Dans le Modèle Standard de la physique des particules, la théorie de l’interaction forte, la chromodynamique quantique (QCD), est une théorie de jauge de groupe de symétrie SU (Nc) par rapport au nombre quantique de couleur. QCD obéit à la propriété de liberté asymptotique, permettant le calcul d’observables physiques à haute énergie en utilisant la QCD perturbative (pQCD). Cette thèse traite de la description en pQCD des taux de production de hadrons dans les collisions hadroniques à haute énergie, en vue d’applications à la phénoménologie des collisions proton-noyau et noyau-noyau dans les collisionneurs de hadrons (RHIC, LHC), où des effets nucléaires (shadowing, perte d’énergie partonique, élargissement de l’impulsion transverse) entrent en jeu. Dans une première partie, j’étudie l’élargissement de l’impulsion transverse d’un système de partons énergétiques traversant un noyau, en mettant l’accent sur la structure de couleur du processus. Un cadre théorique basé sur le formalisme des dipôles est utilisé, et une équation cinétique est dérivée pour la distribution en impulsion transverse de la paire de partons, en demandant que cette paire soit dans un état de couleur donné (représentation irréductible de SU (Nc)) à la fois dans l’état initial et dans l’état final. La structure de couleur est codée dans un opérateur d’évolution de couleur, qui est obtenu pour tout type de paire de partons. Pour une paire compacte de petite taille, la dérivation donne une interprétation physique claire du processus d’élargissement de l’impulsion transverse. Dans une deuxième partie, je discute la matrice de dimension anormale Q, qui est formellement analogue à l’opérateur d’évolution précédent, et qui apparaît lors de l’ étude du rayonnement de gluons mous associé à une diffusion partonique dure 2 −> 2. Il a été remarqué que la matrice Q associée à gg −> gg a une symétrie surprenante (reliant les degrés de liberté externe et interne). J’ai développé des outils pour dériver les matrices Q associées à des diffusions 2 −> 2 impliquant des partons généralisés, afin d’explorer si la symétrie observée pour gg −> gg est fortuite ou non. / In the Standard Model of particle physics,the theory of the strong interaction, Quantum Chromodynamics (QCD), is a gauge theory of symmetry group SU (Nc) with respect to the color quantum number. QCD obeys the property of asymptotic freedom, allowing the computation of high-energy physical observables using perturbative QCD (pQCD). This thesis deals with the pQCD description of hadron production rates in high-energy hadronic collisions, in view of applications to the phenomenology of proton-nucleus and nucleus-nucleus collisions at hadron colliders (RHIC,LHC), where so-called nuclear effects (shadowing, parton energy loss, transverse momentum broadening) come into play. In a first part, I study the transverse broadening of an energetic parton system crossing a nucleus, putting emphasis on the color structure of the process. A theoretical setup based on the dipole formalism is used,and a kinetic equation is derived for the parton pair transverse momentum distribution, requiring the parton pair to be in a given color state (SU (Nc) irreducible representation) both in the initial and final state. The color structure is encoded in a color evolution operator, which is obtained for any type of parton pair. For a small-size compact pair, the derivation yields a transparent physical interpretation of the pair transverse broadening process. In a second part, I discuss the soft anomalous dimension matrix Q, which is formally analogous to the previous evolution operator, and which appears when studying soft gluon radiation associated to 2 −> 2 hard parton scattering. It has been noticed that the Q-matrix associated to gg −> gg has a surprising symmetry (relating external and internal degrees of freedom). I developed tools to derive the Q-matrices associated to2 −> 2 scatterings involving generalized partons, in order to explore if the symmetry observed for gg −> gg is fortuitous or not.

The threshold characteristics of multimode laser oscillators are considered in detail, and a new model is given for semiconductor diode lasers. Analytical expressions and numerical solutions are obtained for mode amplitudes, and over-all spectral characteristics of lasers operating above and below threshold. The theoretical results are i n agreement with experimental data. The band-ta-band absorption is included in the model and i t ' s effect is studied on the mixed broadening.

Diagnostic measurements play a vital role in experiments. Without them we would be in the dark with no way of knowing what was happening; of understanding the processes and behaviour occurring; or even of judging the success or failure of our experiments. The development of fusion plasma devices is no different. In this thesis we concentrate on visible spectroscopy based diagnostics: examining the techniques for measurement and analysis; the breadth of plasma parameters that can be extracted from the spectroscopic data; and how the application of these diagnostic techniques gives us a broader picture of the plasma and the events taking place within. Techniques are developed and applied to plasmas in three fusion experiments, EXTRAP T2R, ASDEX Upgrade and JET. The diagnostic techniques exploit different features of the measurements of the emitted photons to obtain various useful plasma parameters. Determination of the ion temperature and rotation velocity of oxygen impurity ions in the EXTRAP T2R plasma is achieved through measurement and analysis of, respectively, the Doppler broadening and the Doppler wavelength shift of visible wavelength atomic spectral lines. The evolution of the temperature and rotation is studied as a function of the discharge parameters, in particular looking at the effect of applying active feedback control schemes to the resistive wall modes and/or pulsed poloidal current drive. Measurements of multiple ionisation stages are used to estimate radial profiles of the toroidal rotation and the ion temperature and correlations between the ion rotations and the rotation velocities of tearing modes are also established. Radial profiles of the emissivity and density (or concentration) of the oxygen ions are obtained by means of measurements of the spectral line intensities on a small array of linesof- sight through the plasma. Changes to the profiles for different plasma schemes and the implications for particle transport are investigated. The derived emissivity profiles are used in the analysis for some of the other spectroscopic diagnostics. Spectral line intensity measurements (in this case of neutral ions) are also the basis for calculations of both the electron temperature and the particle fluxes at the plasma edge. The latter is an indicator of the degree and type of interaction between the plasma and the surrounding surfaces. Particle fluxes of the operating gas hydrogen and of chromium and molybdenum impurities are investigated in EXTRAP T2R for different operating scenarios, in particular changes in the metallic influx with the application of active feedback mode control are examined along with the correspondence between spectroscopic and collector probe results. In the ASDEX Upgrade divertor estimates of the particle flux of the deuterium operating gas are also made through analysis of spectral intensities. Molecular D2 band structure is explored in addition to the Balmer Dα spectral line intensity to acquire both atomic and molecular particle fluxes, investigate the contribution of the dissociating D2 to the Dα line and study the effect of changes in the divertor. Analysis of the D2 molecular band structure (the relative intensities of the rotational lines and vibrational bands) also enables calculation of the upper state rotational and ground state vibrational temperatures. The locations of emitting atomic ions in JET are estimated from Zeeman splitting analysis of the structure of their spectral lines. The measurement and analysis of visible wavelength light is demonstrated to be a sensitive diagnostic tool in the quest for increased knowledge about fusion plasmas and their operating scenarios. / QC 20100810

The paradigm of drug discovery have been to find the strongest possible binder to the target by high-throughput screening (HTS) but high affinity interactions are related to low kinetic off rates and thus result in severe side-effects and non-approved drugs. Lead molecules working in a transient manner (KD > µM) will allow for rapid off rates and possibly less side-effects. In this study the peak profile method applied to weak affinity chromatography (WAC) was evaluated as a simple way to provide the kinetics of the interaction and thereby allowing for high-throughput determinations. In the peak profile formula all band-broadening effects except the stationary mass transfer is subtracted which simplifies the calculations for the kinetics of the interaction tremendously. The technique was evaluated by screening of 3 different benzamidines at 3 linear flow-rates using zonal chromatography and human α-thrombin as immobilized target protein. The kinetics of the interaction could unfortunately not be determined. This was possibly due to the flow-rates not being high enough as indicated by a low critical ratio (η < 1). Higher flow-rates would increase the contribution to band-broadening due to kinetic effects but would also require more precise estimation of peak variance.

Magic-sized nanocrystals (MSNs) are nanocrystals with a single size distribution. They have narrow spectral features that do not exhibit inhomogeneous line broadening. This enabled us to analyze homogeneous line broadening of CdSe and CdTe MSNs. In solution, we observed two aggregated configurations of CdSe and CdTe MSNs. Sub-peaks within MSN excitonic peaks were caused by these two aggregated configurations and surface states. A two-dimensional photoluminescence spectrum of a mixture of CdTe 427 nm and 500 nm MSNs gave direct evidence of Förster resonant energy transfer (RET) between the two sizes of MSNs. Normalized experimental overlap between donor emission and acceptor absorption spectra was on the order predicted by theory, confirming that there is sufficient overlap for RET to take place in this system. Additionally, within both aggregated configurations, the two sizes of MSNs were within sufficient distance from one another for RET to occur.

Magic-sized nanocrystals (MSNs) are nanocrystals with a single size distribution. They have narrow spectral features that do not exhibit inhomogeneous line broadening. This enabled us to analyze homogeneous line broadening of CdSe and CdTe MSNs. In solution, we observed two aggregated configurations of CdSe and CdTe MSNs. Sub-peaks within MSN excitonic peaks were caused by these two aggregated configurations and surface states. A two-dimensional photoluminescence spectrum of a mixture of CdTe 427 nm and 500 nm MSNs gave direct evidence of Förster resonant energy transfer (RET) between the two sizes of MSNs. Normalized experimental overlap between donor emission and acceptor absorption spectra was on the order predicted by theory, confirming that there is sufficient overlap for RET to take place in this system. Additionally, within both aggregated configurations, the two sizes of MSNs were within sufficient distance from one another for RET to occur.

No description available.

The linewidths and line positions of 4I15/2 to 4I13/2 absorption transitions of trivalent erbium in CsCdBr₃ and CaF₂ were measured as a function of temperature from approximately 10 K to 300 K. By comparing the temperature dependence of these transitions with theoretical models of electron-phonon coupling the primary mechanism involved were determined. For Er3+ doped CaF₂ the Raman scattering processes dominated the line broadening, although the single-phonon direct processes were significant enough to drastically alter the values of the Raman scattering electron-phonon coupling constant. In comparison, the Er³⁺ doped CsCdBr₃ had negligible Raman scattering contributing to the line broadening. This is likely due to the exceedingly low Debye temperature and consequently low number of phonons, reducing the likelihood of two-phonon processes relative to single-phonon processes. The results were then analysed in terms of the bond length with the ligands and compared with other studies showing that as the bond length gets shorter the electron-phonon coupling constant associated with Raman scattering is expected to get smaller. To explain the line shifts in CaF₂:Er³⁺ it is necessary to treat the Debye temperature as a parameter. This indicates that the phonon modes causing the line shifts are different from those causing the line broadening, and in most of the cases are vibronic processes rather than Raman processes. In the case of CsCdBr₃:Er³⁺ there is very little difference between the fits using the fixed Debye temperature and a varied Debye temperature in over half of the cases examined. Given the distribution of phonon modes, it is likely that this small difference arises because combinations of these processes are of similar intensity, meaning that a combination of Raman and optical phonon modes are likely causing the line shift.

No description available.

Aplicações em ambientes expostos a elevados níveis de radiação ionizante impõem uma série de desafios ao desenvolvimento de projetos de circuitos integrados na tecnologia Complementary Metal–Oxide–Semiconductor (CMOS), uma vez que circuitos CMOS estão sujeitos às falhas transientes oriundas de radiação externa. Num circuito do tipo CMOS, as áreas sensíveis aos efeitos da incidência de partículas ionizantes são as regiões dreno-substrato reversamente polarizadas, existentes nos transistores em regime de corte (VARGAS; NICOLAIDIS, 1994). Com o avanço tecnológico e consequente diminuição das dimensões dos dispositivos semicondutores, estes efeitos degradantes tornam-se uma preocupação constante devido às menores características físicas dos transistores (WANG et al., 2007). Os circuitos integrados apresentam, durante a sua vida útil, um processo de degradação das suas características iniciais. Assim, a esse processo de degradação também chamamos de envelhecimento (aging). É um processo lento e cumulativo provocado por todos os mecanismos que acabam por alterar os parâmetros físicos e eléctricos dos circuitos, diminuindo o seu tempo de vida útil (FU; LI; FORTES, 2008). Dentre os efeitos de variabilidade temporal, os que mais têm causado interesse da comunidade científica são o Randon Telegraph Noise (RTN) com sua origem na atividade de traps (armadilhas) de interface e Single Event Transients (SET) com sua origem na radiação ionizante ao qual o circuito é exposto. Em relação aos efeitos de degradação destaca-se o efeito Bias Temperature Instability (BTI) (VALDUGA, 2012), que da mesma forma que o RTS, tem sua origem vinculada aos efeitos das traps.Modelos padrão para simulação elétrica de circuitos não levam em consideração os efeitos causados por armadilhas de cargas tais como Bias Temperature Instability (BTI) e Random Telegraph Noise (RTN). Tais variabilidades em nível de dispositivo podem causar perda de confiabilidade, como por exemplo, o surgimento de Propagation-Induced Pulse Broadening (PIPB). Conforme o escalonamento (scaling) tecnológico, a velocidade das portas lógicas aumenta e os SETs podem ser propagados através de circuito combinacional e, inclusive, sofrer alargamento, caso a largura do pulso transiente supere um valor mínimo crítico que depende da tecnologia (DODD et al., 2004), caracterizando assim um PIPB. Com base nisso, técnicas de injeção de falhas usadas em circuitos complexos não se mostram eficientemente previsíveis, levando a uma subestimativa da sensibilidade de circuitos à propagação de SETs. Com a utilização de um simulador elétrico que agrega a análise de BTI, temos melhores estimativas dos efeitos de PIPB na degradação de um circuito, que pode provocar violações de temporização em sistemas síncronos. Dessa forma, pode-se então trabalhar em uma projeção do circuito de forma a torná-lo mais robusto em relação aos efeitos de envelhecimento e na proteção às falhas transientes. Com base no que foi anteriormente apresentado, este trabalho analisa o comportamento de circuitos através de simulações elétricas de radiação ionizante, permitindo avaliações da suscetibilidade e confiabilidade de circuitos integrados aos efeitos de falhas transientes. Para a realização destes experimentos, foram realizadas simulações elétricas considerando-se os efeitos de envelhecimento. Para uma cadeia lógica de 2000 inversores sequencialmente dispostos na tecnologia 32nm pode-se prever que o pulso transiente está sujeito a um alargamento de sete vezes sua largura inicial no momento da incidência, para transistores em suas dimensões mínimas. A partir da proposta apresentada, pode-se determinar a possibilidade de alargamento ou atenuação de um SET ao longo do circuito de maneira eficiente para que as devidas precauções possam ser tomadas. / Applications in environments exposed to high levels of ionizing radiation impose a number of challenges for the development of integrated circuit designs in CMOS technology. CMOS circuits are vulnerable to transient faults from external radiation. In a CMOS circuit, areas sensitive to the effects of ionizing particle incidence are as reverse polarized drain-substrate regions in the transistors at cut-off (VARGAS; NICOLAIDIS, 1994). The technological advance and consequent downscaling of semiconductor devices, these degrading factors become a constant concern due to the higher vulnerability to transient faults (WANG et al., 2007). The integrated circuits have during their useful life a process of degradation of their initial characteristics. Thus, this process of degradation is also called aging. It is a slow and cumulative process caused by all the mechanisms that end up changing the physical and electrical parameters of the circuits, decreasing their useful timing life (FU; LI; FORTES, 2008). Among the temporal variability effects, the Randon Telegraph Noise (RTN) with its origin in the activity of traps (interface traps) and Single Event Transients (SET) with their origin in the ionizing radiation circuit is exposed. In terms of the effects of degradation, the Bias Temperature Instability (BTI) effect (VALDUGA, 2012) stands out, which, like the RTS, has its origin linked to the effects of the traps. Standard electrical simulation models do not take into account the effects caused by charged traps such as Bias temperature instability (BTI) and random telegraph noise (RTN). Such device-level variability can cause reduced reliability, for example, the Propagation-Induced Pulse Broadening (PIPB). According to the technological scaling, the speed of the logic gates increases and the SETs can be propagated through a combinational circuit and even may suffer broadening if the transient pulse width exceeds a critical minimum value that depends on the technology (DODD et al., 2004 ), characterizing a PIPB. Based on this, fault injection techniques in complex circuits are not efficiently in predicting, leading to an underestimation of circuit sensitivity to propagation of Single Event Transients (SETs). Using an electrical simulator that aggregates a BTI analysis, we have better estimates of PIPB effects on circuit degradation, which may lead to timing violations in synchronous systems. Then we can put effort in circuit design in order to make it more robust regarding to aging effects and transient faults protection. Based on what has been previously presented, this thesis analyzes the behavior of circuits through electrical simulations of ionizing radiation, allowing susceptibility and reliability evaluations of integrated circuits to the effects of transient faults using electrical simulations. For the accomplishment of these experiments, electrical simulations were performance considering the effects of aging. For a logic chain of 2000 inverters sequentially arranged in the 32nm technology it can be predicted that the transient pulse is subjected to a broadening of seven times its initial width at the time of incidence for transistors with minimum dimensions. From the analysis presented, we can evaluate the possibility of broadening or shrinking of SETs thought the circuit in an efficient way to improve radiation-hardening techniques.