprétation des mesures par oscillation pour l'amélioration des données nucléaires by Adrien Gruel( )

1 edition published in 2011 in French and held by 2 WorldCat member libraries worldwide

Reactivity measurements by the oscillation technique, as those performed in the Minerve reactor, enable to access various neutronic parameters on materials, fuels or specific isotopes. Usually, expected reactivity effects are small, about ten pcm at maximum. Then, the modeling of these experiments should be very precise, to obtain reliable feedback on the pointed parameters. Especially, calculation biases should be precisely identified, quantified and reduced to get precise information on nuclear data. The goal of this thesis is to develop a reference calculation scheme, with well quantified uncertainties, for in-pile oscillation experiments. In this work are presented several small reactivity calculation methods, based on deterministic and/or stochastic calculation codes. Those method are compared thanks to a numerical benchmark, against a reference calculation. Three applications of these methods are presented here: a purely deterministic calculation with exact perturbation theory formalism is used for the experimental validation of fission product cross sections, in the frame of reactivity loss studies for irradiated fuel; an hybrid method, based on a stochastic calculation and the exact perturbation theory is used for the readjustment of nuclear data, here 241Am; and a third method, based on a perturbative Monte Carlo calculation, is used in a conception study
Quantum phase and charge in Josephson junction chains by Thomas Weissl( )

1 edition published in 2014 in English and held by 2 WorldCat member libraries worldwide

In this thesis entitled ' Quantum phase and charge dynamics in Josephson junction chains ' an experimental study and theoretical description of quantum effects of phases and charges in chains of Josephsonjunctions is presented.The dynamics of Josephson junction chains are dominated by two different energy scales: the Josephsonenergy, which is related to the overlap of the superconducting wave functions of the two superconductorsforming the junction and the charging energy that is related to the electrostatic energy of the Cooper-pairs on the islands. The realization of a well-defined charge state on a Josephson junction requires a highcharging energy to suppress the quantumfluctuations of the charge. In addition, the charge relaxationtimes must be increased by inserting the junction in a high impedance environment.We have realized such a well-defined charge state on a Josephson junction in an inductive environmentthat is formed by a Josephson junction chain. The localized charge state manifest itself by the appearanceof a high resistive regime in the current-voltage characteristic.A Josephson junction chain is however not a perfect inductor. Electromagnetic resonances related withthe finite ground capacitance of the superconducting islands influence the charge localization.We have characterized the effect of losses and nonlinearities on the electromagnetic resonances of Josephson junction chains in microwave spectroscopy measurements
Development of characterization methods for in situ annealing and biasing of semiconductor devices in the TEM by Rémy Berthier( )

1 edition published in 2018 in English and held by 2 WorldCat member libraries worldwide

Dans cette thèse, nous abordons les défis rencontrés lors de la caractérisation des mémoires non volatiles par microscopie en transmission in situ. Les innovations récentes menées sur les porte-objets de TEM in situ basés sur l'utilisation de puces en silicium apportent de grands avantages comparée aux précédents modèles. Cependant, cette technique reste complexe et les expériences de MET in situ sont difficiles à mener à terme. Ce manuscrit tente d'apporter de nouvelles solutions pour permettre l'observation à l'échelle atomique pendant le recuit, ou la polarisation d'un échantillon dans le MET. Ce projet a été mené à travers plusieurs améliorations effectuées au cours des différentes étapes des expériences de MET in situ. Cette thèse se focalise plus particulièrement sur les problèmes rencontrés lors de la polarisation de dispositifs de mémoires résistives de taille nanométrique. Ces travaux furent conduits à travers une étude des instruments utilisés, le développement de nouvelles méthodes de préparation d'échantillons, et une analyse de l'impact de l'imagerie électronique sur le fonctionnement d'un dispositif dans le MET.Tout d'abord, une nouvelle méthode est développée spécifiquement pour les expériences de MET in situ en température. Grâce à ces développements, la cristallisation de mémoires à changement de phase en GeTe est observée en temps réel. Ces résultats ont notamment permis d'obtenir des informations utiles pour le développement de mémoires à changement de phase de type chalcogénure. Ensuite, de nouvelles puces en silicium dédiées à la polarisation in situ sont développées et produites. Une étude est ensuite menée sur la préparation d'échantillons par FIB afin d'améliorer la qualité des contacts électriques pour la polarisation in situ, ainsi que la technique de préparation elle-même. La qualité de cette méthode est ensuite démontrée à travers des mesures quantitatives obtenues pendant la polarisation in situ d'un échantillon de référence de type jonction PN. Ces développements sont ensuite appliqués afin d'observer des dispositifs de mémoires résistives de type CBRAM en fonctionnement dans le microscope électronique en transmission. Ces résultats ont permis d'apporter de nouvelles informations sur les mécanismes de fonctionnement des mémoires résistives, ainsi que sur la technique de polarisation in situ
Évolution des glaces et des composés organiques interstellaires et cométaires : étude expérimentale et analyse des données VIRTIS/ROSETTA by Mathilde Faure( )

1 edition published in 2016 in French and held by 2 WorldCat member libraries worldwide

Les comètes sont les vestiges de la "nébuleuse solaire", c'est-à-dire du disque proto-planétaire qui a engendré notre système solaire. Elles sont composées de glaces et de poussières contenant des matériaux et molécules organiques ainsi que des minéraux. La composition des comètes reflète au premier ordre celle des glaces interstellaires. Toutefois, cette filiation n'est pas avérée. Au cours de la période pré-accrétionelle, le matériau cométaire a potentiellement subi l'action de nombreux processus physiques (chauffage, irradiation UV et particulaire) qui ont nécessairement altéré sa structure et sa composition.L'objectif ce cette thèse est de mieux comprendre, grâce à des expériences de laboratoire, l'effet des processus de chauffage et d'irradiation ionique sur des analogues de matière cométaire (glaces et matériaux carbonés). Une partie de ces expériences porte sur l'évolution de la deutération des molécules organiques lors du réchauffement des glaces. Elles ont été menées à l'IPAG (Institut de Planétologie et d'Astrophysique de Grenoble) et au PIIM (Laboratoire de Physique des Interactions Ioniques et Moléculaires) à Marseille. Elles démontrent qu'un équilibrage isotopique a lieu au cours de la cristallisation, sur des échelles de temps de l'ordre de l'heure à des températures supérieures à 120 K, pour les groupements chimiques capables de former des liaisons hydrogènes avec l'eau (groupements -OH et -NH2). Cet équilibrage efface ainsi le fractionnement initial de certaines molécules, ou certains groupements chimiques, dans la phase post-sublimation. Ce résultat permet en particulier d'expliquer la deutération sélective des isotopologues du méthanol dans les cœurs chauds des proto-étoiles.Un second volet de la thèse a porté sur l'étude de la formation de la matière organique réfractaire présente dans les astéroïdes et les comètes. Des expériences de chauffage et d'irradiation ont été menées à l'IPAG, au GANIL (Grand accélérateur national d'ions lourds) à Caen, et au CSNSM (Centre de Sciences Nucléaires et de Sciences de la Matière) à Orsay. Nous montrons qu'un chauffage au-delà de 400° C de précurseurs simples permet la formation de carbones désordonnés polyaromatiques dont la structure est proche de celle observée dans les objets primitifs du système solaire. Les effets de l'irradiation ionique sont plus difficiles à évaluer car ils dépendent du pouvoir d'arrêt des précurseurs cibles et des ions projectiles. Des contraintes sur les doses nucléaires maximales reçues par la matière primitive sont néanmoins déduites (D<14 eV/atome). In fine, ces simulations démontrent qu'un processus de chauffage apparaît comme beaucoup plus probable que les processus radiolytiques, mais une combinaison des deux ne peut pas être exclue.Enfin, cette thèse a bénéficié des premières données in situ de la mission spatiale européenne ROSETTA en orbite autour de la comète Churyumov-Gerasimenko (67P) de juillet 2014 à septembre 2016. L'analyse des données du spectro-imageur VIRTIS-M a permis de montrer qu'un matériau organique semi-volatile, contenant notamment des acides carboxyliques, est présent de manière quasi-homogène sur toute la surface de la comète 67P
Modelling of CO2 cooling of the ATLAS ITk Pixel Detector by Pierre Barroca( )

1 edition published in 2019 in English and held by 2 WorldCat member libraries worldwide

The Large Hadron Collider (LHC) physics program has been extended to the period 2026-2037 to deliver an order of magnitude more of proton-proton collisions compared to end 2023. To sustain the harsh conditions imposed to detectors in this period (radiation, high occupancy), the current ATLAS Inner Detector will be replaced by a new one using the most recent silicon sensor technologies. One of them is the generalization of the cooling with two-phase CO2 flowing in titanium tubes located close to the silicon sensor and associated electronics. The choice of CO2 relies on its most favourable thermo-physical properties in boiling state.The radiation damage during the HL-LHC program will be quite harsh and the engineering of the local supports under such extreme conditions requires a deep understanding of the two-phase behaviour of the CO2 flowing inside the titanium pipes, and a precise modelling of the heat transfer through the mechanical structure.However, the data available on CO2 boiling in channels of small hydraulic diameter (say, below 3 mm) is limited and often affected by too large uncertainties. This enforces the detector designers to include large safety factors and long iterative phases of experimental measurements, which could be sensibly reduced by the availability of reliable models.This thesis starts with a quick description of the ATLAS Upgrade Phase II project, a first outlook on the fundamentals of two-phase cooling technology, widely used to cool particle detectors in high-energy physics (HEP) experiments and discussion about the thermal management requirements of the future ATLAS Pixel Detector. Several custom tools were developed in python language to guide the design and optimisation of the the CO2 cooling system: simulation of heat transfer coefficient (HTC) and frictional pressure drops along evaporators, flow distribution studies in manifolds and calculation of thermal requirements.In a second phase, the document presents the thermal test setup to measure thermal performances of thermal prototypes for the new detector (ITk) as well as the associated simulation based on Finite Element analysis and Heat Transfer Coefficient modelling. A novel fit method was implemented to extract from the measurements the different parameters of the ITk elements (in situ material thermal conductivities, manufacturing variability, HTC...). The results are compared the current CO2 model predictions and the discrepancies discussed. A new set of parameters for the CO2 model was built to improve precisions by factor two on the effective HTC values for the ITk working conditions and integrated in the python modelling tool. Finally, the impact of this work on the design of the Pixel detector is presented
Optimisation de la durée de vie de micro-écrans vidéo à diodes électroluminescentes organiques by Julien Boizot( )

1 edition published in 2012 in French and held by 2 WorldCat member libraries worldwide

Ce travail porte sur l'amélioration des performances en vieillissement de micro-écrans vidéo à matrice active en technologie OLED sur Silicium. La perte d'efficacité lumineuse et la dérive en tension induites par le vieillissement des OLED restent depuis plusieurs années un point faible inhérent à cette technologie et représente toujours un verrou dans la commercialisation des micro-écrans sur un marché encore jeune. Nous proposons ici une étude d'optimisation d'un empilement OLED blanc bi-émetteurs à émission vers le haut basée sur l'amélioration systématique des modes de défaillances reconnus des OLED et adaptée aux spécificités de réalisation de micro-écrans à très forte résolution. Des outils originaux tels que des structures simplifiées de types monocouche ou monoporteur seront utilisés pour comprendre et réduire ces différents mécanismes de dégradation. Du fait de la complexité des structures OLED actuelles, des structures simplifiées seront notamment développées et analysées dans le but d'accéder à la compréhension des phénomènes intrinsèques de dégradation opérant au sein des couches organiques, à leurs interfaces ou encore aux interfaces avec les électrodes. Une méthode de caractérisation électrique encore peu utilisée dans le cas des LED organiques, la spectroscopie d'impédance, sera également développée. Cette technique de caractérisation électrique très prometteuse et surtout non destructive permet à travers l'étude des comportements capacitifs des dispositifs l'accès à de nombreuses informations relatives à la dynamique des charges liées ou mobiles dans les zones de bulk ou interfaciales des matériaux
Condensation et évaporation de l'hexane dans les membranes d'alumine poreuse by Victor Doebele( )

1 edition published in 2019 in French and held by 2 WorldCat member libraries worldwide

This manuscript presents a study of condensation and evaporation mechanisms in porous alumina membranes. This porous material has almost cylindrical pores of nanometric diameter with a narrow pore size distribution. Unlike many other porous media, their pores are not interconnected. Porous alumina is therefore an ideal material to probe the effects of confinement on condensation and evaporation in a single pore.The first part discusses my results obtained on membranes with straight pores open at both extremities or closed at one side. Sorption isotherms using hexane coupled to an original study of the membranes optical behaviour allow us to probe the liquid distribution within the pores. The results show that our pores are not perfectly cylindrical but funnel shaped and present corrugations. I numerically reproduced the measured isotherms with a cellular automaton, which takes into account the pores defects. This agreement implies that condensation and evaporation in a single pore are properly described by Saam & Cole theory.The second part evidences evaporation by cavitation in porous alumina membranes. A specific synthesis protocol is used to produce membranes with ink-bottle shaped pores. These membranes undergo a systematic and sudden emptying at 0.33 Psat, as measured by the optic and volumetric signals. This is the signature of the homogeneous cavitation of the liquid contained inside the ink-bottles, i.e. the nucleation of a spherical gas bubble in a liquid under tension. This is the first direct observation of such an evaporation process in porous membranes
Combinaison de la diffusion diffuse thermique de la diffusion inélastique des rayons X et des calculs ab inito pour l'étude de la dynamique de réseau by Björn Wehinger( )

1 edition published in 2013 in French and held by 2 WorldCat member libraries worldwide

The classical methods in the study of lattice dynamics, such as inelastic neutron and x-ray scattering, are and will remain flux-limited, consequently the measurements are time consuming. To maximise the yield of these techniques, measurement strategies need to be established prior to the experiment. These strategies can be elaborated and optimised by lattice dynamics calculations and thermal diffuse scattering. Measuring thermal diffuse scattering is a simple experiment where extended regions of reciprocal space can be rapidly explored in detail and characteristic features of the lattice dynamics identified. Slower spectroscopy measurements can then be applied on the selected regions of interest to gain access to the energy and intensity of individual vibrations. Moreover, in some cases the input of thermal diffuse scattering may become so constraining for the (quasi)harmonic lattice dynamic calculation, that inelastic scattering experiment will not be a necessary ingredient for the recovery of a self-consistent picture of the dynamics. In the frame of this work, the combination of thermal diffuse scattering, inelastic x-ray scattering and lattice dynamics calculations from first principles ab initio is applied to study the lattice dynamics of single crystals. Both diffuse scattering intensities and inelastic spectra determined by experiment are compared to the ones calculated ab initio. The combination of these three techniques gives access to the full lattice dynamics in the harmonic description and permits valuable new insights into the vibrational properties. The reader will be introduced to the key formalism of lattice dynamics, inelastic and thermal diffuse scattering. Methods for the calculation of vibrational properties from first principles are discussed, followed by a guideline for well converged calculations. The experimental techniques used in this work are presented and new possibilities for combined studies examined. The methodology is illustrated for several benchmark systems. Two silica polymorphs - coesite and alpha-cristobalite - were chosen as examples for covalent systems and investigated in detail. The experimentally validated calculation was used for the analysis of eigenvectors and eigenvalues of different modes, and their contribution to the total and partial density of vibrational states. Comparison with the most abundant silica polymorph - alpha-quartz - and germanium oxide in alpha-quartz structure reveals distinct similarities and differences in the low-energy vibrational properties. Metallic tin polymorphs were chosen to study the influence of the electron subsystem on inter-ionic interactions and the lattice dynamics. Tin exhibits both interesting structural properties and a complex Fermi surface. An unusual asymmetry of thermal diffuse scattering is observed which can be explained within the frame of harmonic lattice dynamics. Finally, the established method is applied to ice which exhibits not only characteristic thermal diffuse scattering but also static contributions from the hydrogen disorder. The methodology proposed in the present work provides a powerful tool in the study of lattice dynamics and will be applicable to a large variety of systems. The studies can be extended to extreme conditions involving very high pressures and a large temperature range. It may be also used to study localised properties of atomic vibrations in systems with broken symmetries, e.g. disorder or surface effects
Modélisation de la dynamique de spin dans l'AGS basée sur une méthode de résolution pas-à-pas du mouvement by Yann Dutheil( )

1 edition published in 2015 in English and held by 2 WorldCat member libraries worldwide

Non-linear dynamics in nano-electromechanical systems at low temperatures by Martial Defoort( )

1 edition published in 2014 in English and held by 2 WorldCat member libraries worldwide

The investigation of non-linear dynamics intrinsically opens access to a broad field of researches, and Nano-Electro-Mechanical Systems (NEMS) are valuable tools for this purpose. In the present manuscript, we emphasize the fundamental applications of non-linear nano-resonators for condensed matter. After a careful calibration of our peculiar experimental set-up, we characterize the relevant parameters associated to the resonance of our devices, notably the Duffing non-linearity which is the essence of coupling mechanisms between distinct modes of the system. We present a new scheme emerging from the mode-coupling technique, using a two-tone drive but actuating a single flexural mode: a high precision detection procedure of the initial resonator's response. The Duffing regime also opens an hysteresis within the resonance line of the NEMS, and the device is then employed as a model system for the associated bifurcation process. We explored numerically and experimentally this physical phenomenon and found that both the non-linear behaviour and the universal power laws described in the general theory are still valid far beyond any analytical predictions. We finally describe different techniques using NEMS as sensors to measure fundamental features of condensed matter physics, like signatures of two level systems within the resonator's material or slippage in a rarefied gas
Adhésion, croissance et polarisation de neurones sur substrats micro-et nano-structurés by Ghislain Bugnicourt( )

1 edition published in 2011 in French and held by 2 WorldCat member libraries worldwide

This thesis focuses on in vitro neuronal development, with the long-term goal of building controlled neuron networks that would allow the recording of their electric activity. A collection of intrinsic regulations are involved in neuronal adhesion, growth and polarization, in such a way that the cell can adapt to changes in its environment. Nevertheless, this environment can affect the behavior of the cell through mechanisms that rely on biophysical signals or even physical properties of this environment. The work presented in this thesis is based on the modification of two main aspects of the physical environment: geometry of adhesion and surface roughness. On the one hand, the geometry is controlled by patterns of adhesions, giving the ability to design bipolar motifs that highligt the importance of mechanical forces in neuronal growth, and also more complex motifs that allow the control of neuronal polarization, in particular by an inhibition of axonal differenciation on curved lines. On the other hand, a roughness below the microscale creates a distribution of adhesion points that results in an increase in neuronal growth rate and even influences axonal polarization. The final part of this thesis focuses on the development of an innovative method for placing cells at precise locations on a substrate, by the help of magnetic traps. This method is the final step required for growing model neuron networks on our nanotransistors
Approches effectives dans le MSSM et au-delà : applications à la physique du Higgs et aux observables de matière sombre by Guillaume Drieu-La Rochelle( )

1 edition published in 2012 in French and held by 2 WorldCat member libraries worldwide

Despite the numerous successes of the Standard Model of particle physics, it is believed that the complete picture of particle physics could be larger, as a unified theory for instance, and thus many efforts have been devoted to the development of theories of new physics. Supersymmetry is one of the most popular extensions since in addition to a solution of the naturalness issue, it provides a viable dark matter candidate. This last sector being all the more important now that recent experimental measurements have significantly increased our knowledge about dark matter properties, in particular the experimental determination of the relic density has reached the accuracy of a few percent. When applied to the Minimal Supersymmetric Standard Model (the MSSM, which is the simplest supersymmetric extension of the Standard Model), this constraint will thus shed light on the one-loop structure of the model. The MSSM is however much more liberal with unconstrained parameters than the Standard Model is, and the full one-loop computation of the relic density tends to be too long to be carried out throughout this large parameter space. In this thesis I have thus explored the opportunity of accounting for those loop corrections through a set of effective couplings. This effective approach has the advantage of keeping the simplicity of a tree-level computation but encoding at the same time genuine loop features such as the non-decoupling of heavy particles. Complementary to those constraints are the observables related to the LHC, which started taking data shortly after the beginning of my PhD in fall 2009. The Higgs sector of the MSSM is tightly constrained and this results in a certain fine-tuning of the model, which led to the creation of many models beyond the MSSM (such as the Next-to-Minimal Supersymmetric Standard Model). Arguing for a more general approach, I have decided in this thesis to use again the effective approach but with a different aim : while the effective couplings in the case of dark matter are determined to account for the MSSM loop corrections, the effective operators we add to the Higgs sector of the MSSM are the remnants of the integration of a heavy extra spectrum. This effective approach, called the BMSSM (for Beyond the MSSM) is known to account for many different realisations of non-minimal supersymmetry, and we have used it as a framework to recast the results of the Higgs analyses carried out by ATLAS and CMS collaborations. This study has led to the caracterisation of the rich phenomenology of the Higgs sector in the BMSSM, with in particular the possibility for a signal quite different from Standard Model or MSSM expectations. Though based on distinct aims, the two implementations of the effective approach show the different advantages of an effective field theory. In the first case the effective operators are parametrising the effect of an unknown UV completion, whereas in the second we assume this UV completion to be the MSSM
Interplay between magnetic quantum criticality, Fermi surface and unconventional superconductivity in UCoGe, URhGe and URu2Si2 by Gaël Bastien( )

1 edition published in 2017 in English and held by 2 WorldCat member libraries worldwide

This thesis is concentrated on the ferromagnetic superconductors UCoGe and URhGe andon the hidden order state in URu2Si2. In the first part the pressure temperature phase diagram of UCoGe was studied up to 10.5 GPa. Ferromagnetism vanishes at the critical pressure pc≈1 GPa. Unconventional superconductivity and non Fermi liquid behavior can be observed in a broad pressure range around pc. The superconducting upper critical field properties were explained by the suppression of the magnetic fluctuations under field. In the second part the Fermi surfaces of UCoGe and URhGe were investigated by quantum oscillations. In UCoGe four Fermi surface pockets were observed. Under magnetic field successive Lifshitz transitions of the Fermi surface have been detected. The observed Fermi surface pockets in UCoGe evolve smoothly with pressure up to 2.5 GPa and do not show any Fermi surface reconstruction at the critical pressure pc. In URhGe, three heavy Fermi surface pockets were detected by quantum oscillations. In the last part the quantum oscillation study in the hidden order state of URu2Si2 shows a strong g factor anisotropy for two Fermi surface pockets, which is compared to the macroscopic g factor anisotropy extractedfrom the upper critical field study
Théorie des systèmes de lanthanide : transitions de valence et effet Kondo en presence de désordre by José Luiz Ferreira Da Silva jr( )

1 edition published in 2016 in English and held by 2 WorldCat member libraries worldwide

The topics of the thesis concerns two theoretical aspects of the physics of 4f electron systems.In the first part the topic of intermediate valence and valence transitions in lanthanide systems is explored. For that purpose, we study an extended version of the Periodic Anderson Model which includes the Coulomb interaction between conduction electrons and the localized f electrons (Falicov-Kimball interaction). If it is larger than a critical value, this interaction can transform a smooth valence change into a discontinuous valence transition. The model is treated in a combination of Hubbard-I and mean-field approximations, suitable for the energy scales of the problem.The zero temperature phase diagram of the model is established. It shows the evolution of the valence with respect to the model parameters. Moreover, the effects of an external magnetic field and ferromagnetic interactions on the valence transitions are investigated. Our results are compared to selected Yb- and Eu-based compounds, such as YbCu2Si2, YbMn6Ge6-xSnx and EuRh2Ir2.In the second part of the thesis, we study lanthanide systems in which the number of local magnetic atoms is tuned by substitution of non-magnetic atoms, also known as Kondo Alloys. In such systems it is possible to go from the single Kondo impurity to the Kondo lattice regime, both characterized by different type of Fermi liquids. The Kondo Alloy model is studied within the Statistical Dynamical Mean-Field Theory, which treats different aspects of disorder and is formally exact in a Bethe lattice of any coordination number.The distributions of the mean-field parameters, the local density of states and other local quantities are presented as a function of model parameters, in particular the concentration of magnetic moments x, the number of conduction electrons per site nc and the Kondo interaction strength JK. Our results show a clear distinction between the impurity (x<<1) and the lattice (x≈1) regimes for a strong Kondo interaction. For intermediate concentrations (x≈nc), the system is dominated by disorder effects and indications of Non-Fermi liquid behavior and localization of electronic states are observed. These features disappear if the Kondo interaction is weak. We further discuss the issue of low dimensionality and its relation to the percolation problem in such systems
Contrôle d'électrons et de dopants uniques dans des transistors silicium by Benoit Voisin( )

1 edition published in 2013 in English and held by 2 WorldCat member libraries worldwide

Recent progress in Silicon-On-Insulator transistors fabrication have concerned a dimensions reduction, up to a few tens of nanometers, and an improvement of the leads. This allows to study the few electrons regime at low temperature. These latter are confined in the corners of the nanowire, where the electric field is maximized. This leads for the silicon valley degeneracy to be lifted, with a singlet for the two-electron ground state at zero magnetic field. We also investigate the interactions between these confined electrons and the electrons of the contacts conduction bands, with the Kondo effect and the Fermi-edge singularity.The dopants, essential ingredients of the transistors fabrication, naturally lift the valley degeneracy thanks to their deep confinement potential. First, by tuning the transverse electric field, we investigate the influence of the complex environment on a donor's ionization according to its position in the nanowire. We then realized the first Coupled-Atom Transistor, where the transport is controlled by the alignment of the ground states of two dopants placed in series. We could measure an energy splitting between the two first states of the order of 10 meV, one order of magnitude larger than that of the first electrons of the conduction band. This large separation allows to manipulate the electronic states in the ten's gigahertz regime. We induce one-electron interferences between the ground states of the two dopants, opening the way towards coherent electron manipulations in dopant-based devices
Bases moléculaires de l'adaptation piézophile : études structurales et biochimiques d'enzymes clés du métabolisme provenant d'archées et de bactéries isolées dans les fonds marins by Louise Lassalle( )

1 edition published in 2014 in French and held by 2 WorldCat member libraries worldwide

The recent discovery of marine biodiversity shows that a large part of the biosphere is a high-pressure environment. The existence of a specific pressure adaptation is still an open question. Recently, the first obligate piezophilic hyperthermophilic microorganism was isolated from hydrothermal vent. This finding suggests the existence of a specific enzyme adaptation with respect to high pressure.To deeper understanding protein adaptation with respect to high pressure, we examine the enzymatic properties of two family enzymes, malate deshydrogenases and glyoxylate hydroxypyruvate reductases arising from piezophilic and non-piezophilic organisms.Using an integrated approach combining enzymology, biophysics and X-ray crystallography, we reveal significantly different behaviors with respect to high pressure. Our analysis show that these differences involved the dynamic component of the enzyme. These results suggest that pressure could be a discriminating parameter susceptible to induce an adaptative response.This thesis work allows to set the foundations of a protein-properties comparative method with respect to high pressure to reveal piezophilic adaptation in other protein systems
Dynamique de l'eau d'hydratation de la protéine tau dans des formes native et amyloïde by Yann Fichou( )

1 edition published in 2015 in English and held by 2 WorldCat member libraries worldwide

Proteins that do not have a well-defined structure in their functional state are referred to as intrinsically disordered proteins (IDPs). IDPs are ubiquitous in biological cells and their aggregation is involved in many diseases. The extended conformations of IDPs result in a large water interface, yet, interactions between IDPs and water are only scarcely documented. Water has been termed the matrix of life because it is essential for a variety of molecular processes, including protein folding, stability, and activity. The IDP tau regulates microtubule activity in neurons and is known to form amyloid fibers that are one of the hallmarks of Alzheimer disease. In this PhD thesis, the biological relevance of water dynamics around IDPs is addressed. We combine computational and experimental approaches, including all-atom MD simulations, incoherent neutron scattering, terahertz spectroscopy and small angle X-ray scattering, to study the hydration water dynamics of the tau protein in its native and fibrillated states. Firstly, a translational diffusion of hydration water molecules is found to be essential for biologically relevant dynamics of both IDPs and globular proteins. Secondly, compared to monomers, we find an enhancement of hydration water mobility around tau amyloid fibers that is suggested to play a role in fiber formation. Finally, the investigation of collective water dynamics reveals that the tau protein influences about two times less water molecules than a globular protein, which might be involved in tau's binding mechanisms. In conclusion, this piece of work investigated the dynamical properties of water around IDPs and suggests that the hydration water dynamics might play fundamental roles in binding and aggregation of IDPs
 
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Alternative Names
École doctorale 47

École doctorale de physique de Grenoble

ED 047

ED 47

ED PG

ED PHYS (Grenoble)

ED Physique

ED physique (Grenoble)

ED047

ED47

EDPG

Languages
French (13)

English (9)