Neste trabalho, abordamos dois assuntos independentes e interessantes que permeiam o cotidiano dos pesquisadores da área de resfriamento e confinamento de átomos neutros. O primeiro está relacionado aos processos de perda de átomos ocorrendo em armadilhas magneto-ópticas, a partir das quais o fenômeno é observado. Mostramos que a conjunção de dois modelos tradicionais da literatura é capaz de gerar um modelo semiclássico e semi-analítico básico e robusto, capaz de reproduzir as características fundamentais dos resultados experimentais já obtidos, incluindo os mais recentes. Isto demonstra que os aspectos essenciais dos mecanismos de perda em armadilhas são, agora, bem compreendidos. O segundo assunto abordado aqui está relacionado à observação de moléculas diatômicas formadas em armadilhas magneto-ópticas. Nesse sentido, uma série de experimentos básicos foi realizada, gerando resultados e discussões que constituem uma rica fonte de informação inspirando a continuação e conclusão do trabalho iniciado aqui, cujo objetivo final é a caracterização precisa e o desenvolvimento técnicas de resfriamento e aprisionamento de moléculas diatômicas heteronucleares. / We report the results concerning to two main subjects of laser cooling and trapping community. We begin by presenting the results of modeling two-body trap loss rates as a function of the trap laser intensity. We show that one can merge two simple theories to obtain a semiclassical and semi-analytical model which is able to provide the fundamental properties observed in the experimental results found in the literature. Hence, we concluded that the essential features of the two-body trap loss rates taking place in MOTs are now well understood. On the other hand, we run a set of experiments trying to produce and detect heteronuclear diatomic ultracold molecules. Although this has not been accomplished yet, we have acquired a wide and rich amount of data that will certainly be very helpful for continuing and concluding the work here started. In the near future the photoassociation spectroscopy of ultracold heteronuclear diatomic molecules will provide valuable information to help in its manipulation.

O estudo de teorias de calibre não-Abelianas fortemente acopladas, em especial de aspectos térmicos e fora do equilíbrio, é um problema central para a compreensão da Cromodinâmica Quântica (Quantum Chromodynamics - QCD) - em particular, para entender a evolução do Plasma de Quarks e Glúons (Quark-Gluon Plasma- QGP). A técnica mais promissora, QCD na rede, obteve sucesso ao tratar de fenômenos no vácuo e em equilíbrio térmico, como espectros e termodinâmica, mas enfrenta desafios consideráveis ao lidar com fenômenos fora do equilíbrio. Uma ferramenta adaptada para lidar com problemas envolvendo plasmas fortemente acoplados em tempo real é a dualidade gauge/gravity, que mapeia uma Teoria Quântica de Campos (Quantum Field Theory - QFT) fortemente acoplada em d dimensões em uma teoria de gravitação em d + 1 dimensões, a qual, de modo geral, é mais fácil de ser resolvida. Nesta tese, estudamos diversas aplicações da dualidade gauge/gravity em teorias não-Abelianas fortemente acopladas que modelam qualitativamente o QGP. Nós estudamos o cálculo holográfico do potencial entre um par quark-antiquark pesado (QQ) para dipolos QQ estáticos e se movendo com relação ao plasma, apresentando um formalismo geral para o cálculo da parte real e imaginária para uma grande classe de teorias gravitacionais duais. Um estudo da massa de Debye holográfica, baseado no maior comprimento de correlação de operadores ímpares por transformações de CT, foi empreendido, com aplicações em modelos bottom-up que reproduzem a termodinâmica da teoria de Yang-Mills SU(Nc) pura e da QCD. Para estes modelos, também calculamos vários coeficientes de transporte associados com o transporte de cargas no plasma, como a condutitividade elétrica, a constante de difusão de carga e coeficientes de transporte associados a uma teoria de hidrodinâmica relativística de segunda ordem. / The study of strongly coupled non-Abelian gauge theories, especially concerning their thermal and non-equilibrium aspects, is a central problem for understanding Quantum Chromodynamics (QCD) - in particular, to understand the evolution of the Quark-Gluon Plasma (QGP). The most successful approach, lattice QCD, succeeds in dealing with vacuum and equilibrium phenomena, such as spectra and thermodynamics, but faces a considerable challenge when it comes to with non-equilibrium phenomena. A tool adapted to deal with real time problems in strongly coupled plasmas is the gauge/gravity, which maps a strongly coupled d dimensional Quantum Field Theory (QFT) to a d + 1 dimensional theory of gravity, which, in general, is easier to solve. In this thesis, we study several applications of the gauge/gravity duality to strongly coupled non-Abelian theories which model qualitatively the QGP. We deal with the holographic evaluation of the heavy quark-antiquark (Q Q) potential for static and moving QQ dipoles, presenting a general formalism for the computation of the real and imaginary parts for a large class of dual theories of gravity. A study of the holographic Debye mass, based on the largest screening length of CT-odd operators, is pursued, with applications on bottom-up holographic models that reproduce the thermodynamics of pure SU(Nc) Yang-Mills theory and QCD. For these models, we also compute several transport coefficients associated with charge transport in the plasma, such as the electric conductivity, the charge diffusion constant, and transport coefficients associated with a theory of second order relativistic hydrodynamics.

Neste trabalho, estudamos a fotoassociação de átomos de rubídio no regime de curto alcance. Realizamos espectroscopia por perda de átomos em uma armadilha magneto-óptica de 85Rb usando um laser de fibra de alta potência, o qual possuia largura de linha da ordem de 1MHz e 50W de potência no intervalo de 1060nm a 1070nm. Dois níveis vibracionais do potencial excitado 0u+ foram observados (v=137 e v=138). Além disso, medimos o tempo de vida de uma armadilha óptica de dipolo cruzada. Como esperado, o tempo de vida é menor quando o laser está sintonizado na ressonância. Um modelo teórico prevê a distribuição dessas moléculas nos níveis vibracionais do estado eletrônico fundamental após o processo de fotoassociação. Os resultados, nos sugerem perspectivas para a produção de moléculas de Rb2 no estado vibracional fundamental. / In this work, we studied short-range photoassociation of rubidium atoms. We realize trap-loss spectroscopy in a magneto-optical trap of 85Rb using high power fiber laser, which had around 1MHz linewidth and 50W power at 1060nm to 1070nm interval. Two vibrational levels of the 0u+ excited potential were observed (v=137 e v=138). Besides that, we measured the lifetime of a crossed optical dipole trapped. As expected, the lifetime is shorter when the laser is tuned on resonance. A theoretical model predicts the molecular distribution in the vibrational levels of electronic ground state. The results suggest us perspectives to produce Rb2 molecules in the ground vibrational state.

Dans cette thèse nous implémentons une approche Sturmienne, qui se sert de fonctions Sturmiennes généralisées (GSFs, en anglais), pour étudier l'ionisation de molécules par collisions de photons ou d'électrons. Comme l'Hamiltonian de la cible est non central, la description de l'ionisation des molécules n'est pas simple. En plus, puisque l'orientation spatiale de la molécule n'est généralement pas déterminée lors des expériences, une question importante à considérer est l'orientation aléatoire de la cible. Dans la littérature, des nombreuses méthodes théoriques ont été proposées pour traiter les molécules ; néanmoins, la plupart sont adaptées pour étudier, principalement, des états liés. Une description précise des états non-liés (continuum) des molécules reste un défi. Ici, nous proposons d'attaquer le problème avec les GSFs qui ont, par construction, un comportement asymptotique approprié au système étudié. Cette propriété permet de faire des calculs d'ionisation de façon plus efficace. Dans une première partie, nous validons l'implémentation de notre approche Sturmienne par l'étude de la photo-ionisation (PI) d'atomes. Différents potentiels effectifs sont utilisés pour décrire l'interaction de l'électron éjecté avec la cible ionisée. Les sections efficaces de PI sont calculées dans les jauges de longueur et de vitesse. Pour l'atome d'hydrogène la comparaison avec la formule analytique, indique qu'une convergence très rapide est obtenue avec un nombre modéré de GSFs. Pour He et Ne, nos résultats montrent, également, un très bon accord avec d'autres résultats théoriques et expérimentaux. Dans le cas des molécules, nous avons abordé l'orientation aléatoire avec deux stratégies : une utilise un potentiel moléculaire modèle (non-central), et l'autre un potentiel moyenné (central). Nous étudions la PI de CH4, NH3 et H2O à partir des orbitales de valence extérieure et intérieure, et aussi de SiH4 et H2S à partir des orbitales extérieures. Les sections efficaces de PI et les paramètres d'asymétrie (obtenus à partir des distributions angulaires) sont comparés avec ceux publiés dans la littérature. Nos résultats sont globalement satisfaisants et reproduisent les caractéristiques principales de ce processus d'ionisation. Dans une deuxième partie de la thèse, nous utilisons l'approche Sturmienne pour étudier l'ionisation de molécules par impact d'électrons. Pour le processus (e,2e), les sections efficaces triplement différentielles (TDCSs) sont examinées dans la première et deuxième approximation de Born, également en traitant de deux façons l'orientation aléatoire des molécules. Nous avons testé la méthode en comparent nos TDCSs pour l'atome d'hydrogène, montrant aussi son efficacité. Enfin, nous l'avons apliqué à l'ionisation de CH4, H2O et NH3, et nous avons comparé les résultats avec des données expérimentales et théoriques disponibles dans la littérature. Dans la plupart des cas, nos TDCSs sont en accord satisfaisant avec ces données, en particulier pour H2O et pour des électrons lents dans le cas de CH4 / In this PhD thesis we implement a Sturmian approach, based on generalized Sturmian functions (GSFs), to study the ionization of molecules by collision with photons or electrons. Since the target Hamiltonian is highly non-central, describing molecular ionization is far from easy. Besides, as the spatial orientation of the molecule in most experimental measurements is not resolved, an important issue to take into account is its random orientation. In the literature, many theoretical methods have been proposed to deal with molecules, but many of them are adapted to study mainly bound states. An accurate description of the unbound (continuum) states of molecules remains a challenge. Here we propose to tackle these problems using GSFs, which are characterized to have, by construction, the correct asymptotic behavior of the studied system. This property allows one to perform ionization calculations more efficiently. We start and validate our Sturmian approach implementation by studying photoionization (PI) of H, He and Ne atoms. Different model potentials were used in order to describe the interaction of the ejected electron with the parental ion. We calculated the corresponding PI cross sections in both length and velocity gauges. For H atom, the comparison with the analytical formula shows that a rapid convergence can be achieved using a moderate number of GSFs. For He and Ne we have also an excellent agreement with other theoretical calculations and with experimental data. For molecular targets, we considered two different strategies to deal with their random orientation: one makes use of a molecular model potential (non-central), while the other uses an angular averaged version of the same potential (central). We study PI for CH4, NH3, and H2O, from the outer and inner valence orbitals, and for SiH4 and H2S from the outer orbitals. The calculated PI cross sections and also the asymmetry parameters (obtained from the corresponding angular distributions) are compared with available theoretical and experimental data. For most cases, we observed an overall fairly good agreement with reference values, grasping the main features of the ionization process. In a second part of the thesis, we apply the Sturmian approach to study ionization of molecules by electron collisions. In the so-called (e,2e) processes, fully differential cross sections are investigated within both the first- or the second-Born approximations. Again, we show how to include in the description the random orientation of the molecule. We start with H atom, as a test system: the comparison of the calculated triple differential cross sections (TDCSs) with analytical results illustrates, similarly to the PI case, the efficiency of our GSF method. It is then applied to ionization of CH4, H2O and NH3, and comparisons are made with the few theoretical and experimental data available in the literature. For most cases, our TDCSs can reproduce such data, particularly for H2O and for slow ejected electrons in CH4

Neste trabalho apresentamos a construção de um novo sistema experimental para aprisionamento de átomos e moléculas. Trata-se de uma armadilha de dipolo cruzada totalmente óptica, formada por um laser de fibra com 40 W de potência com comprimento de onda em 1064 nm. Nesse sistema foi demonstrado o aprisionamento de átomos Rb e K e moléculas Rb2. Realizamos dois experimentos distintos neste se novo sistema: No primeiro, estudamos a evolução temporal de amostras dos isótopos 85Rb e 87Rb na armadilha de dipolo cruzada. Pudemos medir pela primeira vez o processo de mudança de estrutura hiperfina em átomos sem a presença de luz ressonante, e observamos a fotoassociação dos átomos pelo laser da armadilha de dipolo. E no segundo, desenvolvemos uma técnica que permite o estudo rápido e direto do decaimento no número de moléculas de Rb2 na armadilha. Com essa técnica, observamos também o comportamento dessas moléculas na presença de átomos preparados em um determinado estado hiperfino do estado fundamental. Estes resultados juntamente com um desenvolvimento teórico, nos sugerem novas perspectivas rumo a produção de um sistema que possa produzir e aprisionar moléculas KRb no estado fundamental 1Σ+ (v = 0). / In this work, we present the construction of a new experimental system for trapping atoms and molecules. It is an all optical crossed dipole trap, formed by a fiber laser with 40 W of power at 1064 nm. In this system, we have trapped K and Rb atoms as well as Rb2 molecules. We have carried out two experiments in this new system. In the first, we studied the temporal evolution of atomic samples of different isotopes, 85Rb and 87Rb, in the crossed trap dipole. We were able to measure for the first time the hyperfine-changing collisions of atoms in the absence of resonant light, and we have observed photoassociation of atoms by the dipole trap laser beam. In the other experiment, we have developed a technique that allows us to study the trapped molecule population decay in the trap. It was also observed the molecule population decay in the presence of atoms prepared in a given hyperfine state of the ground state. These results together with a theoretical development may suggest us new perspectives towards the production of a system that can produce and trap KRb molecules in the ground state 1Σ+ (v = 0).

Cette thèse se place dans un contexte médical de traitements oncologiques, plus particulièrement en protonthérapie robotisée. L’objectif de cette thèse, réalisée sous contrat Cifre avec la société LEONI CIA Cable Systems, est le développement d’une commande en co-manipulation sûre dédiée à un robot médical sériel. Cette commande doit permettre à un opérateur de manipuler intuitivement et précisément un robot de grande inertie positionneur de patients. Les contributions portent sur deux axes, d’une part le développement et l’implémentation sur le robot Orion de l’entreprise LEONI CIA Cable Systems d’une commande en admittance ainsi que la comparaison de trois dispositifs haptiques, et d’autre part le développement d’un mécanisme de détection de collisions proprioceptif permettant l’amélioration de la sécurité de fonctionnement. À partir d’une revue de la littérature concernant les commandes compliantes, nous avons développé et implémenté une commande en admittance dédiée au robot Orion en tenant compte de la discrétisation de la commande par le contrôleur spécifique de ce robot. Une expérience de comparaison sur le robot nous a permis d’identifier le dispositif haptique le mieux adapté au cas clinique considéré. Après une étude de l’état de l’art des mécanismes de détection de collisions, une approche fréquentielle de la modélisation du couple axial prenant en compte les rapports de réduction élevés et de technologie différente du robot a été proposée. Elle permet de modéliser finement le couple théoriquement fourni par les moteurs ; celui-ci est ensuite comparé avec la mesure du couple réellement produit afin de détecter une éventuelle collision. / This PhD thesis takes place in a medical context of oncological treatments, more particularly in robotised protontherapy. The objective of this thesis, carried out under a CIFRE contract with LEONI CIA Cable Systems, is the development of a safe comanipulation control dedicated to a serial medical robot. This control law should allow an operator to intuitively and precisely manipulate a robot of high inertia for accurate patients positioning. The contributions of this thesis focus on the development and implementation of an admittance-controlled Orion robot from LEONI CIA Cable Systems and the comparison of three haptic devices, and on the other hand, on the development of a proprioceptive collision detection mechanism allowing the improvement of operational safety. Based on a review of the literature on compliant controls, we have developed and implemented an admittance control approach dedicated to the Orion robot, taking into account the discretization of the control by the controller specific to this robot. A comparison experiment on the robot allowed us to identify the haptic device best suited to the clinical case considered. Based on a state of the art of collision detection mechanisms analysis, a frequency approach of the modeling of the axial torque taking into account the high reduction ratios and different robot technology has been proposed. It allows us to finely model the torque theoretically provided by the motors ; The latter is then compared with the measurement of the torque actually produced in order to detect a possible collision.

This dissertation is concerned with the understanding of physico-chemical properties of energetic materials (EMs). Recently, a substantial amount of work has been directed towards calculations of equations of state and structural changes upon compression of existing EMs, as well as elucidating the underlying chemistry of initiation in detonating EMs. This work contributes to this effort by 1) predicting equations of state and thermo-physical properties of EMs, 2) predicting new phases of novel EMs, and 3) examining the initial stages of chemistry that result in detonation in EMs. The motivation for the first thrust, is to provide thermodynamic properties as input parameters for mesoscale modeling. Such properties are urgently sought for a wide range of temperatures and pressures, and are often difficult or even impossible to obtain from experiment. However, thermo-physical properties are obtained by calculating structural properties and vibration spectra using density function theory and employing the quasi-harmonic approximation. The second thrust is directed towards the prediction and investigation of novel polymorphs of known azide compounds to identify precursor materials for synthesis of polymeric nitrogen EMs. Structural searches are used to identify new polymorphs, while theoretical Raman spectra for these polymorphs are calculated to aid experimentalists in identifying the appearance of these azide compounds under high pressure. The final thrust is concerned with elucidating the initial chemical events that lead to detonation through hypervelocity collision simulations using first-principles molecular dynamics. The chemical mechanisms of initiation are determined from the atomic trajectory data, while heats of reaction are calculated to quantify energy trends of chemical transformations.

Wherever wildlife share space with boaters, collisions are a potential source of mortality. Establishing protection and speed zones are the primary actions taken to mitigate collision risk. However, creation of protection zones may be a point of contention with stakeholders as new zones can have significant socioeconomic impacts. The Florida Manatee is a prime example of a species whose abundance and viability are constrained by this balance between the needs of humans and wildlife on a shared landscape. The goal of this work is to help further understand the risk to manatees by quantifying the probability of lethal collisions. I hypothesized that higher boat speeds increase the probability of lethal injury to manatee during a collision and aimed to characterize the relationship between vessel speed and the probability of lethal injury to manatee. I used a logistic regression model implemented with a Bayesian approach and fitted to citizen reported collision data as a feasible method for examining the influence of vessel speed in contributing to lethal injury to a manatee when struck. I also present a method for dealing with uncertainty in data used to report collisions. To conduct this analysis, I used citizen reported collision data. These data are typically collected opportunistically, suffer from low sample sizes, and have uncertainty in reported vessel speeds. Uncertainty associated with speed values in reported collision events was assessed by performing a multiple imputation to replace qualitative vessel speed – in other words, “missing data” – with quantitative values. This procedure involves fitting log-normal distributions to radar data that contained precise vessel speeds along with a physical description like ‘planing’, ‘plowing’, or ‘idle’. For each imputation of the data, a quantitative value was selected randomly from that distribution and used in place of its initial corresponding speed category. I evaluated issues related to quasi-separation and model fit using simulated data sets to explore the importance of sample size and evaluated the effect of key sources of error. The prediction that greater strike speed increases the probability of lethal injury was supported by the data that I analyze

This thesis describes an experimental study of superelastic electron scattering from the 6^2P_3/2 state of caesium. The present status of electron-atom collision studies is initially reviewed and the motivation behind the current work is then presented. A description of the theoretical framework is subsequently provided in the context of the present experimental study, followed by an overview of the several theoretical approaches for describing electron-atom interactions which are currently available. The apparatus and experimental setup used throughout the project are also described in detail. Technical specifications and data are provided, including diagrams (where appropriate) for a laser frequency locking system, electron gun and spectrometer, atomic beam source and data acquisition system. The experimental procedures are explained and discussed, including a detailed analysis of the optical pumping process required to excite the atomic target. A substantial component of this project was to address several potential sources of systematic error and to reduce these wherever possible. All of the errors and uncertainties relevant to the experiment are discussed in chapter 5. In chapter 6 the results of the present superelastic electron scattering experiments are reported for incident electron energies of 5.5eV, 8.5eV and 13.5eV, corresponding to superelastic electron energies of 7eV, 10eV and 15eV. These results are presented as three reduced Stokes parameters, P1, P2, P3 and a coherence parameter, P+ . For comparison, predictions from a number of currently available theories are presented alongside the experimental results. Finally, conclusions are drawn on this work in the context of the current status of electron-atom scattering from alkali-metals.

Les propriétés des fragments produits lors des collisions d'ions lourds autour de l'énergie de Fermi ont été étudiées à travers le degré de liberté d'isospin. La première partie de cette étude est basée sur une approche de gaz sur réseau, où le système est consti- tué de deux types de particules (neutron, proton) subissant une interaction coulombienne et dépendante de l'isospin. Le diagramme des phases de ce système présente trois phases (liquide, fission, gaz). L'énergétique de la phase liquide et gazeuse a pu être décrite par une fonctionnelle de la densité, la dépendance en température intervenant seulement dans la densité. Le terme de symétrie de la fonctionnelle a pu être relié au contenu isotopique du plus gros fragment via une analyse de type Isoscaling. La seconde partie est consacrée aux mesures effectuées avec le multidétecteur INDRA au GANIL et à GSI. Une étude systématique des collisions symétriques les plus centrales a été effectuée afin de mesurer le pouvoir d'arrêt de la matière nucléaire et d'étudier l'équilibration en isospin des particules légères. Deux régimes ont été observé. Un régime à basse énergie (<40MeV/A) où le pouvoir d'arrêt diminue avec l'augmentation de l'énergie du faisceau, tandis qu'à haute énergie le pouvoir d'arrêt est gouverné par la quantité de matière traversée. Une autre étude réali- sée sur l'ensemble des réactions Xe+Sn à 32 et 45 MeV/A, avec différents isospin, a permis d'isoler trois mécanismes de réaction à l'aide d'une analyse en composantes principales. Le contenu isotopique des fragments légers ne dépend pas du mécanisme de réaction, mais une dépendance est observée en fonction de la violence de la collision (paramètre d'impact).