Dissertations / Theses on the topic 'Collision Cross Section (CCS)'
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1
Hupin, Sébastien. "Caractérisation d’auto-assemblages de polyoxométallates hybrides organiques-inorganiques par spectrométrie de mobilité ionique couplée à la spectrométrie de masse." Thesis, Normandie, 2018. http://www.theses.fr/2018NORMR062.
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Les polyoxométallates (POM) sont des composés anioniques constitués par l’assemblage de polyèdres d’oxydes métalliques {MOy}, (avec M, MoVI ou WVI) reliés entre eux par des atomes d'oxygène. Les POM forment ainsi une classe remarquable de clusters d’oxydes métalliques inorganiques nanométriques, avec une grande variété de charges et de structures. Il est possible de former des systèmes hybrides incluant la partie inorganique du POM et une partie organique greffée, permettant d’apporter de nouvelles fonctionnalités aux POM, tel que l’auto-assemblage. Nous avons consacré ces travaux de thèse à la caractérisation de systèmes classiques, hybrides et auto-assemblés de POM par spectrométrie de masse couplée à la spectrométrie à la mobilité ionique (IMS-MS). Une première approche expérimentale par spectrométrie de mobilité ionique en tube de dérive (DTIMS) nous a permis de déterminer les sections efficaces de collisions (CCS) de POM étalons dans l’hélium et dans l’azote. Les CCS des étalons POM nous ont ensuite permis d’étalonner une cellule IMS de type Travelling Wave (TWIMS). L’analyse par IMS-MS de POM hybrides organiques-inorganiques seuls ou en présence de PdCl2 a mis en évidence la présence de systèmes auto-assemblés triangulaires [POM3·cation3], carrés [POM4·cation4] ou pentagonaux [POM5·cation5] avec différents états de charges. Des valeurs de CCS de ces auto-assemblages ont également pu être estimées à partir de l’étalonnage de la cellule TWIMS. Par une approche théorique, nous avons modélisé plusieurs structures de POM standards avec et sans contre-ion tetrabutylammonium (TBA+) par la théorie de la fonctionnelle de la densité (DFT). Les structures optimisées ont été utilisées afin de déterminer des CCS théoriques grâce au logiciel MOBCAL, auquel nous avons incorporé les atomes de molybdène et de tungstène pour lesquels nous avons optimisé de nouveaux paramètres de potentiel de Lennard Jones. La correspondance des CCS expérimentales et théoriques des structures de POM standards offre de nouvelles possibilités pour une attribution structurale pour les POM hybrides auto-assemblés par coordination en présence de cations métalliquesPolyoxometalates (POM) are anionic compounds formed by the assembly of metal oxide polyhedra {MOy}, (with M, MoVI or WVI) linked together by oxygen atoms. POM thus form a remarkable class of nanometric inorganic metal oxide clusters, with a wide variety of charges and structures. It is possible to form hybrid systems including the inorganic part of the POM and a grafted organic part, allowing new functionalities to be added to the POM, such as selfassembly. We have dedicated this thesis work to the characterization of standards, hybrid and self-assembled POM systems by mass spectrometry coupled to ion mobility spectrometry (IMS-MS). A first experimental approach using drift tube ion mobility spectrometry (DTIMS) allowed us to determine the collision cross sections (CCS) of standard POM in helium and nitrogen. The CCS of the POM standards then allowed us to calibrate an IMS cell of a Travelling Wave ion mobility instrument (TWIMS). The analysis by IMS-MS of organic-inorganic hybrid POMs alone or in the presence of transition metal cations revealed the presence of self-assembled triangular [POM3·cation3], square [POM4·cation4] or pentagonal [POM5·cation5] systems with different charge states. CCS values of these self-assemblies was estimated from the calibration of the TWIMS cell. Using a theoretical approach, we modelled several standard POM structures with and without tetrabutylammonium counterion (TBA+) using density functional theory (DFT). The optimized structures were used to determine theoretical CCS using the trajectory method of the MOBCAL software, in which we incorporated molybdenum and tungsten atoms for which we optimized new Lennard Jones potential parameters. The correspondence of experimental and theoretical CCS of standard POM structures offers new possibilities for structural attribution of self-assembled hybrid POM by coordination in the presence of metal cations
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Fu, Jun. "FHBS calculation of ionized electron angular and energy distribution following the p+H collision at 20 keV." Diss., Texas A&M University, 2004. http://hdl.handle.net/1969.1/1240.
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A Finite Hilbert Basis Set (FHBS) method to calculate the angular and energy distribution of ejected electrons in an ion-atom collision is presented. This method has been applied to the p + H collision at 20 keV impact energy. An interference effect between the exit channels, where electrons are guided out of the collision region by both the residual target proton and the projectile proton, is discovered. Experimental data appears to confirm this result.
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Bostock, Francis John Douglas. "Measurement of the tt cross section with early lhc collision data at cms." Thesis, University of Bristol, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.549452.
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Ma, Xin. "Ion Mobility Mass Spectrometry of DNA/SgrAI Nuclease Oligomers." Thesis, The University of Arizona, 2012. http://hdl.handle.net/10150/247282.
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SgrAI is a restriction endonuclease (ENase) that cuts a long recognition sequence and exhibits self-modulation of cleavage activity and sequence specificity. Previous research has shown that SgrAI forms large oligomers when bound to particular DNA sequences and under the same conditions where SgrAI exhibits accelerated DNA cleavage kinetics. However, the detailed structure and stoichiometry of SgrAI:DNA as well as the basic building block of the oligomers, has not been fully characterized. Ion mobility mass spectrometry (IM-MS) was employed to analyze SgrAI/DNA complexes and show that the basic building block of the oligomers is the DNA-bound SgrAI dimer (DBD). The oligomers are heterogeneous containing a mixture of species with variable numbers of DBD. The collision cross sections (CCS) of the oligomers were found to have a linear relationship with the number of DBD. Models of the SgrAI/DNA oligomers were constructed and a head-to-tail arrangement was most consistent with the experimental CCS.
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Le, Maître Johann. "Développement de la spectrométrie de masse à ultra- haute résolution associée à la spectrométrie de mobilité ionique pour la caractérisation de coupes pétrolières lourdes. structural analysis of heavy oil fractions afterr hydrodenitrogenation by high-resolution tandem mass spectrometry and ion mobility spectrometry Structural analysis of neutral nitrogen compounds refractory to the hydrodenitrogenation process of heavy oil fractions by high-resolution tandem mass spectrometry and ion mobility-mass spectrometry Chemical characterization of 15 biocrudes obtained from hydrothermal liquefaction of industrially cultivated wild micro algae Chemical characterization with different analytical techniques, a way to understand the process: Case of the paraffinic base oil production line Exploring complex mixtures by cyclic ion mobility high-resolution mass spectrometry – Application towards Petroleum. Simulation and modeling of Collision Cross Section for structural elucidation of heavy oil fraction by ion mobility-mass spectrometry: Using polyaromatic hydrocarbons compounds mixture as calibration standard Characterization of sulfoxides compounds in dimeric distribution of heavy oil fractions by positive-ion electrospray ionization FTICR mass spectrometry Structural analysis of Petroporphyrins from asphaltene by trapped ion mobility coupled with a Fourier transform ion cyclotron resonance mass spectrometer. Cyclic ion mobility spectrometry coupled to high-resolution time-of-flight mass spectrometry equipped with atmospheric solid analysis probe for the molecular characterization of combustion particulate matter. Structural study of analogues of Titan’s haze by trapped ion mobility coupled with a Fourier transform ion cyclotron mass spectrometer." Thesis, Normandie, 2020. http://www.theses.fr/2020NORMR051.
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L'évolution des réserves de pétrole implique l'utilisation en raffinerie de pétroles bruts non conventionnels, bien souvent plus lourds et donc difficiles à caractériser. Les produits pétroliers sont en effet des mélanges chimiques extrêmement complexes. La partie légère et volatile peut être analysée par chromatographie en phase gazeuse couplée à la spectrométrie de masse (GC/MS), permettant l'identification des composés par l'utilisation de mesures de masses précises et de modèles de fragmentation. Cependant ces techniques sont inadaptées à l'analyse des fractions lourdes. Dans la pratique, la caractérisation des mélanges les plus complexes implique l'utilisation de spectromètres de masse à ultra-haute résolution généralement par analyse directe sans séparation chromatographique. La technique de référence est aujourd’hui la spectrométrie de masse à transformée de Fourier par résonance cyclotronique des ions (FTICR). Grâce à une résolution supérieure à 106 et à une précision de mesure de masse inférieure à 0,1 ppm, cet instrument permet de séparer toutes les espèces présentes dans un produit pétrolier et d'attribuer à chaque valeur de m/z une composition élémentaire unique. Ceci permet d'obtenir très facilement des cartes moléculaires qui peuvent être présentées graphiquement en utilisant le diagramme de Kendrick, le diagramme de van Krevelen ou le nombre d'insaturations (DBE) en fonction du nombre de carbones. Ce travail de thèse a permis grâce à la caractérisation moléculaire de produits pétroliers (Vacuum Gas Oil, Pétroles Bruts, Matériel Interfacial, Asphaltènes et Bio-Oil…) d'aborder la complexité de leur traitement dans l’outil de raffinage. Des protocoles d'analyses des échantillons ont été développés, à l'aide de différentes sources d'ionisation à pression atmosphérique (ESI, APCI et APPI) ainsi que par désorption/ionisation laser (LDI) sur le spectromètre de masse FTICR 12T. Les informations sur le contenu isomérique des produits pétroliers ont ensuite été déterminées grâce à l'apport de la spectrométrie de mobilité ionique (IMS)The evolution of oil reserves requires the use in refineries of unconventional crude oils, which are often heavier and therefore difficult to characterize. Petroleum products are in fact extremely complex chemical mixtures. The light and volatile part can be analysed by gas chromatography coupled with mass spectrometry (GC/MS), allowing the identification of compounds by using precise mass measurements and fragmentation models. However, these techniques are inappropriate for the analysis of heavy fractions. In practice, the characterization of the most complex mixtures involves the use of ultra-high-resolution mass spectrometers generally by direct analysis without chromatographic separation. The reference technique today is Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FTICR). With a resolution of more than 106 and a mass measurement accuracy of less than 0.1 ppm, this instrument can separate all the species present in a petroleum product and assign a unique elemental composition to each m/z value. This makes it very easy to obtain molecular maps that can be presented graphically using the Kendrick diagram, the van Krevelen diagram or the number of unsaturations (DBE) as a function of the number of carbons. This thesis work has allowed thanks to the molecular characterization of petroleum products (Vacuum Gas Oil, Crude Oil, Interfacial Material, Asphaltenes and Bio-Oil...) addressing the complexity of their treatment in the refining tool. Protocols for sample analysis have been developed, using different sources of ionization at atmospheric pressure (ESI, APCI and APPI) as well as laser desorption/ionization (LDI) on the FTICR 12T mass spectrometer. Information on the isomeric content of petroleum products was then determined using ion mobility spectrometry (IMS)
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Romano, Marino <1985>. "Measurement of the differential cross section of tt pairs in pp collision at sqrt(s) = 7TeV with the ATLAS detector at the LHC." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2013. http://amsdottorato.unibo.it/5197/.
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In this thesis three measurements of top-antitop differential cross section at an energy in the center of mass of 7 TeV will be shown, as a function of the transverse momentum, the mass and the rapidity of the top-antitop system.
The analysis has been carried over a data sample of about 5/fb recorded with the ATLAS detector. The events have been selected with a cut based approach in the "one lepton plus jets" channel, where the lepton can be either an electron or a muon.
The most relevant backgrounds (multi-jet QCD and W+jets) have been extracted using data driven methods; the others (Z+ jets, diboson and single top) have been simulated with Monte Carlo techniques.
The final, background-subtracted, distributions have been corrected, using unfolding methods, for the detector and selection effects. At the end, the results have been compared with the theoretical predictions. The measurements are dominated by the systematic uncertainties and show no relevant deviation from the Standard Model predictions.In questo lavoro verranno presentate tre misure di sezione d'urto differenziale di eventi top-antitop ad un'energia nel centro di massa pari a 7 TeV in funzione dell'impulso trasverso, della massa invariante e della rapidità del sistema. L'analisi è stata effettuata su un campione di dati pari a circa 5/fb raccolti dal rivelatore ATLAS durante il run del 2011 dell'LHC. Gli eventi sono stati selezionati con un approccio basato sui tagli nel canale "leptone più jet", dove il leptone può essere un elettrone o un muone. I principali fondi (QCD multi-jet e W+ jet) sono stati estratti con metodi "data driven", mentre i rimanenti (Z+ jet, WW/ZZ/WZ e top singolo) sono stati simulati con tecniche Monte Carlo. Le distribuzioni finali, dopo la sottrazione del background, sono state corrette, attraverso procedure di unfolding, dagli effetti del rivelatore e della selezione. In questo modo è possibile confrontare i risultati ottenuti con quelli di altri esperimenti. Le misure risultano dominate dalle incertezze sistematiche e non mostrano alcuna deviazione significativa dalle predizioni del Modello Standard.
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Dutta, Baishali. "Measurement of W+W− production cross section in proton-proton collisions at √s = 13 TeV with the ATLAS detector." Doctoral thesis, Humboldt-Universität zu Berlin, 2018. http://dx.doi.org/10.18452/19352.
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Diese Arbeit stellt eine Messung des W+W- Produktionswirkungsquerschnitts in pp Kollisionen bei einer Schwerpunktenergie von √s = 13 TeV vor. Der verwendete Datensatz wurde mit dem ATLAS Detektor im Jahr 2015 aufgezeichnet und entspricht einer integrierten Luminosität von 3,16 fb-1. Die W+W- Ereignisse werden über leptonische Zerfälle der W-Bosonen selektiert, wobei jeweils eines der W Bosonen in ein Elektron und ein Elektronneutrino und das andere in ein Myon und ein Myonneutrino zerfällt. Der gemessene Wirkungsquerschnitt in einem Referenzphasenraum, der nahe der Detektorakzeptanz definiert ist, beträgt
σ (fiducial, W+W-) = 529 ± 20 (stat.) ± 50 (syst.) ± 11 (lumi.) fb.
Das Ergebnis stimmt innerhalb der Fehlergrenzen mit der besten verfügbaren Standardmodell-Vorhersage von 478 ± 17 fb überein. Die kinematischen Verteilungen der im Zerfall der beiden W Bosonen produzierten Leptonen wurden genauer untersucht, um die drei- Eichbosonenkopplung bei den WWγ und WWZ Vertizes zu messen. Abweichungen dieser Kopplungen vom Standardmodell können ein Hinweis auf neue Physik sein. Für die Größen, welche diese anomalen Kopplungen parametrisieren, wurden Konfidenzintervalle berechnet. Die beobachteten Kopplungen stimmen mit dem Standardmodell überein.This thesis presents a measurement of W+W- production cross section with the pp collision data collected at the ATLAS detector in the year of 2015. The dataset corresponds to a centre-of-mass collision energy of √s = 13 TeV with a total integrated luminosity of 3.16 fb-1. The W+W- signal events are selected using a signature where one of the W bosons decays into an electron and an electron neutrino while the other produces a muon with an associated muon neutrino. The measured cross section in the chosen fiducial phase space close to detector acceptance is σ (fiducial, W+W-) = 529 ± 20 (stat.) ± 50 (syst.) ± 11 (lumi.) fb. The result within the assigned uncertainties is compatible with the best available Standard Model prediction of 478 ± 17 fb. The observed kinematic spectrums of the produced leptons from the decay of the two W bosons are further investigated to study the triple gauge boson couplings at the WWγ und WWZ vertices. The deviation of these couplings from the Standard Model can probe the existence of new physics. The confidence intervals have been calculated for the parameters representing these anomalous couplings. The observations are consistent with the Standard Model expectations.
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Jeanty, Laura Elizabeth. "Measurement of the WZ Production Cross Section in Proton-Proton Collision at \(\sqrt s = 7 TeV\) and Limits on Anomalous Triple Gauge Couplings with the ATLAS Detector." Thesis, Harvard University, 2013. http://dissertations.umi.com/gsas.harvard:11023.
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In this dissertation, we present a study of WZ production in proton-proton collisions at a center-of-mass energy of 7 TeV. The data analyzed was collected by the ATLAS detector and corresponds to an integrated luminosity of \(4.6 fb^{−1}\) provided by the Large Hadron Collider in 2011. We select WZ events in the fully leptonic decay mode with electrons, muons, and missing transverse energy in the final state. Events are required to have three isolated leptons with significant transverse momentum, a large missing transverse energy, a Z candidate reconstructed from two of the selected leptons, and a W candidate reconstructed from the missing transverse energy and third lepton. The major backgrounds to the WZ signal in the leptonic decay channel are Z+jets events, ZZ production, Z+photon events, and events with top quarks. We estimate the Z+jets and top quark background contributions from data and take the expected contribution for the other background processes from simulation. We observe 317 WZ candidates in data, with a background expectation of \(68\pm10\) events. The total production cross section is extracted from the selected sample using a maximum likelihood method and is determined to be \(19.0^{+1.4}_{-1.3} (stat) \pm0.9 (syst) \pm0.4 (lumi) pb\), which is consistent with the next-to-leading Standard Model prediction of \(17.6^{+1.1}_{-1.0} pb\). WZ production in the Standard Model includes a contribution from the WWZ triple gauge boson vertex. If new physics beyond the Standard Model exists and interacts with W and Z bosons, the coupling of the WWZ vertex could differ from the Standard Model prediction. We set limits on anomalous triple gauge boson couplings using the transverse momentum spectrum of Z bosons in the selected sample. We derive the 95% confidence interval for three model-independent anomalous triple gauge couplings using a frequentist approach and set the most stringent bounds to date on two of the three parameters.Physics
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Jhingree, Jacquelyn. "The effect of charge and temperature on gas phase protein conformational landscapes : an ion mobility mass spectrometry investigation." Thesis, University of Manchester, 2018. https://www.research.manchester.ac.uk/portal/en/theses/the-effect-of-charge-and-temperature-on-gas-phase-protein-conformational-landscapes--an-ion-mobility-mass-spectrometry-investigation(1ecd7b47-eca8-4bcb-a13a-2b2606ade74b).html.
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The amino acid sequence of a protein determines its 3D fold, the ease with which its native structure is formed, its function, the conformational preferences sampled and the tendency to interact with itself (aggregation) and binding partners. In addition, certain conformational preferences can lead to dysfunction resulting in different diseased states in organisms. All of these conformations can be described by a protein's energy landscape; a native (functional) state being localised at the energy minimum. As protein dynamics is crucial to function it is important to monitor the sampling of different conformations. Thus the work in this thesis reports on two methods for monitoring protein conformation and conformational change in the gas phase using ion mobility mass spectrometry (IM-MS). The measurement from IM-MS methods allow the determination of a collision cross section (CCS) which is an indicator of a molecule's 3D shape. First, the effect of charge on protein structure is investigated by manipulation of protein charge, post electrospray ionisation (ESI), by exposure to radical anions of the electron transfer reagent, 1,3-dicyanaobenzene; the charge reduced products formed are the result of electron transfer to the charged protein without any dissociation (ETnoD). IM-MS is used to monitor the conformational preferences of the altered and unaltered precursor and its products. Secondly, intermediate (transient) conformers are formed by activating the charged protein in the source region of an instrument post ESI. Activation of the protein precursor allows the sampling of different conformational preferences after energetic barriers have been overcome; IM-MS following activation allows for the monitoring of protein conformational change before and after. Further, variable temperature (VT) IM-MS allows for the deduction of intermediate structures with a focus on measurements at cryogenic temperatures whereby intermediate structures can be 'frozen out' post activation; intermediate structures which would otherwise anneal out at room temperature. With both methods a range of conformer populations are mapped for different protein molecules sampled upon different energetic inputs (via activation) and the disruption of intramolecular neutralising contacts/salt bridges (via charge reduction) one of the main interactions responsible for maintaining the structural integrity (3D fold) of proteins.
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Follega, Francesco Maria. "Search for boosted Higgs bosons decaying to b-quarks at sqrt{s}=13 TeV with the ATLAS detector." Doctoral thesis, Università degli studi di Trento, 2020. http://hdl.handle.net/11572/259651.
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A search for the Higgs boson produced with large transverse momentum and decaying as H -> bb is presented, using the 80 fb^{-1} from the dataset collected by the ATLAS detector at sqrt{s}=13 TeV. The Higgs boson is reconstructed as a large-R jet with two b-tagged variable radius track-jets. The work focuses on a peculiar event topology in which the Higgs is produced in association with another Large-R jet. Considering events with reconstructed pT above 480 GeV and with a reconstructed mass from 70-230 GeV, a signal significance of 1.6 sigma for the Higgs and of 5 sigma for the V (Z boson + W boson) is observed. Furthermore, the new Full Run2 analysis is presented, using 136 fb^{-1} from the dataset collected by the ATLAS detector at sqrt{s}=13 TeV. The strategy up to the computation of the expected sensitivity for the Higgs boson is presented in this thesis. The validation of the background modeling is described in details, including tests on data. A preliminary extraction of the Z boson signal is performed and the measured signal strength corresponds to muZ = 0.82 +/- 0.09.
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Fang, Nannan. "Gas Phase Chiral Recognition, Characterization of Porous Polymer Monolith Nanospray Ionization, and the Negative Mode CRAFTI Method Using Fourier Transform Ion Cyclotron Resonance Mass Spectrometry." Diss., CLICK HERE for online access, 2009. http://contentdm.lib.byu.edu/ETD/image/etd3176.pdf.
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Chawner, Ross. "Combined tandem mass spectrometry and ion mobility spectrometry in proteome analyses." Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/combined-tandem-mass-spectrometry-and-ion-mobility-spectrometry-in-proteome-analyses(3ba76f18-4703-4f6e-a97f-ee2b1dfb1deb).html.
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Proteomic studies aim to identify, quantify and characterise the full complement of proteins in a cell or organism under a defined set of conditions, and are important to our understanding of cellular mechanisms. However, such studies represent a major analytical challenge. A typical proteome analysis involves enzyme-mediated digestion of complex protein mixtures to yield an even more complex mixture of peptides. Combined reverse-phase liquid chromatography and tandem mass spectrometry is then traditionally utilised to ascertain sequence information from the characteristic peptide sequences. Analytical data derived for the peptides are employed as search terms in database searching of protein sequences derived from gene sequences. The extreme complexity of the peptide mixtures analysed means that additional novel approaches are required to fully interrogate the vast number of tandem mass spectra generated, assigning peptide identity and thereby helping to address demanding biological questions. The research reported here aims to further our understanding of both gas phase peptide/peptide fragment ion structure and peptide fragmentation behaviour using a combination of tandem mass spectrometry and ion mobility measurement.To facilitate the determination of peptide ion collision cross section, a novel standard, QCAL-IM, produced using the QconCAT strategy, has been developed to enable calibration of drift time in Travelling Wave Ion Mobility instruments. The standard facilitates empirical determination of the rotationally averaged collision cross section of any peptide/peptide fragment ion that lies within the calibration range encompassed. QCAL-IM was subsequently utilised to determine the collision cross section of a range of peptide ions produced by Lys-C and Lys-N proteolysis of ‘standard’ proteins. Data produced allowed the effect upon gas phase ion conformation through changing the location of the basic residue lysine within a peptide sequence to be assessed.The fragmentation behaviour of peptide ions produced by a variety of digestion regimes during both collision-induced dissociation (CID) and electron transfer dissociation (ETD) has also been extensively studied. The proteases trypsin and Lys-C are those typically utilised during proteomic studies and peptides produced by each have either the basic residues arginine or lysine at their carboxy-terminus. Secondary enzymatic treatment with the exoprotease carboxypeptidase B cleaves these basic residues from the C-terminus. Tandem mass spectrometric analysis of both tryptic/Lys-C peptides and their CBPB truncated analogue highlights that the dominant fragment ion series observed during both CID and ETD is determined, at least in part, by the location of such basic residues.Finally, studies were undertaken to investigate the factors which may promote/inhibit scrambling of peptide fragment ion sequence, which has recently been shown to take place during CID. The effect of modifying the gas phase basicity of the N-terminal amino acid residue is studied through a combination of derivatisation and synthesis of alternative peptide sequences. Increasing the gas phase basicity is shown to inhibit the observed sequence scrambling while promoting concomitant rearrangement/retention of a carboxyl oxygen at the C-terminus to give enhanced formation of bn+H2O product ion species.
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Khazraie, Zamanpour Arash. "Measurement of the ttZ production cross section in the three lepton final state with 13.0 fb−¹ of √s = 8 TeV pp collision data collected by the ATLAS detector." Thesis, University of British Columbia, 2012. http://hdl.handle.net/2429/44055.
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A measurement of the ttZ production cross section with the ATLAS detector in pp collisions at the LHC is presented. The search is performed on 13.0 fb−¹ of data collected in 2012. Only final states with three leptons
are considered, in which the Z boson decays to a pair of leptons and one
of the W bosons coming from t → bW decays gives rise to a lepton after
decay. An excess of 8.95 ± 0.62 (stat) +0.37 -0.59(sys) events above background is observed with a significance of 3.64 standard deviations above zero. We have assumed no statistical error on the acceptance or efficiency of detection. In the trilepton channel, a direct measurement of the ttZ production cross section of σ = 254 ± 104 (stat) ± 19 (sys) fb is obtained.
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Chang, Chih-Hsiang. "Proteomic studies on protein N-terminus and peptide ion mobility by nano-scale liquid chromatography/tandem mass spectrometry." Doctoral thesis, Kyoto University, 2021. http://hdl.handle.net/2433/263596.
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Falk, Saïd. "Diffusion elastique d'electrons (lev-200ev) par des molecules d'interet radiobiologique : contribution a la modelisation de la structure des traces de particules chargees." Université Louis Pasteur (Strasbourg) (1971-2008), 1988. http://www.theses.fr/1988STR13018.
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Developpement d'une approche generale basee sur la formule differentielle de rutherford, avec parametre d'ecran, completee par une formule angulaire parametrique; obtention d'une section efficace differentielle bien adaptee a de nombreuses donnees experimentales et d'une section efficace integree satisfaisante sauf aux tres basses energies de la particule incidente, pour lesquelles on introduit un facteur correctif dependant de deux parametres. Bonne adaptation de ces sections efficaces au code de simulation edifiee au laboratoire pour la modelisation de la structure des traces de particules chargees traversant des tissus vivants
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Bourgin, Dominique. "Réactions de fusion entre ions lourds par effet tunnel quantique : le cas des collisions entre calcium et nickel." Thesis, Strasbourg, 2016. http://www.theses.fr/2016STRAE023/document.
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Les réactions de fusion-évaporation et de transfert de nucléons entre ions lourds à des énergies proches de la barrière de Coulomb jouent un rôle essentiel dans l’étude de la structure nucléaire et des mécanismes de réaction. Dans le cadre de cette thèse, deux expériences de fusion-évaporation et de transfert de nucléons ont été réalisées au Laboratoire National de Legnaro en Italie : 40Ca+58Ni et 40Ca+64Ni. Dans une première expérience, les sections efficaces de fusion de 40Ca+58,64Ni ont été mesurées à des énergies au-dessus et en dessous de la barrière de Coulomb et ont été interprétées à l’aide de calculs en voies couplées et Hartree-Fock dépendants du temps (TDHF). Les résultats montrent l’importance de l’excitation à un phonon octupolaire dans le noyau 40Ca et les excitations à un phonon quadripolaire dans les noyaux 58Ni et 64Ni, ainsi que l’importance des voies de transfert de nucléons dans le système riche en neutrons 40Ca+64Ni. Dans une expérience complémentaire, les probabilités de transfert de nucléons de 40Ca+58,64Ni ont été mesurées dans le même domaine d’énergie que l’expérience précédente et ont été interprétées en effectuant des calculs TDHF+BCS. Les résultats confirment l’importance des voies de transfert de nucléons dans 40Ca+64Ni. Une description conjointe des probabilités de transfert de nucléons et des sections efficaces de fusion a été réalisée pour les deux réactions étudiées en utilisant une approche en voies coupléesHeavy-ion fusion-evaporation and nucleon transfer reactions at energies close to the Coulomb barrier play an essential role in the study of nuclear structure and reaction dynamics. In the framework of this PhD thesis, two fusion-evaporation and nucleon transfer experiments have been performed at the Laboratori Nazionali di Legnaro in Italy : 40Ca+58Ni and 40Ca+64Ni. In a first experiment, fusion cross sections for 40Ca+58,64Ni have been measured from above to below the Coulomb barrier and have been interpreted by means of coupled-channels and Time-Dependent Hartree-Fock (TDHF) calculations. The results show the importance of the one-phonon octupole excitation in the 40Ca nucleus and the one-phonon quadrupole excitations in the 58Ni and 64Ni nuclei, as well as the importance of the nucleon transfer channels in the neutron-rich system 40Ca+64Ni. In a complementary experiment, nucleon transfer probabilities for 40Ca+58,64Ni have been measured in the same energy region as the previous experiment and have been interpreted by performing TDHF+BCS calculations. The results confirm the importance of nucleon transfer channels in 40Ca+64Ni. A simultaneous description of the nucleon transfer probabilities and the fusion cross sections has been performed for both reactions, using a coupled-channels approach
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Gadea, Florent Xavier. "Theorie des hamiltoniens effectifs : applications aux problemes de diabatisation et de collision reactive." Toulouse 3, 1987. http://www.theses.fr/1987TOU30276.
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Etude approfondie sur la theorie des hamiltoniens effectifs et analyse de leurs applications aux methodes de diabatisation et au traitement des collisions reactives. Propositions pour le calcul des valeurs propres de l'hamiltonien par des methodes de perturbation ou iteratives, pour l'emploi d'hamiltoniens effectifs dans le calcul des surfaces quasi diabatiques et le traitement general des collisions reactives. Application a la reaction cs+h::(2) etudiee par les methodes ab initio pour la geometrie colineaire : surfaces de potentiel, sections efficaces et mecanismes predominants
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Endres, Kevin J. "Mass Spectrometry Methods For Macromolecules: Polymer Architectures, Cross-Linking, and Surface Imaging." University of Akron / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=akron1553096604194835.
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Girard, Bertrand. "Etude de la collision reactive ii + f -> if + i par fluorescence induite par laser." Paris 6, 1987. http://www.theses.fr/1987PA066398.
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Etude de cette collision par la methode des faisceaux croises et grace a la transition (b <- x) intense, dans le visible, apres analyse de la saturation du processus d'excitation laser de cette transition de if forme. Deduction des populations des differents niveaux rovibrationnels de l'etat x. Etablissement d'une cartographie detaillee de la distribution rotationnelle des niveaux vibrationnels v = 8 a 20 de l'etat x de if: aspect bimodal qui implique la coexistence de deux chemins reactionnels differents. Attribution a un artefact de l'important signal observe anterieurement pour v = 0. Mesures preliminaires de la section efficace differentielle par effet doppler
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Lévêque-Simon, Kévin. "Collisions assistées par laser pour la formation d'antimatière." Thesis, Strasbourg, 2020. http://www.theses.fr/2020STRAE015.
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L’expérience GBAR vise à mesurer la chute libre d’atomes d’antihydrogène ultra-froids (neV). Cela implique de produire des ions d’antihydrogène, obtenus à l’issue de deux réactions d’échange de charge faisant intervenir des antiprotons et des atomes de positronium. Le but de ce travail est d’étudier la possibilité d’augmenter les taux de production d’atomes et d’ions antihydrogène produits, en assistant les deux réactions par laser. Les sections efficaces sont obtenues aux énergies d’antiproton de GBAR (1 - 10keV), en utilisant une approche semi-perturbative proposée par Byron et Joachain. Celle-ci permet de décrire simultanément l’interaction électron-atome (Coulomb Born Approximation ou Continuum Distorted Waves - Final State), l’interaction électron-laser (états de Volkov),et les interactions laser-atomes (premier ordre de la théorie des perturbations dépendantes du temps). L’excitation depuis l’état 1s du positronium par le processus de transition virtuel à un photon est étudiée, en considérant des lasers dont les longueurs d’onde sont proches de 243 nm (raie Lyman-α). Une adaptation de ces lasers est ensuite proposée afin d’exciter les états 3s et 3d (Paschen-β). Les décalages Doppler résultants de la distribution de vitesse du nuage de positronium sont également pris en compte, aux énergies de confinement de 25 meV et 48 meV. Finalement, le nombre d’antiatomes produits est estimé. Comparativement à la situation où les collisions ne sont pas assistées par un laser, les pertes induites par les processus de photo-ionisation et de photo-détachement sont évaluéesThe GBAR experiment aims at measuring the free fall of ultra-cold antihydrogens (neV).This implies the production of antihydrogen ions, which are obtained by two charge exchange reactions involving antiprotons and positronium atoms. The goal of this study is to analyse the possibility to increase the production rates of the antihydrogens and the antihydrogen ions produced, by assisting the two reactions with a laser. The cross sections are obtained in the antiproton energy range of the GBAR experiment (1 - 10 keV), by using a semi-perturbative approach proposed by Byron and Joachain. This method,simultaneously, allows the description of electron-atom interaction (Coulomb Born Approximation or Continuum Distorted Waves - Final State), the electron-laser interaction (Volkov states), and the laser-atom interactions (first order time dependent perturbation theory). The positronium excitation from the 1s state by one-photon virtual transition process is studied, by considering lasers whose wavelengths are around 243 nm (Lyman-αline). It is then proposed to adapt these laser sources in order to excitate 3s and 3d states (Paschen-β). The Doppler shifts resulting from the positronium cloud velocity distribution are taken into account as well, at the confinement energies of 25 meV and 48 meV. Finally,the number of antiparticules produced is estimated. Compared to the case of non-assisted collisions, the losses induced by the photo-ionization and photo-detachment processes are evaluated
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Amarouche, Mohand. "Modelisation des agregats de gaz rares et dynamique d'ar : :(3)**(+)." Toulouse 3, 1988. http://www.theses.fr/1988TOU30135.
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Calcul de la structure d'equilibre et de l'energie d'agregats ioniques positifs de xe et ar a l'aide d'un hamiltonien de type excitonique, extrait des courbes de potentiel des diatomiques correspondants, en incluant le couplage spin-orbite et les interactions a 3 corps entre dipoles induits instantanement. Emploi de ce modele pour calculer les barrieres de potentiel entre divers isomeres, les diverses possibilites de fragmentation apres photoionisation verticale et les echanges de masse lors de collisions entre agregats; observation d'une stabilite remarquable des agregats a 13 et 19 atomes, formes de couronnes pleines autour de coeurs ionises a 3 ou 4 atomes. Couplage du modele excitonique a la methode de dynamique "hemiquantique" pour etudier la photodissociation de ar::(3)**(+), dont on calcule la section efficace a partir du moment de transition de l'espece diatomique obtenu par des calculs ab initio
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BERGNES, BRASEY CHANTAL. "Etude des processus directs elastique et inelastiques se produisant lors de la collision entre un ion d'helium et une cible d'hydrogene, pour une energie variant de 1,5 a 30 kev." Toulouse 3, 1988. http://www.theses.fr/1988TOU30204.
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Etude des sections efficaces doublement differentielles des processus elastiques et inelastiques au cours de la collision d'un faisceau d'ions de he avec h ou h::(2), entre 1,5 et 30 kev, pour des angles de diffusion compris entre 5' et 30**(o), par spectrometrie de perte d'energie du projectile. Comparaison des resultats a des valeurs calculees et mesurees anterieurement a d'autres auteurs. Proposition d'un modele permettant d'interpreter les resultats pour la cible h
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Yousfi, Mohammed. "Contribution a l'etude de la theorie cinetique des electrons dans un gaz faiblement ionise." Toulouse 3, 1986. http://www.theses.fr/1986TOU30229.
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Buridon, Victor. "Application de la spectrométrie de masse COINTOF à l'étude de la dissociation de petits agrégats d'eau protonés par collision sur un atome d'argon : développement d'une cible de nano-gouttes de gaz rare." Phd thesis, Université Claude Bernard - Lyon I, 2013. http://tel.archives-ouvertes.fr/tel-00994146.
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L'étude de l'irradiation dans le système moléculaire à l'échelle du nanomètre est un domaine d'investigation innovant des sciences des radiations. Le Dispositif d'Irradiation d'Agrégats Moléculaires (DIAM) est conçu en vue les conséquences de l'irradiation dans des petits systèmes moléculaires modèles comme les agrégats d'eau protonés. L'irradiation provoque la fragmentation en plusieurs fragments neutres ou chargés. La technique de spectrométrie de masse COINTOF (Correlated Ion and Neutral Time of Flight) permet la détection corrélées des fragments neutres et chargés issus de la dissociation d'un système moléculaire préalablement sélectionné en masse et en vitesse. Les données collectées sont traitées et structurées pour permettre l'analyse statistique des corrélations sur un grand nombre d'événements de fragmentation. Parallèlement à l'identification des canaux de fragmentation, la technique COINTOF permet la mesure de leur rapport de branchement et de leur section efficace. La méthode est présentée pour la dissociation induite par collision sur un atome d'argon, d'agrégats d'eau protonés H+(H2O)n:[2;7], accélérés à 8keV. L'efficacité de détection, information déterminante pour la production de données quantitatives, est mesurée à partir des données et étudiée en fonction de la distribution l'amplitude des signaux de détection. Enfin, un nouveau système de cible constituée de nanogouttes de gaz rares a été développé
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Hervieux, Paul-Antoine. "Etude théorique et expérimentale de l'excitation des ions multichargés par impact électronique." Grenoble 1, 1992. http://www.theses.fr/1992GRE10183.
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Pour la premiere fois, la section efficace differentielle d'excitation d'un ion multicharge par impact d'electrons a ete mesuree. Dans une experience en faisceaux croises, la transition resonnante 3s-3p de l'ion sodiumoide ar#7#+ a ete etudiee pour une energie electronique incidente de 100 ev. En accord avec cette experience, nous avons calcule les sections efficaces differentielles et totales dans une approximation de born generalisee. Les sections efficaces experimentales sont en bon accord avec ces estimations theoriques. Nous avons montre que l'approximation de coulomb-born qui consiste a prendre les fonctions d'onde de coulomb pour fonctions d'onde du continuum, est justifiee meme pour les grands angles. Une approximation semi-classique a aussi ete developpee. Dans ce modele, le projectile se deplace sur une trajectoire coulombienne classique et l'excitation est traitee par la theorie des perturbations du premier ordre dependantes du temps. Cette approche est similaire a la theorie semi-classique de l'excitation coulombienne des noyaux. Deux resultats nouveaux se degagent de cette etude: a l'inverse de l'excitation des atomes qui est fortement piquee aux angles avant, la section efficace differentielle quantique et semi-classique est pratiquement nulle a zero degre, puis augmente jusqu'a un maximum. On peut estimer la position de ce maximum en egalant le temps de collision sur une trajectoire coulombienne et le temps caracteristique de la transition. Les sections efficaces totales semi-classiques sont pratiquement egales a celles obtenues dans l'approximation de coulomb-born. Ce resultat s'etend a d'autres multipoles et dans une large gamme d'energie, de transfert d'energie, et de charge ionique. Avec ce modele semi-classique, nous avons a notre disposition une methode simple pour obtenir, avec une bonne precision, les sections efficaces d'excitation d'ions multicharges
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Mahfouf, Ali. "Calcul des coefficients de transport dans des plasmas hors de l'équilibre." Thesis, Clermont-Ferrand 2, 2016. http://www.theses.fr/2016CLF22719/document.
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Les propriétés de transport à haute température dans les gaz et/ou dans les plasmas ont une importance capitale dans différents domaines, à savoir dans le domaine de technologie de coupure à arc, plasmas de coupure, de soudure ou de gravure. La connaissance des coefficients de transport est nécessaire pour toute modélisation faisant intervenir les équations hydrodynamiques. Dans le cadre de la théorie cinétique des gaz dilués, une solution approchée de l’équation intégro-différentielle de Boltzmann régissant les fonctions de distribution a été proposée par Chapman-Enskog. Les coefficients de transport sont calculés classiquement par la méthode de Chapman-Enskog via les intégrales de collision. Dans le cadre de notre étude nous avons développé, dans un premier temps, un code numérique permettant l’obtention de ces intégrales de collision en tenant compte des singularités qui peuvent apparaître dans le calcul des sections efficaces relatives aux interactions entre les particules constituant les gaz et/ou les plasmas. Dans un second temps nous avons étudié l’influence du choix des paramètres des potentiels d’interaction sur les coefficients de transport. Par la suite, nous avons utilisé le code numérique ainsi développé pour évaluer les coefficients de transport du plasma d’hélium en étudiant l’influence du choix de la méthode de calcul de composition chimique sur ces coefficients. Enfin, un modèle simplifié d’une interaction entre une onde électromagnétique et un plasma d’hélium a été proposé comme une application directe des coefficients de transportTransport properties at high temperature in gases and/or in plasmas are of very importance in various fields, namely in the field of breaking technology in arc, cutting plasma, welding or burning. Knowledge of transport coefficients is necessary for any modeling involving hydrodynamic equations. As part of the kinetic theory of diluted gas, an approximate solution of the integro-differential Boltzmann equation governing distribution functions was proposed by Chapman-Enskog. Transport coefficients are classically computed using the method of Chapman-Enskog through the collision integrals. In our study we have developed, initially, a numerical code to obtain these collision integral taking into account the singularities that may occur in the calculation of the cross sections relating to interactions between particles forming the gas and/or plasmas. Secondly, we have studied the influence of the choice of parameters of interaction potentials on transport coefficients. Subsequently, we have used the numerical code developed for evaluating and helium plasma transport coefficients by studying the influence of the choice of method for calculating chemical composition on these coefficients. Finally, a simplified model of an interaction between an electromagnetic wave and a helium plasma has been proposed as a direct application of the transport coefficients
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Suraud, Marie-Gabrielle. "Etude par spectrométrie X (10 [angström] [inférieur ou égal à] [lamda] [inférieur ou égal à] 100 [angström]) de l'échange de charge lors de collision à basse énergie, entre un ion multichargé et une cible neutre." Grenoble 1, 1988. http://www.theses.fr/1988GRE10038.
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Mesures des valeurs absolues des sections efficaces d'emission de rayons x, dont on deduit les valeurs absolues des sections efficaces de capture, pour les systemes c**(6+)-he,h::(2), n**(7+)-he,h::(2), o**(8+)-he,h::(c). Pour les projectiles a 2 electrons dans l'etat metastable 1s2s **(3)s, l'echange de charge peut s'accompagner de l'excitation de l'electron "2s" de l'ion incident vers des etats 1s2pnl **(3)p avec une probabilite variant suivant le systeme de collision, l'echange de charge simple restant preponderant dans tous les cas
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Rossi, François-Noël. "Etude théorique des collisions non réactives entre atomes alcalins et molécules d'hydrogène ou de deuterium : Calcul et analyse des surfaces de potentiel, application aux transitions de structure fine du rubidium." Paris 13, 1986. http://www.theses.fr/1986PA132015.
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Calcul des courbes de potentiel adiabatiques pour les géométries colinéaires et perpendiculaires, à l'aide d'un pseudopotentiel dépendant du moment orbital électronique et d'une approche à deux centres; bon accord avec les calculs ab initio existants. Examen des différentes symétries de ces systèmes dans le formalisme de la théorie des groupes, afin d'étudier les valeurs propres et facteurs propres de l'hamiltonien électronique. Calcul quantique des sections efficaces relatives des transitions de structure fine de Rb induites par collision avec H(2) ou D(2). En tenant compte des niveaux rotationnels moléculaires, obtention d'un très bon accord avec les résultats expérimentaux et interprétation de l'effet isotopique
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Van, de Steen Cyril. "Modélisation des propriétés de transport des ions moléculaires de krypton et xénon pour l'optimisation des générateurs de plasma froids utilisant les gaz rares." Thesis, Toulouse 3, 2018. http://www.theses.fr/2018TOU30264/document.
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L'utilisation de plasmas froids à base de gaz rares (Rg) dans des applications biomédicales ainsi que dans la propulsion spatiale est en nette évolution. Pour optimiser ces réacteurs plasmas, une compréhension fine des processus ayant lieu dans ces réacteurs est nécessaire. Ce travail de thèse a pour objectif de fournir les données manquantes dans la littérature (coefficients de transport et réaction) en passant par des données mésoscopiques (sections efficaces) obtenues à partir de données microscopiques (potentiels d'interaction) pour le xénon et krypton dans leur gaz parent. Seul des plasmas froids composés d'un seul type d'atome sont considérés. Comme le krypton et le xénon sont des gaz rares, et ont donc, à l'état de neutralité peu/pas d'interaction entre eux. Par conséquent, seules les collisions ion - atome seront considérées. Du fait des faibles énergies des ions dans le plasma froid, seul les 6 premiers états excités du couple Rg2+ seront pris en compte. Ces 6 états seront classés en deux groupes, 2P1/2 et 2P3/2. Lors de ce travail, deux potentiels d'interaction différents disponibles dans la littérature sont utilisés et comparés pour les systèmes collisionnels Kr+/Kr et Xe+/Xe dans le calcul des sections efficaces. Pour les collisions impliquant des dimères ioniques (Kr2+/Kr et Xe2+/Xe), les potentiels d'interaction sont calculés à partir du modèle DIM (Diatomics In Molecules) qui est une combinaison des potentiels atomiques d'interaction neutre - neutre et ion - neutre. Les sections efficaces, requises pour obtenir les données mésoscopiques manquantes, sont calculées à partir de trois méthodes différentes. La première méthode est la méthode quantique qui permet, par une résolution de l'équation de Schrödinger, d'obtenir de manière exacte les sections efficaces à partir des potentiels d'interaction. Cette méthode exacte, étant grande consommatrice de temps de calcul, est utilisée en tant que référence pour valider les deux autres méthodes approchées. La seconde méthode, nommée semi-classique, est basée sur la même expression que la section efficace quantique mais utilise un déphasage approché (approximation JWKB), induit par le potentiel d'interaction, entre l'onde diffusée et l'onde incidente. [...]The use of cold plasmas based on rare gases (Rg) in biomedical applications as well as in space propulsion is clearly evolving. To optimize these plasma reactors, a fine understanding of the processes taking place in these reactors is necessary. This thesis aims to provide the missing data in the literature (transport coefficients and reaction rates) through mesoscopic data (cross-sections) obtained from microscopic data (interaction potentials) for xenon and krypton in their parent gas. Only cold plasmas composed of a single type of atom are considered. As krypton and xenon are rare gases, and so have, in the neutral state little / no interaction between them. Therefore, only ion - atom collisions will be considered. Due to the low ion energies in the cold plasma, only the first 6 excited states of the Rg2+ pair will be taken into account. These 6 states will be classified in two groups, 2P1/2 and 2P3/2. In this work, two different interaction potentials available in the literature are used and compared for the Kr+/Kr and Xe+/Xe collision systems in the calculation of cross-sections. For collisions involving ionic dimers (Kr2+/Kr and Xe2+/Xe), the interaction potentials are calculated from the DIM model (Diatomics In Molecules) which is a combination of the atomic potentials of neutral - neutral and ionic - neutral interactions. The cross-sections required to obtain the missing mesoscopic data are calculated from three different methods. The first method is the quantum method which allows, by a resolution of the Schrödinger equation, to obtain exactly the cross-sections from the interaction potentials. This exact method, which consumes a lot of computation time, is used as a reference to validate the two other approximate methods. The second method, called semi-classical, is based on the same expression as the quantum cross section but uses an approximate phase shift (JWKB approximation), induced by the interaction potential, between the scattered wave and the incident wave. [...]
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Mercier-Depuydt, Eliane. "Contribution a l'etude des collisions ion-atome a basse energie : un modele semi-diabatique pour les courbes de potentiel des ions moleculaires arh**(+*) et hene**(+*)." Paris 6, 1987. http://www.theses.fr/1987PA066522.
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Proposition d'un modele semi-adiabatique pour les ions dissymetriques excitess, formes d'un "coeur" adiabatique et d'un electron externe (de type h::(2)**(+)) en vue de calculs ab initio precis et de la determination des courbes de potentiel necessaires a l'interpretation des collisions a basse energie. Applicaion a arh**(+*): calcul des courbes de potentiel quasidiabatiques pour r = 1,7 - 7 ua; etude du seuil de la reaction ar**(+) + h -> ar**(+) + h (n=2). Application a hene**(+*). Interpretation des oscillations de rosenthal observees dans la section efficace totale d'excitation; calcul des courbes de potentiel ab initio adiabatiques du coeur hene**(2+), des coefficients d'einstein entre les etats moleculaires de ce coeur et des etats quasi diabatiques de coeur par extension de la methode de l'hamiltonien effectif de b. Levy
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Yuan, Xue-Ping, and 袁學平. "Collision cross section for metastable antiprotonic atom formation." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/f7bc9c.
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碩士國立交通大學
物理研究所
106
Antiproton, the antiparticle of proton has an extremely long lifetime, and only the lower limit can be experimentally estimated as 6.6×〖10〗^33 years. It can decay, however, in much shorter time if it is embedded in media due to the collision with atoms and the pair annihilation with proton. The typical lifetime of antiproton in media is known as pico seconds. When it is in helium media, on the other hand, 3% of antiprotons can have much longer lifetime as long as μsec. The difference between the long and short lifetime is in the captured state of the antiproton. When it is captured into a low l state, the Auger transition removes one electron from the antiprotonic atom promptly, giving rise to enhance the Stark mixing, which cause the pair annihilation between the antiproton and a proton in the atomic nucleus. On the other hand, if antiprotons captured into large l states, it is metastable because the Auger transition hardly takes place. It decays after a cascade of radiative transitions before captured in the Auger state. In this study, we focus on the antiproton capture into metastable states. We propose a simple criterion of Auger and metastable states, which is applicable to general atomic targets. The capture process is discussed using the CTMC method to obtain the energy and angular momentum distribution of captured antiproton. Combining the two theories, we calculate the probability of capturing into metastable state for helium, lithium and sodium to discuss which atom yields higher meta-stability. We find that more than 60% of antiprotons captured by lithium are metastable, which is more than 10 times larger than the helium case.
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Wu, Tianyang. "Ion Mobility Spectrometry : Optimization of Parameters in Collision Cross Sections and Trace Detection of Explosives." Thesis, 2018. http://hdl.handle.net/1805/17956.
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Indiana University-Purdue University Indianapolis (IUPUI)Ion mobility spectrometry is a powerful technique for the study related to molecule. The work of tow major applications are introduced in this paper. The first application is the optimization of parameters in CCS. The accurate calculation of the collision cross section for multiple molecules is a long-time interested topic in the research for substances detection in micro scale. No reliable analytical approach to calculate the collision cross section has been established to date. Different approaches rely on different mechanism will provide different results in significant extent. This work introduce a method for the determination of parameters in the Lennard Jones potential. Experimental data combined with numerical computation was the fundamental strategy during the optimization of the parameters. In the experiment, electrospray is used as the ion source of IMS while a nebulizer was utilized to electrify the aromatic compounds. New parameters show no less accuracy and equal efficiency while can explain the physical meaning of the collision more clearly. The second application is the trace detection of explosives with very low concentration. The detection of explosives is an important topic in security, while the detection will be difficult due to the low vapor pressure of explosives. In this work, two types of devices are designed for the trace detection of explosives at an extremely low concentration. TNT is selected as the explosives in the experiment. The experiment succeed to reach a sensitivity of 1 part per quintillion, and even find out a linear relationship between the logarithm of TNT concentration and TNT vapor pressure.
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(5931161), Tianyang Wu. "Ion Mobility Spectrometry: Optimization of Parameters in Collision Cross Sections and Trace Detection of Explosives." Thesis, 2019.
Find full textAbstract:
Ion mobility spectrometry is a powerful technique for the study related to molecule. The work of tow major applications are introduced in this paper. The first application is the optimization of parameters in CCS. The accurate calculation of the collision cross section for multiple molecules is a long-time interested topic in the research for substances detection in micro scale. No reliable analytical approach to calculate the collision cross section has been established to date. Different approaches rely on different mechanism will provide different results in significant extent. This work introduce a method for the determination of parameters in the Lennard Jones potential. Experimental data combined with numerical computation was the fundamental strategy during the optimization of the parameters. In the experiment, electrospray is used as the ion source of IMS while a nebulizer was utilized to electrify the aromatic compounds. New parameters show no less accuracy and equal efficiency while can explain the physical meaning of the collision more clearly. The second application is the trace detection of explosives with very low concentration. The detection of explosives is an important topic in security, while the detection will be difficult due to the low vapor pressure of explosives. In this work, two types of devices are designed for the trace detection of explosives at an extremely low concentration. TNT is selected as the explosives in the experiment. The experiment succeed to reach a sensitivity of 1 part per quintillion, and even find out a linear relationship between the logarithm of TNT concentration and TNT vapor pressure.
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Dembia, Christopher Lee. "A multi-region collision probability method for determining neutron spectra and reaction rates." Thesis, 2012. http://hdl.handle.net/2152/ETD-UT-2012-08-6179.
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The collision probability approach to neutron transport can be used to obtain the energy-dependent neutron spectrum in nuclear reactor systems as well as other quantities of interest. This method makes the approximation that the neutron distribution is constant within homogeneous regions, or cells, in the system. This assumption restricts geometries that can be modeled by the collision probability approach. The geometry modeled is typically an infinite lattice of two homogeneous cells: a fuel pin cylinder and the coolant that surrounds it. The transport of neutrons between the homogeneous cells is done using probabilities describing the chance that a neutron having a collision in one cell has its next collision in another cell. These collision probabilities can be cast in terms of escape and transmission probabilities for each cell. Some methods exist that extend the collision probability approach to systems composed of more than two homogeneous cells. In this work, we present a novel collision probability method, based on previous work by Schneider et al. (2006a), for an arbitrary number of cells. The method operates by averaging the transmission probabilities across cells of the same shape, and thus assumes a certain level of homogeneity across all cells. When using multigroup cross sections, which the collision probability approach requires, it is necessary to consider the effect that a system's geometry and composition has on those multigroup cross sections. The cross sections must be computed in a way that accounts for the resonance self-shielding that may reduce the reaction rates in the resonance region. The process of developing self-shielded cross sections in a heterogeneous system utilizes an escape cross section. We compute this escape cross section using the same collision probabilities used to obtain the energy spectrum. Results are presented for simple two-cell systems, and preliminary results for four-cell simulations are also given. An extension to the method is provided that accounts for the fact that in thermal systems the assumption of homogeneity is not always valid.text
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Te-ChuanHuang and 黃德荃. "The Muon identification and the measurement of the J/psi cross section in p+p collision at sqrt(s) = 500 GeV at the STAR experiment." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/41325439468716249026.
Full textAbstract:
碩士國立成功大學
物理學系
104
The Solenoid Tracker at RHIC (STAR) is one of the major experiments in the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory. In 2013, a new detector – Muon Telescope Detector (MTD) is installed about 63% of the full system and completely installed in 2014. It provides an excellent opportunity to study heavy quarkonia physics using dimuon channel in the experiments. We studied the muon identification using three different methods with proton-proton collision at sqrt(s) = 500 GeV data collected in 2013. The result shows that the muon identification efficiencies reaches about 80% with p_T 〉 3 GeV/c. The measurement of the J/psi invariant cross section is also studied using dimuon decay channel with Likelihood Ratio method for muon identification. The results in dimuon channel are consistent with the results in dielectron channel in the overlap p_T region and have good agreement with the CGC+NRQCD prediction.
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Chen, Liuxi. "Gas-phase and Solution-phase Peptide Conformations Studied by Ion Mobility-mass Spectrometry and Molecular Dynamics Simulations." Thesis, 2012. http://hdl.handle.net/1969.1/ETD-TAMU-2012-08-11689.
Full textAbstract:
Ion mobility spectrometry (IMS) separates ions on the basis of ion-neutral collision cross-sections (CCS, [omega]), which are determined by the geometry or conformation of the ions. The size-based IM separation can be extended to distinguish conformers that have different shapes in cases where shape differences influence the accessible surface area of the molecule. In recent years, IM has rapidly evolved as a structural characterization technique, which has applied on various structural biology problems. In this work, IMS is combined with molecular dynamics simulation (MDS), specially the integrated tempering sampling molecular dynamics simulation (ITS-MDS) to explore the gas-phase conformation space of two molecular systems (i) protonated tryptophan zipper 1 (trpzip1) ions and its six derivatives (ii) alkali metal ion (Na, K and Cs) adducts of gramicidin A (GA). The structural distributions obtained from ITS-MDS are compared well with results obtained from matrix-assisted laser desorption ionization-ion mobility-mass spectrometry (MALDI-IM-MS) for trpzip 1 series and electrospray ionization-ion mobility-mass spectrometry (ESI-IM-MS) for alkali metal ion adducts of GA. Furthermore, the solvent dependence on conformational preferences of the GA dimer is investigated using a combination of mass spectrometry techniques, viz. ESI-IM-MS and hydrogen/deuterium exchange (HDX)-MS, and MDS. The IM experiments reveal three distinct gramicidin A species, detected as the sodium ion adduct ions, [2GA + 2Na]²⁺, and the equilibrium abundances of the dimer ions varies with solvent polarity. The solution phase conformations are assigned as the parallel and anti-parallel [beta]-helix dimer, and the anti-parallel dimer is the preferred conformation in non-polar organic solvent. The calculated CCS profiles by ITS-MDS agree very well with the experimentally measured CCS profiles, which underscore the utility of the method for determining candidate structures as well as the relative abundances of the candidate structures. The benefit of combining ion mobility measurements with solution-phase H/D exchange is allowing identifications and detail analysis of the solution-phase subgroup conformations, which cannot be uncovered by one method alone.
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後藤, 俊夫, 成基 稲葉, 一博 羽根, and 明広 河野. "プラズマプロセシング用SiH4のラジカル非発光種に関する研究." 1987. http://hdl.handle.net/2237/12922.
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