Tesis sobre el tema "Détecteurs de temps"
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Jürgensen, Nadia. "Étalonnage automatique des détecteurs pour scanner LabPET II". Mémoire, Université de Sherbrooke, 2017. http://hdl.handle.net/11143/11104.
Texto completoJacquemod, Gilles. "Detection de défauts dans des images radiographiques industrielles obtenues en temps reel par des détecteurs linéaires". Lyon, INSA, 1989. http://www.theses.fr/1989ISAL0089.
Texto completoDumez-Viou, Cedric. "Restauration de sources radioastronomiques en milieu radioélectrique hostile : Implantation de détecteurs temps réel sur des spectres dynamiques". Phd thesis, Université d'Orléans, 2007. http://tel.archives-ouvertes.fr/tel-00319939.
Texto completoLes travaux de cette thèse ont eu pour but de développer et d'implanter des méthodes temps réel de traitements numériques visant à atténuer les interférences ambiantes afin de restaurer les radiosources naturelles lors d'observation avec une antenne unique sans informations a priori.
Le cœur de ces traitements est basé sur l'estimation de la moyenne d'un échantillon suivant une loi du Khi-2 en présence de points aberrants.
Un récepteur numérique multi-instruments à grande dynamique élaboré à la station de radioastronomie de Nançay a servi de banc de test à ces divers algorithmes.
La bande corrompue par Iridium est maintenant observable et les sources HI situées dans la bande allouée aux radars sont de nouveau
accessibles. Les observations du Soleil et de Jupiter effectuées en
bande décamétrique sont maintenant de bien meilleure qualité.
Un algorithme a été développé pour configurer le récepteur en tant que détecteur et enregistreur rapide d'évènements très brefs (<100 ms) en milieu parasité. Il est aujourd'hui utilisé pour l'enregistrement de structures fines Joviennes.
Dumez-Viou, Cédric. "Restauration de sources radioastronomiques en milieu radioélectrique hostile : implantation de détecteurs temps-réel sur des spectres dynamiques". Orléans, 2007. http://www.theses.fr/2007ORLE2064.
Texto completoZach, François. "Mesure du temps de vie du méson B0s et étude de ses oscillations temporelles par le détecteur DELPHI au LEP". Lyon 1, 1996. http://www.theses.fr/1996LYO10097.
Texto completoBacchi, Christian. "Nouvelle génération de détecteurs d'ions sensible en position et en temps pour le développement de la sonde atomique tomographique". Thesis, Normandie, 2020. http://www.theses.fr/2020NORMR032.
Texto completoThe Atom Probe Tomography (APT) is an analysis technique allowing the visualization of the atomic structure and the determination of the elemental nature of each atom originating from material samples. In order to get this type of analysis, the APT uses a destructive technique, called the Field Evaporation, allowing the extraction and the detection of atoms constituting the analyzed material. To do so, it is necessary, in a first step, to shape the material sample in the form of a very sharp needle. Then, in a second step, to apply a high electric potential on the tip for ionizing and expelling the atoms from the surface of the tip apex. Surface atoms are then projected towards a position-sensitive detector (PSD), with the aim of reconstructing the internal three-dimensional shape of the analyzed material, layer-by-layer. Concerning the spectrometric aspect of this technique, each detected atom is associated to a time-of-flight (TOF) measurement. Those TOFs are measured between electric (or laser) pulses applied on the tip, and arrival times on the detector. Knowing the resulting electric potential applied on the tip and the projection speed of ions, it is possible to get the mass-to-charge ratio of each collected ion. Regarding the working process of this technique, it may be thought that APT instruments could be the best mean for analyzing materials at the atomic scale. However, since the invention of this technique, more than 30 years ago, APT instruments are still relatively confidential in the panel of high-resolution microscopes used in material sciences. One of the main reasons to this concerns the potential biases brought by the APT detection system. Some of those biases concern the inability of the detector to correctly treat high amounts of ion arrivals in a short period of time. In the case where some elements tend field evaporate in bundles of more than one ion, it is then possible to suffer from selective losses during APT experiments. Secondly, given that the elemental nature of collected ions is determined through time-of-flight mass spectrometry, material analyses may be intrinsically subjected to compositional biases. This is due to interferences between mass peaks originating from different elements, sharing very close mass-to-charge ratios. Based on the foregoing, this thesis is intended to answer to the following issue: How to outperform the limitations of APT detection systems? To do so, theoretical and experimental studies have been conducted for resolving those biases, and finally led to the development of new theoretical models and new type of detectors for APT instruments
Puszka, Agathe. "Tomographie optique diffuse : une approche résolue en temps pour les mesures en réflectance à courtes distances entre sources et détecteurs". Thesis, Grenoble, 2013. http://www.theses.fr/2013GRENY051/document.
Texto completoDiffuse optical tomography (DOT) is an emerging medical imaging technique using near-infrared light to probe biological tissues. This technique can retrieve three-dimensional maps of absorption and scattering coefficients inside organs from non-invasive measurements. With a multispectral approach, the spatial distribution of endogenous chromophores (hemoglobin, water) can even be obtained. For some clinical applications, it is desirable to carry out the measurements for DOT with a compact probe including all sources and detectors. However, the depth sensitivity is a real challenge in this configuration. We propose to tackle this challenge by using time-resolved measurements. A time-resolved approach is developed to perform DOT with reflectance measurements at short source-detector separation. This approach involves methodological aspects including the processing of time-resolved signals by DOT algorithms based on the Mellin-Laplace transform. Then, this approach consists in optimizing the detection chain on two aspects for enhancing the detection and localization of absorption contrast in depth in diffusive media. First, the impact of the temporal response of the detector is studied with commercially available single-photon detectors (classical and hybrid photomultipliers). Second, the enhancements in probed depth permitted with fast-gated single-photon avalanche diodes are explored in a joint work with the Politecnico di Milano. To finish, a study is carried out to illustrate the performance of the proposed approach with respect to spatial resolution in depth for different configurations of sources and detectors in the optical probe. Probes with a width limited to a few centimeters open the gate to multiple clinical interests. They could access intern organs like the prostate or facilitate the measurements on extern organs like the breast or the brain
Borras, Santos Guillem. "Contribution à l'amélioration de la résolution des détecteurs a l'état solide sensibles aux rayons X par restauration et simulation comportementale". Lyon, INSA, 1999. http://www.theses.fr/1999ISAL0113.
Texto completoThe film was the first media used in X- ray imaging. Of a simple use, the film allowed for an important development of the non destructive testing. For the last decades, the film started to share his hegemony with fluoroscopy in some domains of interest where the speed was a predominant factor in the acquisition. More recently, the fluoroscopy is being replaced by the use of solid-state devices. Those new imagers are able to acquire real time numerica1 images. Linear detectors are especially well adapted to a continuous inspection of slow moving objects. However, this kind of detectors often Jack of resolution for some specific applications. Our work is a contribution to the improvement of the solid-state X-Ray detectors resolution. This contribution is specially oriented to real time applications. Our research follows three main axes. The first one deals with the modelling of the degradation of the detector. A new technique is described and tested. In the second part some restoration techniques have been developed. We have treated the real time aspect of the restoration, and some geometrical settings of the detector have been tested. The last part has been worked out to optimise the intrinsic parameters of the detector, using a new behavioral simulation tool
Lafont, Fabien. "Développement du détecteur d'électrons SECOND dédié à la mesure du temps de vie du neutron dans l'expérience HOPE". Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAY065/document.
Texto completoConsidering a low enough kinetic energy, a free neutron can be materially or magnetically trapped in a defined volume. This trapping allows experimenters to study the neutron and its characteristics, and in this case, to measure its mean lifetime. The HOPE experiment commissioned at Laue Langevin Institute in Grenoble is aimed at providing a 1 %- accuracy value. One way to measure lifetime is to record every single neutron beta decay occurring in the trap by counting the emitted electrons. The detector SECOND has been specifically designed to fulfill this goal within HOPE but also to discriminate other types of particles that induce false events. The latter argument is the reason for the two detection stages SECOND is composed of. The plastic scintillators phoswich constitutes the main part of the detector and has been successfully operated during preliminary tests at low temperature. The rejection rate of cosmic muons events is about 98 %, and this value can be drastically enhanced using a more suitable data acquisition system
Borras, David. "Mesure du temps de vie de la composante CP paire du B°s dans LHCb". Clermont-Ferrand 2, 2006. http://www.theses.fr/2006CLF21686.
Texto completoLisowska, Marta. "Exploring the potential of Micro-Pattern Gaseous Detectors technologies in High Energy Physics applications and beyond". Electronic Thesis or Diss., université Paris-Saclay, 2024. http://www.theses.fr/2024UPASP094.
Texto completoThis doctoral dissertation investigates the potential of Micro-Pattern Gaseous Detectors for High Energy Physics and beyond, focusing on time resolution and optical readout advancements. The primary aim was the PICOSEC Micromegas project, concentrating on developing precise-timing gaseous detectors with a target time resolution of O(10) ps for Minimum Ionising Particles. This thesis focused on enhancing performance and scaling it to robust multi-channel detector modules. Research on photocathode materials showed that Diamond-Like Carbon (DLC) was the most promising due to its good time resolution of approximately 32 ps and resistance to humidity. The integration of resistive Micromegas aimed to improve robustness against discharges and ensure stable operation under intense particle beams, achieving a time resolution of approximately 12.5 ps with Cesium Iodide (CsI) photocathode. Finally, multi-channel prototypes were developed to scale to larger detection areas, achieving a time resolution below 18 ps for a 10x10 cm² module. This doctoral dissertation explores the potential benefits of optical readout techniques for MPGDs and aims to enhance their performance. The research included an evaluation of spatial resolution through optical readout, comparing different detector geometries. It investigated various GEM-stack configurations to improve the dynamic range for future modifications of the MIGDAL OTPC, evaluating the maximum achievable gain and light yield across different GEM-based structures. It also recognised the importance of gas optimisation for optical readout by exploring alternative mixtures to CF₄ and wavelength shifters
Chemloul, Mohamed. "Etude et réalisation d'un système rapide pour la localisation des rayons X dans les détecteurs gazeux". Université Joseph Fourier (Grenoble), 1995. http://www.theses.fr/1995GRE10014.
Texto completoSemmaoui, Hichman. "Algorithmes numériques en temps réel appliqués à l'identification de cristaux et à la mesure de l'estampe du temps scanner TEP/TDM tout-numérique à base de photodiodes à avalanche". Thèse, Université de Sherbrooke, 2009. http://savoirs.usherbrooke.ca/handle/11143/1901.
Texto completoGrabas, Hervé. "Développement d'un système de mesure de temps de vol picoseconde dans l'expérience ATLAS". Phd thesis, Université Paris Sud - Paris XI, 2013. http://tel.archives-ouvertes.fr/tel-00982076.
Texto completoWenger, Emmanuel. "Installation et mise en oeuvre d'un détecteur de rayons X à pixels hybrides sur un diffractomètre de laboratoire : applications aux études de densité électronique et aux expériences de cristallographie résolues en temps". Thesis, Université de Lorraine, 2015. http://www.theses.fr/2015LORR0050/document.
Texto completoCompared to X-ray detectors commonly used for crystallography, hybrid pixels detectors provide major advantages primarily due to the use of a counting system proper to each pixel allowing for very fast and individual photon counting. The main innovations of these detectors are: (1) Almost total suppression of noise ; (2) Ultra-fast electronic shutter (about 100 ns) ; (3) Acquisition rate of 500 images per second. These advantages have already been exploited over the past ten years on synchrotron beam lines and are also very promising for laboratory diffractometers. The thesis work was to realize a prototype laboratory diffractometer equipped with such a detector, XPAD, and to achieve single crystal X-ray diffraction measurements. The necessary corrections and calibrations of the detector required for diffraction measurements on single crystals were determined. The methods and image processing techniques to integrate the diffraction intensities were studied. Benefits of the very low noise of the detector for electron density models study were demonstrated; the prototype diffractometer equipped with an XPAD detector gave better results than conventional diffractometers. A second type of application was to use the pixel detector for the implementation of time-resolved diffraction measurements at millisecond timescale. Measurements under switched electric fields have shown the potential of this type of detector in this area of research
Fathallah, Houssem Eddine. "Conception d'un système temps-réel de surveillance de l'exposition aux polluants de l'air intérieur : application au formaldéhyde". Electronic Thesis or Diss., Université de Lorraine, 2016. http://www.theses.fr/2016LORR0100.
Texto completoFormaldehyde is classified as a "high priority" pollutant in the indoor air quality. Because of its health effects, the emerging French regulation (Action 7 of PNSE2) requires the measurement of formaldehyde in public places (schools, kindergartens etc.) from 2017. However, no device on the market is able to provide accurate measurements in real time and at low cost. This thesis forms part of the ANR project CAPFEIN (réseau de CAPteurs de FormaldEhyde intelligents pour la surveillance de l'air Intérieur) whose purpose is to develop a "smart Formaldehyde sensor". The thesis objective is to design a real-time monitoring system of human exposure to formaldehyde, and more generally to indoor air pollutant. The sensors must be equipped with a communication interface to automatically collect measurements at different points of the environment to be monitored. Two monitoring systems have been developed. The first is Designed with commercial off-the-shelf component and a centralized architecture based on the concept of the Internet of Things (IoT). The second was designed from the CRAN and corresponds to the development of a solution based on a distributed approach. A smart badge has been developed. It can monitor exposure levels to each cardholder. The major constraints of this work consist on the ability to locate people in an indoor environment and the ability to optimize the algorithms in terms of memory space and power consumption. For the optimization part, the moving average exponential weighting methods have been implemented and evaluated. Both prototypes were tested in buildings of CRAN and showed interest
Guillemin, Thibault. "Vers une mesure de la section efficace de production inclusive du boson W en électron-neutrino dans l'expérience ATLAS au LHC". Chambéry, 2009. http://www.theses.fr/2009CHAMS019.
Texto completoThe charged W-boson will be abundantly produced at the Large Hadron Collider (LHC) in proton-proton collisions at a center-of-mass energy of 14 TeV : its frequency production is 1 Hz at low luminosity. Its decay in the electron channel will have a clear signature in the ATLAS detector, defined by a high transverse momentum electron and a high missing transverse energy. The ATLAS detector is a multi-purposes detector made up of a tracker, an electromagnetic calorimeter, a hadronic calorimeter and a muon spectrometer. It is fully installed in its cavern and recorded data with the first LHC beam in September 2008. A first part of the thesis presents a full analysis strategy for the W-boson inclusive production cross section with the first ATLAS data, maximizing the inputs from real data with respect to simulated ones. The main contributions to the systematical uncertainty are identified and estimated : a measurement precision better than 10% will be reachable from the first phase of the experiment. A second part is dedicated to the time alignment of the liquid argon calorimeters readout channels, a required step to reach the nominal performances. Timing constants are computed from the data recorded in September 2008 : they will allow a time alignment of all channels at a 2-3 ns level for the start-up
Razan, Florence Anne. "Etude de microcapteurs à ondes acoustiques dédiés à la détection fine de produits chimiques à l'échelle laboratoire et industrielle. Application à la détection de monomères résiduels et à la mesure de cinétique en réacteurs". Bordeaux 1, 2005. http://www.theses.fr/2005BOR13079.
Texto completoGhazaly, Christelle. "Développement d’un capteur spectrophotométrique pour la mesure en temps réel des expositions professionnelles à l’ozone". Electronic Thesis or Diss., Université de Lorraine, 2019. http://www.theses.fr/2019LORR0207.
Texto completoOzone causes headaches, eye burns and lung damage and serious respiratory diseases such as asthma. Ozone is emitted into the atmosphere of workplaces in various sectors, including printing, water treatment, arc welding, and plastics processing. Exposure of workers to concentrations exceeding national and european ozone occupational exposure limit values (OELs), set at 100 ppbv over 8 hours and 200 ppbv over 15 minutes, may cause severe health alterations. Currently, the determination of ozone concentrations is carried out by using colorimetric tubes, providing spot measurements, or by using commercial sensors. Some studies were carried out on electrochemical cells or semiconductors based sensors and more rarely on optical sensors. The detection limit of these sensors is compatible with ozone OELs, but they are fragile and not selective. There is currently no reliable and robust reference method for the assessment of occupational exposures to ozone. The objective of this study is the development of a real-time ozone measurement method, which is characterized by a stable signal under air, high sensitivity, and selectivity. This measurement system must also make it possible to identify the most exposed phases for employees. We chose visible spectroscopy as a simple, fast and accurate detection system. We have successfully developed the sensitive material, based on an inexpensive dye, methylene blue, adsorbed on a thin film of mesoporous silica deposited on a glass plate by dip-coating. This material is stable for more than 50 days stored under ambient air. The system also includes a Nafion® tube; used to stabilize the relative humidity of the air. The measured sensor signal is the absorbance decrease at 600 nm. This reduction results from the oxidation of the dye in the presence of ozone and is irreversible under air. The developed sensor is characterized by sensitivity to low ozone concentrations ranging from 10 to 500 ppbv, reproducible response kinetics and no direct interference in the presence of 500 ppbv of nitrogen dioxide. The temperature dependence of the sensor response is described. The performance of the detection during exposure scenarios for short times and variable concentrations is described. The developed system could be a good candidate for real-time monitoring of occupational ozone exposures. This step will require miniaturization of the test bench components to use the sensor developed in the workplace
Teyssier, Cécile. "Spectrométrie de masse COINTOF : Conception et d'un analyseur à temps de vol et développement de la méthode d'analyse". Phd thesis, Université Claude Bernard - Lyon I, 2012. http://tel.archives-ouvertes.fr/tel-00744850.
Texto completoVezinet, Didier. "Mesure et analyse du rayonnement Xmou d'un plasma de Tokamak en vue d'un contrôle en temps réel". Thesis, Aix-Marseille, 2013. http://www.theses.fr/2013AIXM4749/document.
Texto completoThis thesis focuses on measuring and interpreting the Soft X-Ray (SXR) radiation (approximately [1 keV; 15 keV]) in Tokamaks.As explained in Chapter 2, this radiation conveys information about the plasma density, temperature, magnetic equilibrium and impurity content. However, the measured data is spectrally and spatially-integrated and results from several physical phenomena affecting every ion species. Tore Supra's SXR diagnostics is based on semiconductor diodes presented in Chapter 3, along with a new gas detector successfully tested in laboratory and on Tore Supra. A new methodology for absolute spectral characterisation of photo detectors using a portable SXR tube is presented. Tomographic inversion algorithms, that grant access to reconstructions of the SXR emissivity field in a poloidal cross-section, are presented in Chapter 4. Improvements implemented on one particular algorithm are detailed with examples of application. A comparison between the position of the SXR emissivity maximum and the magnetic axis reconstructed by an equilibrium code is presented in Chapter 5.Chapter 6 presents an approach used to derive an impurity density from its SXR emissivity using the robustness of its SXR cooling factor with respect to impurity transport. The physics accounting for this robustness is studied and a first map of the domain of validity of this method is provided. Chapter 7 addresses poloidal asymmetries of the SXR emissivity field. Two types of asymmetries are presented as well as experiments conducted on ASDEX-U to verify their parametric dependences. A new type of SXR asymmetry, observed on Tore Supra is introduced
Fathallah, Houssem Eddine. "Conception d'un système temps-réel de surveillance de l'exposition aux polluants de l'air intérieur : application au formaldéhyde". Thesis, Université de Lorraine, 2016. http://www.theses.fr/2016LORR0100.
Texto completoFormaldehyde is classified as a "high priority" pollutant in the indoor air quality. Because of its health effects, the emerging French regulation (Action 7 of PNSE2) requires the measurement of formaldehyde in public places (schools, kindergartens etc.) from 2017. However, no device on the market is able to provide accurate measurements in real time and at low cost. This thesis forms part of the ANR project CAPFEIN (réseau de CAPteurs de FormaldEhyde intelligents pour la surveillance de l'air Intérieur) whose purpose is to develop a "smart Formaldehyde sensor". The thesis objective is to design a real-time monitoring system of human exposure to formaldehyde, and more generally to indoor air pollutant. The sensors must be equipped with a communication interface to automatically collect measurements at different points of the environment to be monitored. Two monitoring systems have been developed. The first is Designed with commercial off-the-shelf component and a centralized architecture based on the concept of the Internet of Things (IoT). The second was designed from the CRAN and corresponds to the development of a solution based on a distributed approach. A smart badge has been developed. It can monitor exposure levels to each cardholder. The major constraints of this work consist on the ability to locate people in an indoor environment and the ability to optimize the algorithms in terms of memory space and power consumption. For the optimization part, the moving average exponential weighting methods have been implemented and evaluated. Both prototypes were tested in buildings of CRAN and showed interest
Bajat, Armelle. "Etude des réponses temporelle et spectrale de l'instrument ECLAIRs pour la mission SVOM". Thesis, Toulouse 3, 2018. http://www.theses.fr/2018TOU30151/document.
Texto completoThe french-chinese mission SVOM (Space-based multi-band variable Astronomical Object Monitor), is dedicated to the study of ƴ-rays bursts, brief and intense X and ƴ photons flashes, associated with the catastrophic formation of black holes. SVOM will embark in 2021 four instruments observing from the visible to ƴ rays. ECLAIRs, the main telescope, is a coded mask camera able to detect and locate, about 200 bursts during the three years nominal life time of SVOM. Its detection plan counts 6400 Schottky CdTe detectors, grouped into a matrix of 32 pixels forming a module. The plan is divided into eight electronically independent sectors, each consisting of 25 modules. Each electronic is dedicated to read and encode, the time, the position, the multiplicity and the energies of the detected events on a sector. The validation of each functionality of the readout electronics allows to ensure the correct encoding of the events, to estimate the limits of the electronics and to build an analytical model of lost events efficient correction. An application to a lightcurve of a bright GRB permits to validate theoretically this model and measurements carried out on the prototype validates it experimentally. On the other hand, a complete model of the spectral response has been established to characterize each detector on the sector of the prototype and to estimate the response of the plan of detection of the mono-energetic photons. The physical processes of the radiation-matter interactions are simulated as well as a model of lost charges then a Gaussian convolution takes into account the electronic noise. This model, counting six free parameters, is fitted to spectra measured on the prototype. The study of the extracted parameters characterizes the performance of each detector in every voltage and t peaking configurations optimizing the performance of the instrument
Lochon, Frédéric. "Développement de microcapteurs chimiques à base de micropoutres dédiés au contrôle de la qualité de l'air : détection temps réel de Composés Organiques Volatils (COV)". Phd thesis, Université Sciences et Technologies - Bordeaux I, 2007. http://tel.archives-ouvertes.fr/tel-00399419.
Texto completoBacak, Michael. "Development of a detector for the simultaneous measurement and for the study of uranium-233 capture and fission yields at the CERN n_TOF neutron source". Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS313/document.
Texto completoA low-carbon energy outlook to mitigate the climate change requires the replacement of fossil fuel by sources with low CO2 emissions, like nuclear energy.. One of the options discussed in the Gen-IV International Forum for the the next generation of nuclear reactors is to use the thorium cycle. The fissile isotope 233U is among the most important isotopes in the thorium cycle and directly responsible for the neutron economy. One of the particularities of this nucleus is to have a capture cross section which is one order of magnitude lower than fission, making the measurement of the 233U capture cross section very challenging as indicated by only two high resolution data sets available since the 1960s. In this thesis, a new measurement at the n_TOF neutron source is described employing a novel compact fission chamber inserted in the center of the Total Absorption Calorimeter g-ray detector. The fission chamber allows to tag and subsequently subtract the gamma rays from the fission reaction aiming to improve the accuracy of the 233U capture cross section.The performance of the custom tailored fission chamber is described in detail and allows to extract information about the prompt fission g-rays. A detailed discussion of the data reduction process and the key elements in the analysis is given resulting in the calculation of the 233U-alpha-ratio, the ratio between the capture and fission cross-section
Hamdi, Khaoula. "Détection spectrophotométrique en temps réel d'hydrocarbures monoaromatiques (benzène, toluène et xylènes) dans l'air aux valeurs limites d'exposition professionnelle". Thesis, Université de Lorraine, 2016. http://www.theses.fr/2016LORR0328/document.
Texto completoThe objective of this thesis was to develop a spectrophotometric sensor to quantify benzene, toluene and xylenes (BTX) in real time at the level of the occupational exposure limit values, ie 20 ppmv for toluene, 50 Ppmv for xylenes and 1 ppmv for benzene. The study was carried out with several sensitive layers, a solid silicic material synthesized by the sol-gel process or thin films (less than 5 μm) deposited on quartz by dip-coating a suspension of nanoparticles or a precursor solution leading to mesoporous silica thin films. We were able to demonstrate the effectiveness of BTX detection in real time. The use of continuous mesoporous films has enabled a correct repeatability of the sensor (standard deviation <10%). Nevertheless, neither these silica films nor their functionalization by methyl groups have solved the problem posed by moisture. Only the use of a dryer that we implemented in the measuring device allowed the detection of toluene in the presence of ambient humidity. In this configuration, interference of 40 ppmv of butanone, acetone and ethanol was also eliminated. Finally, the design of a multi-plate cell allowed to reach detection limits of 1 ppmv at 267 nm for toluene, 1 ppmv at 274 nm for p-xylene and 5 ppmv at 252 nm for benzene. Finally, this limit of detection can be lowered to 1 ppmv at 190 nm for benzene
Goetzmann, Christophe. "Validation de l'alignement du trajectographe à l'aide des électrons et recherche de particules à long temps de vie dans le canal électron-muon dans l'expérience CMS au LHC". Thesis, Strasbourg, 2014. http://www.theses.fr/2014STRAE033/document.
Texto completoThe first part of my work concerns the development of an algorithm using CMS data to automatically detect the presence of particular deformations than can occur in the CMS tracker. The method takes advantage of the bias that such deformations induce in the measurement of electron impulsion. The reliability of the method has been proved using Monte-Carlo simulation. The algorithm was then used to certify that none of the considered deformations affected the data recorded in 2012.The second part of my work consists of a statistical analysis of the data recorded by CMS, in order to look for evidence of the presence of exotic long-lived particles. The latter could manifest themselves through their decay to an electron and a muon. Such an observation would provide a strong clue of the existence of new physics. In the absence of any observation statistically significant, a Bayesian method is used to interpret this result in term of constraints on a supersymmetric model (MSSM)
Mottin, Stéphane. "Mise au point chez le rat d'un capteur à fibre optique pour la mesure de la fluorescence résolue en temps induite par laser et émise par le cerveau". Phd thesis, Ecole Nationale Supérieure des Mines de Saint-Etienne, 1993. http://tel.archives-ouvertes.fr/tel-00844337.
Texto completoFarah, Elias. "Detection of water leakage using innovative smart water system : application to SunRise Smart City demonstrator". Thesis, Lille 1, 2016. http://www.theses.fr/2016LIL10103/document.
Texto completoThis work concerns the use of the Smart Water Technology for the detection of water leakage. It is a part of SunRise project which aims at turning the Scientific Campus of the University of Lille into a large scale demonstrator site of the "Smart and Sustainable City". The campus is representative to a small town of 25000 inhabitants. This work is also a part of the European Project SmartWater4 Europe, which aims to develop 4 demonstrators of the Smart Water Technology. This thesis includes five parts. The first part includes a literature review concerning the technologies used in leakage detection. The second part presents the SunRise Smart City demonstrator, which is used as a basis for this thesis. This section details the instrumentation installed in the demo site as well as leak simulations tests to analyze the efficiency of an acoustic system of leakage detection. The third part focuses on the analysis of the water consumption at different time scales. Analysis concerns both sub-meters and bulk meters. It is conducted using a platform for the aggregation and the interpretation of the data. This part presents also major leakage events in 2015. The fourth part concerns leak detection using the water balance calculation based on the top down and bottom up approaches. It also presents the Active Leakage Control (ALC) strategy applied to the demo site in order to reduce the level of Non-Revenue Water (NRW). The last part concerns the use of advanced methods for leak detection with application on the campus data. These methods include the Comparison of Flow Pattern Distribution Method (CFPD), the Minimum Night Flow (MNF) method and two developed statistical approaches
Ley, Jean-Luc. "Mise en oeuvre d’un démonstrateur de caméra Compton pour l’imagerie en médecine nucléaire et pour le contrôle en temps réel de l’hadronthérapie à l’aide des rayonnements gamma prompts". Thesis, Lyon 1, 2015. http://www.theses.fr/2015LYO10334/document.
Texto completoHadrontherapy is one of the modalities available for treating cancer. This modality uses light ions (protons, carbon ions) to destroy cancer cells. Such particles have a ballistic accuracy thanks to their quasi-rectilinear trajectory, their path and the finished profile maximum dose in the end. Compared to conventional radiotherapy, this allows to spare the healthy tissue located adjacent downstream and upstream of the tumor. One of this modality’s quality assurance challenges is to control the positioning of the dose deposited by ions in the patient. One possibility to perform this control is to detect the prompt gammas emitted during nuclear reactions induced along the ion path in the patient. A Compton camera prototype, theoretically allowing to maximize the detection efficiency of the prompt gammas, is being developed under a regional collaboration. This camera was the main focus of my thesis, and particularly the following points : i) studying, throughout Monte Carlo simulations, the operation of the prototype in construction, particularly with respect to the expected counting rates on the different types of accelerators in hadrontherapy ii) conducting simulation studies on the use of this camera in clinical imaging, iii) characterising the silicon detectors (scatterer) iv) confronting Geant4 simulations on the camera’s response with measurements on the beam with the help of a demonstrator. As a result, the Compton camera prototype developed makes a control of the localization of the dose deposition in proton therapy to the scale of a spot possible, provided that the intensity of the clinical proton beam is reduced by a factor 200 (intensity of 108 protons / s). An application of the Compton camera in nuclear medicine seems to be attainable with the use of radioisotopes of an energy greater than 300 keV. These initial results must be confirmed by more realistic simulations (homogeneous and heterogeneous PMMA targets). Tests with the progressive integration of all camera elements will take place during 2016
Curtoni, Sébastien. "Développement d'un démonstrateur d'hodoscope faisceau en diamant pour le contrôle en ligne du parcours des ions en hadronthérapie". Thesis, Université Grenoble Alpes, 2020. http://www.theses.fr/2020GRALY045.
Texto completoThis thesis manuscript introduces the study and development of a diamond hodoscope demonstrator conceived for spatial and temporal beam tagging in hadrontherapy. This work deals with the issue of online ion range verification, and more specifically with the improvement of prompt-gamma imaging systems. Synthetic diamond samples were chosen for their radiation hardness and fast response, enabling 100 ps time resolution that is a key issue to optimize prompt-gamma detection devices. Several crystal qualities were tested and characterized to cope with the defined goals. Characterization was carried out first at lab with the development of test benches to evaluate the charge transport properties as well as the timing and spectroscopic performances of the tested samples. Then, diamond samples were assembled as detectors to be tested on various pulsed particle beams using both photons and light ions. The first developed double-sided stripped detectors, enabling spatial localization of the ions, were also tested. The results from the different beam tests emphasized diamond’s ability to perform single ion tagging with a 98% detection efficiency and a 100 ps time resolution. A precise counting of the number of protons within a bunch was then achieved. Finally, a study at high beam current highlighted individual ion bunches counting capabilities superior to 30 MHz. The manuscript eventually introduces the design and the development of a hodoscope demonstrator made of four diamond samples arranged in a mosaic pattern. They are double-sided stripped and readout with custom broadband preamplifiers and acquisition board developed at laboratory
Perrin, Océane. "Étude de l'autocouplage du boson de Higgs avec le détecteur ATLAS au LHC. Performance d'un détecteur en temps pour la phase de Haute luminosité du LHC". Electronic Thesis or Diss., Université Clermont Auvergne (2021-...), 2023. http://www.theses.fr/2023UCFA0164.
Texto completoA bosonic particle with a mass equal to 125GeV was observed in 2012, by ATLAS and CMS collaborations at the Large Hadron Collider (LHC). This particle was associated with the Higgs Boson or BEH boson, predicted fifty years before its discovery by François Englert, Robert Brout and Peter Higgs. This particle validates the BEH mechanism, explaining the origin of the mass of known particles and the electroweak symmetry breaking.Since its discovery, it has become crucial to probe the various properties of the Higgs boson such as the Higgs self-coupling. The success in probing Higgs self-coupling will bring another probe of the standard model and will provide a direct measurement of the Higgs field potential in the vacuum. This measure is performed through a global analysis of the di-Higgs (HH) production at LHC, decaying into various channels.This thesis focuses on the study of the decay of the Higgs boson pair into two light leptons with the same charge (referred to as 2lSS) within the context of the Run2 at LHC, providing an integrated luminosity of 139 fb⁻¹ and a centre of mass energy of √s = 13 TeV. The study based on Monte-Carlo simulations aims to develop a machine learning-based strategy to discriminate the signal (2lSS originating from the decay of the Higgs boson pair ) from the background (all other processes producing 2lSS events). An analysis of background noise estimation and systematic uncertainty estimation is also presented in this work.Finally, although the measurement of the self-coupling can be constrained by Run2, its direct measurement is expected in the High-Luminosity phase of the LHC (HL-LHC). This phase involves a five-fold increase in instantaneous luminosity, requiring an upgrade of the ATLAS detector to ensure performance comparable to Run2 performances, despite the increase of radiation and pile-up effects. As a result, a new high-granularity timing detector (HGTD) will be added. A study on the readout electronics of this future detector is presented in this thesis, determining its performance in the test bench and during irradiation tests
Ansari, Saba. "Shape evolution in neutron-rich Zr, Mo and Ru isotopes around mass A=100". Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS384/document.
Texto completoThe shape of an atomic nucleus, ie. the deviation of its mass distribution from sphericity, is a fundamental property and governed by a delicate interplay of macroscopic and microscopic effects, such as the liquid-drop like binding energy and the nuclear shell structure, respectively. Studying nuclear shape properties using gamma ray spectroscopic methods allows detailed tests of different nuclear models, which were originally developed for stable nuclei. We proposed a project to study the evolution of nuclear shapes in exotic nuclei, far from the valley of stability, specifically in neutron-rich nuclei in the isotopic chains from Zr (Z=40) to Pd (Z=46). Usually, nuclear shapes are slowly evolving from spherical shapes around closed-shell or (doubly-) magic nuclei to elongated (prolate) shapes in nuclei with many valence nucleons. The nuclei of interest, however, show rapidly evolving patterns of excited states, which can be interpreted as rapid variations of the nuclear shape, including the rare observation of oblate (disk-like) and triaxial shapes. So far the known properties for these nuclei are (mainly) limited to excitation energies. Information on the nuclear collectivity, which can be deduced from the lifetime of the excited states, are sparse, while direct information of the shape is practically non existing. The simplest estimate of nuclear deformation in even-even nuclei can be obtained from the energy of the first 2⁺ state. For Sr (Z = 38) and Zr (Z = 40) isotopes this energy is observed to decrease dramatically at N = 60, while its evolution is much more gradual in Mo nuclei (Z = 42). Precise lifetime measurements provide a key ingredient in the systematic study of the evolution of nuclear deformation and the degree of collectivity in this region. Neutron-rich nuclei in the mass region of A = 100-120 were populated through the fusion-fission reaction of a ²³⁸U beam at 6.2 MeV/u on a ⁹Be target. The compound nucleus ²⁴⁷Cm was produced at an excitation energy of around 45 MeV before undergoing fission. The setup used for this study comprised the high-resolution mass spectrometer VAMOS in order to identify the nuclei in Z and A, the Advanced gamma ray Tracking Array AGATA of 35 germanium detectors to perform gamma ray spectroscopy, as well as a plunger mechanism to measure lifetimes down to a few ps using the Recoil Distance Doppler Shift method (RDDS). In addition, the target was surrounded by 24 Lanthanum Bromide (LaBr₃) detectors for a fast-timing measurement of lifetimes longer than 100 ps. The sophisticated set of spectrometers used in this experiment allowed measurement of nuclear lifetimes in a range from 100’s of picoseconds down to a few picoseconds. In this thesis, we will report on new lifetime results for short-lived states in neutron-rich (A ~ 100) nuclei, with an emphasis on the Zr, Mo and Ru chains. We will discuss the experimental techniques used to evaluate the lifetimes as well as their interpretation in terms of state-of-the-art nuclear structure models
Burgei, Rémi. "Une chambre à plaques parallèles à avalanche pour la localisation d'ions lourds relativistes". Paris 11, 1989. http://www.theses.fr/1989PA112289.
Texto completoIn order to determine the interaction point of relativistic heavy ions in the Diogene target, we have built and tested an X-Y low pressure parallel plate avalanche chamber. It uses three thin metallized foils and is filled with isobutane. A preliminary study shows that it is the only detector with the required specifications: efficiency, accurate position determination and a small uniform amount of material (1. 9 mg/cm²) for the particle beam to go through. The electronics system is designed for reliability, easy adjustments and high stability. The interaction point is given on delay-line read-out. This represents the optimum compromise between low price and good performance. Laboratory measurements of gain, efficiency and position accuracy are done with an alpha-particle source. Two of these detectors are working at the Saturne National Laboratory. They allow the trajectory of several tens of particles (among a million per second) to be reconstructed. With an argon beam at 400 MeV per nucleon, the position uncertainty in the target has been measured to be 0. 5 mm (standard deviation). This uncertainty is 0. 3 mm for each detector, with an efficiency of 94 per cent. Our set-up, which is now operational, improves the accuracy of the results and speed of analysis of Diogene experiments devoted to the study of central collisions between heavy ions
Clapson, André-Claude. "Recherche de signaux impulsionnels sur le détecteur d'ondes gravitationnelles Virgo". Phd thesis, Université Paris Sud - Paris XI, 2006. http://tel.archives-ouvertes.fr/tel-00085885.
Texto completoLes sources astrophysiques attendues sont principalement les coalescences de systèmes binaires d'objets compacts et les supernovas gravitationnelles. Les amplitudes des signaux sont à la limite de la sensibilité de l'instrument, les taux d'événements observables sont faibles et les formes d'ondes mal connues, notamment pour les effondrements gravitationnels.
L'analyse des données repose sur la recherche de signaux de faible amplitude dans du bruit coloré. Dans ce contexte, ce travail propose l'utilisation de décompositions temps-fréquence des séries temporelles pour la détection de signaux courts. Les performances de cette approche sont estimées en simulation et comparées à celles d'autres méthodes de détection disponibles dans la communauté.
Une autre difficulté pour l'analyse est la présence de structures spectrales étroites dans la distribution d'énergie en fréquence des données. Elles proviennent de résonances mécaniques des miroirs et du système d'isolation sismique de l'instrument. L'utilisation de filtres de Kalman pour éliminer ces bruits bien modélisés avant l'analyse est présentée. Le problème essentiel
de l'estimation des paramètres du modèle est traité, avec l'objectif d'une réestimation dynamique.
Enfin ces outils sont appliqués aux données Virgo disponibles, avec comme résultat principal la mise en évidence de sources de bruits instrumentaux importantes, dont la suppression demandera une amélioration du fonctionnement et une meilleure isolation de l'environnement.
Ghennioui, Hicham. "Séparation aveugle de mélanges linéaires convolutifs de sources corrélées". Phd thesis, Toulon, 2008. https://theses.hal.science/tel-00325910/fr/.
Texto completoIn this thesis, we study the problem of the blind separation of over-determined linear convolutive real or complex mixtures of deterministic or random, statistically independent or correlated, stationary, cyclo-stationary or non-stationary and real or complex sources. We have developed approaches that combine the new (non-unitary) joint (block) diagonalization to two novel detectors of particular points to build the matrices set to be joint (block) diagonalized. The main avantages of the proposed approaches are that they are more direct since they do not require a pre-whitening stage any more and that they can be used with correlated signals. Concerning the joint lock-diagonalization algorithms, we have proposed four joint block-diagonalization algoritms. The first algorithm is iterative and based on an algebraic optimization scheme. The three other ones are based on gradient approaches. The first one relies upon a gradient approach, but the matrix gradient is approximated, whereas the two other ones are based on an exact calculus (one is based on the gradient approach, the other is based on the relative gradient approach). The optimal step size versions of these three algorithms is provided to accelerate their convergence. It means that the step size is computed algebraically at each iteration as the rooting of a 3rd-degree polynomial. The main advantage of the proposed algorithms is that they are more general (the real, positive definite or hermitian assumptions about the matrices belonging to the considered set are no more necessary and the found joint block diagonalizer can be either a unitary or a non-unitary matrix). They can also be applied to solve the joint diagonalization problem
Ghennioui, Hicham. "Séparation aveugle de mélanges linéaires convolutifs de sources corrélées". Phd thesis, Université du Sud Toulon Var, 2008. http://tel.archives-ouvertes.fr/tel-00325910.
Texto completoFonteille, Isabelle. "Etude et conception d’un détecteur 2D transparent permettant le suivi en temps réel de l'administration des traitements rcmi". Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAS039/document.
Texto completoIntensity Modulated Radiotherapy (IMRT) is a high-precision radiotherapy technique based on the use of a multi-leaf collimator, placed at the output of the accelerator. The modulation is adapted to the patient's anatomical structures and obtained by leaves movement during the beam administration. To ensure that the delivered fluence is consistent with the expected one, a control is necessary. In clinical routine, this control isn't achieved on the patient, but on a phantom, before the beginning of the treatment New emerging solutions make possible an online control, done during the treatment of the patient. They can be divided into three classes: those which use data acquired by the accelerator, those which exploit the portal imager and those which use a dedicated detector placed at the exit of the head of the accelerator, upstream of the patient. The thesis work presented here relate to the development of a detector of this third class, Tradera (Transparent Detector for Radiotherapy). The choice was made to use a segmented plane ionization chamber.The first phase of the project was to design the detector thanks to studies made by Monte Carlo simulations. For this it was necessary to model the photon beam. The choice of a point source of photons, quick to set up, has been retained. The characteristics of the particles at the detector input obtained with our model were compared with those obtained with a more complex model: a phase space obtained from the database of the IAEA. Once the model validated, Geant4 code was used to size the various elements of our detector. A innovative geometry has been proposed. It consists in introducing material in the sensitive volume of the detector to limit the lateral travel of the electrons from the interaction of photons, and thus improve the spatial resolution of the detector. In practice, a checkerboard with plastic pads is introduced in the sensitive volume. The benefit of this solution has been shown by simulations.The second phase was to assess a prototype in a clinical beam with radiation equipment and test the performance of various associated acquisition electronics. For a long time, reading was made at the output of a single channel at a time. First, a picoammeter was used to measure the average output current. Then the ionization current has been studied at the time scale of a pulse of the beam, allowing the development of a charge preamplifier dedicated to our application. This charge preamplifier permit to know, for a single beam pulse, the electrical charge measured by one channel of the prototype with a uncertainty of 5%, and thus makes it possible to study the evolution of the charge pulse as a function of irradiation time. Once the choice of this readout electronics was validated, the charge preamplifier was realized in small series : the acquisition in multi-channels on an area of 3 cm square was possible. The first beam images could then be obtained for static and dynamic beam
Ismail, Iyas. "Développement d'un détecteur sans temps mort sensible en temps et en position : Application à l'étude des collisions de petits agrégats d'argon Ar+n sur une cible d'argon". Phd thesis, Université Paris Sud - Paris XI, 2005. http://tel.archives-ouvertes.fr/tel-00011289.
Texto completoNous avons étudié la fragmentation induite par collision des petits agrégats d'argon (Ar2+ et Ar3+) avec une cible d'argon atomique dans la gamme des énergies du keV. Toutes les voies de fragmentation : la dissociation induite par collision (CID) et l'échange de charge dissociatif (DCT) sont analysées par la corrélation vectorielle de tous les fragments détectés en coïncidence. En particulier, nous avons montré que le processus DCT dépendait fortement de l'énergie interne initiale de l'agrégat (i.e. du défaut de résonance). La comparaison de diverses observables mesurées en collision Ar2+-Ar et Ar3+-Ar nous a conduit à conclure que les agrégats Ar3+ produits dans notre source ont majoritairement la structure d'un dimère chargé (Ar2+) autour duquel orbite un troisième atome peu lié.
Brizard, Christine. "Développement d'un détecteur CCD programmable pour l'imagerie, les études en temps réel et d'autres applications relatives à un synchrotron". Grenoble 1, 1991. http://www.theses.fr/1991GRE10118.
Texto completoGey, Guillaume. "Etude de noyaux riches en neutrons dans la région du coeur doublement magique de ¹³²Sn". Thesis, Grenoble, 2014. http://www.theses.fr/2014GRENY033/document.
Texto completoEvolution of nuclear structure in the vicinity of the doubly magic nuclei 132Sn will be discussed in this work, through the spectroscopy of 136Sb, 136Sn and 138Sn isotopes. Several Sb and Sn known isotopes beyond the Z=50 and N=82 shell closures will be briefly presented in the first chapter, aswell as some of the problems arising from the current shell model descritpion of nuclei in this region. Reader will also find in the same chapter a brief description of the most important tools needed to understand such calculations. Excited state of 136Sb have been populated at the Institut Laue-Langevin (Grenoble) through thermal neutron-induced fission on a 241Pu target. Fission fragments produced were separated with the Lohengrin mass spectrometer. Conversion electrons and gammas from 136Sb were measured and confirmed the previously proposed schemed. A new 31(7) ns isomer has been measured and assigned to the 4- state. Details of the experiment and analysis are presented in the first part. The second part is devoted to the 136,138Sn isotopes, produced via in-flight fission of 238U on a 9Be target at the RIBF of the RIKEN (Tokyo). Mass separators BigRIPS and ZDS allowed separation and identification of produced fragments, before implantation in the higly segmented silicon detector WAS3ABi surrounded by the germanium array EURICA. The first energy measurement of the 6+ -> 4+, 4+ -> 2+ and 2+ -> 0+ transitions has been performed for each of the 136,138Sn isotopes, aswell as an 46(7) and 219(58) ns half-life for the 6+ state of the 136Sn and 138Sn respectively
Nasreddine, Rouba. "Développement d'une méthode analytique et d'un microanalyseur miniaturisé pour la détection des BTEX dans l'air". Thesis, Strasbourg, 2016. http://www.theses.fr/2016STRAF010.
Texto completoBTEX are very widespread indoor air pollutants. Their harmful effects on human health had led the legislator to set thresholds in order to limit the population exposure. The aim of this thesis is to develop a sensitive, accurate and fast analytical method based on a measurement device. Therefore, the device implemented is a miniaturized gas chromatography (GC) equipped with a mini photo ionization detector dedicated to BTEX detection in indoor air in near-real time. The miniaturized GC is very portable with a very low gas consumption which enhances its autonomy over a long period. Its operation mode is based on air sampling inside a sample loop which is connected to a six port valve. The injection over a heated analytical column is ensured by switching the valve position before detection by a photo ionization detector. This novel device was used in real conditions during two field campaigns conducted in an energy efficient college. This study focused on the temporal monitoring of indoor air pollutant concentrations including BTEX. The results obtained with our miniaturized device for BTEX were compared to those given by other techniques known as reference techniques. These field campaigns have therefore enabled us to validate the analytical performances, the robustness and the autonomy of this novel analytical method
Guillard, Goulven. "Étude de la sensibilité du télescope à neutrinos ANTARES aux photons de très haute énergie — Contribution à l'étalonnage en temps du détecteur". Phd thesis, Université de Strasbourg, 2010. http://tel.archives-ouvertes.fr/tel-00555462.
Texto completoGuillard, Goulven. "Etude de la sensibilité du télescope à neutrinos Antares aux photons de très haute énergie : contribution à l'étalonnage en temps du détecteur". Strasbourg, 2010. https://publication-theses.unistra.fr/public/theses_doctorat/2010/GUILLARD_Goulven_2010.pdf.
Texto completoFrom the seafloor, the 900-odd photomultiplier tubes of the Antares neutrino telescope scrutinize the abysses attempting to discern, amid bioluminescence and marine radioactivity, Cerenkov photons emitted by muons from astrophysical neutrinos, and to distinguish these muons from those generated by air showers produced by cosmic rays. Antares has been collecting data since 2006 ; this feat of engineering has paved the way for submarine neutrino astronomy : Antares is expected to be the forerunner of a larger instrument, KM3NeT. A telescope’s performance is characterized in part by its angular resolution. In the case of Antares, the angular resolution is directly related to the time resolution of the detector’s elements. This manuscript presents a correction for one of the main sources of deterioration of this time resolution, the walk effect induced by the set up of a fixed threshold for triggering the photomultiplier tubes signal. This correction, implemented in the official software chain of the Antares collaboration, improves in particular the events reconstruction quality estimator. This implementation allows further optimizations. The author also attempts to evaluate, using a complete Monte-Carlo simulation, the possibility of using very high energy photon sources as calibrated muon beams in order to estimate the absolute pointing and the angular resolution of the telescope. Although limited by large uncertainties, it is demonstrated that the possibility to detect such sources is extremely small. In addition, it is shown that the atmospheric neutrino background induced by very high-energy photons is negligible
Syed, Mohamad Jamalullil Bilfagih. "Transmission multiple porteuses utilisant un codage détecteur/correcteur d'erreur de type LDPC sur canaux MIMO : Détection multi-utilisateurs, turbo égalisation, diversité temps, espace, fréquence". Limoges, 2005. http://aurore.unilim.fr/theses/nxfile/default/fdaa373f-c0da-4eb9-abf9-3aed67119b83/blobholder:0/2005LIMO0006.pdf.
Texto completoWe are continuously looking for high-speed mobile system using at it best all the allocated and available radio resources. In order to increase the communication reliability and quantity, the error correcting codes such as LDPC and turbo detection are often used together with diversity techniques. In this thesis, four major points have been investigated. The first point relates to the transmitter created space, time and frequency diversity techniques. Diversity methods namely STBC, SFBC and STFBC were studied here. A novel matrix representation for SFBC and STFBC have been elaborated and presented. The second point focus on the turbo equalizer for space-time diversity systems. Our studies were based on the structure proposed by Lu. LDPC code and EM algorithm were the basic blocs of the turbo receiver. Some modifications have been made to the basic receiver structure especially on the initialization method in order to increase the systems performances. The SAGE algorithm was applied to speed up the overall convergence rate of the system. The third point was the uplink quasi synchronous multiple user detection in MIMO systems. We proposed two multiple user systems with an equivalent performances as single user system when some conditions were fulfilled. We have also elaborated in our proposed system that the potential very high rate system mixing and the Combined Array Processing techniques as proposed by Calder bank. Finally, in the fourth point, we presented using computer simulations proven that, in some cases, an additional symbol interleaver is required for multiple carrier space diversity system to concatenate with LDPC codes over frequency selective channels. It is well known that the LDPC codes have an intrinsic interleaver. However, the computer simulations showed that the intrinsic interleaver might be insufficient in this configuration
Convert, Laurence. "Système microfluidique d'analyse sanguine en temps réel pour l'imagerie moléculaire chez le petit animal". Thèse, Université de Sherbrooke, 2012. http://hdl.handle.net/11143/6623.
Texto completoEl, Rifai Ibrahim. "Mesure de la polarisation du baryon lourd Λb avec le détecteur LHCb. Recherche de la violation directe de la symétrie de renversement du temps T". Thesis, Clermont-Ferrand 2, 2015. http://www.theses.fr/2015CLF22560/document.
Texto completoThis thesis subject focuses on the study of the weak decay of the beauty baryon Λb →Λ J/Ψ with the LHCb detector. Firstly, it offers the opportunity to test the validity of the CP symmetry in the baryon sector and, secondly, the one of time-reversal symmetry T whose experimental evidence is tiny. Emphasis is put on the measurement of the components of the polarization-vectors of the Λb and the ones of the intermediate resonances Λ and J/Ψ, whose some components exhibit a clear sign of direct T violation. The development of a phenomenological model of the Λb → Λ J/Ψ decay in the framework of the helicity formalism of Jacob-Wick and Jackson leads to the calculations of the angular distributions which allow to deduce the values of the polarization vector components. A thorough study of the reconstruction and the selection of the data recorded by LHCb in 2011 and 2012 is exposed, as well as a full Monte Carlo simulation. The compatibility between the measured values of the polarization-vector of Λb and Λ ̄b implies the absence of CP violation. The direct violation of the T symmetry has not been observed in the hadronic decays of Λb ( Λ ̄b). On another side, first measurements of the longitudinal polarization of Λb and of Λ ̄b well as the longitudinal polarization of the vector-meson J/Ψ have been performed in the context of this work
Agapopoulou, Christina. "Search for supersymmetry with the ATLAS detector and development of the High Granularity Timing Detector". Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASP019.
Texto completoThe Standard Model of particle physics is an extremely successful theoretical framework, describing the elementary particles and their interactions.With the discovery of the Higgs boson by the ATLAS and CMS experiments in 2012, the Standard Model is now complete. However, open questions remain unanswered, calling for a larger theoretical model that encapsulates the Standard Model, while providing mechanisms for the unexplained phenomena. Supersymmetry offers such a framework by introducing a new symmetry between bosons and fermions. It provides potential solutions to the hierarchy problem for the Higgs boson mass and also offers a candidate to explain the dark matter of the universe.The first part of this thesis is the search for supersymmetry with the ATLAS detector at LHC, using the full dataset of Run 2, amounting to an integrated luminosity of 139 fb⁻¹. The focus is on the search for squarks and gluinos, the "super-partners" of quarks and gluons, in models where R-parity is conserved and in final states with jets and large missing transverse momentum. My main contribution to this analysis was the development and optimization of a novel technique named Multi-Bin fit to enhance the signal to background separation and extend the exclusion reach of the search. The expected gain in the excluded cross section from using a Multi-Bin fit configuration, opposed to the traditional "cut&count" approach, was estimated to be 40 - 70 % in the studied models. In addition, I worked on the statistical inference of the search, ranging from the evaluation of various systematics to the interpretation of the results in various simplified supersymmetric models. No excess above the Standard Model prediction was found and therefore squarks and gluinos with masses up to 1.85 TeV and 2.34 TeV were excluded, respectively. This result is a significant improvement over the previous round of the analysis and one of the strongest constraints on squark and gluino masses today.The high-luminosity data acquisition phase (HL-LHC) will see an increase of the collision rate by a factor of 5 to 7. In order to mitigate the increase of pile-up, ATLAS will install a new highly granular silicon detector with a very good time resolution that would be located at the forward region, the High Granularity Timing Detector (HGTD). The goal of this detector is to provide a time resolution better than 50 ps per track. The second part of this thesis focuses on two main aspects in the development of HGTD. On one hand, I performed simulation studies to evaluate the occupancy and read-out requirements of the detector under various geometries. The occupancy of the detector must remain below 10%, in order to correctly assign energy deposits to tracks crossing the detector. It was found that this requirement was met with a sensor size of 1.3 x 1.3 mm², which is now the baseline for the future detector. Additionally, the organization of the on-detector read-out system was optimised, in order to maximise the available space and minimise the necessary components. The performance of any silicon detector is strongly linked to the design of the front-end electronic circuit. As part of my work in HGTD, I also participated in the characterization of two front-end electronic prototypes, ALTIROC0 and ALTIROC1, both in laboratory with a calibration system and in testbeam with highly energetic electrons and protons. The temporal resolution was found to be better than 55 ps in all tested devices, with a best achieved performance of 34 ps
Arnaud, Nicolas. "Contrôle global de la partie centrale du détecteur d'ondes gravitationnelles Virgo. Recherche de signaux impulsionnels: application aux coincidences entre interféromètres". Phd thesis, Université Paris Sud - Paris XI, 2002. http://tel.archives-ouvertes.fr/tel-00006624.
Texto completoChauveau, Pierre. "Design, simulations and test of a Time-of-Flight spectrometer for mass measurement of exotic beams from SPIRAL1/SPIRAL2 and gamma-ray spectroscopy of nuclei close to 100Sn". Caen, 2016. http://hal.in2p3.fr/tel-01469429.
Texto completoThe new generation of nuclear facilities calls for new technological developments to produce, accelerate, manipulate and analyse exotic nuclei. The main topic of this thesis work was the simulation, design and test of a Multi-Reflection Time-of-Flight Mass spectrometer (MR-ToF-MS) for fast mass separation and fast mass measurement of radioactive ions in the installations S3 and DESIR at SPIRAL2. Such a device could separate isobaric nuclei and provide SPIRAL2 with high purity beams. Also, its mass measurement capabilities would help to determine binding energies of exotic and superheavy nuclei with a high precision. This apparatus has been simulated with the SIMION 8. 1 software and designed accordingly. First offline tests have been performed with a stable ion source at LPC Caen. In addition a low-aberration electrostatic deflector has been simulated and designed to operate with this MR-ToF-MS without spoiling its performances. This work also describes the analysis and results of the first online tests of a FEBIAD-type ion source intended to provide SPIRAL1 and SPIRAL2 radioactive beams of competitive intensities. Finally, we describe the analysis of a nuclear physics experiment, including the calibration of the different detectors and the gamma-spectroscopy of nuclei in the vicinity of the doubly magic 100Sn