Vegeu vvresum1de1.pdf

At the Los Alamos Neutron Science Center accelerator complex, protons are accelerated to 800 MeV and directed to two tungsten targets, Target 4 at the Weapons Neutron Research facility and the 1L target at the Lujan Center. The Department of Energy requires hazard classification analyses to be performed on these targets and places limits on certain radionuclide inventories in the targets to avoid characterizing the facilities as nuclear facilities. Gadolinium-148 is a radionuclide created from the spallation of tungsten. Allowed isotopic inventories are particularly low for this isotope because it is an alpha-particle emitter with a 75-year half-life. The activity level of Gadolinium-148 is low, but it encompasses almost two-thirds of the total dose burden for the two tungsten targets based on present yield estimates. From a hazard classification standpoint, this severely limits the lifetime of these tungsten targets. The cross section is not well-established experimentally and this is the motivation for measuring the Gadolinium-148 production cross section from tungsten. In a series of experiments at the Weapons Neutron Research facility, Gadolinium-148 production was measured for 600- and 800-MeV protons on tungsten, tantalum, and gold. These experiments used 3 m thin tungsten, tantalum, and gold foils and 10 m thin aluminum activation foils. In addition, spallation yields were determined for many short-lived and long-lived spallation products with these foils using gamma and alpha spectroscopy and compared with predictions of the Los Alamos National Laboratory codes CEM2k+GEM2 and MCNPX. The cumulative Gadolinium-148 production cross section measured from tantalum, tungsten, and gold for incident 600-MeV protons were 15.24.0, 8.310.92, and 0.5910.155, respectively. The average production cross sections measured at 800 MeV were 28.63.5, 19.41.8, and 3.690.50 for tantalum, tungsten, and gold, respectively. These cumulative measurements compared best with Bertini and were within a factor of two to three of CEM2k+GEM2.

Tube bending is a widely used manufacturing process in the aerospace, automotive, and other industries. During tube bending, considerable in-plane distortion and thickness variation occurs. The thickness increases at the intrados (surface of tube in contact with the die) and it reduces at the extrados (outer surface of the tube). In some cases, when the bend die radius is small, wrinkling occurs at the intrados. In industry a mandrel is used to eliminate wrinkling and reduce distortion. However, in the case of a close bend die radius, use of a mandrel should be avoided as bending with the mandrel increases the thinning of the wall at the extrados, which is undesirable in the manufacturing operation. The present research focuses on additional loadings such as axial force and internal pressure which can be used to achieve better shape control and thickness distribution of the tube. Based on plasticity theories, an analytical model is developed to predict cross section distortion and thickness change of tubes under various loading conditions. Results from both the FEA and analytical model indicated that at the intrados the increase in thickness for bending with internal pressure and bending with combined axial pull and internal pressure was nearly the same. But in the case of bending with the combination of axial pull and internal pressure there was a significant reduction of thickness at the extrados. A parametric study was conducted for the case of bending with combined internal pressure and axial pull and it was seen that with proper selection of the pressure and axial pull wrinkling can be eliminated, thickness distribution around the tube can be optimized, and cross section distortion of the tube can be reduced. Predictions of the analytical model are in good agreement with finite element simulations and published experimental results. The model can be used to evaluate tooling and process design in tube bending.

Proefschrift--Groningen. / "Stellingen" [2] p. inserted. Summary in Dutch. Includes bibliographical references.

Proefschrift--Groningen. / "Stellingen" [2] p. inserted. Summary in Dutch. Includes bibliographical references.

Polydimethylsiloxane (PDMS) microfluidic channels, fabricated using low cost and simple soft lithography methods, conventionally have rectangular cross-sections. Despite being often used for organs-on-a-chip and cardiovascular research, these devices do not mimic the circular cross-sections of blood vessels in the human body, creating potential inaccuracies in observed flow conditions and cell behaviours. The purpose of this thesis is to (i) compare and optimize fabrication techniques for microchannels with circular cross-sections, (ii) assess biocompatibility of different surface functionalization approaches for Human Umbilical Vein Endothelial Cell (HUVEC) adhesion and growth, (iii) culture HUVECs within circular microchannels to mimic blood vessel features, and (iv) compare gene expression of HUVECs cultured in 3D circular microchannels to those cultured on 2D surfaces. We show that wire molding is superior to the gas stream technique for producing circular cross-section microchannels with high aspect ratios, circularity, and channel geometry precision. Fibronectin (FN) and polydopamine (PD) surface coatings on PDMS, as well as alternative collagen substrates, were tested for biocompatibility with HUVECs in 2D cultures; fibronectin coated PDMS (PDMS-FN) substrates facilitated cell attachment, spreading and growth. We demonstrate the capability of growing HUVECs on the inner surface of circular PDMS microchannels created using the wire-mold method and treated with fibronectin. A syringe pump was used to induce shear stress on the HUVECs grown in circular microchannels. Relative to static growth conditions, longer cell culture growth periods were more feasible under flow and altered cell morphology was observed. Finally, Microarray analysis revealed significantly different gene expression profiles for HUVECs cultured within PDMS-FN circular cross-section microchannels as compared to HUVECs cultured on PDMS-FN in a 2D environment, thereby highlighting the critical importance of in vitro conditions for mimicking the in vivo reality.

No description available.

This diploma thesis is aimed at radar cross section of passenger cars. Basic scattering parameters of simple targets are described. Some numeric methods used for computing radar cross section are discussed. CST Microwave Studio is used for simulation of passenger car with two different solvers. For the results there are plots of radar cross section of a car for 1 GHz, 24.125 GHz and 33 GHz. There is a plot of visualized hotspots.

La prise de données réalisée en 2015 par la collaboration COMPASS au CERN a permis de collecter un nombre significatif de paires de muons de grande masse. Ces dernières proviennent de l’interaction d’un faisceau de pions négatifs d’impulsion 190 GeV/c sur des cibles d’ammoniac (NH₃), d’aluminium (Al) ou de tungstène (W). Ce travail de thèse décrit les différentes étapes d’analyse des données de Drell-Yan dans la région de masse entre 4.3 et 8.5 GeV/c², depuis la reconstruction des traces du pion incident et des muons diffusés, jusqu’à l'extraction des sections efficaces finales. Ces étapes comprennent la détermination du flux incident et des densités des trois cibles, l’évaluation des différentes efficacités expérimentales, le calcul de l’acceptance de l’appareillage par simulation Monte-Carlo et la réduction des données à des paires de muons. Présentées en fonction de la variable de Feynman xF et de l’impulsion transverse pT, les sections efficaces Drell-Yan sont comparées aux calculs théoriques aux ordres NLO et NNLO, ainsi qu’aux résultats des expériences antérieures. Une interprétation plus poussée des résultats donnera accès aux distributions des partons dans le pion et à l’étude des effets de la matière froide dans les noyaux. / The COMPASS collaboration at CERN collected a significant amount of Drell-Yan data in 2015. The measured lepton pairs originate from the interaction of a negatively charged pion beam at 190 GeV/c with ammonia targets (NH₃), aluminum (Al) or tungsten (W). The analysis step using the Drell-Yan data are discussed in the mass range between 4.3 and 8.5 GeV/c², starting from the reconstruction of the incoming pion beam and the scattered muons, until the extraction of the Drell-Yan cross-sections. These steps include the determination of the incoming beam flux and the three target densities, the overall efficiency of the experimental apparatus, the acceptance of this spectrometer using Monte-Carlo simulations, and the reduction of the initial data to muon pairs. The Drell-Yan cross-sections, expressed in terms of the scaling variable xF and the transverse momentum pT, are compared with theoretical predictions at NLO and NNLO, as well as some previously published results. An advanced interpretation of these results would give access to the partonic distribution of the pion and lead to the study of cold nuclear matter effects.

T2K (Tokai to Kamioka) est une expérience d’oscillation de neutrinos muoniques sur une longue ligne de base, située au Japon. Elle est conçue pour mesurer le changement de saveur des neutrinos d’un faisceau produit à l’aide d’un accélérateur au laboratoire JPARC de Tokai. Les détecteurs proche et lointain sont placés légèrement hors axe par rapport au faisceau. Depuis la découverte en 2013 de l’apparition de neutrinos électroniques, T2K a inversé la polarité des cornes magnétiques intervenant dans la production du faisceau, afin de produire un faisceau d’antineutrinos et d’augmenter la sensibilité de l’expérience à la violation de la charge-parité dans le secteur leptonique. Le faisceau produit est alors dominé par les antineutrinos muoniques avec une composante mesurable de neutrinos muoniques. L’analyse simultanée, dans les données prises avec le faisceau de neutrinos et le faisceau d’antineutrinos, des interactions par courant chargé dans le détecteur proche ND280, permet de réduire l’impact sur les analyses d’oscillation des incertitudes liées au flux de (anti)neutrinos et à leur section efficace d’interaction. Les données de ND280 permettent également de mesurer les sections efficaces d’interaction des antineutrinos d’énergie proche de 600 MeV. La bonne connaissance du processus d’interaction des (anti)neutrinos avec les noyaux atomiques est cruciale pour interpréter les résultats de l’expérience en termes d’oscillations. De nombreux modèles théoriques ont été développés pour décrire les effets nucléaires lors des interactions des (anti)neutrinos, mais une vison globale cohérente n’a pas encore émergé. En particulier, des mesures variées de section efficace d’interaction par courant chargé sans production de pion dans l’état final suggèrent la possibilité pour les neutrinos d’interagir avec des paires de nucléons corrélés, entrainant l’éjection de plus d’un nucleon hors du noyau (composante dite “multi-nucléon”). Divers modèles ont proposé des estimations différentes de ce processus et une mesure précise et sans ambiguité n’est pas encore disponible. Ce travail de thèse se concentre sur trois études. La première détaille la sélection des interactions de neutrinos muoniques par courant chargé dans le détecteur proche hors axe. Dans un premier temps l’échantillon de données était divisé en deux selon le nombre de traces chargées de l’événement, puis l’accumulation de davantage de données a permis la séparation de l’échantillon en trois lots selon le contenu en pions de l’événement. La seconde étude consiste en la mesure simultanée de la section efficace d’interaction des neutrinos et des antineutrinos muoniques par courant chargé, conduisant à un état final sans pion mesuré dans le détecteur ND280. Ces sections efficaces sont extraites en fonction de l’impulsion et de l’angle du muon issu de l’interaction, permettant ainsi d’évaluer la somme, la différence et l’asymétrie entre les sections efficaces des neutrinos et des antineutrinos. La somme permet d’isoler la composante d’interférence vecteur-axial de la section efficace, et la différence est sensible à la composante multi-nucléons. L’asymétrie permet d’estimer directement le biais éventuel sur la mesure de la phase de violation de CP dû à la modélisation des sections efficaces, dans l’analyse d’oscillation de neutrinos. La dernière partie de la thèse étudie la proposition d’utiliser la technologie dite de multi-PMT pour le detector Hyper-Kamiokande, version à plus grande échelle de Super-Kamiokande, ainsi que la possibilité d’étudier le flux de neutrinos avec un détecteur basé sur le rayonnement Cherenkov dans l’eau, et placé à environ 2 km de l’origine du faisceau de neutrinos. Un multi-PMT est une sphère de plastique contenant 26 tubes photomultiplicateurs, qui pourrait améliorer l’efficacité des futurs détecteurs basés sur le rayonnement Cherenkov dans l’eau. / T2K (Tokai to Kamioka) is a long-baseline neutrino oscillation experiment installed in Japan and designed to measure neutrino flavor oscillation using an off-axis neutrino beam produced at the J-PARC accelerator facility in Tokai. Since its discovery of electron neutrino appearance in 2013, T2K has switched its beam magnet polarities to run in antineutrino beam mode in order to enhance its sensitivity to the charge-parity violation in the leptonic sector. The beam is dominated by muon antineutrinos, but it also contains a sizable contamination from muon neutrinos. The analysis of both neutrino and antineutrino charged-current interactions in the off-axis near detector ND280, provides a significant reduction of the flux prediction and cross-section modeling systematic uncertainties in the oscillation analysis. ND280 data also gives us the opportunity to measure antineutrinos cross-sections at the energy around 600 MeV. Information on (anti)neutrino scattering is vital for the interpretation of neutrino oscillation. Many theoretical models have been developed to describe the nuclear effects in (anti)neutrino scattering, but a consistent picture has yet to emerge. In particular, various measurements of charged-current cross-section without production of pions in the final state have suggested the presence of another channel where neutrinos interact with pairs of correlated nucleons and more than one nucleon is knocked-out from the nucleus (multi-nucleon component). Various models have proposed different estimations of such process and a precise and unambiguous measurement is not yet available. This thesis work is focused on three different arguments. First the selections of CC interactions of muon neutrinos in antineutrino beam in the off-axis near detector. In a first iteration this sample has been divided into two sub-sample based on the track multiplicity, then with more statistic a separation into three sub-samples based on the pion content in each event was possible. Then on the simultaneous measurement of the double-differential muon neutrino and antineutrino charged-current cross-section without pions in the final state using the off-axis near detector. The neutrino and antineutrino cross-sections will be simultaneously extracted as a function of muon momentum and angle with a likelihood fit, including proper estimation of the correlations, allowing the evaluation of the sum, difference and asymmetry between the two cross-sections. The sum isolates the axial-vector interference term of the cross-section, and the difference enhances the sensitivity to the multinucleon component. The asymmetry is a direct estimation on any possible bias due to mismodeling of (anti)neutrino interactions on the measurement of the CP violation phase in neutrino oscillation. The last topic concerns the proposal of the multi-PMT technology as detector for Hyper-Kamiokande, the upgrade of Super-Kamiokande, and the intermediate water v Cherenkov proposed to study the neutrino flux at ~2 $km$ from the beam production point. A multi-PMT is a plastic sphere filled with 26 photomultiplier tube that could improve the efficiency of the Cherenkov detectors foreseen in the future.