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1
Li, Kwan-lok, und 李君樂. „Study of x-ray supernovae and supersoft/quasisoft x-ray sources with an automated source search program“. Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2011. http://hub.hku.hk/bib/B46084125.
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2
Ribbing, Carolina. „Microfabrication of miniature x-ray source and x-ray refractive lens“. Doctoral thesis, Uppsala University, Department of Materials Science, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-3099.
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In several x-ray related areas there is a need for high-precision elements for x-ray generation and focusing. An elegant way of realizing x-ray related elements with high precision and low surface roughness is by the use of microfabrication; a combination of semiconductor processing techniques and miniaturization. Photolithographic patterning of silicon followed by deposition, etching, bonding and replication is used for batchwise fabrication of small well-defined structures. This thesis describes microfabrication of a miniature x-ray source and a refractive x-ray lens. A miniature x-ray source with diamond electrodes has been tested for x-ray fluorescence. Another version of the source has been vacuum encapsulated and run at atmospheric pressure. One-dimensionally focusing saw-tooth refractive x-ray lenses in silicon, epoxy, and diamond have been fabricated and tested in a synchrotron set-up. Sub-micron focal lines and gains of up to 40 were achieved. The conclusion of the thesis is that the use of microfabrication for construction of x-ray related components can not only improve the performance of existing components, but also open up for entirely new application areas.
3
Fuchs, Matthias. „Laser-Driven Soft-X-Ray Undulator Source“. Diss., lmu, 2010. http://nbn-resolving.de/urn:nbn:de:bvb:19-121352.
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4
Petersen, Timothy W. „Tabletop internal source ensemble x ray holography /“. Thesis, Connect to this title online; UW restricted, 1997. http://hdl.handle.net/1773/9747.
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5
Nazary, Mineh. „Optimization of X-ray Source for Digital Mammography - X-ray Optics Approach“. Thesis, Linköpings universitet, Institutionen för medicinsk teknik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-84857.
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The work presents a new design of X-ray source for digital mammography imaging with the help of crystal sources and X-ray optics technology. The aim of the project was to introduce a new source for medical x ray imaging and evaluate its ability of performance. The source is build of an array of multiple micro-emitters instead of a single source. These sources are made of pyroelectric crystals. The produced Xrays are then getting focused by passing through prism array lenses. These lenses are used as focusing pre-object collimator, to reduces the divergence of the beam and increases the utilization of the available X-rays. The lenses are coupled with collimators to avoid scatter rays. The software used for the simulations of the system and evaluations is MATLAB. Several methods, like calculating the point spread function and modulation transfer function, have been applied in order to evaluate the system imaging ability and the system efficiency. Later on in calculations, an anti scatter grid is added as a post collimator and system efficiency is calculated again before and after the grid. The ability of the system to perform is calculated for digital mammography. The results in the end showed how the lenses perform while using different photon energies. However the current results were not enough to approve the ability of the system for medical imaging uses. For achieving more comprehensive and certain answers further investigations will be necessary.
6
Froud, Christopher Andrew. „Designing a nanoscale X-ray source : towards single molecule X-ray scattering“. Thesis, University of Southampton, 2007. https://eprints.soton.ac.uk/52042/.
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This thesis describes the design and construction of a femtosecond X-ray source based on high harmonic generation in an argon filled hollow capillary waveguide. The system has demonstrated excellent efficiency at generating harmonics in the range 20-50 eV and is tuneable by exploiting the ionization-induced blue-shift that occurs in the waveguide. The X-ray source is designed for X-ray scattering experiments, which will ultimately allow the imaging of single biomolecules. Such experiments will require an intense, focused X-ray beam. Towards this aim, this thesis demonstrates focusing techniques based on tapered capillary optics, including a model that was developed to understand their behaviour.
7
Stemprok, Roman. „Improved design of a lithography X-ray source“. Thesis, McGill University, 1989. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=55639.
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8
Hurley, David. „Laser Copper Plasma X-Ray Source Debris Characterization“. ScholarWorks @ UVM, 2008. http://scholarworks.uvm.edu/graddis/115.
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Laser copper plasma sources are a compact, economical means of producing high intensity x-rays at the correct wavelengths for x-ray lithography. Copper debris in the form of vapor, ions, dust, and high-speed particles is an unwanted byproduct of the laser copper plasma technique. Improved methods for debris mitigation are essential for production x-ray lithography using laser copper plasma sources. The objective of this project was to develop and implement a tool for the study of the size, amount, and velocity spectrum of high speed particulate debris. The measurements used a source-laser-pulse-synchronized high speed spinning disc. An optical scanning boom microscope analyzed debris collected on a target. Debris target imagery was analyzed using an image processing and pattern recognition program. This provided an unbiased assessment of debris accumulation. The position of debris particles was used to determine their velocity using kinematic triangulation. Velocities of copper debris particles were found to be in the hundreds of meters per second, roughly one order of magnitude slower than previously believed. The accuracy of these results was compromised by multi-pulse aliasing. The new understanding of debris velocities suggests reconsideration of a host of countermeasures previously thought to be too slow to effectively stop high speed debris particles. This study also suggests that x-rays emitted at high laser pulse rates could be blocked by the low speed debris generated during the previous laser pulse. The target location and laser spot size and focal point are critical elements in the plasma generation process and were found to have a low tolerance for variation. This finding identified the mechanics of plasma generation and parameter control as areas requiring further refinement and study.
9
Immler, Stefan. „The X-Ray Source Population of Nearby Spiral Galaxies“. Diss., lmu, 2000. http://nbn-resolving.de/urn:nbn:de:bvb:19-3274.
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10
May, Anna, Johannes Wachs und Anikó Hannák. „Gender differences in participation and reward on Stack Overflow“. Springer Nature, 2019. http://dx.doi.org/10.1007/s10664-019-09685-x.
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Programming is a valuable skill in the labor market, making the underrepresentation of
women in computing an increasingly important issue. Online question and answer platforms
serve a dual purpose in this field: they form a body of knowledge useful as a reference and
learning tool, and they provide opportunities for individuals to demonstrate credible, verifi-
able expertise. Issues, such as male-oriented site design or overrepresentation of men among
the site's elite may therefore compound the issue of women's underrepresentation in IT. In
this paper we audit the differences in behavior and outcomes between men and women on
Stack Overflow, the most popular of these Q&A sites. We observe significant differences in
how men and women participate in the platform and how successful they are. For example,
the average woman has roughly half of the reputation points, the primary measure of success
on the site, of the average man. Using an Oaxaca-Blinder decomposition, an econometric
technique commonly applied to analyze differences in wages between groups, we find that
most of the gap in success between men and women can be explained by differences in
their activity on the site and differences in how these activities are rewarded. Specifically,
1) men give more answers than women and 2) are rewarded more for their answers on aver
age, even when controlling for possible confounders such as tenure or buy-in to the site.
Women ask more questions and gain more reward per question. We conclude with a hypo
thetical redesign of the site's scoring system based on these behavioral differences, cutting
the reputation gap in half.
11
Grätz, Matthias. „Characterisation and application of a laser-based hard X-ray source“. Lund : Lund Institute of Technology, 1998. http://catalog.hathitrust.org/api/volumes/oclc/68945036.html.
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12
Hemberg, Oscar. „Compact Liquid-Jet X-Ray Sources“. Doctoral thesis, KTH, Physics, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3716.
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This thesis describes the development, characterization andoptimization of compact, high-brightness, liquid-jet-targetx-ray sources. Two different source types have been developedfor different wavelength regions and applications.
A laser-plasma source for generating soft x-ray andextreme-ultraviolet radiation has been further developed forsoft x-ray microscopy and extreme-ultraviolet lithography. Thiswork focused on improved target stability, increased conversionefficiency and decreased debris production. For x-raymicroscopy applications using carbon-containingliquid-jetdroplet targets, the droplet stability has beeninvestigated and a method for source stabilization introduced.This source has also been optimized in terms of flux per debriswith respect to target material and size. Forextreme-ultraviolet lithography applications, aliquid-xenon-jet-target laser-plasma source system has beengreatly improved, especially in terms of stability andconversion efficiency. This source has also been characterizedin terms of, e.g., source size, angular distribution, andrepetition-rate capability. For extremeultraviolet lithography,the possible use of tin as a target material has also beenstudied and conversion efficiency and debris measurementsperformed.
A new anode concept for electron-impact hard x-ray sourcesbased on high-speed liquidmetal jets has been introduced.Initial calculations show that this new target concept couldpotentially allow more than a hundred-fold increase in sourcebrightness compared to existing state-of-the-art technology. Alow-power, proof-of-principle, experiment has been performed,verifying the basic source concept. Scaling tohigh-poweroperation is discussed and appears plausible. A main obstaclefor high-power operation, the generation of a microscopichigh-speed jet in vacuum, is investigated usingdynamic-similarity experiments and shown to be feasible.Finally, initial medium-power experiments, approaching currentstate-of-the-art sources in terms of brightness, have beenperformed.
13
Otendal, Mikael. „A Compact High-Brightness Liquid-Metal-Jet X-Ray Source“. Doctoral thesis, Stockholm, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4005.
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14
Müller, Bernhard. „Medical imaging with a laser-driven undulator x-ray source“. Diss., Ludwig-Maximilians-Universität München, 2013. http://nbn-resolving.de/urn:nbn:de:bvb:19-167164.
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15
WULVERYCK, JEAN-MICHEL. „Contribution a la mise au point d'une microscopie x analytique quantitative avec une source x polychromatique“. Reims, 1999. http://www.theses.fr/1999REIMS035.
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La microscopie x par projection est utilisee pour observer de maniere non-destructive des echantillons dont la taille varie de l'echelle nanoscopique a l'echelle humaine. La technique consiste a recueillir l'image projetee sur un detecteur plan par une radiation x issue d'une source microfocale, radiation attenuee lors de la traversee de l'echantillon. La mise en uvre experimentale d'une microscopie x analytique quantitative pose le probleme de la nature spectrale de la source employee. En effet, a l'exception des travaux utilisant la radiation synchrotron, la majorite des sources x est polychromatique. L'attenuation des photons x dans la matiere etant un phenomene non - lineaire, l'emploi d'une telle source polychromatique rend complexe l'extension analytique de la technique. Pour resoudre le probleme inverse qui consiste en la deduction des concentrations massiques a partir de plusieurs images d'un echantillon, nous avons opte pour une caracterisation spectrale preliminaire des elements situes en amont de l'echantillon, a savoir la source x, et en aval de celui-ci, le systeme de formation des images, avant de reflechir aux phenomenes prenant place dans l'echantillon. Un logiciel a ete concu, fonde sur des modeles analytiques utilises en microanalyse par sonde electronique. Il s'agit d'un logiciel de modelisation de la distribution spectrale d'une source x obtenue par bombardement electronique d'une cible metallique. La reponse spectrale a ete etablie experimentalement au moyen d'une source x accordable. Les resultats montrent que la reponse spectrale suit la loi d'absorption des photons x dans l'ecran scintillateur. Nous avons alors elabore une procedure mathematique pour relier l'intensite attendue en un pixel du detecteur a la composition et a l'epaisseur locale de l'echantillon. L'etude de deux echantillons tests nous a permis de valider la procedure proposee et de discuter la precision des resultats obtenus.
16
Luani, Giacomo. „Optimization of e-beam and x-ray target geometry of a solid x-ray anode source“. Thesis, Uppsala universitet, Materialfysik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-446042.
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The X-ray tube is one of the most common types of X-ray sources, which is widely used in research laboratories and industry. Electrons are accelerated towards a metallic target to generate X-ray photons, thus creating a significant thermal load on the metal. In order to reduce the risk of damage, some techniques, such as the focus line principle or the installation of a very thin target, are implemented in most cases. In addition, the geometry of the target is chosen to maximise the amount of X-rays for the intended application. The aim of this thesis is to investigate how the incident angle of the electron beam, consequence of the line focus principle, and the thickness of the target influence the total photon yield of the source. Monte Carlo simulations of electron/photon transport have been made with a modified version of the PENELOPE program using a novel variance reduction technique. The results from the calculations are validated with experiments conducted with a prototype source, in the laboratory of Excillum AB. Since thermal capabilities and X-ray yield have opposite dependence on target angle and thickness, by combining the thermal results from Sara Högnad$\acute{\mathrm{o}}$ttir's thesis and the ones produced in this thesis, it is possible to isolate an optimal configuration of the source. In this geometry, the best compromise between high brightness and high maximum allowed power is found.
17
Lux-Baumann, Jessica, und Darryl A. Burkes. „HYPER-X (X-43A) FLIGHT TEST RANGE OPERATIONS OVERVIEW“. International Foundation for Telemetering, 2005. http://hdl.handle.net/10150/604791.
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ITC/USA 2005 Conference Proceedings / The Forty-First Annual International Telemetering Conference and Technical Exhibition / October 24-27, 2005 / Riviera Hotel & Convention Center, Las Vegas, NevadaThe Hyper-X program flew X-43A research vehicles to hypersonic speeds over the Pacific Ocean in March and November 2004 from the Western Aeronautical Test Range, NASA Dryden Flight Research Center, Edwards, California. The program required multiple telemetry ground stations to provide continuous coverage of the captive carry, launch, boost, experiment, and descent phases of these missions. An overview is provided of vehicle telemetry and distributed assets that supported telemetry acquisition, best-source selection, radar tracking, video tracking, flight termination systems, and voice communications. Real-time data display and processing are discussed, and postflight analysis and comparison of data acquired are presented.
18
Picquenot, Adrien. „Introduction and application of a new blind source separation method for extended sources in X-ray astronomy“. Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASP028.
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Certaines sources étendues, telles que les vestiges de supernovae, présentent en rayons X une remarquable diversité de morphologie que les téléscopes de spectro-imagerie actuels parviennent à détecter avec un exceptionnel niveau de précision. Cependant, les outils d’analyse actuellement utilisés dans l’étude des phénomènes astrophysiques à haute énergie peinent à exploiter pleinement le potentiel de ces données : les méthodes d’analyse standard se concentrent sur l’information spectrale sans exploiter la multiplicité des morphologies ni les corrélations existant entre les dimensions spatiales et spectrales ; pour cette raison, leurs capacités sont souvent limitées, et les mesures de paramètres physiques peuvent être largement contaminées par d’autres composantes.Dans cette thèse, nous explorerons une nouvelle méthode de séparation de source exploitant pleinement les informations spatiales et spectrales contenues dans les données X, et leur corrélation. Nous commencerons par présenter son fonctionnement et les principes mathématiques sur lesquels il repose, puis nous étudierons ses performances sur des modèles de vestiges de supernovae. Nous nous pencherons ensuite sur la vaste question de la quantification des erreurs, domaine encore largement inexploré dans le milieu bouillonnant de l’analyse de données. Enfin, nous appliquerons notre méthode à l’étude de trois problèmes physiques : les asymétries dans la distribution des éléments lourds du vestige Cassiopeia A, les structures filamentaires dans l’émission synchrotron du même vestige, et la contrepartie X des structures filamentaires visibles en optique dans l’amas de galaxies PerseusSome extended sources, among which we find the supernovae remnants, present an outstanding diversity of morphologies that the current generation of spectro-imaging telescopes can detect with an unprecedented level of details. However, the data analysis tools currently in use in the high energy astrophysics community fail to take full advantage of these data : most of them only focus on the spectral information without using the many spatial specificities or the correlation between the spectral and spatial dimensions. For that reason, the physical parameters that are retrieved are often widely contaminated by other components. In this thesis, we will explore a new blind source separation method exploiting fully both spatial and spectral information with X-ray data, and their correlations. We will begin with an exposition of the mathematical concepts on which the algorithm rely, and particularly on the wavelet transforms. Then, we will benchmark its performances on supernovae remnants models, and we will investigate the vast question of the error bars on non-linear estimators, still largely unanswered yet essential for data analysis and machine learning methods. Finally, we will apply our method to the study of three physical problems : the asymmetries in the heavy elements distribution in the supernova remnant Cassiopeia A, the filamentary structures in the synchrotron of the same remnant and the X-ray counterpart to optical filamentary structures in the Perseus galaxy cluster
19
Staufer, Theresa Maria [Verfasser], und Florian [Akademischer Betreuer] Grüner. „X-Ray Fluorescence Imaging with a Laser-Driven X-Ray Source / Theresa Maria Staufer ; Betreuer: Florian Grüner“. Hamburg : Staats- und Universitätsbibliothek Hamburg, 2020. http://d-nb.info/1217408878/34.
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20
Misanovic, Zdenka. „Classification of the X-ray source population in the M33 field“. [S.l.] : [s.n.], 2005. http://edoc.ub.uni-muenchen.de/archive/00004793.
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21
Misanovic, Zdenka. „Classification of the X-ray source population in the M33 field“. Diss., lmu, 2006. http://nbn-resolving.de/urn:nbn:de:bvb:19-47936.
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22
Badaye, Massoud. „Investigation and improvement of a Z-pinch plasma X-ray source“. Thesis, McGill University, 1992. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=39468.
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A thorough investigation of a pulsed plasma x-ray source is presented with the intent of improving its design and maximizing its x-ray emission efficiency. In this approach a hollow gas column is puffed in the z-pinch diode by magnetically ionizing and compressing an inert gas in an annular plenum. This gas column is preionized by the radiation coming out from the plasma in the plenum and pinched by a fast electrical discharge.It is shown that the system can be improved considerably by modifying the gas puff design. Three gas puffs developed in this work are optimized for x-ray emission from argon, krypton, and neon gases. In the optimized conditions the output x-ray energies of 0.5 J from Ar-K shell, 2 J from Kr-L shell, and more than 2 J from Ne-K shell are obtained.
The implosion dynamics is studied with different gases under varying conditions. The average implosion velocity, the final pinch diameter, the current waveform, and the emitted x-ray energy are measured. The pinched plasma parameters such as temperature, density, and the average ionic state are estimated using the corona model calculations, and the pinched current waveforms. The spectrum of the neon radiation clearly shows the characteristic H-like and He-like lines. The neon spectrum is used to estimate the plasma temperature.
The dynamic performance of the magnetically induced compression gas puff is studied carefully. A special ion probe was developed for studying the dynamic parameters of the gas puff. The ion measurements with the probe have led to the characterization of the gas puff performance under varying operating conditions. It is shown that ions are generated through photoionization of the injected gas by the UV light emitted from the inside of the gas puff plenum through the nozzle. It is found that the jet velocity and ion density can be in excess of $3 times10 sp3$ m/s and $2 times10 sp{14}$ cm$ sp{-3}$, respectively.
A theoretical model is developed to simulate the plasma evolution in the gas puff. This model uses the magneto hydrodynamic (MHD) equations solved by the finite difference method. The magnetic field in the vacuum is calculated using the Laplace equation and self consistent boundary conditions. The model predicts the evolution of plasma variables such as density, temperature, velocity, and magnetic field. It also calculates the variation of the total mass flow rate, optical output, and the ionic signal. The simulation results are shown to compare favourably with the experimental measurements.
23
Kelly, Kathryn L. „Phase contrast imaging with a laboratory-based microfocus X-ray source“. Thesis, Durham University, 2007. http://etheses.dur.ac.uk/2453/.
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This project looks at the design of an in-line X-ray phase contrast imaging system, based around the Bede Microsource®, on a suitable scale for imaging small pathological samples. The system is applied to two test objects to assess feasibility of its use in practice. The system comprises: microfocus X-ray source, copper and rhodium targets, phase object and detector. By altering sample position, phase contrast is seen to vary proportionally with propagation distance. By increasing source size, phase contrast is seen to degrade with increasing source dimensions. It is furthermore determined that transverse coherence in the direction perpendicular to a sample boundary dominates the result. Using different operating voltages with an image manipulation approach, the importance of monochromaticity is investigated. It is determined that less polychromatic X-rays provide better phase contrast. However, applying a filter method of monochromation reduces phase contrast due to beam hardening, so this method is unsuitable for phase imaging with this system. By increasing sample thickness, phase contrast is seen to plateau at a certain thickness, dependant on X-ray energy, revealing a practical limitation of the system. Introduction of water and glass to the system is seen to be detrimental to phase contrast, due to beam hardening. However phase contrast is not destroyed by the presence of water. When imaging a mammographic test object comprising low-contrast details and breast tissue morphology, the system detects all low-contrast details extremely well. Furthermore, using a phase object together with breast tissue morphology, with the harder rhodium X-rays, the system detects an anomaly of -500J.!m through the noise of simulated breast tissue. Finally, we see the difference in two scorpion sting images: an absorption image taken at the beginning of the project and a phase image taken after the system has been improved.
24
Edgell, Michael John. „A study of the silver X-ray source for photoelectron spectroscopy“. Thesis, University of Surrey, 1986. http://epubs.surrey.ac.uk/847393/.
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A novel x-ray anode for electron spectroscopy is investigated for application in the surface analysis field, monochromatic Ag Lalpha (hnu =2984. 3eV), its energy being capable of exciting 1s electrons up to chlorine in the periodic table. Resolution available with this source is satisfactory, with a limitation of approximately 1. 3eV. An increase in sensitivity is achieved for those peaks in the range 1500-3000BE, whilst there is no serious reduction within the conventional XPS energy range. The agreement between experimental sensitivity factors and theoretical cross-section values is good, allowing the transmission function for the VG ESCA3 Mkll spectrometer to be confirmed constant from 0-3000eV. A comprehensive investigation of the LEG51 electron flood gun preceded its successful application for the charge neutralisation of insulating materials. This allowed the application of this source to such materials as chlorides, pertinent to the breakdown in passivity on stainless steels, and silicon compounds, involving thermal oxides on silicon of interest to the microchip industry, zeolites for catalysis in the petrochemical industry and siloxane copolymers for the opthalmic industry. The ability to excite the 1s orbital, together with the 2p and KLL Auger lines, affords calculation of Auger parameters and extra-atomic relaxation energies for the accurate description of the chemical environment of a particular chemical species. A method for internal energy referencing is investigated, involving the vaccum-deposition of Au, Cu and Pt metals. This allows the measurement of photoelectron binding energies to an accuracy of +/-0.1-0.2eV for insulating materials, when referenced to the vacuum level.
25
Fogelqvist, Emelie. „Laboratory Soft X-Ray Cryo Microscopy: Source, System and Bio Applications“. Doctoral thesis, KTH, Biomedicinsk fysik och röntgenfysik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-206428.
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Soft x-ray microscopes routinely perform high-resolution 3D imaging of biological cells in their near-native environment with short exposure times at synchrotron radiation facilities. Some laboratory-sized microscopes are aiming to make this imaging technique more accessible to a wider scientific community. However, these systems have been hampered by source instabilities hindering routine imaging of biological samples with short exposure times. This Thesis presents work performed on the Stockholm laboratory x-ray microscope. A novel heat control system has been implemented, improving the stability of the laser-produced plasma source. In combination with recent upgrades to the imaging system and an improved cryofixation method, the microscope now has the capability to routinely produce images with 10-second exposure time of cryofixed biological samples. This has allowed for tomographic imaging of cell autophagy and cell-cell interactions. Furthermore, a numerical 3D image formation model is presented as well as a novel reconstruction approach dealing with the limited depth of focus in x-ray microscopes.QC 20170505
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Fajardo, Marta. „Etude spectroscopique de l'ionisation d'un plasma d'aluminium par absorption d'une source X“. Palaiseau, Ecole polytechnique, 2001. http://www.theses.fr/2001EPXX0044.
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La spectroscopie de rayons X en absorption constitue un diagnostic privilégié d'un plasma produit par laser, lorsque celui-ci est non-émetteur. Nous avons utilisé des sources X, que nous avons caractérisées, pour l'étude par spectroscopie d'absorption de plasmas à l'équilibre thermodynamique local (ETL) et hors-ETL. Premièrement, un plasma à l'ETL a été crée en chauffant radiativement des cibles minces composées de couches aluminium/nickel, par le rayonnement X provenant de feuilles d'or et thermalisé par une cavité. L'aluminium a prouvé être un bon thermomètre selon le degré de mélange, et les températures déduites à partir de comparaisons avec des codes de physique atomique à l'ETL ont montré un bon accord avec des simulations hydrodynamiques. La dynamique d'ionisation d'un plasma d'aluminium en expansion, crée par un laser nanoseconde, a été étudiée ensuite. Une sonde X créée par laser femtoseconde sondait le plasma en absorption par projection ponctuelle, permettant d'obtenir une carte spatio-temporelle de la distribution ionique avec résolution temporelle de l'ordre de la picoseconde. Le plasma d'aluminium était hors-ETL et un modèle collisionnel-radiatif détaillé a été couplé à un code hydrodynamique radiatif réaliste pour l'interprétation de nos résultats expérimentaux.
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Berglund, Magnus. „A compact soft X-ray microscope based on a laser-plasma source“. Doctoral thesis, KTH, Physics, 1999. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-2845.
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Stiele, Holger. „X-ray Source Population Study of the Local Group Galaxy M 31“. Diss., lmu, 2010. http://nbn-resolving.de/urn:nbn:de:bvb:19-114258.
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29
Kilgard, Roy E. „The X-ray point source population of spiral and star-forming galaxies“. Thesis, University of Leicester, 2008. http://hdl.handle.net/2381/4082.
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In this thesis, I study a sample of 11 nearby “normal” spiral galaxies and one starburst galaxy with the Chandra X-ray Observatory and supporting ground-based telescopes, with particular emphasis on the characterisation of the discrete X-ray point source population. Emission from discrete point sources dominates the X-ray flux from spiral galaxies. This survey spans the Hubble sequence for spirals and, hence, a range in star formation, allowing insights into the X-ray source population of many diverse systems. The inclusion of M82, the prototypical starburst galaxy in the nearby universe, allows for comparison with a system at the extreme of star formation. Presented here is a detailed catalogue of the source population of these galaxies. For each source, I have derived fluxes, luminosities, X-ray colours, and variability properties. I have also searched for optical and radio counterparts. For the most luminous sources, detailed spectral and temporal analyses have been performed. For galaxies as a whole, I have examined X-ray point source luminosity functions and how these relate to star formation of those galaxies. I have also devised a strategy for initial classification of X-ray sources based upon their position within a colour-colour diagram. The luminosity function analysis has then been performed on each class of sources, showing 1) that the method of classification appears to be robust to the first order, and 2) that the old and young (i.e. low-mass X-ray binary and high-mass X-ray binary) populations can be segregated, providing insight into the star formation history of each individual galaxy. I have also studied the environments in which the sources fall within their host galaxies and what this can tell us about the nature of the sources. I have included a discussion of the enigmatic ultraluminous X-ray sources (ULXs), which may be candidates for intermediate mass (100-10,000 Mסּ) black holes.
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Burkes, Darryl A. „X-33 TELEMETRY BEST SOURCE SELECTION, PROCESSING, DISPLAY, AND SIMULATION MODEL COMPARISON“. International Foundation for Telemetering, 1998. http://hdl.handle.net/10150/609673.
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International Telemetering Conference Proceedings / October 26-29, 1998 / Town & Country Resort Hotel and Convention Center, San Diego, CaliforniaThe X-33 program requires the use of multiple telemetry ground stations to provide continuous coverage of the launch, ascent, re-entry and approach phases for flights from Edwards AFB, California, to landings at Dugway Proving Grounds, Utah, and Malmstrom AFB, Montana. This paper will discuss the X-33 telemetry requirements and design, including information on the fixed and mobile telemetry systems, automated best source selection system, processing/display support for range safety officers (RSO) and range engineers, and comparison of real-time data with simulated data using the Dynamic Ground Station Analysis model. Due to the use of multiple ground stations and short duration flights, the goal throughout the X-33 missions is to automatically provide the best telemetry source for critical vehicle performance monitoring. The X-33 program was initiated by National Aeronautics and Space Administration (NASA) Cooperative Agreement No. NCC8-115 with Lockheed Martin Skunk Works (LMSW).
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Duboeuf, François. „L'absorptiométrie à rayons X : évolution par rapport aux appareils à source isotopique“. Lyon 1, 1990. http://www.theses.fr/1990LYO1T060.
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Morris, Samuel Alexander. „X-ray studies of zeolites and MOFs“. Thesis, University of St Andrews, 2016. http://hdl.handle.net/10023/9891.
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This thesis is largely a study of the ADOR process (assembly-disassembly-organisation-reassembly) when applied to zeolite UTL. The final chapter of this thesis deals with the adsorption of the medical gases NO and CO onto the metal organic framework NiNaSIP. Chapter 4 is devoted to the disassembly and organisation steps of the ADOR process. Calcined UTL was hydrolysed using 0.1 – 12 M HCl solutions from 75 – 95 °C run over 10 mins to 72 hrs. A three step mechanism is proposed, which is comprised of an initial rapid hydrolysis that removes the majority of the interlayer constituents of UTL, causing the silica-rich layers to largely collapse. This is followed by a slow, temperature and molarity dependent, deintercalation process that sees the remainder of the interlayer material removed resulting in the full collapse of the layers to form IPC-1P. The third step is a temperature and molarity dependent rebuilding process, whereby the interlayer region is slowly rebuilt, eventually forming a precursor which upon calcination becomes IPC-2 (OKO). Chapter 5 uses the pair distribution function (PDF) technique to structurally confirm the intermediate of the ADORable zeolite UTL. The intermediate, IPC-1P, is a disordered layered compound formed by the hydrolysis of UTL in 0.1 M HCl. Its structure is unsolvable by traditional X-ray diffraction techniques. The PDF technique was first benchmarked against high-quality synchrotron Rietveld refinements of IPC-2 (OKO) and IPC-4 (PCR) – two end products of IPC-1P condensation that share very similar structural features. An IPC-1P starting model derived from density functional theory was used for the PDF refinement, which yielded a final fit of Rw = 18% and a geometrically reasonable structure. This confirms that the layers do stay intact throughout the ADOR process, and shows that PDF is a viable technique for layered zeolite structure determination. Chapter 6 examines the reassembly stage by following the in-situ calcination of a variety of hydrolysed intermediates into their three-dimensional counterparts. Beamline I11 at Diamond Light Source provided high-quality PXRD patterns as a function of temperature, which were refined against using sequential Pawley refinements to track the unit cell changes. 0.1, 1.75, 2.5 and 12 M hydrolysed lamellar precursor phases were calcined. The largest unit cell changes were observed for 0.1 M, and the smallest for 12 M. This shows that increasing the molarity must prebuild most of the interlayer connections, such that upon calcination, only minimal condensation occurs to fully connect the layers. Chapter 7 probes the uptake of the medical gases CO and NO into the metal organic framework NiNaSIP. An in-situ single-crystal XRD study was undertaken using an environmental gas cell at beamline 11.3.1 at the Advanced Light Source. NiNaSIP was first dehydrated to reveal an open nickel site, which acted as the main site of adsorption for the inputted gases. NO was observed in a bent geometry at an occupancy of 40 % and a Ni – N bond length of 2.166(16) Å. The oxygen was modelled to be disordered over two sites. CO was not fully observed, as only the carbon was able to be modelled with an occupancy of 31.2 % and a Ni – C bond length of 2.27(3) Å.
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Duffy, Ryan. „X-ray gas belts and radio source feedback in low-redshift radio galaxies“. Thesis, University of Bristol, 2018. http://hdl.handle.net/1983/4882aef4-8e75-4b6d-85ce-7499c3fbaccc.
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This thesis studies how typical nearby radio sources are participating in radio plasma-gas interactions, with a specific emphasis on understanding the occurrence, morphologies and origins of X-ray gas belts, and their impact upon AGN feedback and fuelling. These excesses (belts) are not likely to be normal undistorted group or galaxy atmospheres. Firstly, I report measurements from an XMM-Newton observation of the low-excitation radio galaxy 3C 386. The study focusses on an X-ray-emitting gas belt, which lies between and orthogonal to the radio lobes of 3C 386 and has a mean temperature of 0.94 +/- 0.05 keV, cooler than the extended group atmosphere. The gas in the belt shows temperature structure with material closer to the surrounding medium being hotter than gas closer to the host galaxy. I suggest that this gas belt involves a `buoyancy-driven inflow' of part of the group-gas atmosphere where the buoyant rise of the radio lobes through the ambient medium has directed an inflow towards the relic cold core of the group. This analysis is then expanded to the full low-redshift 3CRR sample which contains 35 radio galaxies. X-ray gas belts are found to be common among the sample, with 15 sources exhibiting an excess of X-ray emitting counts between the lobes but away from the active nucleus. I use Chandra data to investigate the origins of these X-ray belts. I show that all the belts in the sample are primarily composed of thermally emitting gas. In all cases where belt temperature structure can be measured, the outer belt gas is hotter than the inner. It is probable that the belts have a variety of histories including inflow, outflow and mergers. I detect inverse-Compton emission in the plumes of five of the nine FRI radio galaxies in the sample of belted sources, allowing a measurement of magnetic field strength. I find that the amount by which magnetic field strength tends to be lower than the minimum-energy value is similar for FRIs and FRIIs, if minimum energy for both is calculated assuming no protons. Since FRIs in clusters are known to need protons for pressure support with the external medium, these results provide the first evidence that magnetic field strengths are largely oblivious to non-radiating particles in radio galaxy plumes and lobes. Finally, I use new and archival Chandra observations of Cygnus A, totalling ~1.9 Ms, to investigate the distribution and temperature structure of gas lying within the projected extent of the cocoon shock and exhibiting a rib-like structure. I confirm that the X-rays are dominated by thermal emission with an average temperature of around 4 keV, and have discovered an asymmetry in the temperature gradient, with the southwestern part of the gas cooler than the rest by up to 2 keV. Pressure estimates suggest that the gas is a coherent structure of single origin located inside the cocoon, with a mass of roughly 2 x 10^10 solar masses. I conclude that the gas is debris resulting from disintegration of the cool core of the Cygnus A cluster after the passage of the jet during the early stages of the current epoch of activity. The 4 keV gas now lies on the central inside surface of the hotter cocoon rim. The temperature gradient could result from an offset between the centre of the cluster core and the Cygnus A host galaxy at the switch-on of current radio activity.
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Landahl, Eric Carl. „A compact Compton scattering x-ray source for cancer detection, diagnosis, and treatment /“. For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2002. http://uclibs.org/PID/11984.
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Kubota, Kaori. „Optical Spectroscopic and X-ray Observations of the Galactic Jet Source SS 433“. 京都大学 (Kyoto University), 2010. http://hdl.handle.net/2433/120661.
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Stolidi, Adrien. „Développement de méthodes d'imagerie par contraste de phase sur source X de laboratoire“. Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS076/document.
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L'imagerie par rayons X est fortement développée dans notre société et notamment dans les domaines industriels, médicaux ou sécuritaires. L'utilisation de cette méthode d'imagerie des structures internes (pour la détection d'irrégularité, de contrôle non destructif de pièces ou de menaces) est quotidienne. En radiographie, le contraste produit sur les images est relié à la variation de l'atténuation du flux de rayons X, qui est fonction de la densité, de l'épaisseur du matériau étudié ainsi que de la longueur d'onde utilisée. Ainsi par exemple, des gaines métalliques, des os ou des armes amènent du contraste sur l'image. Mais en plus de leur atténuation, les rayons X vont subir un déphasage qui est d'autant plus important que le matériau est peu atténuant. Ce phénomène va amener du contraste, dit de phase, permettant d'imager des matériaux peu denses tels que des plastiques, composites, tissus mous ou explosifs. Ce travail de thèse présente le développement et l'adaptation, dans le domaine des rayons X, de méthodes d'imagerie par contraste de phase sur des équipements de laboratoire. Le but est de compléter, d'une manière plus accessible et quotidienne, les demandes d'évaluation non destructives. Ce manuscrit se découpe suivant deux axes portant sur la simulation d'une part et sur le développement instrumental d'autre part. Un outil de simulation a été développé portant sur une description hybride alliant optique géométrique et optique ondulatoire. Les limites du modèle et des validations sont présentées. La partie instrumentale se focalise sur l'étude de deux techniques d'imagerie différentielle de phase. La première technique est de l'interférométrie à décalage multilatéral, dont l'adaptation sur tube à rayons X est réalisée pour la première fois. Une exploitation intéressante de la redondance de la mesure que produit la technique sera notamment introduite. La deuxième approche est une technique d'interférométrie de suivi de tavelure, dont nous présenterons une nouvelle exploitationX-ray imaging is widely used in non-destructive testing dedicated to industry, medical or security domain. In most of the radiographic techniques, the image contrast depends on the attenuation of the X-ray beam by the sample. This attenuation is function of the density and thickness of the object and of the wavelength. Therefore, objects like metal covers, bones or weapons bring contrast on the image. In addition to attenuation, phase shifting happens, in particular for low-attenuating material. This phenomenon brings contrast, called phase contrast, and allows a X-ray image of low-attenuating material as plastics, composites, soft tissues or explosives. This work presents development and adaptation, in the X-ray domain, of phase contrast imaging techniques on laboratory equipment. The goal is to bring phase contrast imaging in daily use. This manuscript is split in two parts, simulation and instrumentation. A simulation tool has been developed, mixing geometrical optic and wave optic. Limits of the model and validation are presented. For the instrumental part, two interferometric techniques have been considered. The first one is multi-lateral interferometry where adaptation on X-ray tube is presented for the first time. Interesting use of the measurement recurrence will be introduced. The second one is speckle tracking interferometry, recently adapted on X-ray tube, for which we present new advancements
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Pires, Abel. „Optimisation de la source X impulsionnelle par diffusion Compton inverse d'un accélérateur linéaire d'électrons“. Electronic Thesis or Diss., université Paris-Saclay, 2024. http://www.theses.fr/2024UPASP156.
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Ma thèse porte sur l’optimisation d’une source de rayons X par effet Compton inverse, ce qui consiste à faire interagir un paquet d’électrons provenant d’un accélérateur avec un faisceau laser. J’ai travaillé sur l’optimisation du passage du compresseur magnétique (permettant de réduire la durée des paquets d’électrons). J’ai étudié cet élément avec 3 codes de simulation, et expérimentalement, pour déterminer les effets physiques responsables de l’évolution de la qualité du paquet (émittance), en fonction du nombre d’électrons.Pour le laser, mes travaux permettent d’atteindre des énergies laser plus élevées au niveau du point d’interaction. J’ai mis en place un système CPA (Chirped Pulse Amplification), ce qui consiste à étirer la durée des impulsions laser avant de les amplifier pour éviter le risque de casse. J’ai aussi travaillé sur un dispositif, le SMILE 2, permettant de superposer 8 impulsions laser au point d’interaction. La nouvelle version permet d’automatiser l’alignementMy thesis focuses on optimizing an X-ray source through inverse Compton scattering, which consists in the interaction between an electron bunch from an accelerator and a laser beam.I worked on optimizing the transport through the magnetic compressor, which reduces the duration of electron bunches. I analyzed this component using three simulation codes, as well as experimentally, to identify the physical effects that influence the bunch quality (emittance) as a function of the number of electrons in the bunch.For the laser, my work enables us to achieve higher laser energies at the interaction point. I implemented a Chirped Pulse Amplification (CPA) system, which stretches the laser pulse duration before amplification to prevent damage. I also worked on a device, SMILE 2 that enables the superposition of 8 laser pulses at the interaction point. The new version allows for automated alignment
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Parmee, Richard. „X-ray generation by field emission“. Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/284924.
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Since the discovery of X-rays over a century ago the techniques applied to the engineering of X-ray sources have remained relatively unchanged. From the inception of thermionic electron sources, which, due to simplicity of fabrication, remain central to almost all X-ray applications at this time, there have been few fundamental technological advances. The emergence of new materials and manufacturing techniques has created an opportunity to replace the traditional thermionic devices with those that incorporate Field Emission electron sources. One of the most important attributes of Field Emission X-ray sources is their controllability, and in particular the fast response time, which opens the door to applying techniques which have formerly been the preserve of optical systems. The work in this thesis attempts to bridge the gap between the fabrication and optimisation of the vacuum electronic devices and image processing aspects of a new approach to high speed radiographic imaging, particularly with a view to addressing practical real-world problems. Off the back of a specific targeted application, the project has involved the design of a viable field emission X-ray source, together with the development of an understanding of the failure modes in such devices, both by analysis and by simulation. This thesis reviews the capabilities and the requirements of X-ray sources, the methods by which nano-materials may be applied to the design of those devices and the improvements and attributes that can be foreseen. I study the image processing methods that can exploit these attributes, and investigate the performance of X-ray sources based upon electron emitters using carbon nanotubes. Modelling of the field emission and electron trajectories of the cathode assemblies has led me to the design of equipment to evaluate and optimise the parameters of an X-ray tube, which I have used to understand the performance that is achievable. Finally, I draw conclusions from this work and outline the next steps to provide the basis for a commercial solution.
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Janot-Pacheco, Eduardo. „Etude des sources transitoires x a compagnon be a travers l'analyse de leurs comportements x et optique“. Paris 7, 1987. http://www.theses.fr/1987PA077212.
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Analyse d'un grand nombre de donnees d'observation, visant quelques objets-cibles, de plusieurs types (photometrie visible, ir et rx, spectrometrie visible) afin de mieux comprendre les phenomenes physiques conduisant a l'existence des systemes binaires be/rx. Recherche du mecanisme d'accretion utilisant un modele d'enveloppe equatoriale pour les etoiles be. Utilisation des compagnons compacts comme sondes des enveloppes des etoiles be permettant de determiner differents parametres physiques
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Lauzon, Michael. „Reconstruction of Convex Bodies in the Plane from Three Non-Collinear Point Source Directed X-Rays“. Scholarship @ Claremont, 2000. https://scholarship.claremont.edu/hmc_theses/121.
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When one takes an x-ray, one learns how much material is along the line between the x-ray source and the x-ray sensor. The goal of tomography is to learn what one can about an object, by knowing how much material is on a collection of lines or rays passing through that object. Mathematically, this is a collection of line integrals of density function of the object. In this paper, we provide and prove reconstructions for a class of convex objects of uniform density using x-rays from three point sources.
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Jochmann, Axel. „Development and Characterization of a tunable ultrafast X-ray source via Inverse Compton Scattering“. Forschungszentrum Dresden, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:d120-qucosa-154801.
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Ultrashort, nearly monochromatic hard X-ray pulses enrich the understanding of the dynamics and function of matter, e.g., the motion of atomic structures associated with ultrafast phase transitions, structural dynamics and (bio)chemical reactions. Inverse Compton backscattering of intense laser pulses from relativistic electrons not only allows for the generation of bright X-ray pulses which can be used in a pumpprobe experiment, but also for the investigation of the electron beam dynamics at the interaction point.
The focus of this PhD work lies on the detailed understanding of the kinematics during the interaction of the relativistic electron bunch and the laser pulse in order to quantify the influence of various experiment parameters on the emitted X-ray radiation.
The experiment was conducted at the ELBE center for high power radiation sources using the ELBE superconducting linear accelerator and the DRACO Ti:sapphire laser system. The combination of both these state-of-the-art apparatuses guaranteed the control and stability of the interacting beam parameters throughout the measurement.
The emitted X-ray spectra were detected with a pixelated detector of 1024 by 256 elements (each 26μm by 26μm) to achieve an unprecedented spatial and energy resolution for a full characterization of the emitted spectrum to reveal parameter influences and correlations of both interacting beams. In this work the influence of the electron beam energy, electron beam emittance, the laser bandwidth and the energy-anglecorrelation on the spectra of the backscattered X-rays is quantified.
A rigorous statistical analysis comparing experimental data to ab-initio 3D simulations enabled, e.g., the extraction of the angular distribution of electrons with 1.5% accuracy and, in total, provides predictive capability for the future high brightness hard X-ray source PHOENIX (Photon electron collider for Narrow bandwidth Intense X-rays) and potential all optical gamma-ray sources.
The results will serve as a milestone and starting point for the scaling of the Xray flux based on available interaction parameters of an ultrashort bright X-ray source at the ELBE center for high power radiation sources. The knowledge of the spatial and spectral distribution of photons from an inverse Compton scattering source is essential in designing future experiments as well as for tailoring the X-ray spectral properties to an experimental need.
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Jochmann, Axel. „Development and Characterization of a tunable ultrafast X-ray source via Inverse Compton Scattering“. Forschungszentrum Dresden, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:d120-qucosa-162231.
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Ultrashort, nearly monochromatic hard X-ray pulses enrich the understanding of the dynamics and function of matter, e.g., the motion of atomic structures associated with ultrafast phase transitions, structural dynamics and (bio)chemical reactions. Inverse Compton backscattering of intense laser pulses from relativistic electrons not only allows for the generation of bright X-ray pulses which can be used in a pumpprobe experiment, but also for the investigation of the electron beam dynamics at the interaction point. The focus of this PhD work lies on the detailed understanding of the kinematics during the interaction of the relativistic electron bunch and the laser pulse in order to quantify the influence of various experiment parameters on the emitted X-ray radiation. The experiment was conducted at the ELBE center for high power radiation sources using the ELBE superconducting linear accelerator and the DRACO Ti:sapphire laser system. The combination of both these state-of-the-art apparatuses guaranteed the control and stability of the interacting beam parameters throughout the measurement. The emitted X-ray spectra were detected with a pixelated detector of 1024 by 256 elements (each 26μm by 26μm) to achieve an unprecedented spatial and energy resolution for a full characterization of the emitted spectrum to reveal parameter influences and correlations of both interacting beams. In this work the influence of the electron beam energy, electron beam emittance, the laser bandwidth and the energy-anglecorrelation on the spectra of the backscattered X-rays is quantified. A rigorous statistical analysis comparing experimental data to ab-initio 3D simulations enabled, e.g., the extraction of the angular distribution of electrons with 1.5% accuracy and, in total, provides predictive capability for the future high brightness hard X-ray source PHOENIX (Photon electron collider for Narrow bandwidth Intense X-rays) and potential all optical gamma-ray sources. The results will serve as a milestone and starting point for the scaling of the Xray flux based on available interaction parameters of an ultrashort bright X-ray source at the ELBE center for high power radiation sources. The knowledge of the spatial and spectral distribution of photons from an inverse Compton scattering source is essential in designing future experiments as well as for tailoring the X-ray spectral properties to an experimental needUltrakurze, quasi-monochromatische harte Röntgenpulse erweitern das Verständnis für die dynamischen Prozesse und funktionalen Zusammenhänge in Materie, beispielsweise die Dynamik in atomaren Strukturen bei ultraschnellen Phasenübergängen, Gitterbewegungen und (bio)chemischen Reaktionen. Compton-Rückstreuung erlaubt die Erzeugung der für ein pump-probe-Experiment benötigten intensiven Röntgenpulse und ermöglicht gleichzeitig einen Einblick in die komplexen kinematischen Prozesse während der Wechselwirkung von Elektronen und Photonen. Ziel dieser Arbeit ist, ein quantitatives Verständnis der verschiedenen experimentellen Einflüsse auf die emittierte Röntgenstrahlung bei der Streuung von Laserphotonen an relativistischen Elektronen zu entwickeln. Die Experimente wurden am ELBE - Zentrum für Hochleistungs-Strahlenquellen des Helmholtz-Zentrums Dresden - Rossendorf durchgeführt. Der verwendete supraleitende Linearbschleuniger ELBE und der auf Titan-Saphir basierende Hochleistungslaser DRACO garantieren ein Höchstmaß an Kontrolle und Stabilität der experimentellen Bedingungen. Zur Messung der emittierten Röntgenstrahlung wurde ein Siliziumdetektor mit 1024x256 Pixeln (Pixelgröße 26μm × 26μm) verwendet, welcher für eine bisher nicht erreichte spektrale und räumliche Auflösung sorgt. Die so erfolgte vollständige Charakterisierung der Energie-Winkel-Beziehung erlaubt Rückschlüsse auf Parametereinflüsse und Korrelationen von Elektronen- und Laserstrahl. Eine umfassende statistische Analyse, bei der ab-initio 3D Simulationen mit den experimentellen Daten verglichen und ausgewertet wurden, ermöglichte u.a. die Bestimmung der Elektronenstrahldivergenz mit einer Genauigkeit von 1.5% und erlaubt Vorhersagen zur zu erwartenden Strahlung der zukünftigen brillianten Röntgenquelle PHOENIX (Photon electron collider for Narrow bandwidth Intense X-rays) und potentiellen lasergetriebenen Gammastrahlungsquellen. Die Ergebnisse dienen als Fixpunkt für die Skalierung des erwarteten Photonenflusses der Röntgenquelle für die verfügbaren Ausgangsgrößen am Helmholtz-Zentrum Dresden - Rossendorf. Das Wissen um die räumliche und spektrale Verteilung der Röntgenstrahlung ist entscheidend für die Planung zukünftiger Experimente sowie zur Anpassung der Quelle an experimentelle Bedürfnisse
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Schettino, Giuseppe. „Development of a focused X-ray source as a microprobe of cellular radiation response“. Thesis, King's College London (University of London), 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.311928.
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Alnaimi, Radhwan. „Development of a low-debris laser driven soft X-ray source for lithographic applications“. Thesis, Imperial College London, 2016. http://hdl.handle.net/10044/1/61658.
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This work comprehensively describes the design, build and characterisation of a low-debris laser driven soft x-ray source for a variety of applications in particular lithography, in combination with the optimized multilayer structures in order to use the source output as efficiently as possible. The aim of this work was to study the debris emission from different target materials and to minimise or eliminate debris from laser irradiated thin tapes used in multi-shot and long run-time applications. VHS video tape is used as the primary test target in this work and is made of a Mylar (C10H8O4) carrier film coated with a fine magnetic powder of both Fe2O3 and chromium dioxide CrO2 together with a backing layer of carbon black for static control and a binding agent (polyester-polyurethane). VHS video tape is inexpensive, readily available and amenable for use in multi-hour experiments at high repetition rate. The x-ray source described here is built around a 1064 nm Nd:YAG laser, frequency doubled to 532 nm (green) or tripled to 355 nm, with a pulse length of ~800 ps and a repetition rate up to 50 Hz. A versatile cubic target chamber was designed to accommodate the source and a set of computer controlled stage motors are used to allow positioning of the x-ray emission point. A glass plate between the focusing lens and the target prevents the lens from being coated with debris and the use of a low pressure N2 buffer gas (2-6 mbar) was explored as collisions of atomic size debris particles with gas molecules reduces their kinetic energy and consequently their adhesion to the surrounding surfaces. The chamber can also be continually pumped close to the laser-tape interaction point to ensure continuous removal of debris particles. In the VHS video tape target, the source emitted a range of x-ray wavelengths between 0.19 and 2.3nm relevant to kα line emission of both Fe (7.1 keV) and O (0.5 keV) resolved using the mica crystal spectroscopy. In copper target, a 0.13nm wavelength of k edge (8.9 keV) was resolved, and a 0.79nm x-ray light of Al k edge (1.5 keV) was obtained in aluminium tape target. The measured flux of x-ray photons under vacuum was (7.3 × 109 Photons/s) at 100mJ laser energy and the calculated efficiency of the system (laser energy in versus x-rays out) was (1.1 × 10-6). C/Cr multilayer mirrors of variable layer numbers (N= 30- 200) were designed using the IMD software. A magnetron sputtering technique was used to fabricate the multilayers which were then probed using a hard x-ray diffraction method (Cu Kα radiation, λ = 0.154 nm) to characterize their reflectivity, bi-layers structure and surface roughness. Atomic force microscope was used to determine the surface topography and to analyze the surface structure imperfections such as roughness and stress induced damage. The design developed and refined over the course of this work has been shown to be better at reducing target debris than other mitigation strategies described in the literature. A reduction of "large" and potentially damaging particles ranging from 140 to 5 microns in size by a factor of 28 was achieved, and a 10% reduction in the flux of small particles (~5 microns) was observed if only a buffer gas was used. A reduction of 50% in the flux of these smaller particles was seen if both buffer gas and pumping strategies were employed. This should provide longer life time for the delicate optics used in close proximity to a long run time laser plasma x-ray source, and at the same time reduces the cost of running such sources for a range of different applications.
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Svensson, Matilda. „Investigation and Evaluation of Pump Types for a Liquid Metal Jet X-Ray Source“. Thesis, KTH, Maskinkonstruktion (Avd.), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-274342.
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Since Wilhelm C. Röntgen discovered the x-rays in 1895 little has been done to improve the x-ray technology. In 2003 a group of scientists at KTH Royal Institute of Technology suggested a new type of x-ray source, namely a liquid metal jet x-ray source. The solid anode in the original source was changed to a liquid metal jet anode. This concept was commercialized by Excillum AB as the MetalJet in 2007. It is important that the x-ray beam is stable to obtain clear x-ray pictures demanding that the metal jet is non-fluctuating. The nozzle and the pump are the two parts in the system affects the metal jet the most. Today a diaphragm pump is used which give rise to a pulsating flow in the liquid. This report will investigate what different pump types exist and what pump types are suitable to pump a liquid metal for this application. A smaller investigation will take place to see if there is an off-the-shelf pump which can be put in the system directly. From the weighted evaluation of pump types it was found that all but one type of electromagnetic pumps, thermoelectric pumps and canned motor pumps are the most suitable pump types to be used in this application. From the smaller investigation into off-the-shelf pump it was concluded that some customization of the considered pump is necessary before the pump can be integrated into the system directly. Mostly, the customization regards material choice.Lite har gjorts för att utveckla röntgenkällor sedan Wilhelm C. Röntgen upptäckte röntgenstrålning 1895. År 2003 föreslog en grupp med forskare på KTH en ny typ av röntgenkälla, nämligen en flytande metall röntgenkälla. Den solida anoden som vanligen används i röntgenkällor är utbytt mot en jetstråle av flytande metall istället. Detta koncept kommersialiserades av Excillum AB 2007. För att kunna ta tydliga röntgenbilder är det nödvändigt att röntgenstrålen är stabil vilket betyder att jetstrålen inte kan fluktuera. Två delar i systemet påverkar jetten mer än andra och de är munstycket och pumpen. I dagsläget används en membranpump som ger upphov till ett pulserade flöde i metallen. Den här rapporten undersöker vad det finns för olika pumptyper och vilka pumptyper som är mest lämpade för en denna applikation. En mindre undersökning kommer också göras för att undersöka om det finns en pump som kan plockas direkt från hyllan och integreras i systemet. Utifrån en viktad utvärdering av de funna pumptyperna kunde slutsatsen att alla utom en typ av elektromagnetiska pumpar, termoelektriska pumpar och ”canned motor” pumpar är mest lämpade för den här applikationen. Från den mindre undersökning stod det klart att det inte fanns en pump som kunde plockas från hyllan för att integreras i systemet direkt. Mestadels var det materialvalet som var den begränsande faktorn och måste ändras.
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Calderón-Colón, Xiomara Zhou Otto. „Fabrication, characterization and integration of carbon nanotube cathodes for field emission x-ray source“. Chapel Hill, N.C. : University of North Carolina at Chapel Hill, 2009. http://dc.lib.unc.edu/u?/etd,2721.
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Thesis (Ph. D.)--University of North Carolina at Chapel Hill, 2009.Title from electronic title page (viewed Mar. 10, 2010). "... in partial fulfillment of the requirement for the degree of Doctor of Philosophy in the Curriculum in Applied Science and Engineering." Discipline: Applied and Materials Sciences; Department/School: Applied and Materials Sciences.
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Dušan, Vapa. „Varijabilnost mikrosatelitskih lokusa X hromozoma u populaciji Vojvodine“. Phd thesis, Univerzitet u Novom Sadu, Medicinski fakultet u Novom Sadu, 2016. https://www.cris.uns.ac.rs/record.jsf?recordId=95598&source=NDLTD&language=en.
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Kratki uzastopni ponovci predstavljaju klasu mikrosatelitskih segmenata DNK, rasprostranjenih širom genoma čoveka. Građeni su od uzastopno ponavljajućih sekvenci dužine 2-6 parova nukleotida. Zahvaljujući različitom broju ponavljanja repetitivne jedinice, većina mikrosatelitskih markera pokazuje visok stepen polimorfizma dužine, koji je moguće ispitati primenom tehnike lančane reakcije polimeraze. Pored utvrđivanja spornih srodničkih odnosa, analiza X hromozom mikrosatelitskih markera može se uspešno koristiti i u oblastima kriminalistike, humane identifikacije, populaciono-genetičkim i demografskim istraživanjima i dr. Cilj istraživanja je izrada populacione studije, iz koje će se izračunati broj i frekvencija alela, struktura i frekvencija haplotipova, utvrditi vrednosti relevantnih statističkih parametara, oceniti mogućnost primene analize X-STR markera u slučajevima iz oblasti medicinske kriminalistike, humane identifikacije i veštačenja spornih srodničkih odnosa u populaciji Vojvodine. Istraživanjem je obuhvaćeno 200 odraslih, međusobno nesrodnih osoba. Izolacija DNK materijala iz krvnih mrlja vršena je Chelex metodom, a amplifikacija dobijenih uzoraka DNK metodom PCR, uz korišćenje komercijalnog Mentype® Argus X-12 PCR Amplification Kit – a. Razdvajanje i detekcija dobijenih fragmenata izvršeno je kapilarnom elektroforezom GeneScan i Genotyper programom. Statististička obrada rezultata izvršena je pomoću Arlequin i GENEPOP programa. Za vizuelizaciju interpopulacionih genetičkih odnosa, upotrebljen je program POPTREE2 i koordinatna analiza (Principal Coordinate Analysis - PCoA). Dobijeni rezultati ukazuju da se analiza ispitivanih X-STR markera može uspešno primeniti u slučajevima iz oblasti medicinske kriminalistike, humane identifikacije i veštačenja spornih srodničkih odnosa u populaciji Vojvodine, kao i da mogu poslužiti kao osnova za dalja istraživanja u populacionogenetičkim, antropološkim, demografskim i drugim oblastima.Short tandem repeats (STR) represent a class of microsatellites, widely spread throughout the human genome, consisting of tandemly repeated sequences of 2-6 bp. Related to variation in the number of repeat unit displayed, most of microsatellites show a high degree of length polymorphism, investigated by the PCR techniques. The aim of this research is to create a population study, which will be used to calculate allele and haplotype frequencies, determine the value of relevant statistical parameters and assess the possibility of applying X-STR markers analysis in the fields of forensics, human identification and kinship testing. The study included 200 unrelated adults. DNA isolation was performed by Chelex method and DNA amplification by PCR, using commercial Mentype Argus X-12 PCR Amplification Kit. Separation and detection of fragments was obtained by capillary electrophoresis using Gene Scanand Genotyper program. Statistical analysis of the result was performed using Arlequin and GENEPOP program. For visualization of inter population genetic distances POPTREE2 program and coordinate analysis (PCoA) was used. The results show that the analysis of X-STR markers can be successfully applied in the field of forensics, human identification and kinship testing in the population of Vojvodina, as well as to serve as a basis for further research in population genetic, anthropological, demographic and other scientific areas.
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IKHLEF, ABDELAZIZ. „Imagerie x appliquee a l'etude d'un detecteur a fibres optiques scintillantes et d'une source de photons x a etincelle dans le vide“. Paris 6, 1993. http://www.theses.fr/1993PA066574.
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Cette these porte sur la detection de rayonnement x a l'aide de materiaux plastiques scintillants: films minces, fibres optiques, matrices de fibres et d'un ecran phosphorescent et sur leur application a la caracterisation d'un plasma genere par une decharge electrique dans le vide: tension 70 kv, duree 50 ns, energie stockee 1j. Il a donc ete d'abord procede a une etude systematique des proprietes des fibres optiques scintillantes (fos): rendement de conversion, resolution energetique jusqu'a 1,5 mev, mecanisme de conversion, distribution spatiale des rayons emis. Ces scintillateurs associes a une camera intensifiee permettent une etude du plasma dont l'image est fournie par un stenope ; le diagnostic est complete par la mesure de l'energie emise a l'aide d'une diode pin calibree, celle du courant a l'aide d'une bobine de rogowski. L'energie emise dans 2 steradian est de l'ordre de 8 mj. Deux impulsions de rayons x (d'energie de 8 a 10 kev) sont identifiees: la premiere, a lieu avant le claquage et provient du teflon et de la base de l'anode ; la seconde, se produit apres le claquage et provient de la pointe de l'anode. L'evolution des differentes mesures en fonction de la distance entre electrodes permet de donner des indications sur le role des ions dans le mecanisme d'emission. Differentes geometries de cathode ont ete etudiees: cathode massive, cathode cylindrique et cathode conique. Dans le cas d'une cathode massive, des preuves de depot provenant de l'anode ont ete identifiees. La vitesse de propagation mesuree est de 20 km/s. Le delai de declenchement de l'etincelle est relie a cette propagation. Les images integrees montrent que l'emission du teflon provient du bremsstrahlung des electrons energetiques. L'emission de l'anode est constituee principalement par les raies l du tungstene
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Mao, Peter Hsih-Jen. „Hard x-ray observations of the extragalactic sky : the high energy focusing telescope and the seredipitous extragalactic x-ray source identification survey“. Diss., Pasadena, Calif. : California Institute of Technology, 2002. http://resolver.caltech.edu/CaltechETD:etd-06132002-131531.
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Dubus, Guillaume. „Observations et modèles d’étoiles binaires X“. Paris 7, 1998. http://www.theses.fr/1998PA077043.
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L'observation X des galaxies proches permet d'accéder directement aux différentes populations d'objets hautes énergies qui les composent, en particulier les étoiles binaires X, systèmes formes d'un astre compact (étoiles à neutrons, trou noir) et d'une étoile normale. Je présente un catalogue et une étude de la variabilité des sources X de m33 détectées par le satellite rosat. En particulier, la source X-7 est identifiée sans ambiguïté comme un pulsar binaire X. Près de 70% de l'émission X de m33 provient de la source X-8 associée au noyau de la galaxie. Je montre que la luminosité de cette source ( 10#3#9 ergs s##1) est modulée sur une période de 106 jours. Des observations complémentaires de cette source avec le télescope spatial Hubble montrent une source UV quasi-stellaire au centre du noyau. X-8 est sans doute un système binaire X avec un trou noir de 10m. . Dans un tel système, l'illumination du disque d'accrétion qui se forme autour du trou noir peut être extrêmement importante. Un disque est thermiquement et visqueusement instable autour de la température d'ionisation de l'hydrogène ( 7500 k). Cette instabilité est supposée être à l'origine des éruptions des novae naines et des transitoires X molles. Le modèle numérique mis au point par Jean-Marie Hameury permet de suivre l'évolution d'un disque instable avec précision. Ce modèle est adapté pour tenir compte de l'illumination, on montre que, contrairement a ce qu'indiquent les observations de binaires X, l'illumination par une source ponctuelle ne modifie pas les propriétés du disque si celui-ci est plan (non gauchi). Par contre, si la source d'illumination n'est pas dans le plan du disque, l'illumination a un effet stabilisateur comme prévu par van Paradijs (1996). Contrairement aux idées reçues, l'illumination dans les binaires X est très mal connue.