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The WENDI-II rem meter is one of the most popular neutron dosemeters used to assess a useful quantity of radiation protection, namely the ambient dose equivalent. This is due to its high sensitivity and its energy response that approximately follows the conversion function between neutron fluence and ambient dose equivalent in the range of thermal to 5 GeV. The simulation of the WENDI-II response function with the Geant4 toolkit is then perfectly suited to compare low- and high-energy hadronic models provided by this Monte Carlo code. The results showed that the thermal treatment of hydrogen in polyethylene for neutron <4 eV has a great influence over the whole detector range. Above 19 MeV, both Bertini Cascade and Binary Cascade models show a good correlation with the results found in the literature, while low-energy parameterised models are not suitable for this application., Journal Article, SCOPUS: ar.j, info:eu-repo/semantics/published

L'expérience nommée femto-FT-CEAS a été mise en place durant ce travail. Ellecombine une source d'absorption laser femto-opo, une cavité optique haute finesseet un interféromètre à transformée de Fourier. Ce montage instrumental a permisd'enregistrer des spectres sur un domaine de 100 cm−1 avec un coefficient d'absorptionminimal détectable de 5 10−10cm−1 pour des paramètres de résolution spectrale de2 10−2cm−1 et un temps d'enregistrement d'une heure. Le coefficient d'absorptionequivalent par moyenne quadratique par élément spectral correspondant est de 1.210−12cm−1 Hz−1/2. Un chemin optique équivalent de 13 km a été obtenu dans unecellule de 77 cm de long. La gamme spectrale accessible est de 6000 − 6700 cm−1 et7800 − 8300 cm−1.Les spectres enregistrés à l'aide du montage femto-FT-CEAS ont permis d'attribuerplus de 1000 transitions rovibrationelles d'échantillons de CO2 enrichis en 17O,d'OCS, CS2, H12C13CD, et CH3CCH. Les bandes suivantes ont été enrégistrées :pour 12C17O2, les bandes 30013e, 30012e, 30011e, 31113e, 31113f, 31112e, 31112f,et 31111e; pour 17O12C18O, les bandes 30013e, 30012e, et 30011e; pour 16O12C32S,les bandes 540, 0, 501, 0, 511, 1e, 511, 1f, 601, 0, 460, 0, 421, 0, 431, 1e, 431, 1f,521, 0, 341, 0, 351, 1e, 351, 1f, 302, 0, 312, 1e, 312, 1f, 402, 0, 322, 2e, et 322, 2f;pour 16O12C34S, les bandes 501, 0 et 302, 0; pour 16O13C32S, la bande 302, 0 ;pour16O12C33S, la bande 302, 0; pour 12C32S2, les bandes 0403, 0114, 3003 et 2203; pour32S12C34S, la bande 3003. Les conventions de notation vibrationelles utilisées ici sontpour CO2, ν1 ν2 l ν3 n où les bandes vibrationelles perturbées par la résonance deFermi ν1 2ν2 sont ordonnées selon n par ordre décroissant d'énergie. Pour l'OCS,les conventions de notation sont ν1 ν2 ν3, l et pour le CS2, ν1 νl2 ν3. Leur analysespectrale a été réalisée, aboutissant à de nouvelles constantes rovibrationelles ou desconstantes améliorées par rapport, Doctorat en Sciences de l'ingénieur, info:eu-repo/semantics/nonPublished

Hard X-ray photoelectron spectroscopy (HXPS) using X-rays in the 1.5-15 keV energy range generated by synchrotron sources becomes an increasingly important analysis technique due to its potential for bulk sensitive measurements. However, besides their high energy, another characteristic of photons generated by synchrotron sources is their linear polarization while X-rays from Al Kα or Mg Kα for instance are unpolarized. This difference implies a possible variation in total path travelled by the photoelectrons generated by the X-rays inside the medium and consequently a modification of the resulting spectrum shape. We show the influence of the polarization on the partial intensity distributions, namely the number of electrons escaping after n inelastic scattering events, for photoelectron with energies of 0.5, 1, 2, 3, 4 and 5 keV and originating from Si 1s 1/2, Cu 1s 1/2, Cu 2p 3/2, Au 4d 3/2 and Au 4f 7/2 subshells. Moreover, we point out the influence of the dipole approximation leading to an underestimation of the partial intensity distributions due to the neglect of the forward-backward asymmetry of the angular photoelectron distribution. © 2011 Elsevier B.V. All rights reserved., SCOPUS: ar.j, info:eu-repo/semantics/published

Treatments delivered by proton therapy are affected by uncertainties on the range of the beam within the patient, requiring medical physicists to add safety margins on the penetration depth of the beam. To reduce these margins and deliver safer treatments, different projects are currently investigating real-time range control by imaging prompt gammas emitted along the proton tracks in the patient. This study reports on the feasibility, development and test of a new concept of prompt gamma camera using a slit collimator to obtain a one-dimensional projection of the beam path on a scintillation detector. This concept was optimized, using the Monte Carlo code MCNPX version 2.5.0, to select high energy photons correlated with the beam range and detect them with both high statistics and sufficient spatial resolution. To validate the Monte Carlo model, spectrometry measurements of secondary particles emitted by a PMMA target during proton irradiation at 160MeV were realized. An excellent agreement with the simulations was observed when using subtraction methods to isolate the gammas in direct incidence. A first prototype slit camera using the HiCam gamma detector was consequently prepared and tested successfully at 100 and 160MeV beam energies. Results confirmed the potential of this concept for real-time range monitoring with millimetre accuracy in pencil beam scanning mode for typical clinical conditions. If we neglect electronic dead times and rejection of detected events, the current solution with its collimator at 15 cm from the beam axis can achieve a 12mm standard deviation on range estimation in a homogeneous PMMA target for numbers of protons that correspond to doses in water at the Bragg peak as low as 15 cGy at 100MeV and 25 cGy at 160MeV assuming pencil beams with a Gaussian profile of 5mm sigma at target entrance. © 2012 Institute of Physics and Engineering in Medicine., SCOPUS: ar.j, info:eu-repo/semantics/published

Méthodes numériques pour le calcul des valeurs propres les plus à droite des matrices creuses et non-hermitiennes de très grande taille, Doctorat en Sciences de l'ingénieur, info:eu-repo/semantics/nonPublished

In a growing number of cutting edge centres around the world, radiotherapy treatments delivered by beams of protons and carbon ions offer the opportunity to target tumours with unprecedented conformality. But a sharper dose distribution increases the need for efficient quality control. Treatments are still affected by uncertainties on the penetration depth of the beam within the patient, requiring medical physicists to add safety margins. To reduce these margins and deliver safer treatments, different projects investigate real time range control by imaging prompt gammas emitted along the proton or carbon ion tracks in the patient.This thesis reports on the feasibility, development and test of a new type of prompt gamma camera for proton therapy. This concept uses a knife-edge slit collimator to obtain a 1-dimensional projection of the beam path on a gamma camera. It was optimized, using the Monte Carlo code MCNPX version 2.5.0, to select high energy photons correlated with the beam range and detect them with both high counting statistics and sufficient spatial resolution for use in clinical routine. To validate the Monte Carlo model, spectrometry measurements of secondary particles emitted by a PMMA target during proton irradiation at 160 MeV were realised. An excellent agreement with the simulations was observed when using subtraction methods to isolate the gammas in direct incidence. A first prototype slit camera using the HiCam gamma detector was consequently prepared and tested successfully at 100 and 160 MeV beam energies. If we neglect electronic dead times and rejection of detected events, the current solution with its collimator at 15 cm from beam axis can achieve a 1-2 mm standard deviation on range estimation in a homogeneous PMMA target for numbers of protons that correspond to doses in water at Bragg peak as low as 15 cGy at 100 MeV and 25 cGy at 160 MeV assuming pencil beams with a Gaussian profile of 5 mm sigma at target entrance.This thesi, Doctorat en Sciences de l'ingénieur, info:eu-repo/semantics/nonPublished

Surface excitations significantly influence the measured peak intensities in elastic peak electron spectroscopy. They are characterised by the surface excitation parameter (SEP) defined as the change in excitation probability of an electron caused by the presence of the surface in comparison with an electron moving in an infinite medium. It is thus important to have a large database of SEP values or to have the possibility to determine it with a user-friendly software. Recently, Novák developed the programme Software for Electron Solid Inelastic Interaction Parameter Calculations (SESINIPAC) within the model of Tung, Chen, Kwei and Chou, which allows to determine inelastic mean free path, differential inelastic mean free path, SEP and differential SEP for various energy loss function models and dispersion relations with as only input the energy loss function of the material. Using SESINIPAC, we calculate SEP for 27 different types of materials (metals, semiconductors and insulators) and for various angles and energies. We compare these results with those obtained previously with the software Quantitative Analysis of Electron Energy Losses at Surfaces (QUEELS), which uses the Yubero-Tougaard model. We show that the dependence on angle of emission and energy is quite similar for the two models. However, the absolute values calculated with SESINIPAC are generally larger than those calculated with QUEELS, and the mean relative difference is 20% for metals and semiconductors but exceeds 50% for insulators. Copyright © 2012 John Wiley & Sons, Ltd. Copyright © 2012 John Wiley & Sons, Ltd., SCOPUS: cp.j, FLWIN, info:eu-repo/semantics/published

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Cette thèse étudie deux aspects d'interaction entre deux joueurs dans le modèle du calcul et de la communication quantique.Premièrement, elle étudie deux primitives cryptographiques quantiques, des briques de base pour construire des protocoles cryptographiques complexes entre deux joueurs, comme par exemple un protocole d'identification.La première primitive est la "mise en gage quantique". Cette primitive ne peut pas être réalisée de manière inconditionnellement sûre, mais il est possible d'avoir une sécurité lorsque les deux parties sont soumises à certaines contraintes additionnelles. Nous étudions cette primitive dans le cas où les deux joueurs sont limités à l'utilisation d'états et d'opérations gaussiennes, un sous-ensemble de la physique quantique central en optique, donc parfaitement adapté pour la communication via fibres optiques. Nous montrons que cette restriction ne permet malheureusement pas la réalisation de la mise en gage sûre. Pour parvenir à ce résultat, nous introduisons la notion de purification intrinsèque, qui permet de contourner l'utilisation du théorème de Uhlman, en particulier dans le cas gaussien.Nous examinons ensuite une primitive cryptographique plus faible, le "tirage faible à pile ou face", dans le modèle standard du calcul quantique. Carlos Mochon a donné une preuve d'existence d'un tel protocole avec un biais arbitrairement petit. Nous donnons une interprétation claire de sa preuve, ce qui nous permet de la simplifier et de la raccourcir grandement.La seconde partie de cette thèse concerne l'étude de méthodes pour prouver des bornes inférieures dans le modèle de la complexité en requête. Il s'agit d'un modèle de complexité central en calcul quantique dans lequel de nombreux résultats majeurs ont été obtenus. Dans ce modèle, un algorithme ne peut accéder à l'entrée uniquement qu'en effectuant des requêtes sur chacune des variables de l'entrée. Nous considérons une extension de ce modèle dans lequel un algor, Doctorat en Sciences de l'ingénieur, info:eu-repo/semantics/nonPublished

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Relations between propagators and Greenfunctions of Hamiltonians which are SUSY partners have been obtained. New exact propagators for the family of multi-well, time-dependent and non-hermitian potentials have been calculated.Non-conservative SUSY transformation has been studied inthe case of multichannel Schrodinger equation with different thresholds. Spectrum (bound/virtual states and resonances) of thenon-conservative SUSY partner of zero potential has been founded. Exactly solvable model of the magnetic induced Feshbach resonancehas been constructed. This model was tested in the case of Rb$^{85}$.Conservative SUSY transformations of the first and the second order have been studied in the case of multichannel Schrodinger equation with equal thresholds. Transformations which introduce non-trivial coupling between scattering channels have been founded. The first order SUSY transformation which preserves $S$-matrix eigen-phase shifts andmodifies mixing parameter has been founded in the case of two channel scattering with partial waves of different parities. In the case of coinciding parities we have found the second order SUSY transformation which preserves $S$-matrix eigen-phase shifts and modifies mixing parameter. Phenomenological two channel $^3S_1-^3D_1$neutron-proton potential has been obtained by using single channel, phase equivalent and coupling SUSY transformations applied to zero potential., Doctorat en Sciences de l'ingénieur, info:eu-repo/semantics/nonPublished

De nombreux noyaux atomiques et hypernoyaux se modélisent comme des structures à trois corps. C'est le cas, par exemple, de noyaux à halo, comme 6He, ou de noyaux stables, comme 12C et 9Be. En effet, 6He se caractérise comme un système à trois corps, formé d'un coeur (une particule alpha) et de deux neutrons de valence faiblement liés. Le noyau de 12C peut s'étudier comme un système lié formé de trois particules alphas, tandis que 9Be peut être décrit comme la liaison de deux particules alphas et d'un neutron.Dans les exemples précédents, les particules alphas sont des amas de nucléons. Elles possèdent donc une structure interne dont il faut tenir compte en raison du principe de Pauli.Les modèles les plus réalistes pour décrire les structures à trois corps sont les modèles "microscopiques". Ces modèles prennent en compte explicitement tous les nucléons et respectent exactement le principe d'antisymétrisation de Pauli. Cependant, l'application de ces modèles est fortement limitée en pratique, car ils exigent de trop nombreux et trop longs calculs.Par conséquent, pour simplifier considérablement les calculs et permettre l'étude des structures à trois corps, des modèles moins détaillés, de type "semi-microscopiques", sont également développés. Dans ces modèles, on représente les amas de nucléons comme de simples particules ponctuelles. Dans ce cas, la modélisation consiste à construire les potentiels effectifs entre les amas, puis à les employer dans les modèles à trois corps.Dans ce travail, nous avons développé les modèles "semi-microscopiques à trois corps". Les potentiels effectifs entre amas sont directement déduits des forces entre nucléons (selon la RGM à 2 corps). Ces potentiels sont "non-locaux", et dépendent des énergies des amas qui interagissent. Ils permettent de simuler le principe de Pauli et les échanges de nucléons entre les amas. La dépendance en l'énergie se révèle être un inconvénient dans les modèles à trois corps. Les poten, Doctorat en Sciences de l'ingénieur, info:eu-repo/semantics/nonPublished

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Nuclear fuel performance is highly affected by the behaviour of fission gases, particularlyat elevated burnups, where large amounts of gas are produced and canpotentially be released. The importance of fission gas release was the motivationfor large efforts, both experimentally and theoretically, in order to increase ourunderstanding of the different steps of the process, and to continuously improveour models.Extensions to higher burnups, together with the growing interest in novel typesof fuels such as inert matrix fuels envisaged for the transmutation of minor actinides,make that one is still looking for a permanently better modelling, basedon a physical understanding and description of all stages of the release mechanism.Computer simulations are nowadays envisaged in order to provide a betterdescription and understanding of atomic-scale processes such as diffusion, but evenin order to gain insight on specific processes that are inaccessible by experimentalmeans, such as the fuel behaviour during thermal spikes.In the present work simulation techniques based on empirical potentials havebeen used, focusing in a first stage on pure uranium dioxide. The behaviour ofpoint defects was at the core of this part, but also the estimation of elastic andmelting properties.Then, in a second stage, the study has been extended to the behaviour of heliumand xenon. For helium, the diffusion in different domains of stoichiometrywas considered. The simulations enabled to determine the diffusion coefficient andthe migration mechanism, using both molecular dynamics and static calculationtechniques. Xenon behaviour has been investigated with the additional intentionto model the behaviour of small intragranular bubbles, particularly their interactionwith thermal spikes accompanying the recoil of fission fragments. For thatpurpose, a simplified description of these events has been proposed, which opensperspect, Doctorat en Sciences de l'ingénieur, info:eu-repo/semantics/nonPublished

Ce travail s’inscrit dans le cadre d’étude de la sûreté de fonctionnement.La sûreté de fonctionnement est progressivement devenue partie intégrante de l’évaluation des performances des systèmes industriels. En effet, les pannes d’équipements, les pertes de production consécutives, et la maintenance des installations ont un impact économique majeur dans les entreprises. Il est donc essentiel pour un manager de pouvoir estimer de manière cohérente et réaliste les coûts de fonctionnement de l’entreprise, en tenant notamment compte des caractéristiques fiabilistes des équipements utilisés, ainsi que des coûts induits entre autres par le non-fonctionnement du système et la restauration des performances de ses composants après défaillance.Le travail que nous avons réalisé dans le cadre de ce doctorat se concentre sur un aspect particulier de la sûreté de fonctionnement, à savoir les politiques de remplacement d’équipements basées sur la fiabilité des systèmes qu’ils constituent. La recherche menée part de l’observation suivante :si la littérature consacrée aux politiques de remplacement est abondante, elle repose généralement sur l’hypothèse implicite que les nouveaux équipements envisagés présentent les mêmes caractéristiques et performances que celles que possédaient initialement les composants objets du remplacement.La réalité technologique est souvent bien différente de cette approche, quelle que soit la discipline industrielle envisagée. En effet, de nouveaux équipements sont régulièrement disponibles sur le marché ;ils assurent les mêmes fonctions que des composants plus anciens utilisés par une entreprise, mais présentent de meilleures performances, par exemple en termes de taux de défaillance, consommation d’énergie, " intelligence " (aptitude à transmettre des informations sur leur état de détérioration).De plus, il peut devenir de plus en plus difficile de se procurer des composants de l’ancienne génération pour remplacer ceux qui ont été déclassé, Doctorat en Sciences de l'ingénieur, info:eu-repo/semantics/nonPublished

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REELS = reflection electron energy loss spectroscopy, info:eu-repo/semantics/nonPublished

11 pages, REELS = reflection electron energy loss spectroscopy, info:eu-repo/semantics/published

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The backward and forward electron emission yields γB and γF have been calculated by Monte Carlo simulations for helium (He++, He+ or He0) ions incident on thin amorphous carbon foils with energies around the electronic stopping power maximum (0.2-2 MeV). Besides the direct excitation of target electrons by the incident projectile, we have taken into account the different charge changing processes (He++ ↔ He+ ↔ He0) undergone by the helium ion in the target. We discuss in particular the connection between the electron emission yield γ and the electronic stopping power (dE/dx)e. We compare our results with previously published experimental results. © 2006 Elsevier B.V. All rights reserved., SCOPUS: ar.j, info:eu-repo/semantics/published

Les Etudes Probabilistes de Sûreté (EPS) de niveau 2 en centrale nucléaire visent à identifier les séquences d’événements pouvant correspondre à la propagation d’un accident d’un endommagement du cœur jusqu’à une perte potentielle de l’intégrité de l’enceinte, et à estimer la fréquence d’apparition des différents scénarios possibles.Ces accidents sévères dépendent non seulement de défaillances matérielles ou d’erreurs humaines, mais également de l’occurrence de phénomènes physiques, tels que des explosions vapeur ou hydrogène. La prise en compte de tels phénomènes dans le cadre booléen des arbres d’événements s’avère difficile, et les méthodologies dynamiques de réalisation des EPS sont censées fournir une manière plus cohérente d’intégrer l’évolution du processus physique dans les changements de configuration discrète de la centrale au long d’un transitoire accidentel.Cette thèse décrit l’application d’une des plus récentes approches dynamiques des EPS – la Théorie de la Dynamique Probabiliste basée sur les Stimuli (SDTPD) – à différents modèles de déflagration d'hydrogène ainsi que les développements qui ont permis cette applications et les diverses améliorations et techniques qui ont été mises en oeuvre.Level-2 Probabilistic Safety Analyses (PSA) of nuclear power plants aims to identify the possible sequences of events corresponding to an accident propagation from a core damage to a potential loss of integrity of the containment, and to assess the frequency of occurrence of the different scenarios.These so-called severe accidents depend not only on hardware failures and human errors, but also on the occurrence of physical phenomena such as e.g. steam or hydrogen explosions. Handling these phenomena in the classical Boolean framework of event trees is not convenient, and dynamic methodologies to perform PSA studies are expected to provide a more consistent way of integrating the physical process evolution with the discrete changes of plant configura, Doctorat en Sciences de l'ingénieur, info:eu-repo/semantics/nonPublished

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REELS = reflection electron energy loss spectroscopy, info:eu-repo/semantics/nonPublished

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The forward and backward electron emission yields γF and γB have been calculated by Monte Carlo simulation for protons (H+) and hydrogen atoms (H0) (with energies between 25 keV and 5 MeV) incident on thin amorphous carbon foils. Direct electron excitations by the incident projectiles as well as electron excitations resulting from charge exchange processes undergone by H+ or H0 have been taken into account. For the latter, Auger and Shell processes have been considered. Subsequent electron transport has been considered in order to calculate the forward and backward electron emission yields γF and γB. © 2004 Elsevier B.V. All rithts reserved., SCOPUS: cp.j, info:eu-repo/semantics/published

The forward (γF) and backward (γB) electron emission yields have been measured for protons incident on thin carbon foils for incident energies between 2 and 7 MeV as a function of the target thickness. Comparisons with theoretical results obtained by Monte Carlo simulations are presented. In particular, the Meckbach factor R γ = γF/γB is discussed. © 2005 Elsevier B.V. All rights reserved., SCOPUS: cp.j, info:eu-repo/semantics/published

About 60 percent of the electricity production in Belgium originates from nuclear power plants. Belgium owns 7 nuclear pressurized water reactors, which are located in two sites: 4 reactors in Doel and 3 reactors in Tihange. Together they have a capacity of approximately 5900 MWe. All these reactors use classical uranium oxide fuel assemblies. Two of them (Doel3, Tihange2) have also accepted a limited number of mixed (uranium and plutonium) oxide fuel assemblies. These mixed fuel assemblies came from the reprocessing of spent uranium oxide fuel assemblies in La Hague (France). The reprocessing of spent fuel gives birth to vitrified high-level waste, and to different isotopes of uranium and plutonium, which can be used in the manufacture of mixed oxide fuel assemblies. Each country producing radioactive waste must find a solution to dispose them safely. The internationally accepted solution is to dispose high-level radioactive waste in a deep and stable geological layer. This seems to be the most secure and environment-friendly way to get rid of the high-level radioactive waste. One of the few stable geological layers, which could accept radioactive waste in Belgium, is the Boom clay layer. Another possible layer is the Ypresian clay layer, but it is not the reference option for the moment. The Boom clay layer is quite thin (about 100 m thick) and is not at a large depth (about 240 m below the ground surface) at the proposed disposal site, beneath the SCK CEN Nuclear Research Centre in Mol. A large number of studies have already been performed on the Boom clay layer, and on the possibility of building a high-level radioactive waste repository in this geological medium. Since 1993, the Belgian government has promulgated a moratorium on the reprocessing of spent uranium oxide fuels in La Hague. Since then, spent fuel assemblies are considered as waste, and ONDRAF/NIRAS (the Belgium Agency for Radioactive Waste and Enriched Fissile Materials) has thus to deal with them, Doctorat en sciences appliquées, info:eu-repo/semantics/nonPublished

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WM'04, info:eu-repo/semantics/published

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Stopping power dE/dx and electron emission yield γ are known to be strongly influenced by electron capture and loss processes. In this work we consider proton impact on thin Al foils for impact velocities below two atomic units. We investigate the effect of the charge changing processes on the forward/backward electron emission yields, γF and γ B as well as on the specific yields, ΛF and ΛB (Λ=γ/(dE/dx)). The dependence of the emission yields and of the specific yields as a function of the target thickness is discussed in terms of the charge changing processes. © 2003 Elsevier B.V. All rights reserved., SCOPUS: cp.j, info:eu-repo/semantics/published

When a monoenergetic electron beam bombards a solid target, some electrons are backscattered without energy loss. This elastic electron backscattering effect plays an important role in many experimental techniques, like low-energy electron diffraction, scanning electron microscopy and others. Recently, the elastic peak has been used for the experimental determination of electron inelastic mean free paths (IMFPs) in the solid. This experimental determination (which is now considered as the most reliable [J. Phys. Chem. Ref. Data 28 (1999) 19] consists in comparing the measurement to a model calculation in which the IMFP is a parameter. In most cases for the model calculation, a simple non-analog Monte Carlo simulation (where the inelastic events are considered as absorptions and taken into account by a weight) is used. In many cases, long computational times are needed, especially when the solid angle of the electron detector is small. In this work, we introduce a new weighted Monte Carlo algorithm, which combines several techniques for variance reduction. Results of extensive numerical tests are presented, demonstrating the increased effectiveness of the new algorithm. © 2002 IMACS. Published by Elsevier Science B.V. All rights reserved., SCOPUS: cp.j, info:eu-repo/semantics/published

Charge changing processes are known to have a strong influence on ion-induced electron emission characteristics. However, up to now, only a few theoretical models incorporate electron capture and loss cross-sections. For protons with velocities around 1 a.u. a correct theoretical model of the various charge changing processes undergone by the proton is necessary. In particular, all the electrons excited in the different processes have to be taken into account. It is precisely the aim of the present paper to give a description of all the possible charge changing processes and to incorporate these processes in a Monte Carlo simulation of proton induced electron emission from polycrystalline aluminium. The influence of charge changing processes on backward electron emission yield is evaluated. The contributions of H+, H0, H- fractions as well as of electrons excited by the charge changing processes for incident H+ (1

ICEM'03, info:eu-repo/semantics/published

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Electron emission induced by the impact of highly charged ions on metal surfaces is due to different mechanisms. During the interaction of the ion with the metal surface, hollow atoms are formed above and below the surface. At low impact energies, autoionization processes in front of the surface mostly determine the emission properties. With increasing impact energy, excitation processes from below the surface gain in importance. When the hollow atom moves inside the metal, empty inner orbitals are successively filled by Auger transitions and collisional charge transfers. The filling dynamics of the hollow atom determines the strength of the excitation by Auger processes as well as the depth distribution of this excitation. The ion transport process in the first layers of the metal also influences this depth distribution. In this work, electron emission due to the release of K- and L-Auger electrons is calculated by Monte Carlo simulation for Ne9+ impact on Al. The transport of incident ions and of the excited electrons as well as the filling dynamics of the hollow atom are taken into account. © 2002 Elsevier Science B.V. All rights reserved., SCOPUS: cp.j, info:eu-repo/semantics/published

IHLRWM'03, info:eu-repo/semantics/published

The charge-state dependence of the kinetic electron emission induced by slow Nq+ ions incident on a Au target was studied. It was shown that the electronic excitation depends strongly on the electronic configuration of the ion., SCOPUS: ar.j, SCOPUS: ar.j, info:eu-repo/semantics/published

It is well known that the charge state of incident ions has an influence on the stopping power as well as on the electron emission characteristics. We have studied here electron emission for protons and hydrogen atoms incident on polycrystalline Al targets for impact velocities up to 2v0 (v 0 is the Bohr velocity). Besides the direct excitation of target electrons by the incident projectile, we have considered different charge changing processes that give rise to additional electron excitation, hence contributing to electron emission. These processes are also responsible for the charge state dynamics of the moving projectile. We compare our results with previous results and in particular with the predictions of the simple model proposed by Ghosh and Khare [Phys. Rev. 125 (1962) 1254]. © 2003 Elsevier B.V. All rights reserved., SCOPUS: cp.j, info:eu-repo/semantics/published

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It is often assumed that the kinetic electron emission yield γ is proportional to the electronic stopping power dE/dx for ions incident on solid targets. Though these two phenomena are based on the same physical process in which the incident ions lose their energy in the target in electron excitations, there is no reason why the ratio Λ = γ/(dE/dx) should be constant. We present in this paper a comparison between experimental and theoretical results for protons incident on thin carbon foils in a wide energy range (200 keV-9.2 MeV). The ratios ΛB = γB/(dE/dx) and ΛF = γF/(dE/dx) for both the backward (B) and forward (F) emission yields are studied as a function of the incident proton energy as well as the target thickness. © 2002 Published by Elsevier Science B.V., SCOPUS: cp.j, info:eu-repo/semantics/published

Charge changing processes are known to have a strong influence on ion-induced electron emission characteristics. However, up to now, only a few theoretical models of electron emission incorporate electron capture and loss cross sections. For incident protons with velocities around 1 a.u. a thorough theoretical model of the various charge changing processes undergone by the proton is necessary for a correct description of the electron emission induced by the projectile. Indeed, all the electrons excited in the various processes have to be taken into account. In this work, we consider conduction band Auger capture and loss processes. In particular, we consider plasmon assisted processes, which are not negligible with respect to electron-hole pair assisted Auger processes for electron capture. © 2002 Elsevier Science B.V. All rights reserved., SCOPUS: cp.j, info:eu-repo/semantics/published

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