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The Physics of the B Factories
No full text928 pages - The journal version of this book should be used as the correct citation, and the full citation reference is \Ed. A.J. Bevan, B. Golob, Th. Mannel, S. Prell, and B.D. Yabsley, submitted to EPJC, SLAC-PUB-15968, KEK Preprint 2014-3."International audienceThis work is on the Physics of the B Factories. Part A of this book contains a brief description of the SLAC and KEK B Factories as well as their detectors, BaBar and Belle, and data taking related issues. Part B discusses tools and methods used by the experiments in order to obtain results. The results themselves can be found in Part C
The interplay between photo-and radiation-induced darkening in ytterbium-doped fibres
No full textInternational audienceThis letter demonstrates a remarkable interplay between photo-and radiation-induced darkening of ytterbium-doped alumino-silica optical fibres operated in amplifying conditions and harsh environments (as e.g. in space-based applications). Influences of the pump power, ionizing dose and dose rate on this interaction are characterized. The pump is capable of accelerating or slowing-down the radiation-induced darkening build-up depending on the ionizing dose. The steady state photo-radio-darkening level is independent of the dose and at least equal to the equilibrium level of pure photo-darkening. This lower limit is notably reached at low dose rates, including those encountered in space. We therefore argue that photo-resistant ytterbium-doped fibres will resist against a space mission, whatever the dose
An axially propagating two-stream instability in the Hall thruster plasma
No full textÉquipe 107 : Physique des plasmas chaudsInternational audienceCollective Thomson scattering experiments reveal the presence of high-frequency, axial electron density fluctuations at millimetric wavelengths in the Hall thruster plasma. The properties of these fluctuations are investigated experimentally and via linear kinetic theory. The relative drift of electrons and ions in the axial direction is found to be insufficient to cause excitation of the observed mode. Instead, the mode is determined to be a two-stream instability arising due to the velocity difference between singly and doubly charged ion populations in the plume
Parameter estimation for energy balance models with memory
No full textInternational audienceWe study parameter estimation for one-dimensional energy balance models with memory (EBMMs) given localized and noisy temperature measurements. Our results apply to a wide range of nonlinear, parabolic partial differential equations (PDEs) with integral memory terms. First, we show that a space-dependent parameter can be determined uniquely everywhere in the PDE's domain of definition D, using only temperature information in a small subdomain E ⊂ D. This result is valid only when the data correspond to exact measurements of the temperature. We propose a method for estimating a model parameter of the EBMM using more realistic , error-contaminated temperature data derived, for example, from ice cores or marine-sediment cores. Our approach is based on a so-called mechanistic-statistical model, which combines a deterministic EBMM with a statistical model of the observation process. Estimating a parameter in this setting is especially challenging because the observation process induces a strong loss of information. Aside from the noise contained in past temperature measurements, an additional error is induced by the age-dating method, whose accuracy tends to decrease with a sample's remoteness in time. Using a Bayesian approach , we show that obtaining an accurate parameter estimate is still possible in certain cases
Integrative taxonomy of New Caledonian beetles: species delimitation and definition of the [i]Uloma isoceroides[/i] species group (Coleoptera, Tenebrionidae, Ulomini), with the description of four new species
No full textNew Caledonia is an important biodiversity hotspot with much undocumented biodiversity, especially in many insect groups. Here we used an integrative approach to explore species diversity in the tenebrionid genus Uloma (Coleoptera, Tenebrionidae, Ulomini), which encompasses about 150 species, of which 22 are known from New Caledonia. To do so, we focused on a morphologically homogeneous group by comparing museum specimens with material collected during several recent field trips. We also conducted molecular phylogenetic analyses based on a concatenated matrix of four mitochondrial and three nuclear genes for 46 specimens. The morphological study allowed us to discover and describe four new species that belong to the group of interest, the Uloma isoceroides group. Molecular analyses confirmed the species boundaries of several of the previously described species and established the validity of the four new species. The phylogenetic analyses also provided additional information on the evolutionary history of the group, highlighting that a species that was thought to be unrelated to the group was in fact a member of the same evolutionary lineage. Molecular species delimitation confirmed the status of the sampled species of the group and also suggested some hidden (cryptic) biodiversity for at least two species of the group. Altogether this integrative taxonomic approach has allowed us to better define the boundaries of the Uloma isoceroides species group, which comprises at least 10 species: Uloma isoceroides (Fauvel, 1904), Uloma opacipennis (Fauvel, 1904), Uloma caledonica Kaszab, 1982, Uloma paniei Kaszab, 1982, Uloma monteithi Kaszab, 1986, Uloma robusta Kaszab, 1986, Uloma clamensae sp. n., Uloma condaminei sp. n., Uloma jourdani sp. n., and Uloma kergoati sp. n. We advocate more studies on other New Caledonian groups, as we expect that much undocumented biodiversity can be unveiled through the use of similar approache
Calorimétrie hadronique semi-digital super-granulaire pour un future collisineur linéaire e+e-, et mesure independente du model du Boson de Higgs dans le canal ZH→qq+X
No full textThe International Linear Collider (ILC) is a concept for a linear electron-positron acceleratorwith a centre-of-mass energy of up to 1 TeV. Its main purpose is the precise measurement ofparticles discovered by the LHC such as the Higgs boson particle. The International LargeDetector (ILD) is one of its detector concepts, specifically designed for the usage of ParticleFlow Algorithms requiring highly granular calorimeters. Within the CALICE collaboration,several prototypes of such calorimeters, exploring different technologies, have been developedand tested. This thesis focuses on one of them: a semi-digital hadron calorimeter (SDHCAL)equipped with Glass Resistive Plate Chambers (GRPC) sensors. It is a sampling calorimetercomposed of 48 layers segmented in cells of one square centimetre for a total of half a millionschannels. The first part of the present thesis describes the analysis of the data taken duringbeam tests at CERN, in which the detector was operated in a trigger less mode; saving of allincoming information in local memory. Thus an event-builder was devloped and used to extractphysics events using new algorithm based on a time clustering methods.A detailed study of the SDHCAL quality of the detector in term of detection efficiency and padmultiplicity, is performed by a well-reconstructed muons tracks using the imaging capabilityof the detector. Additionally, a method to measure the induced charge spectrum and theelectronic avalanche size in the GRPC sensors is presented, which allows the extraction of thekey parameters required to tune an accurate detector simulation. The information acquiredby the muons reconstruction was also used to improve the calorimeter response to the pionswith a visible impact on its resolution. The sensor’s and the electronics’s response needs to bemodelled for the Monte Carlo simulation (using GEANT-4) in a so-called ”digitisation” module;we developed a general digitisation method which can be applied to various high granulargaseous sensors. It has been successfully tested with GRPC and MicroMegas detectors. Afterthis detailed study of the characteristics of our calorimeter, the response to pions is then treated.The test beam at CERN provide a large sample of pions of different energy ranging between 5to 80 GeV. A detailed selection is applied to choose the hadronic showers, exploring new kindof identification variable such as fractal dimension and hit density. The selected pions are thenused for the calibration of the calorimeter in term of linearity and energy resolution.To assess the performance in the full ILD configuration, the second part of this thesis is devotedto the investigation of the model independent Higgs boson production associated with the ZHprocess. The final state is characterised by the presence of at least two jets originating from aZ boson beside the Higgs decay products. In order to perform a model independent measure-ment, the events selection does not constrain Higgs boson decaying modes. The hadronic Zdecay is characterised by a high branching ratio with respect to the leptonic one, providing anincrease of the statistics of about a factor of ten. In addition, the model-independent contextmay pinpoint a deviation from the SM expectations of Higgs boson decays. The first analysisdemonstrated the feasibility of the model-independent Higgs tagging using the hadronic decayof the Z boson at 250GeV. This was achieved using boosted decision trees implemented inthe Toolkit for Multivariate Analysis (TMVA). Further investigation demonstrated the impor-tance of the beam polarisation the sensitivity of this channel and for the background reductionallowing the measurement of the ZH process cross section with 2% of precision.Le collisionneur linéaire international (ILC) est le concept d'un accélérateur d'électrons-positrons linéaire avec une énergie dans le centre de masse allant jusqu'au TeV. Son but est la mesure de haute précision des propriétés des particules découvertes par le LHC, en particulier celles du boson de Higgs. L'ILD est l'un des concepts de détecteurs spécialement conçus pour l'utilisation de l'algorithme de suivis des particules (PFA) nécessitant une calorimétrie très granulaire. Dans le cadre de la collaboration CALICE, quelques prototypes de calorimètres, explorant des technologies différentes, ont été développés et testés en faisceau. Cette thèse se concentre sur l'un d'eux: un calorimètre hadronique semi-digital (SDHCAL) basé sur des chambres à plaques résistives (GRPC). Il est composé de 48 couches segmentée en cellules d'un centimètre carré pour un total de 500 000 canaux, lues de façon sommaire (en 3 seuils). La première partie de cette thèse se focalise sur l'analyse des données recueillies pendant les tests en faisceau au CERN, dans lequel le détecteur a fonctionné en mode d'auto-déclenchement; enregistrant toutes les informations entrantes dans le détecteur. Une méthode de reconstruction d’événement a été développée qui permet d'extraire les événements physiques utilisant un nouvel algorithme basé sur une méthode de regroupement temporel. Une étude détaillée de la qualité du SDHCAL en terme d'efficacité de détection et multiplicité des cellules touchées, est effectuée utilisant des traces de muons reconstruits avec le détecteur. Un procédé pour mesurer le spectre de charge induite et la taille de l'avalanche électronique dans les capteurs GRPC est aussi présentée. L'extraction de ces paramètres clés est nécessaire pour une simulation précise du détecteur. La réponse des capteurs et de l'électronique d'acquisition doit être modélisés pour la simulation Mote-Carlo (avec GEANT-4) dans un module dit de "digitisation"; un procédé de digitisation générale a été développé au cours de cette thèse, qui peut être appliquée à divers capteurs gazeux a granularité élevée. Il a été testé avec succès sur les GRPC et les MicroMegas. La réponse aux pions est ensuite traitée. Les tests faisceau au CERN fournissent un grand échantillon de pions d'énergie allant de 5 à 80 GeV. Une sélection fine des gerbes hadroniques est appliqué, a l'aide de nouveaux type de variables d'identification telles que la dimension fractale des gerbes. Les pions ainsi sélectionnés sont ensuite utilisés pour l'étalonnage du calorimètre en terme de linéarité et de résolution en énergie. L'information acquise par la reconstruction des muons a été également utilisée pour améliorer la réponse du calorimètre aux pions avec un impact visible sur sa résolution. Pour évaluer les performances dans une configuration complète d'un grand détecteur, la deuxième partie de cette thèse est consacrée à l'étude du mode production du boson de Higgs associé au processus ZH avec l'ILD. L'état final recherché est caractérisé par la présence d'au moins deux jets provenant de boson Z à côté des produits de désintégration du Higgs. Pour effectuer mesure indépendante du Higgs, la sélection des événements ne contraint pas les modes de désintégration du Higgs. Le boson Z étant caractérisée par un rapport d'embranchement hadronique plus élevé par rapport à celui leptonique, il offre une meilleure statistique. En outre, le contexte d'indépendance au modèle du boson de Higgs peut identifier des éventuels écarts par rapport aux attentes du modèle standard de la physique des particules. La première analyse consiste à la démonstration de la faisabilité du marquage du boson de Higgs en utilisant la désintégration hadronique du boson Z. Ceci a été réalisé en utilisant des arbres de décision boostés (BDT). Une analyse plus poussée démontre l'importance de la polarisation du faisceau sur sensibilité de ce canal et pour la réduction du bruit de fond, et ainsi prédire une mesure de la section efficace du processus de ZH avec une précision de 2\%
Dynamics of receptor-mediated nanoparticle internalization into endothelial cells.
No full textInternational audienceNanoparticles offer a promising medical tool for targeted drug delivery, for example to treat inflamed endothelial cells during the development of atherosclerosis. To inform the design of such therapeutic strategies, we develop a computational model of nanoparticle internalization into endothelial cells, where internalization is driven by receptor-ligand binding and limited by the deformation of the cell membrane and cytoplasm. We specifically consider the case of nanoparticles targeted against ICAM-1 receptors, of relevance for treating atherosclerosis. The model computes the kinetics of the internalization process, the dynamics of binding, and the distribution of stresses exerted between the nanoparticle and the cell membrane. The model predicts the existence of an optimal nanoparticle size for fastest internalization, consistent with experimental observations, as well as the role of bond characteristics, local cell mechanical properties, and external forces in the nanoparticle internalization process
Collagen microstructural factors influencing optic nerve head biomechanics.
No full textInternational audiencePrevious studies have suggested that the lamina cribrosa (LC) and its surrounding sclera are biomechanically important in the pathogenesis of glaucoma, but many were limited by assumptions of tissue isotropy and homogeneity. Here, we used an improved biomechanical model driven by experimental measurements of scleral and LC collagen fiber organization to more accurately evaluate optic nerve head (ONH) biomechanics. Collagen fiber organization was quantitatively mapped across human ONH cryosections (three normal and three glaucomatous) using small-angle light scattering (SALS) and fed into two-dimensional finite element models loaded under biaxial stress to simulate raised intraocular pressure. Effects of artificial variations in collagen fiber microstructure and stiffness on LC and scleral strains were also investigated. Scleral collagen fibers were circumferential and exhibited the highest alignment in a region not immediately adjacent to, but at a distance (400-500 μm) away from, the LC. In models, such a fiber arrangement yielded rings of low strain (second principal and effective) in the scleral region immediately adjacent to the LC. Further sensitivity analyses showed that scleral fiber alignment was crucial in determining LC strain levels. Moderate scleral anisotropy (as observed physiologically) was more effective than isotropy or high anisotropy in limiting LC and scleral strain magnitude. The presence of a heterogeneous collagen fiber organization in the peripapillary sclera appears effective in limiting LC strain and is able to reduce strain levels at the scleral canal boundary: a transition zone prone to LC disinsertion, focal lamina cribrosa defects, and optic disc hemorrhages in glaucoma
Etude des ondes de gravité dans l’atmosphère au moyen de ballons et de simulations
No full textThe goal of this thesis is to obtain a better knowledge of the atmospheric gravity waves in the atmosphere, of their sources and characteristics, and their propagation using balloon observations and modeling. The superpressure balloons (SPBs) used in this thesis are one of the best platforms to observe gravity waves, and allow us to retrieve the ensemble of their characteristics. High-resolution models provide a complete description of the flow, not only of the waves, but also of their sources. We have combined SPB measurements and modeling in order to describe the gravity waves and evaluate the gravity wave field in model outputs. Using the observations from PreConcordiasi (2010), the convective gravity waves are described in the Tropics during the whole campaign, and also for a case of developing Tropical Cyclone. Second, observations from the Concordiasi campaign (2010) allow us to quantify the realism of the resolved gravity wave field in the ECMWF analyses at high latitudes (Southern Hemisphere). A good geographical and seasonal agreement is found for the momentum fluxes and the intermittency. However, it is shown that the magnitude is underestimated in the ECMWF. Finally, we bring a contribution to the operational balloon campaigns, with a focus on the open stratospheric balloons, which constitute the greatest challenge for the CNES. For cases during the Strapol ́et ́e campaign, we show that the uncertainty on the final touchdown position of the balloons can be reduced using a simple setup that assimilates radiosoundings.L’objectif de cette thèse est d’obtenir une meilleure connaissance des ondes de gravité atmosphériques, de leurs sources et caractéristiques, et de leur propagation au moyen d’observations ballons et de simulations. Les ballons pressurisés (SPBs) utilisés dans cette thèse sont une des meilleures plateformes d’observations des ondes de gravité, et permettent d’obtenir l’ensemble de leurs caractéristiques. Les modèles à haute résolution donnent une description complète de l’écoulement, non seulement des ondes, mais aussi de leurs sources. Nous avons combiné mesures par SPBs et modélisation pour décrire les ondes de gravité et évaluer le réalisme des champs d’ondes de gravité dans des sorties de modèles. En s’appuyant sur les observations de PreConcordiasi (2010), les ondes de gravité convectives sont décrites aux Tropiques sur l’ensemble de la campagne, ainsi que sur un cas de cyclone tropical en développement. Dans un deuxième temps, les observations de la campagne Concordiasi (2010) nous permettent de quantifier le réalisme du champ d’onde de gravité résolu aux hautes latitudes (hémisphère sud) décrit dans les analyses de l’ECMWF. Un bon accord géographique et saisonnier est observé pour les flux de quantité de mouvement et l’intermittence. Cependant, il est montré que la magnitude des flux est sous-estimée dans les analyses de l’ECMWF. Enfin, une contribution aux campagnes opérationnelles ballons est apportée, en se focalisant sur les ballons stratosphériques ouverts qui sont le plus grand défi pour le CNES. Pour des cas d’étude lors de la campagne Strapolété (2009), nous montrons que l’incertitude sur la position de retombée des ballons peut être réduite dans une configuration simple en assimilant des observations par radiosondages