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1
Li, Gang. « Electron-neutrino angular correlation measurement in the decay of lithium-8 ». Thesis, McGill University, 2012. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=110473.
Texte intégralRésumé :
The Standard Model has been very successful in describing existing experimental data in nuclear and particle physics, but it still depends on numerous experiments for the determination of several important properties. For example, the assumption that only Vector(V) and Axial-Vector(A) interactions are present out of five possible types of weak interactions: V, A, Scalar(S), Pseudoscalar(P) and Tensor(T) is based on experimental results. The ion trap is an promising way for precise measurement of the beta-neutrinoangular correlation parameter "a" in beta decay. The unperturbed observation of the recoiled nucleus and electron allows reconstruction of the full decay kinematics. The goal of the BPT (Beta-decay Paul Trap) project is to measure "a" in the decay of 8Li. A deviation from the predicted value a =―1/3 would be an indication of a tensor contribution. 8Li was produced at the Argonne National Laboratory and about 20,000 events were recorded. By measuring the energy shift of the alpha particles in the 8Li decay, "a" is determined to be a =―0.329±0.009. This measurement is consistent with the Standard Model prediction. Upgrade of the system for a higher precision measurement is discussed.Le Modèle Standard a connu un très grand succès pour décrire les mesures expérimentales autant en physique nucléaire qu'en physique des particules. Cependant, plusieurs expériences tentent toujours de vérifier certaines de ses hypothèses de base. Par exemple, c'est grace à des résultats expérimentaux, que l'on sait que seules les interactions de type Vecteur (V) et Axial-Vecteur (A) sont présentes dans le Modèle Standard, bien qu'il y a théoriquement trois autres types d'interactions faibles possibles : Scalaire (S), Pseudoscalaire (P) et Tenseur (T). Les pièges d'ions sont une avenue prometteuse pour mesurer précisément le paramètre de correlation angulaire bêta-neutrino, "a", des désintégrations bêta. L'observation du noyau de recul et de l'électron en l'absence de perturbations externes permet la reconstruction de la cinématique complète des désintégrations. Le but du projet BPT (Beta-decay Paul Trap) est de mesurer "a" à partir de désintégrations d'ions 8Li. Toute déviation des mesures par rapport à la valeur théorique a = ―1/3 serait une indication d'une contribution d'interactions de type Tenseur. Des ions 8Li ont été produits au Argonne National Laboratory, où prês de 20 000 événements ont été enregistrés. En mesurant le décalage énergétique des particules alpha originant de désintégrations 8Li, une valeur de a =―0.329±0.009 a été déterminée pour le paramètre de corrélation angulaire. Cette valeur est en accord avec la prédiction du Modèle Standard. Une amélioration du dispositif pour permettre des mesures de plus grande précision est discutée.
2
Caló, A. (Antonio). « Electron spectroscopy of atoms and molecules using synchrotron radiation, UV radiation and electron impact ». Doctoral thesis, University of Oulu, 2007. http://urn.fi/urn:isbn:9789514286650.
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Abstract
The present thesis investigates the electronic structure of selected atoms and molecules in vapor phase. Electron spectroscopy is applied for studying the electronic transitions following excitation and ionization with electron and photon bombardment. The work focuses on the photoionization and Auger decay of selected noble gasses, and on the photoionization and Auger decay of core ionized or resonant excited alkali halide molecules. The experimental results are compared with theoretical predictions.
3
Ginkel, John Fred. « A search for the rare decay kaon(L) going to muon/electron ». W&M ScholarWorks, 1989. https://scholarworks.wm.edu/etd/1539623782.
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A sensitive search has been carried out for the rare decay $\rm K\sb{L}\to\mu e$. This decay violates conservation of separate lepton-number and thus is forbidden in the Standard Model of electro-weak interactions. Many new models have been proposed which could permit this process. The data were collected in the B5 beamline of the Alternating Gradient Synchrotron facility at the Brookhaven National Laboratory during the Spring, 1988 slow-extracted beam running period. The experiment was sensitive to approximately fifty million $\rm K\sb{L}\to\pi\pi$ decays. No $\rm K\sb{L}\to\mu e$ candidate events were detected. The 90% confidence level upper limit for the branching ratio is $\rm B(K\sb{L}\to\mu e) < 2.2 \times 10\sp{-10}$. This limit places a constraint on the mass of exotic particles proposed in many new theories.
4
Lundwall, Marcus. « Rare-gas Clusters Studied by Electron Spectroscopy : Structure of Heterogeneous Clusters and Effects of Electron Scattering on Auger Decay ». Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-7431.
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5
Niclasen, Rune. « Measuring the branching ratio of the rare decay neutral pion going to electron-positron ». Diss., Connect to online resource, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3207725.
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Martin, Robert David III. « First observation of the very rare decay neutral kaon(long) going to electron positron ». W&M ScholarWorks, 1998. https://scholarworks.wm.edu/etd/1539623919.
Texte intégralRésumé :
Brookhaven National Laboratory AGS Experiment 871 (E871) has carried out a search for the very rare, GIM and helicity suppressed decay of the long-lived neutral kaon into an electron-positron pair. This decay is predicted within the Standard Model to occur with a branching ratio of {dollar}(9.0 \pm 0.4)\times 10\sp{lcub}-12{rcub}.{dollar} Data were taken during the 1995 and 1996 AGS HEP running periods on the B5 beamline. A signal of (4 {dollar}\pm{dollar} 2) {dollar}K\sbsp{lcub}L{rcub}{lcub}0{rcub} \to e\sp+e\sp-{dollar} events is seen with a physics background expectation of 0.2 events. The ratio of the partial decay widths {dollar}\Gamma(K\sbsp{lcub}L{rcub}{lcub}0{rcub} \to e\sp+e\sp-)/\Gamma(K\sbsp{lcub}L{rcub}{lcub}0{rcub}\to\mu\sp+\mu\sp-){dollar} is determined to be {dollar}(1.3\sbsp{lcub}-0.6{rcub}{lcub}+0.8{rcub} \pm 0.2)\times 10\sp{lcub}-3{rcub}.{dollar} Using the Particle Data Group value for the branching fraction of {dollar}K\sbsp{lcub}L{rcub}{lcub}0{rcub}\to\mu\sp+\mu\sp-{dollar} this corresponds to a branching fraction of {dollar}B(K\sbsp{lcub}L{rcub}{lcub}0{rcub}\to e\sp+e\sp-) = (9.4\sbsp{lcub}-4.6{rcub}{lcub}+5.9{rcub}) \times 10\sp{lcub}-12{rcub}.{dollar} This result represents the lowest branching fraction ever measured in particle physics.
7
Brown, Nathaniel J. « Studies in the mass 160 decay chain. gamma-ray and conversion electron spectroscopy for the 160lu-160yb, 160yb-160tm, 160tm-160er decay schemes ». Diss., Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/33956.
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Excited states in the transitional nucleus 160Yb have been studied using gamma-ray and conversion electron spectroscopy following the beta+/EC decay of 160Lu. Excited states in the nuclei 160Tm and 160Er have been studied following the beta+/EC decay of 160Yb and 160Tm, respectively. The data for the present study were obtained at TRIUMF in Vancouver, Canada at the ISAC-1 facility through radioactive sources moved into the combination of the 8pi gamma-ray spectrometer array and the Pentagonal Array for Conversion Electron Spectroscopy (PACES). Analysis of gamma-ray gated gamma-ray, gamma-ray gated conversion electron and conversion electron gated gamma-ray spectra resulted in the discovery of a new first excited state and the establishment of a level scheme for 160Tm which differs from the one adopted; as well as a test of the rotational characteristics of 160Er with intensity comparisons to both the spin-5 beta-decaying isomer study of by Singh et al. and the spin-parity 1- beta decay study of by Strusny et al. and Bykov et al.
8
Vassilakopoulos, Vassilios Ioannis. « First observation of the decay of the long-lived neutral kaon into an electron and a positron / ». Digital version accessible at:, 1998. http://wwwlib.umi.com/cr/utexas/main.
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Mäkinen, A. (Ari ). « Experimental spectroscopic studies of metals with electron, ion, and optical techniques ». Doctoral thesis, University of Oulu, 2014. http://urn.fi/urn:isbn:9789526203149.
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In this thesis, different spectroscopic methods are used for studying metals. Electron spectroscopy is applied for the study of binding energy shifts between atomic vapor and solid metals. Photoionization and Auger decay of high temperature aluminum vapors are investigated. Ionization of atomic chromium metal vapor by light absorption is studied with synchrotron radiation and time-of-flight ion mass spectroscopy. Optical spectroscopy is used for studying light emission from electric arc furnace plasma in experimental apparatuses developed during this work. Experimental techniques and sample preparation methods are presented.
10
Mäkinen, A. (Ari). « Experimental spectroscopic studies of metals with electron, ion, and optical techniques ». Doctoral thesis, University of Oulu, 2014. http://urn.fi/urn:isbn:9789526203140.
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Abstract In this thesis, different spectroscopic methods are used for studying metals. Electron spectroscopy is applied for the study of binding energy shifts between atomic vapor and solid metals. Photoionization and Auger decay of high temperature aluminum vapors are investigated. Ionization of atomic chromium metal vapor by light absorption is studied with synchrotron radiation and time-of-flight ion mass spectroscopy. Optical spectroscopy is used for studying light emission from electric arc furnace plasma in experimental apparatuses developed during this work. Experimental techniques and sample preparation methods are presentedOriginal papers The original publications are not included in the electronic version of the dissertation. Huttula, M., Jänkälä, K., Mäkinen, A., Aksela, H., & Aksela, S. (2008). Core shell electron spectroscopy on high temperature vapors: 2s photoionization and Auger decay of atomic aluminium. New Journal of Physics, 10(1), 13009. https://doi.org/10.1088/1367-2630/10/1/013009 Huttula, M., Partanen, L., Mäkinen, A., Kantia, T., Aksela, H., & Aksela, S. (2009). KLL Auger decay in free aluminum atoms. Physical Review A, 79(2). https://doi.org/10.1103/physreva.79.023412 Aksela, S., Kantia, T., Patanen, M., Mäkinen, A., Urpelainen, S., & Aksela, H. (2012). Accurate free atom–solid binding energy shifts for Au and Ag. Journal of Electron Spectroscopy and Related Phenomena, 185(8–9), 273–277. https://doi.org/10.1016/j.elspec.2012.05.007 Mäkinen, A., Patanen, M., Aksela, S., & Aksela, H. (2012). Atom-solid 3p level binding energy shift of transition metals Cr, Mn, Fe, Co, and Ni. Journal of Electron Spectroscopy and Related Phenomena, 185(12), 573–577. https://doi.org/10.1016/j.elspec.2012.12.006 Mäkinen, A., Niskanen, J., & Aksela, H. (2012). Relative photoionization cross section of Cr atoms in the valence region. Physical Review A, 85(5). https://doi.org/10.1103/physreva.85.053411 Mäkinen, A., Niskanen, J., Tikkala, H., & Aksela, H. (2013). Optical emission from a small scale model electric arc furnace in 250–600 nm region. Review of Scientific Instruments, 84(4), 43111. https://doi.org/10.1063/1.4802833
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Mohtasham, Dowlatshahi Niloufar. « Development of a Wien filter electron polarimeter ». Thesis, University of Sussex, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.297955.
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Sankari, A. (Anna). « Relativistic atomic structure calculations applied to electronic transitions in atoms ». Doctoral thesis, University of Oulu, 2008. http://urn.fi/urn:isbn:9789514287282.
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Abstract
In this thesis, the electronic structure of selected atoms was investigated by means of electron and uorescence spectroscopy. Synchrotron radiation was used to excitate atoms in gas phase. In particular, the photoionization and subsequent Auger decay processes in metal vapours were studied as well as the resonant Auger decay in rare gases. The experimental results were analyzed together with theoretical predictions obtained utilizing the multiconfiguration Dirac-Fock method.
13
van, der Aa Olivier. « CMS Trigger strategies for the selection of MSSM Higgs bosons using electron tau-jet decay modes ». Université catholique de Louvain, 2005. http://edoc.bib.ucl.ac.be:81/ETD-db/collection/available/BelnUcetd-06022006-190457/.
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The thesis work concentrated on the developments of selection strategies for the observation of MSSM Higgs bosons in the context of the CMS experiment. The thesis shows, by an example with a MSSM (Minimal Supersymmetric Standard Model) Higgs decaying into two tau, how to define the trigger strategy. The method can be applied for any final state.
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Page, Tom. « Conversion electron spectroscopy of ²âµÂ³ no and fine structure in its subsequent alpha decay ». Thesis, University of Liverpool, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.288127.
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15
McEver, Jimmie Greene III. « Coexisting triaxial shapes in ¹⁸⁶Pt : Gamma- and electron-spectroscopic studies of the radioactive decay of gold 186 ». Diss., Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/27588.
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Brandstetter-Kunc, Adam. « Decay of plasmonic excitations in one dimensional assemblies of metallic nanoparticules ». Thesis, Strasbourg, 2016. http://www.theses.fr/2016STRAE042/document.
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Nous avons étudié la dynamique des électrons dans des réseaux de nanoparticules métalliques. Nous avons d'abord considéré le réseau le plus simple, c'est-à-dire le dimère de nanoparticules. Nous avons trouvé des fréquences propres du dimère hétérogène et ensuite nous avons appliqué l'approche du système quantique ouvert pour décrire les processus d’amortissement présents dans le système. Nous avons étudié deux processus d’amortissement qui dépendent de la taille des nanoparticules constituant le dimère: l'amortissement de Landau avec une proportionnalité inverse à la taille du système, et l’amortissement radiatif, proportionnel au volume du système. En utilisant les résultats de l'étude des dimères, nous avons étendu notre approche du système quantique ouvert pour étudier des chaînes de nanoparticules unidimensionnelles. Nous avons dérivé une équation maîtresse qui a été utilisée pour étudier la propagation des plasmons le long de la chaîne. Nous avons constaté que la propagation du plasmon est limitée que par les sources non radiatives d'amortissement. Enfin, nous avons dérivé l'expression analytique de la longueur de propagation d'un plasmon dans une chaîne de nanoparticulesWe studied the electron dynamics in metallic nanoparticle arrays. We first considered the simplestarray i.e. a nanoparticle dimer. We found the eigenfrequencies of the heterogeneous dimer andthen we applied the open quantum system approach to describe the decay processes present inthe system. We investigated two decay processes which depend on the size of the nanoparticlesbuilding up the dimer : the Landau damping, inversly proportional to the system-size, and radiationdamping, proportional to the volume of the system. Using the results of the dimer study weextended our open quantum system approach to study one-dimensional nanoparticle chains. Wederived a master equation and used it to investigate the propagation of plasmons along the chain.We found that the propagation of the plasmon is limited by the non-radiative sources of damping.Finally we derived an analytical expression for the propagation length of a plasmon in ananoparticle chain
17
Khalal, Mehdi Abdelbaki. « Photoionisation multiple des vapeurs métalliques Multi-electron coincidence spectroscopy : Triple Auger decay of Ar 2p and 2s holes 4d -inner-shell ionization of Xe+ ions and subsequent Auger decay ». Thesis, Sorbonne université, 2018. http://www.theses.fr/2018SORUS552.
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Ce travail de thèse porte sur l’étude expérimentale des processus de photoionisation multiple de vapeurs alcalines par rayonnement synchrotron. Je me suis intéressé particulièrement à la désexcitation par déclin Auger des atomes ionisés en couche interne. Le dispositif expérimental HERMES mis au point par l’équipe est un spectromètre par temps de vol de type bouteille magnétique qui permet de détecter en coïncidence tous les électrons émis lors du processus d’ionisation (photoélectrons) et de relaxation (électrons Auger). Une partie importante de ma thèse a été consacrée à l’améliorer pour permettre également la détection en coïncidence des ions formés. J’ai reconstitué les différentes voies de désexcitation par simple, double et triple Auger qui suivent l’ionisation en couche 2p du potassium (de configuration électronique [Ar] 4s). Les proportions des ions finaux Kn+ (n=2,3 et 4) sont établies et comparées avec les proportions des ions formés par la désexcitation du trou en couche 2p dans l’argon. Cela permet de mettre en évidence le rôle de l’électron 4s lors du processus de désexcitation (spectateur lors de la première étape puis participateur lors de la seconde étape du déclin). Le déclin Auger qui suit l’ionisation et l’excitation de l’électron en couche 3d dans le rubidium est présenté ensuite. Dans la dernière partie de la thèse je présente la double ionisation 4d-15p-1 dans le Xénon que l’on compare à la photoionisation d’un faisceau d’ion Xe+ (expérience MAIA). Le but étant de montrer que ce processus de double ionisation cœur valence permet de simuler le processus d’ionisation en couche interne 4d des ions atomiques Xe+ et le déclin Auger qui s’en suitThe increasing availability of modern x-ray light sources with high tunability, high brightness and narrow photon-energy bandwidth has allowed a deep understanding of the physics behind light and matter interactions. During my PhD, I investigated experimentally different process of photoexcitation and photoionization of rare gas atoms (Argon and Xenon) and alkali metals (Potassium and Rubidium) by the means of synchrotron radiation. Our experimental setup is a 2m long magnetic bottle time-of-flight spectrometer that collect in coincidence almost all the electrons emitted in the 4π solid angle. We investigate the multiple Auger decay of the potassium 2p core holes which has an electronic configuration similar to Ar with an additional 4s valence electron. We show the spectator role of this electron in the decay mechanism and the enhancement of double and triple Auger rates comparing with the Argon 2p holes decay. We also investigated the multiple Auger decay of the rubidium 3d core holes. Finally, we investigated the core valence double photoionization of Xenon atom 4d-15p-1 which is compared with the direct ionization of Xe+ ions (MAIA experiment). We showed that the core valence double photoionization process will populate the same states that the ones populated by the photoionization of the ions. One should note that this process is very weak compared to the 4d inner shell ionization of Xe atom but thanks to the coincidence technique we are able to clearly separate and disentangle each ionization process. Our experiment confirmed the results of MAIA and allowed us to extract the Auger spectra associated with the decay of these Xe+ ions, when ionized in the 4d shell
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Charaf, Otman. « Study of Drell-Yan production in the di-electron decay channel and search for new physics at the LHC ». Doctoral thesis, Universite Libre de Bruxelles, 2010. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210031.
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Cette these a pour sujet la recherche de nouvelle physique et l'etude de la production Drell-Yan dans le canal di-electron a l'aide du detecteur CMS au LHC. Certaines theories au dela du Modele Standard (extra dimensions, theories de grande unification) predisent l'existence de particules massives pouvant se desintegrer en une paire d'electrons. La selection des evenements recherches est presentee et etudiee. La strategie d'analyse est introduite et testee. Enfin, l'analyse des premieres donnees a 7 TeV est decrite et les resultats sont commentes.Doctorat en Sciences
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Schnorr, Kirsten [Verfasser], et Robert [Akademischer Betreuer] Moshammer. « XUV Pump-Probe Experiments on Electron Rearrangement and Interatomic Coulombic Decay in Diatomic Molecules / Kirsten Schnorr ; Betreuer : Robert Moshammer ». Heidelberg : Universitätsbibliothek Heidelberg, 2014. http://d-nb.info/1177811189/34.
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Samimi, Alireza. « Study of Narrow-Band Spectral Characteristics of Stimulated Electromagnetic Emission (SEE) During Second Electron Gyro-Harmonic Heating ». Diss., Virginia Tech, 2013. http://hdl.handle.net/10919/51833.
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Stimulated Electromagnetic Emissions SEEs may provide important diagnostic information about space plasma composition, energetics, and dynamics during active experiments in which ground-based high powered radio waves are transmitted into the ionosphere. The nonlinear plasma processes producing this secondary radiation are not well understood particularly for some recent observations where the transmitter (pump) frequency is near the second harmonic of the electron gyro-frequency. New, more comprehensive, experimental observations of spectral features within 1kHz of the pump wave frequency are reported here in order to begin more careful comparisons of the experimental observations and a possible theoretical underpinning which is also provided. The experimental observations typically show two distinct types of secondary radiation spectra which are a) discrete narrowband harmonic spectral structures ordered by the ion gyro-frequency, so-called stimulated ion Bernstein Scatter (SIBS) and, b) broadband spectral structure with center frequency near 500 Hz and similar spectral bandwidth named ion acoustic parametric decay (IAPD). A theoretical model is provided that interprets these spectral features as resulting from parametric decay instabilities in which the pump field ultimately decays into high frequency upper hybrid/electron Bernstein and low frequency neutralized ion Bernstein and/or obliquely propagating ion acoustic waves at the upper hybrid interaction altitude. Detailed calculations of the threshold level, growth rate, unstable wavenumber and frequency bandwidth of the instabilities are provided for comparisons with experimental observations. An assessment of the effect of the critical instability parameters are provided including pump electric field strength, proximity of the pump frequency to the electron gyro-frequency and pump electric field geometry. The model shows quite reasonable agreement with the experimental observations.
Next, a two dimensional Particle-In-Cell Monte-Carlo Collision computational model (PIC-MCC) is employed in order to consider nonlinear aspects such as 1) electron acceleration through wave-particle heating, 2) more complex nonlinear wave-wave processes and 3) temporal evolution of electron irregularities through nonlinear saturation. The simulation results show that the IB associated parametric decay is primarily associated with electron acceleration perpendicular to the geomagnetic field. More gyro-harmonic lines are typically associated with more intense heating. Heating is reduced when the pump frequency is sufficiently close to 2fce. The IA associated parametric decay instability is primarily associated with electron tail heating along the magnetic field and heating is reduced when the pump frequency is sufficiently close to 2fce. Characteristics of caviton collapse behavior become prevalent in this case. Results are discussed within the context of some recent experimental observations. Further discussions are provided of connections with past observed SEE spectral features and potential new diagnostic information provided by these newly categorized spectra.Ph. D.
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Allatt, Roger Giles. « Fine structure in the alpha decay of '1'9'2Po : shape coexistence in '1'8'8Pb ». Thesis, University of Liverpool, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367136.
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Filippin, Livio. « Relativistic study of electron correlation effects on polarizabilities, two-photon decay rates, and electronic isotope-shift factors in atoms and ions : ab initio and semi-empirical approaches ». Doctoral thesis, Universite Libre de Bruxelles, 2017. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/261670.
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The first aim of this thesis is to perform relativistic calculation of atomic and ionic polarizabilities and two-photon decay rates. Hydrogenic systems are treated by the Lagrange-mesh method. The extension to alkali-like systems is realized by means of a semiempirical-core-potential approach combined with the Lagrange-mesh method. The studied systems are partitioned into frozen-core electrons and an active valence electron. The core orbitals are defined by a Dirac-Hartree-Fock (DHF) calculation using the GRASP2K package. The valence electron is described by a Dirac-like Hamiltonian involving a core-polarization potential to simulate the core-valence electron correlation. Polarizabilities appear in a large number of fields and applications, namely in cold atoms physics, metrology and chemical physics. Two-photon transitions are part of a priori highly unlikely processes and are therefore called forbidden radiative processes. Experimental situations report decays from metastable excited states through these channels. Long lifetimes were measured for highly charged Be-like ions in recent storage-ring experiments, but their interpretation is problematic. The study of the competition between forbidden (one-photon beyond the dipole approximation, or multi-photon) and unexpected (hyperfine-induced or induced by external magnetic fields) radiative processes is all obviously relevant. The second aim of this thesis is to perform relativistic ab initio calculations of electronic isotope-shift (IS) factors by using the multiconfiguration DHF (MCDHF) method implemented in the RIS3/GRASP2K and RATIP program packages. Using the MCDHF method, two different approaches are adopted for the computation of electronic IS factors for a set of transitions between low-lying levels of neutral systems. The first one is based on the estimate of the expectation values of the one- and two-body nuclear recoil Hamiltonian for a given isotope, including relativistic corrections derived by Shabaev, combined with the calculation of the total electron densities at the origin. In the second approach, the relevant electronic factors are extracted from the calculated transition shifts for given triads of isotopes. These electronic quantities together with observed ISs between different pairs of isotopes provide the changes in mean-square charge radii of the atomic nuclei. Within this computational approach for the estimation of the mass- and field-shift factors, different models for electron correlation are explored in a systematic way to determine a reliable computational strategy, and to estimate theoretical error bars of the IS factors.Doctorat en Sciences de l'ingénieur et technologie
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Wardrope, David Robert. « Preparations for measurement of electroweak vector boson production cross-sections using the electron decay modes, with the Compact Muon Solenoid detector ». Thesis, Imperial College London, 2009. http://hdl.handle.net/10044/1/5517.
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The Compact Muon Solenoid was designed to make discoveries at the TeV scale : to elucidate the nature of electroweak symmetry breaking and to search for physics beyond the Standard Model. For any such discovery to be credible, it must first be demonstrated that the CMS detector is understood. One mechanism to make this demonstration is to measure "standard candle" processes, such as W and Z production. This thesis describes preparations undertaken to make these measurements using the electron decay modes, with [derivative]Ldt = 10 pb-1 of collision data. The energy resolution of the electromagnetic calorimeter was measured in test beam data. An improved method of deriving the optimised weights necessary for amplitude reconstruction is described. The measurement of electron charge using tracks is impaired by the electron showering in the tracker material. A novel charge measurement technique that is complementary to the existing method was assessed. Missing transverse energy is a powerful discriminating variable for the selection of W+/ -> e+/ [upsilon]e events, however it is difficult to simulate accurately due to its global nature. The Ersatz Missing Energy method was developed to provide reliable and accurate descriptions of missing energy from data using readily reconstructible [gamma]*/Z -> e+e- events. The method is described and evaluated. Finally, the measurement strategy for W and Z boson production cross-sections in early data is outlined and analysed using simulated data. Significant results can be obtained with only [derivative] Ldt = 10 pb-1.
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Wrona, Bozydar Adam. « Measurement of the W+- boson cross section in the electron decay channel at [square root] s=7 TeV with the ATLAS detector ». Thesis, University of Liverpool, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.569161.
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At the LHC, the process pp -+ W± X followed by the leptonic decays W- -+ e-v and W+ -+ e+lI is investigated to test the Standard Model in a completely new kinematic range. This thesis describes W± cross-section measurements using pp collisions recorded by the ATLAS detector in 2010. The charge dependence is measured both integrated and differentially in lepton pseudorapidity 'f); and analysis of the systematic uncertainties is presented. The results are compared with a recent publication by ATLAS which uses different reconstruction and background estimations. The cross-sections are also compared with theoretical predictions based on recent P DF sets determined recently by the CTEQ, MSTW, ABKM, HERAPDF and JR groups. The values of the W± cross-sections and their respective uncertainties, for 35.1 pb-1 at 7 TeV centre of mass energy, determined by this analysis, are: δfid/w+ x BR(W -+ e+ve) = 2.907 ± 0.015(stat.) ± 0.113(syst.) ± 0.099(lumi.) [nb] δfid/w+ x BR(W -+ e+ve) = 1.913 ± 0.012(stat.) ± 0.077(syst.) ± 0.065(lumi.) [nb]
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Yuan, Junhua Filippone Bradley. « Progress towards a high precision measurement of the neutron spin--electron angular correlation in polarized neutron beta decay with ultra-cold neutrons / ». Diss., Pasadena, Calif. : Caltech, 2006. http://resolver.caltech.edu/CaltechETD:etd-01302006-153024.
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Kelly, Mandy Sharon. « A search for gauge mediated supersymmetry breaking using signal e'+e'-#-># ». Thesis, University of Sheffield, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.301725.
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Presland, A. D. « Identification and measurement of low energy electrons and the decay B'0â†s->J/#psi##phi# at CMS ». Thesis, University of Bristol, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367940.
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Chadwick, Matthew. « Measurement of the tt̄ cross-section at 7 TeV with 36 PB⁻¹ of data in the electron+jets decay channel using the CMS detector ». Thesis, Brunel University, 2012. http://bura.brunel.ac.uk/handle/2438/6498.
Texte intégralRésumé :
A measurement of the top-pair production cross-section at a centre-of-mass energy of 7 TeV using proton-proton collisions with 36 pb-1 of data collected by CMS at the Large Hadron Collider is presented. The analysis is performed using the nal state that consists of one isolated electron with jets, one of which is required to be identified as being consistent with including the decay of a B hadron. The measured cross-section with three or more selected jets is 169 +/- 13(stat:)+37 +32(sys:)+8 -7(lumi:) pb and 197 +/- 17(stat:)+38 -35(sys:)+9 -8(lumi:) pb for four or more jets. The results are consistent with NLO and approximate NNLO theoretical predictions.
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HILARIO, KATIA A. F. « Desenvolvimento de metodos de medida de atividade empregando sistemas de coincidencia para radionuclideos que desintegram pela dupla emissao beta sup(-) - beta sup(+) / captura eletronica - aplicacao na padronizacao do sup(192)Ir, sup(152)Eu e sup (186) Re ». reponame:Repositório Institucional do IPEN, 2002. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11018.
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Made available in DSpace on 2014-10-09T12:47:00Z (GMT). No. of bitstreams: 0Made available in DSpace on 2014-10-09T14:10:33Z (GMT). No. of bitstreams: 1 07614.pdf: 6594444 bytes, checksum: 0bd72d3764d638a649ad00b67ff5aa44 (MD5)
Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
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Lindblad, Andreas. « A Treatise on the Geometric and Electronic Structure of Clusters : Investigated by Synchrotron Radiation Based Electron Spectroscopies ». Doctoral thesis, Uppsala University, Department of Physics and Materials Science, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-8463.
Texte intégralRésumé :
Clusters are finite ensembles of atoms or molecules with sizes in the nanometer regime (i.e. nanoparticles). This thesis present results on the geometric and electronic structure of homogeneous and heterogeneous combinations of atoms and molecules. The systems have been studied with synchrotron radiation and valence, core and Auger electron spectroscopic techniques.
The first theme of the thesis is that of mixed clusters. It is shown that by varying the cluster production technique both structures that are close to that predicted by equilibrium considerations can be attained as well as far from equilibrium structures.
Electronic processes following ionization constitute the second theme. The post-collision interaction phenomenon, energy exchange between the photo- and the Auger electrons, is shown to be different in clusters of argon, krypton and xenon. A model is proposed that takes polarization screening in the final state into account. This result is of general character and should be applicable to the analysis of core level photoelectron and Auger electron spectra of insulating and semi-conducting bulk materials as well.
Interatomic Coloumbic Decay is a process that can occur in the condensed phases of weakly bonded systems. Results on the time-scale of the process in Ne clusters and mixed Ar/Ne clusters are herein discussed, as well observations of resonant contributions to the process. In analogy to Auger vis-à-vis Resonant Auger it is found that to the ICD process there is a corresponding Resonant ICD process possible. This has later been observed in other systems and by theoretical calculations as well in subsequent works by other groups.
Delocalization of dicationic valence final states in the hydrogen bonded ammonia clusters and aqueous ammonia has also been investigated by Auger electron spectroscopy. With those results it was possible to assign a previously observed feature in the Auger electron spectrum of solid ammonia.
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Borsato, Martino. « Study of the BO to Kstar0 electron positron decay with the LHCb detector and development of a novel concept of PID detector : the Focusing DIRC ». Sorbonne Paris Cité, 2015. https://theses.hal.science/tel-01456521.
Texte intégralRésumé :
Les courants neutres changeant le saveur de type b —>sy sont interdites au niveau de l'arbre dans le Modèle Standard (MS) et ils se produisent au premier ordre à travers des diagrammes radiatives à boucle. Par conséquent, ils sont sensibles à la Nouvelle Physique (NP), qui peut contribuer soit au niveau de l'arbre ou de la boucle. En outre, la chiralité de l'interaction faible dans le MS implique que le photon émis a une polarisation gauche. Cependant, toute une classe de théories de NP ne partagent pas cette caractéristique du MS et pourraient se manifester sans ambiguïtés comme une contribution droite à la polarisation. Cette thèse présente la première étude de la polarisation du photon provenant du processus b —>sy à travers une analyse angulaire du canal BO —>K* 0 e+e-. Même si BO —> *K* 0 e+e- n'est pas une transition b—>s de type radiative, la contribution avec un photon virtuel qui se couple à la paire de leptons domine dans la région de bas q carré. De plus, le canal avec des électrons plutôt que des muons permet de mieux isoler cette contribution à l'extrémité inférieure du spectre de q carré. La luminosité intégrée de 3 fb-1 recueillie par LHCb au cours du Run 1 du LHC a permis pour la première fois de sélectionner un échantillon d'évènements B0—>K* 0 e+e¬ assez grands pour mesurer les asymétries transverses AT(2)=-0. 23±0. 23±0. 05 et ATIm=0. 14±0. 22±0. 05 dans la région de bas q carré entre 0. 002 GeV2/c4 et 1 GeV2/c4. Ces mesures sont consistent avec les prédictions du MS et ils fournissent de nouvelles contraintes sur les contributions droitiers à la polarisation avec le même niveau de précision que ceux venant des mesures faites avec des désintégrations radiatives. Les expériences de physique du saveur nécessitent de détecteurs avancés dédiés à l'identification des différentes saveurs des hadrons chargés. Ces détecteurs sont pour la plupart basés sur la détection de la lumière Cherenkov émise par ces particules lorsqu'elles traversent un milieu diélectrique. Cette thèse présente également l'activité de R&D sur un nouveau concept de détecteur basé sur le détecteur DIRC de l'expérience BABAR : le FDIRC. Son design est destiné à l'utilisation dans un environnement avec un bruit de fond deux ordres de grandeurs plus grand que dans BABAR grâce à une caméra d'imagerie plus rapide, de dimension réduite et composée de silice fondue résistant à l'irradiation. Le premier prototype à grande échelle a été testé au télescope à rayons cosmiques de SLAC et a démontré la faisabilité du concept de détecteurFlavour-changing neutral current processes of the type b --+ sy are forbidden at the tree level in the Standard Model (SM) and occur at leading order through radiative loop diagrams. Therefore, they are sensitive to new physics (NP), which may contrebute either at the tree or loop level. Furthermore, the chirality of the weak interaction in the SM implies that the photon emitted has left-handed polarisation. However, a whole class of NP theories do not share this SM feature and may manifest unambiguously as a right-handed contribution to the polarisation. This thesis presents the first study of the b-* sy photon polarisation through an angular analysis of the B0-*K* 0 e+e- channel. Even though BO-*K* 0 e+e- is not a radiative b s transition, the contribution from a virtual photon coupling to the lepton pair dominates in the low-q2 region. Furthermore, the channel with electrons rather than muons allows to better isolate the virtual photon contribution at the low end of the q 2 spectrum. The integrated luminosity of 3 fb-1 collected by LHCb during LHC Run 1 allowed for the first time to select a sample of B0-›K* 0 e+e- events large enough to measure the transverse asymmetries AT(2)=-0. 23±0. 23±0. 05 and ATIm=0. 14±0. 22±0. 05 in the low q2 region between 0. 002 GeV2/c4 and 1 GeV2/c4. These measurements are found to be consistent with SM predictions and provide new constraints on right handed contributions to the photon polarisation at the same level of precision as the ones from measurements involving radiative decays. Flavour physics experiments require advanced detectors dedicated to the identification of the different flavours of charged hadrons. Most of them are based on the detection of the Cherenkov light emitted by these particles as they traverse a dielectric medium. This thesis presents also the R&D activity on a new detector concept based on the BABAR DIRC, the FDIRC. Its design is intended to operate the detector in an environment with background two orders of magnitude larger than BABAR thanks to a faster and smaller imaging camera made of radiation-hard fused silica. The first full-scale prototype of the FDIRC was tested at the SLAC Cosmic Ray Telescope and demonstrated the feasibility of the detector concept
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Moss, Joshua J. « Measurement of the branching fraction for the decay neutral kaon(long) going to pion-antipion-positron-electron in the high M(pi-pi) invariant mass region ». W&M ScholarWorks, 2007. https://scholarworks.wm.edu/etd/1539623516.
Texte intégralRésumé :
A measurement of the branching fraction for the rare decay K0L → pi+pi-e +e- was performed using data collected from experiment E871 which ran at the AGS of Brookhaven National Laboratory. Analysis of the data revealed 27.7 +/- 7.4 signal events in the signal region, 0.4905 GeV < Mpipiee < 0.505 GeV together with 13.3 +/- 3.7 background events. The branching fractions of ( 8.5+/-2.3stat +/-1.0sys ) x 10-6 using the phenomenological model acceptance and ( 2.3+/-0.6stat +/-0.3sys ) x 10-6 using the chiral perturbation model represent the first measurements for K0L → pi+pi-e +e- in the dipion invariant mass region 0.475 GeV < Mpipi < 0.497 GeV. These results support the prediction of chiral perturbation theory rather than that of the phenomenological model.
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Lück, Thomas. « Determination of the CKM-matrix element |Vub| from the electron energy spectrum measured in inclusive B -> ; X u e[Ypsilon] decay with the BABAR detector ». Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2013. http://dx.doi.org/10.18452/16718.
Texte intégralRésumé :
Dieses Dokument präsentiert eine Messung des CKM Matrixelementes Vub in inklusiven semileptonischen B nach Xu e nu Ereignissen, auf einem Datensatz von 471 Millionen BB Ereignissen, aufgezeichnet vom BABAR Detektor. Inklusive B nach Xu e nu Zerfälle wurden selektiert indem hochenergetische Elektronen (Positronen) rekonstruiert wurden. Untergrundunterdrückung wurde erreicht indem Ereignisse selektiert wurden mit Elektron- (Positron-) Energien in der Nähe des kinematischen Endpunktes von B nach Xu e nu Zerfällen. Ein Veto für B nach Dstern e nu wurde angewendet um den Untergrund weiter zu reduzieren. Dieses Veto benutzt Dstern Mesonen die mit einer Partiellen Rekonstruktionstechnik rekonstruiert wurden.This document presents a measurement of the CKM matrix-element Vub in inclusive semileptonic B to Xu e nu events on a dataset of 471 million BB events recorded by the BABAR detector. Inclusive B to Xu e nu decays are selected by reconstructing a high energetic electron (positron). Background suppression is achieved by selecting events with electron (positron) energies near the kinematical allowed endpoint of B to Xu e nu decays. A B to Dstar e nu veto is applied to further suppress background. This veto uses Dstar mesons which have been reconstructed with a partial reconstruction technique.
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Chakma, Rikel. « Characterization of the multi-detector GABRIELA and decay spectroscopy of ²⁵⁵Rf and ²⁵¹No ». Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASP066.
Texte intégralRésumé :
Une question sans réponse qui se trouve au carrefour de la physique et de la chimie est : quelle est la limite du tableau périodique. Les théories nucléaires suggèrent l'existence de ce qu'on appelle "l'îlôt de stabilité", habitée par des éléments super-lourds à longue durée de vie. Ces éléments ne doivent leur existence qu’à d’importants effets quantiques. Ainsi, les éléments super-lourds forment un laboratoire unique pour l'étude de la structure et de la dynamique nucléaires sous l'influence d’une très forte répulsion Coulombienne entre les nombreux protons du noyau. Cependant, un défi théorique réside dans la prédiction de la position exacte de cet îlôt, car différents modèles prédisent la position des prochaines fermetures de couches au delà de Z=82 et N=126 à Z = 114, 120 ou 126, et N = 172, 184 de façon plutôt inharmonieuse. Pour mieux comprendre le comportement de la matière nucléaire dans des conditions extrêmes du nombre de protons et de neutrons et contraindre les modèles nucléaires, il est donc nécessaire d'étudier la nature et la séquence d’états dans des noyaux transactinides plus légers et plus accessibles par des études spectroscopiques. Dans ce travail, des états de ²⁵⁵Rf ont été peuplés par la réaction de fusion-évaporation ⁵⁰Ti(²⁰⁷Pb, 2n)²⁵⁵Rf en utilisant un faisceau intense de ⁵⁰Ti fourni par le cyclotron U400 du FLNR à Dubna. Les résidus d'évaporation ont été séparés du faisceau et du fond d'autres produits de réaction à l'aide du séparateur de noyaux de recul SHELS et implantés dans le détecteur d'implantation du dispositif GABRIELA. Le multidétecteur GABRIELA permet d'effectuer des corrélations de temps et en position entre les noyaux implantés et leurs désintégrations ultérieures et est sensible à l'émission de rayonnemments gamma, d'électrons de conversion interne, de particules alpha et de produits de fission. Pour interpréter les spectres de désintégration expérimentaux, le multidétecteur GABRIELA a été caractérisé à l'aide de simulations GEANT4, qui ont été validées avec des données d'étalonnage. En particulier, l'impact des effets de sommation sur l'efficacité de la détection des rayons gamma et des électrons a été étudié et a montré que les simulations sont essentielles pour interpréter des résultats expérimentaux obtenus grâce à des dispositifs compactes et efficaces comme GABRIELA. Une nouvelle méthode pour estimer le profil de profondeur d'implantation des résidus d'évaporation a été mise au point, ce qui est essentiel notamment pour la spectroscopie des électrons de conversion interne.Afin de pouvoir utiliser GEANT4 pour des éléments plus lourds que Fm (Z=100), le code source a été modifié et les données de fluorescence et d’émission Auger ont été extrapolées pour permettre des simulations précises de décroissances radioactives jusqu'à l’élément Rf. En utilisant les données expérimentales obtenues sur le noyau ²⁵⁷Rf étudié à Dubna et le schéma de désintégration connu de l'isomère 21/2+ de haut K, la fonctionnalité du code GEANT4 modifié a été validée. Les simulations ont ensuite été utilisées pour étudier la structure fine de décroissance alpha du ²⁵⁵Rf et dériver les rapports d’embranchements vers les états du ²⁵¹No. Les rapports d’embranchements de décroissance gamma et les coefficients de conversion interne de transitions du ²⁵¹No ont également été extraits. Dans le ²⁵⁵Rf, deux nouveaux états isomériques de haut K ont été identifiés et l'existence à basse énergie d’excitation d'un isomère de spin a été confirmée. Les comparaisons quantitatives et qualitatives des spectres expérimentaux aux simulations ont permis d'établir les schémas de désexcitation les plus probables et d'assigner les configurations quasi-particules possibles pour les 3 isomèresOne unanswered question that lies at the crossroad of physics and chemistry is: what is the limit of the periodic table. Nuclear theories suggest the existence of the so-called "island of stability", inhabited by long-lived superheavy elements. These elements can materialize only because of strong quantum shell stabilizing effects. Thus, superheavy elements form a unique laboratory for studying nuclear structure and dynamics under the influence of very large Coulomb forces between the numerous protons in the nucleus. However, a theoretical challenge lies in the prediction the exact position of this island as different models predict the position of the next shell closures at Z = 114, 120, or 126, and N=172, 184 beyond the closed spherical shells at Z = 82 and N = 126 rather inharmoniously. To better understand the behavior of nuclear matter for extreme values of proton and neutron numbers and constrain nuclear models it is, therefore, necessary to investigate the nature and sequence of states in lighter, more accessible, transactinide nuclei through spectroscopic studies. In this work, states of ²⁵⁵Rf were populated through the fusion-evaporation reaction ⁵⁰Ti(²⁰⁷Pb,2n)²⁵⁵Rf using an intense ⁵⁰Ti beam provided by the U400 cyclotron of FLNR in Dubna. The evaporation residues were separated from the beam and background of other reaction products using the recoil separator SHELS and implanted into the implantation detector of the GABRIELA setup. The GABRIELA multidetector array allows to perform time and position correlations between the implanted nuclei and their subsequent decays and is sensitive to the emission of gamma rays, internal conversion electrons, alpha particles and fission products. To interpret the experimental decay spectra, the GABRIELA multidetector was characterized using GEANT4 simulations, which were validated with calibration data. In particular, the impact of summing on the gamma-ray- and electron-detection efficiencies was investigated and showed that simulations are vital for interpreting experimental results obtained using compact and efficient setups like GABRIELA. A novel method to estimate the implantation depth profile of the evaporation residues was devised, which is essential especially for internal-conversion-electron spectroscopy.To be able to use GEANT4 for elements heavier than Fm (Z=100), the source code was modified and the Fluorescence and the Auger emission data were extrapolated to allow accurate radioactive decay simulations up to the element Rf. Using ²⁵⁷Rf experimental data obtained in Dubna and the known decay scheme of the 21/2+ high-K isomer, the functionality of the modified GEANT4 code was validated. Simulations were then used to study the fine structure alpha decay of ²⁵⁵Rf and derive branching ratios to states in ²⁵¹No. The gamma-decay branching ratios and internal conversion coefficients for transitions in ²⁵¹No were also extracted. In ²⁵⁵Rf, two new high-K isomeric states were identified and the existence of a low-lying spin isomer was confirmed. Quantitative and qualitative comparisons of the experimental spectra to simulations have allowed to establish the likely decay schemes and assign possible quasiparticle configurations for all 3 isomers
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BRITO, ANDREIA B. de. « Determinação da taxa de desintegração de Tc-99m e In-111 em sistemas de coincidências ». reponame:Repositório Institucional do IPEN, 2011. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10047.
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Dissertação (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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Andress, John Charles. « Development of the BaBar trigger for the investigation of CP violation ». Thesis, University of Bristol, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.322355.
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Luzio, Marco Aurelio. « Study of analytical methods for electron track detection from heavy quark decays generated by sqrt(s)=8TeV pp collisions at ALICE ». Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/43/43134/tde-07062017-140205/.
Texte intégralRésumé :
A study of the usage of ALICEs time of flight (TOF), time projection chamber (TPC), and electromagnetic calorimeter (EMCal), aiming at detecting and separating electrons and positrons (e±) originated from different sources, was carried out. To accomplish the objectives of the research, data gathered from the 2012 proton-proton (pp) collision experiment were used. At a center of mass energy of sqrt(s)=8TeV, the collision of the proton beams liberates heavy quarks, charm and bottom, with approximate lifetimes of approximately 10^13s and 10^12s, respectively. The e± generated through weak semileptonic heavy flavor decays are of interest for studying quarks, therefore it served solely as motivation and incentive for the research carried out and described herein. The introduction of carefully selected cuts, with the purpose of separating partial data collected in the three detectors, permitted the understanding of their effect on the results. Furthermore, due to the fact that the TOFs design was not meant to separate e± from the other heavier particles, only the general effects of introducing a simple cut in the beta=v/c values were analyzed. The more specific cuts were only used for the data generated by the events detected by the TPC and the EMCal. A combination of cuts based on the particles energy loss as a function of traveled distance (dE/dx), with the ratio of energy to momentum (E/p) of the particle, was adopted to enable the separation process, thus allowing for the isolation of e± from the other particles, namely pi±, K±, and p/p. The analysis was performed for values of total particle momentum in the range 0<=p<=6GeV/c. A comparison of the raw data with the results obtained by applying this procedure, indicated a substantial increase in the e± yield and efficiency, reaching average values above 90% over the entire momentum range.Um estudo do uso dos detetores de tempo de voo (TDV), câmara de projeção de tempo (CPT), e calorímetro eletromagnético (CalEM) do ALICE, visando detectar elétrons e pósitrons (e±) originados por diferentes fontes, foi realizado. Para atingir os objetivos da pesquisa, dados coletados durante o experimento de colisões próton-próton em 2012 foram utilizados. Com um nível de enegia do centro de mass igual a raiz(s)=8TeV, a colisão dos feixes de prótons libera quarks pesados, charm e bottom, com tempo de vida de aproximadamente 10^13s e 10^12s, respectivamente. Os e± gerados pelo decaimento fraco semileptônico de sabores pesados é de interesse para o estudo dos quarks, portanto, o conceito serviu somente como motivação e incentivo para a pesquisa realizada e descrita nesta dissertação. A introdução de cortes específicos, com a finalidade de parcialmente separar dados coletados nos três detectores, permitiu adquirir entendimento sobre os efeitos do cortes nos resultados. Adicionalmente, em virtude do projeto do TDV não ter sido feito visando separar e± oriundos do decaimento dos sabores pesados das demais partículas mais massivas, somente os efeitos gerais de introduzir um corte simples nos valores de beta=v/c, foram analisados. Os cortes mais específicos foram somente nos dados detectados pelo CPT e pelo CalEM. Uma combinação de cortes baseados na perda de energia da partícula em função da distância percorrida (dE/dx), com a razão entre a energia e o momento da partícula (E/p), foi adotada para viabilizar o processo de separação, desta forma permitindo a separação dos e± das demais partículas, ou seja, dos pi±, K±, and p/p. A análise foi realizada para valores de momento total das partículas na faixa 0<=p<=6GeV/c. Uma comparação dos dados originais com os resultados obtidos pela aplicação do procedimento, indicou um aumento substancial do rendimento e eficiência dos e±, atingindo valores médios acima de 90% na faixa inteira de momento.
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Lorenzo, Martinez Narei. « Observation of a Higgs boson and measurement of its mass in the diphoton decay channel with the ATLAS detector at the LHC ». Phd thesis, Université Paris Sud - Paris XI, 2013. http://tel.archives-ouvertes.fr/tel-00924105.
Texte intégralRésumé :
The Standard Model of the particle physics predicts the existence of a massive scalar boson, usually referred to as Higgs boson in the literature, as resulting from the Spontaneous Symmetry Breaking mechanism, needed to generate the mass of the particles. The Higgs boson whose mass is theoretically undetermined, is experimentally looked for since half a century by various experiments. This is the case of the ATLAS experiment at LHC which started taking data from high energy collisions in 2010. One of the most important decay channel in the LHC environment is the diphoton channel, because the final state can be completely reconstructed with high precision. The photon energy response is a key point in this analysis, as the signal would appear as a narrow resonance over a large background. In this thesis, a detailed study of the photon energy response, using the ATLAS electromagnetic calorimeter has been performed. This study has provided a better understanding of the photon energy resolution and scale, thus enabling an improvement of the sensitivity of the diphoton analysis as well as a precise determination of the systematic uncertainties on the peak position. The diphoton decay channel had a prominent role in the discovery of a new particle compatible with the Standard Model Higgs boson by the ATLAS and CMS experiments, that occurred in July 2012. Using this channel as well as the better understanding of the photon energy response, a measurement of the mass of this particle is proposed in this thesis, with the data collected in 2011 and 2012 at a center-of-mass energy of 7 TeV and 8 TeV. A mass of 126.8 +/- 0.2 (stat) +\- 0.7 (syst) GeV/c2 is found. The calibration of the photon energy measurement with the calorimeter is the source of the largest systematic uncertainty on this measurement. Strategies to reduce this systematic error are discussed.
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Zagorodskikh, Sergey. « Single-photon multiple ionisation of atoms and molecules investigated by coincidence spectroscopy : Site-specific effects in acetaldehyde and carbon dioxide ». Doctoral thesis, Uppsala universitet, Molekyl- och kondenserade materiens fysik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-301128.
Texte intégralRésumé :
In this thesis, multiple ionisation processes of free atoms and molecules upon single photon absorption are studied by means of a versatile multi-electron-ion coincidence spectroscopy method based on a magnetic bottle, primarily in combination with synchrotron radiation. The latter offered the possibility to access not only valence but also core levels, revealing processes, which promote the target systems into different charge states. One study focuses on double and triple ionisation processes of acetaldehyde (ethanal) in the valence region as well as single and double Auger decay of initial 1s core vacancies. The latter are investigated site-selectively for the two chemically different carbon atoms of acetaldehyde, scrutinising theoretical predictions specifically made for that system. A related study concentrates on core-valence double ionisation spectra of acetaldehyde, which have been investigated in the light of a previously established empirical model, and which have been used as test cases for analysing this kind of spectra by means of quantum chemical electronic structure methods of increasing sophistication. A third study investigates site-specific fragmentation upon 1s photoionisation of acetaldehyde using a magnetic bottle augmented with an in-line ion time-of-flight mass spectrometer. Experimental evidence is presented that bond rupture occurs with highest probability in the vicinity of the initial charge localisation and possible mechanisms are discussed. A site-specificity parameter P∆ is introduced to show that differences in fragmentation behavior between initial ionisations at chemically different carbon atoms probably persist even for identical internal energy contents in the nascent dications. In another study where both electrons and ions from Auger decay of core-excited and core-ionised states of CO2 are detected in coincidence, it is confirmed that O2+ is formed specifically in Auger decay from the C1s → π* and O1s → π* resonances, suggesting a decisive role of the π* orbital in the molecular rearrangement. Also, the molecular rearrangement is found to occur by bending in the resonant states, and O2+ is produced by both single and double Auger decay. A new version of the multi-electron-ion coincidence method, where the ion time-of-flight spectrometer is mounted perpendicularly to the electron flight tube, which affects less the electron resolution and which allows for position sensitive detection of the ions, is employed in combination with tunable soft X-rays to reveal the branching ratios to final Xen+ states with 2 < n < 9 from pure 4d-1, 4p-1, 4s-1, 3d-1 and 3p-1 Xe+ hole states. The coincident electron spectra give information on the Auger cascade pathways.Byte av lokal vid disputation till Polhemssalen.
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Dongol, Amit. « Carrier Dynamics and Application of the Phase Coherent Photorefractive Effect in ZnSe Quantum Wells ». University of Cincinnati / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1396453493.
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Raeven, Barbara Maartje. « Measurements of the mass and width of W boson from e'+e'- -> ; W'+W'- -. (e/#mu#)#nu#qq'- events with the ALEPH detector ». Thesis, University of Glasgow, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.325433.
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MAIANO, CECILIA GIOVANNA. « Analysis of surface radioactive background contributions and study of rare decays in the cuore experiment ». Doctoral thesis, Università degli Studi di Milano-Bicocca, 2011. http://hdl.handle.net/10281/20194.
Texte intégralRésumé :
Rare Physics event is playing a crucial role, not only in Fundamental Interaction Physics,
but also in Astroparticle Physics and in Cosmology. These signals, if detected, would give
an importatnt evidence of new Physics.
The CUORE experiment (Cryogenic Underground Observatory for Rare Events) is a
proposed tightly packed array of 988 TeO2 bolometers, each being a cube 125 cm3 on
a side with a mass of 750 g. The array consists of 19 vertical towers, arranged in a
compact cylindrical structure. Each tower will consist of 13 layers of 4 crystals. The
design of the detector is optimized for ultralow-background searches.
Neutrinoless double-beta decay (ββ0ν) is the main goal of CUORE. What is new is
the fact that positive observation of neutrino oscillations gives new motivation for more
sensitive searches.
Neutrino oscillation experiments can only provide data on the mass differences of the
neutrino mass-eigenstates. The absolute scale can only be obtained from direct mass
measurements (β-decay end point measurements), or in the case of Majorana neutrinos,
more sensitively by neutrinoless double-beta decay observation.
ββ0ν is not the only exotic process which can be observed in the CUORE experiment.
Other rare events, from cold dark matter, to rare nuclear decays and electron decay can
in principle be studied with the CUORE experimental facility. I will discuss the last
process in the 6th chapter.
The topic which joins the exotic and rare processes discussed is the unwanted radioactive
background which is inevitably present in the experimental measurements.
CUORICINO, almost a single CUORE tower, was constructed as a smaller scale ex-
periment and operated from december 2003 to June 2008. Besides being a sensitive
experiment on 130Te double beta decay, CUORICINO is a conclusive test of CUORE.
CUORICINO provided important results concerning both the technical performances of
the bolometric tower (CUORE will be made of 19 such towers), the background level .In
particular, one of the information gained is that the most probable candidates for the
continuum background observed in the spectra, are the surface α contaminations of the
copper mounting frame. Rare Physics event is playing a crucial role, not only in Fundamental Interaction Physics,
but also in Astroparticle Physics and in Cosmology. These signals, if detected, would give
an importatnt evidence of new Physics.
The CUORE experiment (Cryogenic Underground Observatory for Rare Events) is a
proposed tightly packed array of 988 TeO2 bolometers, each being a cube 125 cm3 on
a side with a mass of 750 g. The array consists of 19 vertical towers, arranged in a
compact cylindrical structure. Each tower will consist of 13 layers of 4 crystals. The
design of the detector is optimized for ultralow-background searches.
Neutrinoless double-beta decay (ββ0ν) is the main goal of CUORE. What is new is
the fact that positive observation of neutrino oscillations gives new motivation for more
sensitive searches.
Neutrino oscillation experiments can only provide data on the mass differences of the
neutrino mass-eigenstates. The absolute scale can only be obtained from direct mass
measurements (β-decay end point measurements), or in the case of Majorana neutrinos,
more sensitively by neutrinoless double-beta decay observation.
ββ0ν is not the only exotic process which can be observed in the CUORE experiment.
Other rare events, from cold dark matter, to rare nuclear decays and electron decay can
in principle be studied with the CUORE experimental facility. I will discuss the last
process in the 6th chapter.
The topic which joins the exotic and rare processes discussed is the unwanted radioactive
background which is inevitably present in the experimental measurements.
CUORICINO, almost a single CUORE tower, was constructed as a smaller scale ex-
periment and operated from december 2003 to June 2008. Besides being a sensitive
experiment on 130Te double beta decay, CUORICINO is a conclusive test of CUORE.
CUORICINO provided important results concerning both the technical performances of
the bolometric tower (CUORE will be made of 19 such towers), the background level .In
particular, one of the information gained is that the most probable candidates for the
continuum background observed in the spectra, are the surface α contaminations of the
copper mounting frame. Silicon Barrier Detectors (SBD) are a powerful instrument to study charged particle
radiation (like α particles). During my PHD one of the activity I focused on was the
optimization of the SBD used in the radioactivity laboratoty of the the University of
Milano Bicocca A complete procedure for the calibration of these detectors was set-
tled. In fact, one of the main problem to face with, (due also to the extremely low
activity measured), is the discrimination of their intrinsic background level from that of
the sample measured. The SBD are always operated in Ultra Low Background vacuum
chambers. In the context of the discrimination of the background, evaluation of the
muon and shower contribution to the acquired spectra were performed. The latter were
done through a coincidence measurement between the SBD and a scintillator. The result
of the measurements and of their ananlysis showed that the major contribution to the
spurious counts comes from the showers.
A dedicated acquisition was done for the detectors, with a module which lets to have
event’s temporal imformation. To give limits on the surface activities of the samples the
use of Monte Carlo (MC) simulation is mandatory in order to have an estimation of the
efficiency of energy detection. The use of the MC simulation was optimized: different
depht and profiles of contamination were studied and tested. This optimization allows
to give limits on surface 232Th, 238U and 210Pb-Po activities which depend on the depht
of contamination. The drastic reduction of the sensitivity achieved (from 10−5 to 10−7
and 10−8 Bq · cm2 fo the cleanest material measured) is due to the described optimiza-
tion. Last, but non least, the SBD measurements played a crucial role in the material
selection, depending on the radiopurity required, for the CUORE experiment.
Concering the ββ0ν, a crucial role, in the theoretical interpretation of the experimental
result, is played by the Nuclear Matrix Element (NME) used to transalte the observed
rate (in the energy region where the signal is expected) in a sensitivity on the effective
neutrino mass |mν|. I performed a study in order to
compare and understand the different nuclear models used nowadays, and the respective
Phase Space Factors (PSF) used. This study allows to compare, in a quantitative way,
the different experiments on neutrinoless double beta decay. A database was realized
in which all the inputs are collected, comments and references on NME and PSF are
illustrated and the kind of short range correlation is used in the calculation of the matrix
element. The database, with the information collected and properly organized, allows
to evaluate the sensitivity on |mν| of all the experiments now at work, depending on the
nuclear model used. The difficulties encountered in the comprehension of the nuclear
models and in the PSF used are due to three main reasons. • the PSF shoul be in principle standard and unambiguous, not depending on the
nuclear model, but just on the initial and final states JP . This is not what the
study showed: the PSF, in the different formulation, show discrepancies of a factor
5 or 6.
• the nuclear models assume different approaches to the process and should lead to
different results. Two models, i.e., the Shell Model and the IBM (Interactive Boson
Model) have a similar approach, but they differ in handling the states which are
’far from closed shells’, so in the handling of the nuclear deformations. The QRPA,
(in the version pnQRPA an rQRPA, Quasi Random Phase Approximation), have a different approach to the previous models, because it introduces the concept of
quasiparticle, which are states built with a ’mixing’ of creation and annihilation
operators (a theory very similar to BCS for the superconductivity) and it leads to
a correlation between particles and holes and not just between particles (gph and
not only gpp pairing).
• the SRC (shot range correlation) used should be univocal, but this is not the case.
The theoreticians don’t give a clear choice of the proper SRC to be used.
Finally I performed a study on the electron decay, in the channel e− ← γ + ν, using
CUORICINO data. Moreover I performed a calculation of the cross section for the
process, assuming a massless neutrino in the first step and a massive neutrino in the
second step. The study of the channel implies to evaluate the signature of the decay,
which depends on the material and atomic shell from which the electron disappears. In
fact the visible energy changes if the decay happens in the active volume of the detector
or in the surroinding materials: Ev =
(mec2−Eb)
2 + EX =
(mec2+Eb)
2 where me is the
electron mass, Eb is the binding energy, EX is the X-ray energy following the decay. The
last term is included only if the decay happens inside the active volume of the detectors.
Thus, there are several signatures which can be discriminated from the background only
if the detector resolution is excellent. Moreover the doppler broadening of the lines, due
to the orbital motion of the electron in the shell, must be considered. I thus studied the
different signatures in several materials, (potential emitters). In the analysis I included
the efficiences for the signatures, using Monte Carlo simulations, expressely conformed to
experimental set-up and charachteristics (such as real thresholds, active channels). The
correction to the efficiencies, i.e. the loss of ’good events’, due to the analysis cuts, was
evaluated. All the analysis done led to a promising result for this decay, in competition
with the current limits given from other collaborations.
The cross section calculation allowed to give an estimation of the CNC parameter, using
as inputs the available experimental data.
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Ottosson, Niklas. « Aqueous Solutions as seen through an Electron Spectrometer : Surface Structure, Hydration Motifs and Ultrafast Charge Delocalization Dynamics ». Doctoral thesis, Uppsala universitet, Yt- och gränsskiktsvetenskap, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-151435.
Texte intégralRésumé :
In spite of their high abundance and importance, aqueous systems are enigmatic on the microscopic scale. In order to obtain information about their geometrical and electronic structure, simple aqueous solutions have been studied experimentally by photo- and Auger electron spectroscopy using the novel liquid micro-jet technique in conjunction with synchrotron radiation. The thesis is thematically divided into three parts. In the first part we utilize the surface sensitivity of photoelectron spectroscopy to probe the distributions of solutes near the water surface. In agreement with recent theoretical predictions we find that large polarizable anions, such as I- and ClO4-, display enhanced surface propensities compared to smaller rigid ions. Surface effects arising from ion-ion interactions at higher electrolyte concentrations and as function of pH are investigated. Studies of linear mono-carboxylic acids and benzoic acid show that the neutral molecular forms of such weak acids are better stabilized at the water surface than their respective conjugate base forms. The second part examines what type of information core-electron spectra can yield about the chemical state and hydration structure of small organic molecules in water. We demonstrate that the method is sensitive to the protonation state of titratable functional groups and that core-level lineshapes are dependent on local water hydration configurations. Using a combination of photoelectron and X-ray absorption spectroscopy we also show that the electronic re-arrangement upon hydrolysis of aldehydes yields characteristic fingerprints in core-level spectra. In the last part of this thesis we study ultrafast charge delocalization dynamics in aqueous solutions using resonant and off-resonant Auger spectroscopy. Intermolecular Coulombic decay (ICD) is found to occur in a number of core-excited solutions where excess energy is transferred between the solvent and the solute. The rate of ultrafast electron delocalization between hydrogen bonded water molecules upon oxygen 1s resonant core-excitation is found to decrease upon solvation of inorganic ions. The presented work is illustrative of how core-level photoelectron spectroscopy can be valuable in the study of fundamental phenomena in aqueous solutions.
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Martschei, Daniel Michael [Verfasser], et M. [Akademischer Betreuer] Feindt. « Measurement of the t-channel single top quark production cross section in the electron and muon decay channel with the CMS detector at the LHC / Daniel Michael Martschei. Betreuer : M. Feindt ». Karlsruhe : KIT-Bibliothek, 2012. http://d-nb.info/1024729516/34.
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Pokapanich, Wandared. « Solvent–Solute Interaction : Studied by Synchrotron Radiation Based Photo and Auger Electron Spectroscopies ». Doctoral thesis, Uppsala universitet, Yt- och gränsskiktsvetenskap, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-138749.
Texte intégralRésumé :
Aqueous solutions were studied using photoelectron and Auger spectroscopy, based on synchrotron radiation and a liquid micro-jet setup. By varying the photon energy in photoelectron spectra, we depth profiled an aqueous tetrabutylammonium iodide (TBAI) solution. Assuming uniform angular emission from the core levels, we found that the TBA+ ions were oriented at the surface with the hydrophobic butyl arms sticking into the liquid. We investigated the association between ions and their neighbors in aqueous solutions by studying the electronic decay after core ionization. The (2p)−1 decay of solvated K+ and Ca2+ ions was studied. The main features in the investigated decay spectra corresponded to two-hole final states localized on the ions. The spectra also showed additional features, related to delocalized two-hole final states with vacancies on a cation and a neighboring water molecule. These two processes compete, and by comparing relative intensities and using the known rate for the localized decay, we determined the time-scale for the delocalized process for the two ions. We compared to delocalized electronic decay processes in Na+, Mg2+, and Al3+, and found that they were slower in K+ and Ca2+, due to different internal decay mechanisms of the ions, as well as external differences in the ion-solute distances and interactions. In the O 1s Auger spectra of aqueous metal halide solutions, we observed features related to delocalized two-hole final states with vacancies on a water molecule and a neighboring solvated anion. The relative intensity of these feature indicated that the strength of the interaction between the halide ions and water correlated with ionic size. The delocalized decay was also used to investigate contact ion pair formation in high concentrated potassium halide solutions, but no concrete evidence of contact ion pairs was observed.Felaktigt tryckt som Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 726
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Lück, Thomas [Verfasser], Heiko [Akademischer Betreuer] Lacker, Alexander [Akademischer Betreuer] Kappes et Jochen [Akademischer Betreuer] Dingfelder. « Determination of the CKM-matrix element |Vub| from the electron energy spectrum measured in inclusive B -> ; X u e[Ypsilon] decay with the BABAR detector / Thomas Lück. Gutachter : Heiko Lacker ; Alexander Kappes ; Jochen Dingfelder ». Berlin : Humboldt Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2013. http://d-nb.info/1033837229/34.
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Bajracharya, Pradeep. « Relaxation Dynamics and Decoherence of Excitons in II-VI Semiconductor Nanostructures ». University of Cincinnati / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1186757546.
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Khalil, Sadia. « Measurement of the branching fraction of D+ meson going to muon+ neutrino and the pseudoscalar decay constant fD+ using the full psi'' sample and search for neutral D meson going to proton-electron and neutral D meson going to antiproton-positron ». Related electronic resource : Current Research at SU : database of SU dissertations, recent titles available full text, 2009. http://wwwlib.umi.com/cr/syr/main.
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Irwin, Blake A. « Electro-weak corrections to top decay ; and the Upsilon inclusive JPsi decay width in perturbative Q.C.D ». Thesis, McGill University, 1991. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=70312.
Texte intégralRésumé :
The order $G sb{F}m sbsp{t}{2}$ electro-weak corrections to the decay $t to bW sp+$ are calculated, arising essentially from virtual radiation of the Higgs boson. For large $m sb{t}$ these represent the dominant effect serving to shift the top lifetime from its tree level value. In practice, for $m sb{t}$ $<$ 240 $GeV$ these corrections are typically 0.1%. A comparison with recent calculations of the complete electro-weak and strong effects is made.Several contributions to the branching ratio for the inclusive decay $ Upsilon to J/ psi X$ are calculated using perturbative Q.C.D. to lowest order in the relative quark momentum and the strong coupling $ alpha sb{s}$. In addition to the direct transition, decay to J/$ psi$ through the states $ psi sp prime$ and $ chi sb1$ is also considered. The following results are obtained: $Br( Upsilon to psi sp prime X$) = (0.26 $ pm$ 0.13) $ times$ 10$ sp{-3}$, $Br( Upsilon to chi sb1 X$) $ le$ 0.17 $ times$ 10$ sp{-3}$, and $Br( Upsilon to J/ psi X$) = (0.44 $ pm$ 0.15) $ times$ 10$ sp{-3}$. The latter may just be consistent with the experimental result (1.1 $ pm$ 0.4 $ pm$ 0.2) $ times$ 10$ sp{-3}$ where the first error is statistical and the second systematic.
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Nilsson, Kent. « Detection of wood decay using an electronic nose / ». Uppsala : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 1998. http://epsilon.slu.se/avh/1998/91-576-5602-9.gif.
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