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Dissertations / Theses on the topic 'High-Energy Particle'
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Grönqvist, Hanna. "Fluctuations in High-Energy Particle Collisions." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLS155/document.
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Nous étudions des fluctuations qui sont omniprésentes dans des collisions entre particules aux hautes énergies. Ces fluctuations peuvent être de nature classique ou quantique et nous allons considérer ces deux cas. D'abord, nous étudions les fluctuations quantiques qui sont présentes dans des collisions entre protons. Celles-ci sont calculables en théorie quantique des champs, et nous allons nous concentrer sur une certaine classe de diagrammes dans ce cadre. Dans un second temps nous allons étudier des fluctuations qui sont présentes dans des collisions entre particules plus lourdes que le proton. Celles-ci sont décrites par les lois quantiques de la nature qui donnent les positions des nucléons dans le noyau, ou bien des fluctuations classiques, d'origine thermique, qui affectent l'évolution hydrodynamique du milieu produit dans une collision. Les fluctuations dans des collisions entre protons peuvent être calculées analytiquement jusqu'à un certain ordre en théorie quantique des champs. Nous allons nous concentrer sur des diagrammes à une boucle, d'une topologie donnée. Ces diagrammes aux boucles donnent des intégrales, qui typiquement sont difficiles à calculer. Nous allons démontrer comment des outils des mathématiques modernes peuvent être utilisés pour faciliter leur évaluation. En particulier, nous allons étudier des relations entre des coupures d'un diagramme, la discontinuité à travers d'un branchement et le coproduit. Nous allons démontrer comment l'intégrale originale peut être reconstruit à partir de l'information contenue dans le coproduit. Nous nous attendons à ce que ces méthodes seront utiles pour le calcul des diagrammes avec des topologies plus difficiles et ainsi aident au calcul des nouvelles amplitudes de diffusion. A la fin, nous étudions les deux types de fluctuations qui ont lieu dans des collisions entre ions lourds. Celles-ci sont liées soit à l'état initial de la matière, soit à l'état intermédiaire produit dans une telle collision. Les fluctuations de l'état initial ont été mesurées expérimentalement, et on voit qu'elles donnent lieu à des non-Gaussianités dans le spectre final de particules. Nous allons démontrer comment ces non-Gaussianités peuvent être comprises comme des positions et des énergies d'interaction aléatoires des 'sources' dans les noyaux entrant en collision. En plus, nous étudions le bruit hydrodynamique dans le milieu produit juste après une collision. Le comportement de ce milieu est celui d'un fluide à basse viscositéWe study fluctuations that are omnipresent in high-energy particle collisions. These fluctuations can be either of either classical or quantum origin and we will study both. Firstly, we consider the type of quantum fluctuations that arise in proton-proton collisions. These are computable perturbatively in quantum field theory and we will focus on a specific class of diagrams in this set-up. Secondly, we will consider the fluctuations that are present in collisions between nuclei that can be heavier than protons. These are the quantum laws of nature that describe the positions of nucleons within a nucleus, but also the hydrodynamic fluctuations of classical, thermal origin that affect the evolution of the medium produced in heavy-ion collisions. The fluctuations arising in proton-proton collisions can be computed analytically up to a certain order in perturbative quantum field theory. We will focus on one-loop diagrams of a fixed topology. Loop diagrams give rise to integrals that typically are hard to evaluate. We show how modern mathematical methods can be used to ease their computation. We will study the relations among unitarity cuts of a diagram, the discontinuity across the corresponding branch cut and the coproduct. We show how the original integral corresponding to a given diagram can be reconstructed from the information contained in the coproduct. We expect that these methods can be applied to solve more complicated topologies and help in the computation of new amplitudes in the future. Finally, we study the two types of fluctuations arising in heavy-ion collisions. These are related either to the initial state or the intermediate state of matter produced in such collisions. The initial state fluctuations are experimentally observed to give rise to non-Gaussianities in the final-state spectra. We show how these non-Gaussianities can be explained by the random position and interaction energy of `sources' in the colliding nuclei. Furthermore, we investigate the effect of hydrodynamical noise in the evolution of the medium produced just after a collision. This medium behaves like a fluid with a very low viscosity, and so the corresponding evolution is hydrodynamical
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Wilkason, Thomas Frederick Jr. "Exclusive cone jet algorithms for high energy particle colliders." Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/100326.
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Thesis: S.B., Massachusetts Institute of Technology, Department of Physics, 2015.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 59-62).
In this thesis, I develop an exclusive cone jet algorithm based on the principles of jet substructure and demonstrate its use for physics analyses at the Large Hadron Collider. Based on the event shape N-jettiness, this algorithm, called "XCone," partitions the event into a fixed number of conical jets of size RO in the rapidity-azimuth plane. This algorithm is designed to locate substructure independent of momentum, allowing accurate resolution of jets at both low and high energy scales. I present three potential analyses using XCone to search for heavy resonances, Higgs bosons, and top quarks at various momenta and show that it reconstructs these particles with efficiencies between 60% and 80% without any additional substructure techniques, and maintains this efficiency over a wide kinematic range. This algorithm provides many key advantages over traditional jet algorithms that make it appealing for use at the LHC and other high energy particle colliders.
by Thomas Frederick Wilkason, Jr.
S.B.
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Blanco-Pillado, José Juan. "Topological defects and ultra-high energy cosmic rays /." Thesis, Connect to Dissertations & Theses @ Tufts University, 2001.
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Thesis (Ph.D.)--Tufts University, 2001.Adviser: Alexander Vilenkin. Submitted to the Dept. of Physics. Includes bibliographical references (leaves 108-114). Access restricted to members of the Tufts University community. Also available via the World Wide Web;
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Papaefstathiou, Andreas. "Phenomenological aspects of new physics at high energy hadron colliders." Thesis, University of Cambridge, 2011. https://www.repository.cam.ac.uk/handle/1810/239399.
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This thesis contains studies of phenomenological aspects of new physics at hadron colliders, such as the Large Hadron Collider (LHC). After a general introduction in chapter 1, in chapter 2 we outline the main features of the Standard Model (SM) of particle physics and the theoretical motivations for going beyond it. We subsequently provide brief descriptions of a few popular models that aim to solve the issues that arise within the SM. In chapter 3 we describe the general Monte Carlo method for evaluating multidimensional integrals and show how it can be used to construct a class of computational tools called Monte Carlo event generators. We describe the main generic features of event generators and how these are implemented in the HERWIG++ event generator. By applying resummation techniques, we provide, in chapter 4, analytical calculations of two types of hadron collider observables. The first, global inclusive variables, are observables that make use of all measured particle momenta and can provide useful information on the scale of new physics. The second observable is the transverse energy of the QCD initial state radiation (ET ), associated with the either Drell-Yan gauge boson production or Higgs boson production. In both cases we provide comparisons to results obtained from Monte Carlo event generators. In chapter 5 we examine two well-motivated models for new physics: one of new heavy charged vector bosons (W prime), similar to the SM W gauge bosons, and a model motivated by strong dynamics electroweak symmetry breaking that contains new resonances, leptoquarks, that couple primarily to quarks and leptons of the third generation. In the prior model, we improve the current treatment of the W' by considering interference effects with the SM W and construct an event generator accurate to next-to-leading order which we use to conduct a phenomenological analysis. For the leptoquark model, starting from an effective Lagrangian for production and decay, we provide an implementation in the HERWIG++ event generator and use it to form a strategy for mass reconstruction. The thesis ends with some conclusions and suggestions for extensions of the work presented. Further details and useful formulæ are given in the appendices.
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Webb, S. "Unusual effects in particle diffraction." Thesis, University of Manchester, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234226.
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Allport, P. P. "High energy neutrino scattering at low Q'2." Thesis, University of Oxford, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.376865.
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Sritragool, Kunlapaporn. "Modification of Rubber Particle filled Thermoplastic with High Energy Electrons." Doctoral thesis, Universitätsbibliothek Chemnitz, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-201000954.
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In present study, high energy electrons were used to modify blends based on RP and PP under two conditions: stationary and in-stationary conditions. Modification of blend under stationary condition is a process which is established in industrial application and where required absorbed dose is applied to form parts (after molding) at room temperature and in solid state. On the contrary, the modification of blend with high energy electrons under in-stationary condition is a new process (electron induced reactive processing) where required absorbed dose is applied to a molten state during melt mixing process. The modification of blend based on RP and PP under stationary condition resulted in slightly enhancement of tensile properties while the modification of this blend under in-stationary condition resulted in deterioration of tensile properties due to degradation of the PP matrix. Thus, special grafting agent (GA) is required for improving the tensile properties. The effect of different GAs on tensile, thermal, dynamic mechanical as well as morphological properties and melt flow properties of blends based on RP and PP were determined. The optimum absorbed dose for modification of blend based on RP and PP under both conditions was evaluated. In addition, the effect of treatment parameters of electron induced reactive processing was investigated.
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CARNITI, PAOLO. "Electronic Instrumentations for High Energy Particle Physics and Neutrino Physics." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2018. http://hdl.handle.net/10281/198964.
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La presente dissertazione descrive il design, la caratterizzazione e il funzionamento di sistemi elettronici per esperimenti di Fisica delle particelle (LHCb) e Fisica del neutrino (CUORE e CUPID). A partire dal 2019, l'esperimento LHCb presso l'acceleratore LHC sarà aggiornato per lavorare a luminosità più elevata e molti dei suoi rivelatori dovranno essere riprogettati. Il rivelatore RICH, in particolare, dovrà adottare un sistema optoelettronico totalmente nuovo. Lo sviluppo di questo sistema ha già raggiunto una fase avanzata e diversi test eseguiti su fascio hanno permesso di verificare le prestazioni dell'intero sistema. Per migliorare la stabilità, il filtraggio e la regolazione delle tensioni di alimentazione del circuito di front-end, è stato sviluppato un regolatore lineare a basso dropout e resistente alla radiazione, denominato ALDO. Sono qui presentate le strategie di progetto, la misurazione delle prestazioni e i risultati delle campagne di irraggiamento di questo dispositivo. Nel campo della fisica del neutrino, grandi array di macrobolometri, come quelli adottati dall'esperimento CUORE e dal suo futuro aggiornamento CUPID, offrono delle caratteristiche uniche per lo studio del doppio decadimento beta senza neutrini. Il loro funzionamento richiede particolari strategie progettuali nel sistema elettronico di lettura, che è qui descritto nella sua interezza. Sono anche presentate nel dettaglio le misure di qualifica e ottimizzazione dei parametri di funzionamento di tutto il sistema, oltre che l'integrazione all'interno dell'area sperimentale. Infine sono presentati gli aggiornamenti di alcuni sottosistemi elettronici in vista della fase finale di CUPID.The present dissertation describes design, qualification and operation of several electronic instrumentations for High Energy Particle Physics experiments (LHCb) and Neutrino Physics experiments (CUORE and CUPID). Starting from 2019, the LHCb experiment at the LHC accelerator will be upgraded to operate at higher luminosity and several of its detectors will be redesigned. The RICH detector will require a completely new optoelectronic readout system. The development of such system has already reached an advanced phase, and several tests at particle beam facilities allowed to qualify the performance of the entire system. In order to achieve a higher stability and a better power supply regulation for the front-end chip, a rad-hard low dropout linear regulator, named ALDO, has been developed. Design strategies, performance tests and results from the irradiation campaign are presented. In the Neutrino Physics field, large-scale bolometric detectors, like those adopted by CUORE and its future upgrade CUPID, offer unique opportunities for the study of neutrinoless double beta decay. Their operation requires particular strategies in the readout instrumentation, which is described here in its entirety. The qualification and optimization of the working parameters as well as the integration of the system in the experimental area are also thoroughly discussed, together with the latest upgrades of two electronic subsystems for the future CUPID experiment.
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Patrick, Richard J. II. "The search for supersymmetry in particle physics." Thesis, California State University, Long Beach, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=1527406.
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Experimental high energy physics (HEP) techniques are applied to accurate simulated collider data in search for existence or exclusion of supersymmetric (SUSY) particles. Supersymmetry is a leading candidate to resolve the hierarchy problem in particle physics as well as offer a stable dark matter candidate. Techniques and practices are explored and applied to the leptonic decay process production followed by and where is the proton, is the chargino, , are neutralinos and , are the standard model W and Higgs Bosons respectively. Signal yields are in general agreement with other researchers and ranged from 0.5 to 62.6 events. Reduction in the background to signal ratio is demonstrated through isolating the SUSY process and applying theoretical knowledge of the signal and associated dominant backgrounds. Results from this study establish procedures for future work with actual data, offer a benchmark for this specific leptonic decay process and may motivate variable selection and cut criteria choices in future analysis of similar signal processes.
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Feige, Ilya Eric Alexander. "Factorization and Precision Calculations in Particle Physics." Thesis, Harvard University, 2015. http://nrs.harvard.edu/urn-3:HUL.InstRepos:17467340.
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We state and prove to all orders in perturbation theory a factorization theorem in Quantum Chromodynamics that concisely describes the separation of the physics associated with jet formation from that associated with the hard-scattering in high-energy particle collisions. We show how the factorization theorem, which provides an equality between amplitudes in gauge theories, can be readily applied to precision calculations of cross-sections. In the resulting factorized cross sections, the components relevant to jet production are universal and perturbatively calculable. Their renormalization group evolution can be used to sum large logarithms of scale ratios to all orders in perturbation theory, thus enabling quantitive predictions in the regime of disparate scales relevant to many important collider-physics observables. As an application, we calculate the observable 2-subjettiness at next-to-next-to-next-to-leading-logarithmic order for the decay of boosted heavy color-singlet particles such as Electroweak bosons. Our calculation is the first analytic calculation of a jet substructure observable.Physics
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Marsh, Colin. "Theoretical aspects of dissipative particle dynamics." Thesis, University of Oxford, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.244720.
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Kohani, Shahab. "3D Trench Detectors for Charged Particle Tracking and Photon Science Applications." Thesis, New York University, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10928035.
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Silicon tracking detectors are frequently used in particle collider experiments, as they can provide excellent spatial precision with little material in order to cause minimal track disruption. Due to a progressive increase in collider luminosities, a common trend in these experiments is the need for higher levels of radiation damage resistance. One proposed class of designs for pixel trackers in high luminosity colliders is the Silicon 3D trench detector. The same design can be scaled up for photon science applications.
The work discussed in this dissertation was performed as part of a collaboration between BNL, NYU, CNM and SUNY Stony Brook. The central aim of the work presented here was to evaluate the manufactured 3D trench detector prototypes and study their behavior in detail by performing a series of experimental measurements and TCAD simulations.
An experiment to measure the detector response to an Americium radioactive source was designed and used to study the noise level and charge collection efficiency of detector prototypes. An experimental system which measured the detector response to an infrared laser with computer controlled precision positioning was developed. This system was used to obtain laser pulse response maps of detectors, which in turn were utilized to investigate the dependence of charge collection efficiency of detectors on position, collection time and bias voltage. The same mapping technique was also used to study the change in irradiated detector response.
Detector response was simulated using the Silvaco TCAD Suite. These simulations were used to study depletion in large photon detectors and charge collection in response to laser hits. Approximate simulations of radiation damage were also performed to investigate the behavior of irradiated detectors. Leakage current and capacitance simulations before and after irradiation were also performed and compared to the experimental measurements. While significant variations in detector response between different prototypes were observed during the experiments, simulation results are still capable of explaining the general properties of the detectors. The combination of the simulation and the experimental results provides an understanding of the signal generation process in these detectors.
One observed problem is the large bias currents due to manufacturing surface defects. A double-sided version of the trench detector is proposed to mitigate this problem. Electric fields, depletion region shape and formation, bias voltage and transient current response of these detectors are simulated and compared with those of the standard trench detectors. Computer simulations show that the double-sided detectors also have some performance advantages over the original designs including larger more uniform spatial charge collection efficiency and higher radiation damage resistance. These simulation results and the general insensitivity of the proposed detectors to surface defects make the double-sided detectors worthy of further study.
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Tremblay, Luc 1969. "Effects of a particle spontaneously breaking Lorentz invariance." Thesis, McGill University, 2002. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=38526.
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In this thesis, we add a new vectorial particle to the standard model, a new particle that has the special property of having a vacuum state breaking Lorentz invariance and, therefore, CPT invariance. At the level of energy of the world we live in, this particle is expected to be in this vacuum state and we therefore should see around us some phenomenon that do not respect Lorentz invariance that comes from the interaction of this vectorial particle with ordinary matter. This thesis is presented in two parts. In the first part, we write every possible term involving our new vectorial field with ordinary matter while, in the second part, we calculate the effects of some of those terms and look at any experimental evidence for the calculated effects.
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Kistler, Matthew David. "The Theory and Phenomenology of the High-Energy and Transient Universe." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1274474065.
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Barbot, Cyrille. "Super-heavy X-particle decay and ultra-high energy cosmic rays." [S.l. : s.n.], 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=969379846.
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Forty, R. W. "Charmed particle production and decay in a high energy photoproduction experiment." Thesis, Imperial College London, 1988. http://hdl.handle.net/10044/1/47064.
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Carter, Jeremy. "A measurement of charmed particle lifetime in experiment NA1 at the CERN SPS." Thesis, Royal Holloway, University of London, 1988. http://repository.royalholloway.ac.uk/items/697f1280-d01f-4bb4-aa54-6668138f54b8/1/.
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An analysis of data collected In the NA1 high energy photoproduction experiment at the CERN SPS is presented. The theoretical status of charmed particle decay is reviewed. The NA1 experimental apparatus is discussed. Experiment NA1 used an active semiconductor target exposed to a 70-225 GeV tagged photon beam and the forward spectrometer FRAMM to collect data on the decay of particles carrying the charm quantum number. FRAMM was equipped with three lever arms for charged particle momentum analysis, electromagnetic calorimeters for neutral particle reconstruction and Cerenkov detectors for charged particle identification. The active target measured the charged particle multiplicity development along the beam axis to determine the decay length of particles. The proper time resolution of the target was -0.2x10-13s. A sample of sixty-three Ac charmed baryons are isolated in the decay channel via an inclusive analysis. Twenty-four of these Acs havedecay lengths resolved in the NA1 active target which can be matched to the information in the forward spectrometer FRAMM. A study of the sixty-three reconstructed in FRAMM indicates that a large proportion decayed via the channel, a decay which is believed to proceed exclusively through W exchange.
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Old, Rob. "Asymptotic safety and high-energy scattering at the Large Hadron Collider." Thesis, University of Sussex, 2015. http://sro.sussex.ac.uk/id/eprint/61482/.
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The fascinating idea that in higher-dimensional models the fundamental scale of gravity, the Planck scale, could be as low as the electroweak scale has stimulated a substantial body of work in the past decade. In addition to solving the hierarchy problem, a low quantum gravity scale also o↵ers the exciting prospect that collider experiments become sensitive to the quantum nature of gravity. Quantum gravity signatures include missing energy due to graviton emission, enhancement of standard model reference processes via virtual graviton exchange, or the production and decay of mini black holes. Dedicated searches for all of these are presently under way at the Large Hadron Collider. Previous predictions for colliders have been encumbered by the absence of a complete theory of quantum gravity. However, the recent years have also seen important progress in the understanding of gravity as an asymptotically safe quantum field theory, in which the high-energy behaviour is controlled by an interacting fixed point. The notorious divergences of perturbation theory are thus avoided, and the theory remains predictive at arbitrarily high energies. In this thesis, we investigate the effects of asymptotic safety upon predictions for graviton-mediated processes in higher-dimensions at colliders. We consider single-graviton mediated effects in the Born approximation as well as the multi-graviton exchanges which dominate the forward scattering region at transplanckian energies, as described by the eikonal approximation. Cross sections are derived and a detailed comparison with findings from effective theory is made. Using the PYTHIA event generator we find that for some regions in parameter space quantum gravity effects are enhanced over the semiclassical predictions, as well as over standard model backgrounds. The use of our results to constrain our theory parameters is discussed.
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Panella, Comellas J. "Measurement of some charm particle decay branching ratios." Thesis, University of Oxford, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382501.
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Senosi, Kgotlaesele Johnson. "Vector boson production with the ALICE detector." Doctoral thesis, University of Cape Town, 2017. http://hdl.handle.net/11427/27310.
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The main objective of this thesis is to study and investigate the production of massive vector bosons (W+ and W−). This a priori mentioned production is not sensitive to hot nuclear matter effects because of the weak coupling nature of these vector bosons. Thus, in heavy ion collisions they provide a good reference for the medium-induced effects on other probes. The production mechanism of these vector bosons is highly isospin dependent and thus they are affected by the initial state effects. Initial state effects include isospin, Fermi motion, EMC effect, shadowing and nuclear absorption. Hence their production in lead-lead (Pb-Pb) and proton-lead (p-Pb) collisions can be used to test some of these initial state effects. In this thesis only two of these initial state effects will be considered namely, isospin and shadowing (referring to shadowing and anti-shadowing). Eke, these vector bosons can be used to provide a non-arbitrary reference to the probes affected by the medium. Traditionally, in heavy ion collisions, hard processes are expected to scale with the number of binary collision thus a precise study of these vector bosons can be used to test the factorisation assumed in models used to determine centrality. This unique property of electroweak (W) bosons makes them essential probes to study the possible inherent bias in centrality determination. In proton-proton (pp) collisions, their production can be used to obtain information on quark parton distribution functions (PDF). The data used in the analysis was collected by A Large Ion Collider Experiment (ALICE) at the Large Hadron Collider (LHC). The ALICE detector is designed to study ultrarelativistic heavy-ion collisions, in which a hot and dense, strongly-interacting medium is created. The production of W bosons is studied in p-Pb, p-p and Pb-Pb collisions at 5.023, 8 and 5.023 TeV centre-of-mass energies, respectively. The forward muon spectrometer with the pseudorapidity acceptance −4.0 < ŋ < −2.5 is used. W bosons are studied via the inclusive single muon differential pT spectrum.
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Casey, James David. "Search for high energy GRB neutrinos in IceCube." Diss., Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/53839.
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The IceCube Neutrino Observatory has reported the observation of 35 neutrino events above 30 TeV with evidence for an astrophysical neutrino flux using data collected from May 2010 to May 2013. These events provide the first high-energy astrophysical neutrino flux ever observed. The sources of these events are currently unknown. IceCube has looked for correlations between these events and a list of TeV photon sources including a catalog of 36 galactic sources and 42 extragalactic sources, correlations with the galactic plane and center, and spatial and temporal clustering. These searches have shown no significant correlations. The isotropic distribution of the event directions gives indications that the events could be extragalactic in nature and therefore may originate in the same processes that generate ultra-high-energy cosmic rays (UHECRs). The sources of these UHECRs are still unknown; however, gamma-ray bursts (GRBs) have been proposed as one possible source class. By determining the source of these high-energy neutrinos, it may be possible to determine the sources of UHECRs as well. This study is a search for directional and temporal correlation between 856 GRBs and the astrophysical neutrino flux observed by IceCube. Nearly 10,000 expanding time windows centered on the earliest reported time of the burst were examined. The time windows start at ±10 s and extend to ±15 days. We find no evidence of correlations for these time windows and set an upper limit on the fraction of the astrophysical flux that can be attributed to the observed GRBs as a function of the time window. GRBs can contribute at most 12% of the astrophysical neutrino flux if the neutrino-GRB correlation time is less than ≈20 hours, and no more than 38% of the astrophysical neutrino flux can be attributed to the known GRBs at time scales up to 15 days. We conclude that GRBs observable by satellites are not solely responsible for IceCube’s astrophysical neutrino flux, even if very long correlation time scales are assumed.
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Chien, Yang-Ting. "Jet Physics at High Energy Colliders." Thesis, Harvard University, 2013. http://dissertations.umi.com/gsas.harvard:11096.
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The future of new physics searches at the LHC will be to look for hadronic signals with jets. In order to distinguish a hadronic signal from its background, it is important to develop advanced collider physics techniques that make accurate theoretical predictions. This work centers on phenomenological and formal studies of Quantum Chromodynamics (QCD), including resummation of hadronic observables using Soft Collinear Effective Theory (SCET), calculating anomalous dimensions of multi-Wilson line operators in AdS, and improving jet physics analysis using multiple event interpretations.Physics
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Kemp, Dayne Hilton. "A compact high-energy particle detector for low-cost deep space missions." Master's thesis, University of Cape Town, 2015. http://hdl.handle.net/11427/20046.
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Over the last few decades particle physics has led to many new discoveries, laying the foundation for modern science. However, there are still many unanswered questions which the next generation of particle detectors could address, potentially expanding our knowledge and understanding of the Universe. Owing to recent technological advancements, electronic sensors are now able to acquire measurements previously unobtainable, creating opportunities for new deep-space high-energy particle missions. Consequently, a new compact instrument was developed capable of detecting gamma rays, neutrons and charged particles. This instrument combines the latest in FPGA System-on-Chip technology as the central processor and a 3x3 array of silicon photomultipliers coupled with an organic plastic scintillator as the detector. Using modern digital pulse shape discrimination and signal processing techniques, the scintillator and photomultiplier combination has been shown to accurately discriminate between the di_erent particle types and provide information such as total energy and incident direction. The instrument demonstrated the ability to capture 30,000 particle events per second across 9 channels - around 15 times that of the U.S. based CLAS detector. Furthermore, the input signals are simultaneously sampled at a maximum rate of 5 GSPS across all channels with 14-bit resolution. Future developments will include FPGA-implemented digital signal processing as well as hardware design for small satellite based deep-space missions that can overcome radiation vulnerability.
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Zeng, Houdun, Yuliang Xin, Siming Liu, J. R. Jokipii, Li Zhang, and Shuinai Zhang. "EVOLUTION OF HIGH-ENERGY PARTICLE DISTRIBUTION IN MATURE SHELL-TYPE SUPERNOVA REMNANTS." IOP PUBLISHING LTD, 2017. http://hdl.handle.net/10150/623101.
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Multi-wavelength observations of mature supernova remnants (SNRs), especially with recent advances in gamma-ray astronomy, make it possible to constrain energy distribution of energetic particles within these remnants. In consideration of the SNR origin of Galactic cosmic rays and physics related to particle acceleration and radiative processes, we use a simple one-zone model to fit the nonthermal emission spectra of three shell-type SNRs located within 2 degrees on the sky: RX J1713.7-3946, CTB 37B, and CTB 37A. Although radio images of these three sources all show a shell (or half-shell) structure, their radio, X-ray, and gamma-ray spectra are quite different, offering an ideal case to explore evolution of energetic particle distribution in SNRs. Our spectral fitting shows that (1) the particle distribution becomes harder with aging of these SNRs, implying a continuous acceleration process, and the particle distributions of CTB 37A and CTB 37B in the GeV range are harder than the hardest distribution that can be produced at a shock via the linear diffusive shock particle acceleration process, so spatial transport may play a role; (2) the energy loss timescale of electrons at the high-energy cutoff due to synchrotron radiation appears to be always a bit (within a factor of a few) shorter than the age of the corresponding remnant, which also requires continuous particle acceleration; (3) double power-law distributions are needed to fit the spectra of CTB 37B and CTB 37A, which may be attributed to shock interaction with molecular clouds.
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Akhtar, Jahanzeb. "Particle tracking using the unscented Kalman filter in high energy physics experiments." Thesis, Brunel University, 2015. http://bura.brunel.ac.uk/handle/2438/11482.
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The extended Kalman lter (EKF) has a long history in the field of non-linear tracking. More recently, statistically-based estimators have emerged that avoid the need for a deterministic linearisation process. The Unscented Kalman filter (UKF) is one such technique that has been shown to perform favourably for some non-linear systems when compared to an EKF implementation, both in terms of accuracy and robustness. In this Thesis, the UKF is applied to a high energy physics particle tracking problem where currently the EKF is being implemented. The effects of measurement redundancy are investigated to determine improvements in accuracy of particle track reconstruction. The relationship between measurement redundancy and relative observability is also investigated through an experimental and theoretical analysis. Smoothing (backward filtering), in the high energy physics experiments, is implementedusing the Rauch Tung Striebel (RTS) smoother with the EKF , however, in Unscented Kalman filter algorithms, the Jacobian matrices required by the RTS method, are not available. The Unscented Rauch Tung Striebel (URTS) smoother addresses this problem by avoiding the use of Jacobian matrices but is not effi cient for large dimensional systems such as high energy physics experiments. A technique is implemented in the RTS smoother to make it suitable for the UKF. The method is given the name the Jacobian Equivalent Rauch Tung Striebel (JE-RTS) smoother. The implementation of this method is quite straight forward when the UKF is used as an estimator.
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Nodari, Benedetta. "Intelligent systems for particle detectors in environmental applications and High-Energy Physics." Doctoral thesis, Università degli studi di Bergamo, 2017. http://hdl.handle.net/10446/77221.
Full textAbstract:
Over the last decades, improvements in microelectronics technology have
fostered signicant progress in all fields of engineering, science and also in
radiation detection. The main challenge in designing radiation detectors is
to develop systems based on front-end electronics that is able to cope with
high radioactive environment, satisfy very high resolution requirements and
comply with high particle rates. This thesis work focuses on the analysis and
development of novel and intelligent solutions for electronics system, especially
suited for radiation detectors. In particular, two different applications are
considered here.
The first one concerns the design of a portable and affordable detector
system for continuous indoor Radon detection, based on SiPM technology. A
simple analog front-end with optimized low-noise performances and reduced
power consumption has been designed for counting each alpha particle that
occurs in the detector after Radon decay. The readout electronics is integrated
with a suite of environmental sensors on a full-custom Printed Circuit Board.
Compared to all the commercial Radon detector nowadays available, the developed system is able to detect reliable value of indoor Radon concentration
within few hours. The system also exploits the recent capabilities of microelectronic devices by including advanced functions such as Bluetooth data
transmission and energy harvesting.
In high-energy physics experiments, with particular emphasis on the HL-LHC environment, pixel detectors have to satisfy aggressive requirements
concerning high granularity, high rate capability and low power consumption.
With the advent of accessible modern technology such as 65 nm CMOS, the
processing speed and reduced power consumption can be achieved. In order
to meet such specications, a new pixel mixed signal ASIC has been designed
as a prototype front-end for the HL-HLC pixel readout system, within the
framework of RD53 collaboration. The ASIC front-end includes signal processing and synchronous analog-to-digital conversion within one Bunch Crossing
period. Thus, the emphasis of the work is on the feasibility of a synchronous
ADC within the HL-LHC environment, able to ensure high performances in
terms of low noise, power dissipation and high speed. Finally, a novel and
intelligent digital architecture has been proposed, in order to focus the eorts
of the front-end on the implementations of three main features: a novel data
sparsication method, a clusterization scheme at the hardware level itself and
fast Region-Of-Interest (ROI) trigger capability.
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Liu, Hongqin 1956. "Simulation of a plasma particle generator." Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=31571.
Full textAbstract:
The goal of this research was to simulate the nucleation and particle growth in a tubular plasma particle generator and investigate the effects of various entrance and boundary conditions on the particle size distribution and production rate.The fluid flow is laminar and its domain is two-dimensional axi-symmetric and a radial quench gas injection is introduced. The method of moments was used to model the particle generation and growth starting with the dynamic aerosol equation and the assumption of a log-normal distribution function. The governing equations are solved numerically and the velocity, concentration, temperature, particle size and density profiles are obtained for various entrance and boundary conditions.
The following conclusions were reached: increasing the length of the generator tube or metal concentration gives more product, larger particle size and narrower size distribution; higher quench gas injection rates or entrance flow rate produces finer particles with a broader size distribution; increasing entrance temperature leads to smaller particles with narrower size distribution.
In addition, for a quick prediction, an artificial neural network (ANN) model was used. The ANN was trained with the data from the numerical simulations. Within the ranges of conditions examined, the output can be obtained in few seconds rather than several hours needed in the original simulations.
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Martineau, Patrick. "On particle production and brane cosmology." Thesis, McGill University, 2003. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=80328.
Full textAbstract:
Particle production is examined within the context of brane cosmology. Non-perturbative formalisms are reviewed and employed to calculate particle number (or the energy density associated with such particles) produced in dynamical spacetimes arising from various brane configurations. Specifically, reheating from tachyon condensation, the quantum instability of a class of S-brane spacetimes, and particle production on an orbiting brane-antibrane system are investigated.
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Lacasse, Roger. "Test of particle identification at target rapidity in the E814 experiment." Thesis, McGill University, 1991. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=61174.
Full textAbstract:
One of the unique features of the E814 experimental setup at the BNL-AGS, is its nearly 4$ pi$ calorimetry. Calorimeters, however, do not provide information on the nature of particles and their multiplicity. Particle identification is important to understand the expansion phase of the hot nuclear matter produced in relativistic heavy ion collisions. In the present 814 experiment the charged particle multiplicity is measured at forward angles only, by a Si pad detector. The addition of a similar Si detector in the target rapidity region, overlapping the Target Calorimeter, is being considered. Initial calculations have shown a possibility of particle identification by using the signals from a silicon detector and from the highly segmented Target Calorimeter. In this thesis, the potential for particle identification of an upgraded silicon multiplicity detector at target rapidity is evaluated using a silicon surface barrier detector and part of the Target Calorimeter. The measured response is compared to the predictions of the event generator HIJET followed by complete tracking using the code GEANT.
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LaHurd, Danielle V. "Searching for Quark Gluon Plasma Signatures in Ultra High Energy Cosmic Rays." Case Western Reserve University School of Graduate Studies / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=case1479298851843212.
Full text
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Ullmann, Rainer Thomas. "Neutral strange particle production in neutral current deep inelastic scattering at HERA." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=34473.
Full textAbstract:
This thesis presents a first study of various aspects of $K sp0$ and $ Lambda$ production in neutral current deep inelastic scattering of 27.5 GeV positrons and 820 GeV protons. The data were accumulated with the ZEUS detector at HERA in the 1994 run period. The average multiplicities for the neutral strange particle production as functions of pseudorapidity $ eta$ and transverse momentum $p sb{t}$ have been determined in the kinematic range 10 $GeV sp20.04.$ The particle and energy flow with respect to the struck quark direction, as well as the dependence of the average production rate as function of the four-momentum transfer $Q sp2$ and the hadronic centre of mass energy W of the ep scattering process have been studied. The K$ sp0$ and $ Lambda$ multiplicities in the kinematic range 10 $GeV sp20.04$ are compared with the results from data from the 1993 run period with 26.7 GeV electrons and 820 GeV protons. The production mechanisms of $K sp0$ in events with and without large rapidity gaps with respect to the proton direction are compared in order to probe differences in diffractive and non-diffractive scattering processes.
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Manuel, Mario John-Errol. "Characterization of mono-energetic charged-particle radiography for high energy density physics experiments." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/45302.
Full textAbstract:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2008.Includes bibliographical references (p. 75-76).
Charged-particle radiography, specifically protons and alphas, has recently been used to image various High-Energy-Density Physics objects of interest, including Inertial Confinement Fusion capsules during their implosions, Laser-Plasma Interactions, and Rayleigh-Taylorinstability growth. An imploded D23He-filled glass capsule - the backlighter - provides monoenergetic 15-MeV and 3-MeV protons and 3.6-MeV alphas for radiographing these various phenomena. Because the backlighter emits mono-energetic particles, information about areal density and electromagnetic fields in imaged systems can be obtained simultaneously. One of the most important characteristics of the backlighter is the fusion product yield, so understanding the experiment parameters that affect it is essential to the future of chargedparticle radiography. Empirical studies of backlighter performance under a variety of conditions are presented, along with proton yield parameterizations based on backlighter and laser parameters. In order to investigate the limits and capabilities of this diagnostic, the Geant4 Transport Toolkit is introduced as the supplementary simulation tool to accompany this novel diagnostic; benchmark simulations with experimental data are presented.
by Mario John-Errol Manuel.
S.M.
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Baroncelli, Leonardo. "Use of POWER8 architecture for High Energy Physics simulations." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018.
Find full textAbstract:
Il seguente elaborato di tesi è svolto nel contesto di una accordo tra le organizzazioni INAF e CERNOpenLab per esplorare le possibilità computazionali dell’architettura IBM POWER nel contesto della fisica delle alte energie. Nel primo capitolo si illustrano le sfide che la prossima generazione di esperimenti porranno alla comunità scientifica. Tra queste sfide, è evidenziata la grande richiesta di tempo di calcolo dei metodi Monte Carlo per il Particles Transport. Anche un piccolo incremento di velocità delle simulazioni farebbe risparmiare alla comunità scientifica centinaia di migliaia di euro all’anno. Viene quindi descritto il software Geant4 e presentata la sua evoluzione, il progetto GeantV. Lo scopo di quest’ultimo è sfruttare completamente le caratteristiche dei processori moderni, come l’architettura IBM POWER di cui vengono delineate le caratteristiche principali. Nel secondo capitolo si porta a termine la validazione scientifica di un insieme di modelli fisici di Geant4 sulla CPU POWER8E, nel contesto della missione e-ASTROGAM. Nel terzo capitolo vengono confrontate le velocità delle CPU POWER8NVL e Xeon E5-2697 misurando il tempo di calcolo su di un codice Geant4 di simulazione. Si mostra un problema di efficienza nel test a singolo thread. La causa del problema viene ricondotta all’utilizzo del compilatore GCC. Il problema viene risolto attraverso l’utilizzo del compilatore XL. Lo stesso codice di simulazione viene quindi eseguito in modalità multi thread e viene verificata la scalabità in entrambe le CPU. Nel quarto capitolo, si compilano sull’architettura POWER8NVL, le librerie delle dipendenze software di GeantV, risolvendo gli errori di compilazione
incontrati. Infine si compilano le librerie di GeantV come primo passo verso una futura integrazione tra GeantV e l’architettura POWER. Nel capitolo conclusivo, si riassumono i risultati ottenuti e vengono prestantate una serie di possibili strategie per aumentare l’efficienza computazionale del POWER.
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Alves, Cardoso Mário. "Implementation of Variational Autoencoder on the simulated particle collider data." Thesis, Uppsala universitet, Högenergifysik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-435325.
Full textAbstract:
We study the possibility of applying deep learning algorithms, suchas Variational Autoencoders, on simulated particle collider data to detectBeyond the Standard Model events. In this report, we apply three dif-ferent processes of training the data for better eciency and the resultsof said training on detecting anomalies. Links to the training and testingdata can be found here: https://www.phenomldata.org/
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Wang, Gang 1958 Nov 28. "Transverse energy and charged particle multiplicity in 14.6 GeVc proton-nucleus collisions." Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=28956.
Full textAbstract:
Transverse energy and charged particle multiplicity produced in 14.6 GeV/c p + Al and p + Pb collisions have been studied using the E814 set-up at the BNL-AGS. Measurements of d$ sigma$/d$E sb{T}$, d$E sb{T}$/d$ eta$,d$ sigma$/d$N sb{c}$, and d$N sb{c}$/d$ eta$ are presented. From the present data the mean transverse energy per particle is obtained and it is compared to values observed in Si induced collisions at the same energy. In contrast to what is observed in nucleus-nucleus collisions, a very weak correlation is found between the transverse energy and the charged particle multiplicity. These results are compared to the predictions of various theoretical models used to describe heavy-ion collisions. The event generators RQMD and HIJET reproduce well the pseudorapidity distribution of both the transverse energy and charged particle multiplicity, whereas FRITIOF fails to reproduce the measured distributions. Contrary to what had been suggested previously in a Si + A study, the present study shows that the pseudorapidity dependence of charged particle multiplicity distributions do not follow KNO scaling.
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Rosten, Jonatan Hans Niclas. "The ZZ → 4l process and anomalous triple gauge couplings with ATLAS at the LHC." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/271838.
Full textAbstract:
This thesis is a presentation of an analysis of the $ZZ\rightarrow 4\ell$ ($\ell = e,\mu$) process in proton-proton collisions with centre-of-mass energy $\sqrt{s}$ = 13 TeV at the LHC during 2015 and 2016 (a total integrated luminosity of 36.1 fb$^{-1}$), using the ATLAS detector. Candidate $ZZ \rightarrow 4\ell$ events are selected in the three decay channels, $4e$, $2e2\mu$ and $4\mu$. The cross section of the $ZZ\rightarrow 4\ell$ process is measured in four fiducial regions closely matching the detector acceptance: one for each decay channel ($4e$, $2e2\mu$ and $4\mu$) and one for the combination of all decay channels. The total cross section of $pp\rightarrow ZZ$ is measured in a phase-space in which both $Z$ bosons have a mass $m_{Z}$ in the range 66 GeV $ < m_{Z} < $ 116 GeV to be 16.5 $\pm 0.5$ (stat.) $\pm 0.4$ (syst.) $\pm 0.5$ (lumi.)$\,$ pb which is consistent with a next-to-next-to-leading-order prediction of $16.9^{+0.6}_{-0.5}$ pb. Observed event yields in four bins of transverse momentum are used to set 95{\%} CL$_{\text{s}}$ limits on four neutral triple gauge couplings ($f^{V}_{i}$, $V=Z,\gamma$, $i=4,5$) which parameterise an effective $ZZV$ vertex (assuming both $Z$ bosons are on shell). The obtained limits are of the order of $|f^{V}_{i}|<0.0017$.
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Coughlan, G. D. "Cosmological inflation and supersymmetric particle physics : Implications for the big-bang theory." Thesis, University of Oxford, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.355735.
Full text
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Williams, Megan L. (Megan Louise). "An investigation of GaAs as a particle detector material for high energy physics applications." Thesis, The University of Sydney, 1997. https://hdl.handle.net/2123/27617.
Full textAbstract:
This thesis describes the examination of some of the properties of Gallium Arsenide
(GaAs), primarily semi-insulating (SI) GaAs, in an effort to assess their impact on the
performance of high energy physics (HEP) detectors fabricated from this material. Of
particular interest was the shape of the electric field across such devices and its
progression with increasing reverse bias, and the impurities and defect levels in the
material. These combine to dictate the charge transport properties of the material
which in turn determine the quality of the signal from SI GaAs devices.
Chapter 1 discusses the relevance of SI GaAs devices to the Large Hadron Collider
and ATLAS, and introduces the primary concerns regarding the properties of the
material including the growth methods. The fabrication of the devices investigated
here is described in Chapter 2 as are routine measurements such as current-density
vs voltage, capacitance—voltage (CV) and (x—spectroscopy measurements.
Chapter 3 details the use of the transient current technique to study the current pulses
which result due to the motion of charge carriers in the material. These current pulses
are directly related to the shape and strength of the electric field across the devices,
and an investigation into whether Ramo’s Theory correctly predicts the current pulses
in SI GaAs was undertaken. The investigation included the effects of circuit
parameters and the electron lifetime, resulting in a better understanding of the field
shape as well as the sensitivity of the current pulses to these effects.
Chapter 4 describes the application of charge transient spectroscopy (QTS) and
optical QTS to SI GaAs. It is demonstrated that these techniques are ideal for
investigating the majority and minority carrier traps in both conducting and high
resistivity GaAs. Chapter 5 details the low—frequency CV measurements for SI GaAs
devices, and shows that it is a promising way of obtaining information about the
electron lifetime in the material and the concentration of deep level donors.
Chapter 6 summarises the main findings of the thesis and describes further
experiments for and improvements to the techniques presented here.
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Coull, Jonathan. "Single-particle production and photon-hadron correlations in proton-proton collisions at next-to-leading order." Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=104670.
Full textAbstract:
In this thesis, we study photon production and photon-hadron correlations at next-to-leading order (NLO) in proton-proton collisions, in both the cases of isolated and non-isolated photons. To begin, fundamentals of perturbative Quantum Chromodynamics (pQCD) are reviewed, with an emphasis on describing how to compute spectra for single particle production and correlated pairs at both leading order (LO) and NLO in hadronic collisions. In particular, a discussion of infrared and collinear singularities at NLO will provide a natural introduction to the concept of factorization. These results are then specifically applied to the case of computing photon and pion single-particle cross-sections in proton-proton collisions at Relativistic Heavy-Ion Collider (RHIC) and Large Hadron Collider(LHC) energies, and compared to experimental data from the PHENIX and CMS experiments respectively. Included in this will be a short study of the theoretical systematic uncertainty generated by the dependence on factorization scales, and a discussion of the modifications needed when moving from inclusive to isolated observables. Following this, double inclusive cross-sections for production of photon-tagged hadrons are computed and compared to data from PHENIX. Once again, a full NLO treatment is given, and the effects of isolation are implemented. We will conclude with a final section on the application of photon-hadron correlations to the tomographic mapping of energy loss in heavy-ion collisions.Dans cette dissertation, nous étudions la production au seconde ordre (NLO) de photons ainsi que la corrélation entre photons durs et hadrons dans les collisions proton-proton. Dans les deux cas est inclus l'effet de l'application de critères d'isolement sur les photons. Nous commençons par une synthèse des résultats fondamentaux de la chromodynamique quantique perturbative (pQCD), dans laquelle nous résumons les méthodes principales pour calculer des sections efficaces aux premier et second ordres. En particulier, nous discutons des singularités infrarouges et colinéaires qui se produisent au seconde ordre, ce qui nous amènera à introduire la théorie de la factorisation. Ces outils sont par la suite utilisés pour calculer les section efficaces pour la production de photons et de pions dans les collisions proton-proton aux énergies atteintes au Relativistic Heavy Ion Collider (RHIC)et au Grand collisionneur de hadrons (LHC). Ces résultats sont comparés aux données des expériences PHENIX et CMS respectivement. Nous étudions aussi l'incertitude théorique due aux choix des échelles de factorisation et la différence entre les sections efficaces inclusives et isolées. Finalement, nous calculons les sections efficaces pour les paires photon-hadron corrélées et comparons les résultats aux données de PHENIX, tout en incluant les effets de second ordre et d'isolement. Nous concluons avec une description qualitative de l'application des corrélations pour établir une tomographie des collisions d'ions lourds.
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Marsh, James W. "High resolution measurements of neutron energy spectra from Am-Be and Am-B neutron sources." Thesis, Kingston University, 1990. http://eprints.kingston.ac.uk/20540/.
Full textAbstract:
A modelling methodology, consisting of tools and techniques, has been developed to achieve quality improvement in any area of a manufacturing organisation. A 3 step approach was piloted within the Test Department at ICL Kidsgrove which tests printed circuit boards manufactured at the factory. The first step was to produce a full process model and to use this to highlight non-conformances. The next step was to develop a cost of quality model. The information from this model is used to take cost prioritised and cost justified corrective actions. The final step is to prepare a procedure which defines to the customers how to use the cost of quality information effectively. This 3 step pilot methodology was then applied to indirect functions such as Finance and Maintenance through an implementation team. The process modelling step was also developed in other quality applications such as auditing and procedure preparation. The final methodology is currently being considered for adoption as a problem solving approach throughout ICL. The process modelling step is being incorporated into auditor training. The modelling methodology, developed through this research, provides a structured, disciplined approach to quality improvement.
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Kao, Yee. "Constraints on New Physics from Neutrino and Other Particle Experiments." Diss., Virginia Tech, 2010. http://hdl.handle.net/10919/40435.
Full textAbstract:
In this thesis we analyze a number of past, current, and future experiments to extract information on physics beyond the Standard Model. We use the Jacobi method to derive a set of simplified expressions for the probabilities of neutrino oscillations in matter. we show the possible constraints that can be placed on various models beyond the Standard Model.
In several cases, we find that the limits thus thus obtained could be competitive with those expected from direct searches at the Large Hadron Collider. We then consider the possible effects of new physics beyond the Standard Model on precision measurements. In particular, we look at recent Bell/Babar results on the B meson branching fraction, and the bounds on Tau-decays from Babar.
As a general framework of analyzing new physics beyond the Standard Model, we discuss what constraints can be placed on R-parity violating SUSY from these experiments.
To complete our analysis, we update the single-coupling bounds on R-parity violating supersymmetry using the most up to date data as of October 2009. In addition to the data listed in the latest Review of Particle Properties, we utilize a new measurement of the weak charge of cesium-133, and preliminary Tau-decay branching fractions from Babar. Analysis of semileptonic D-decay is improved by the inclusion of experimentally measured form-factors into the calculation of the Standard Model predictions.Ph. D.
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Kling, Felix, and Felix Kling. "Exotic Higgs Decays." Diss., The University of Arizona, 2016. http://hdl.handle.net/10150/620861.
Full textAbstract:
Many models of physics beyond the Standard Model include an extended Higgs sector, responsible for electroweak symmetry breaking, and predict the existence of additional Higgs bosons. The Type II Two-Higgs-Doublet Model (2HDM) is a particularly well motivated scenario and a suitable framework for phenomenological studies of extended Higgs sectors. Its low energy spectrum includes two CP-even Higgses h and H, one CP-odd Higgs A, and a pair of charged Higgses H±. We study the implication of the LHC Higgs search results on the Type II 2HDM and identify regions of parameter space which are consistent with all experimental and theoretical constraints and can accommodate the observed 125 GeV Higgs signal. This includes parameter space with a distinctive mass hierarchy which permit a sizable mass splitting between the undiscovered non-Standard Model Higgs states. If this mass splitting is large enough, exotic Higgs decay channels into either a Higgs plus a Standard Model gauge boson or two lighter Higgses open up. This can significantly weaken the reach of the conventional Higgs decay channels into Standard Model particles but also provide the additional opportunity to search for exotic Higgs decay channels. We provide benchmark planes to explore exotic Higgs decay scenarios and perform detailed collider analyses to study the exotic decay channels H/A -> AZ/HZ and H± -> AW/HW. We find that these exotic decays offer complementary discovery channels to the conventional modes for both neutral and charged Higgs searches and permit exclusion and discovery in large regions of parameter space.
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Torres, i. Albà Núria. "High Energy Processes in Active Galaxies." Doctoral thesis, Universitat de Barcelona, 2019. http://hdl.handle.net/10803/668158.
Full textAbstract:
This thesis has as an objective the study of very energetic phenomena in the central regions of active galaxies. Intense star formation is triggered by mergers of galaxies, and the funneling of large quantities of gas toward the inner regions is thought to also cause accretion onto the central black hole. Whether the two processes necessarily take place together as a step of galaxy evolution is still debated.
Regardless of the origin of their connection, star formation and strong AGN activity often coexist in the nuclei of galaxies. Even after star formation is no longer ongoing, the nuclear starburst in a merger results in the formation of galactic bulges. Therefore, stellar densities in the inner kiloparsecs of a galaxy are typically high. As stars, or star forming regions, are close to the AGN, interaction between the two is expected to be frequent, and it can result in a multitude of phenomena worthy of study.
The thesis thus focuses on high energy processes taking place in regions where AGN activity and stellar presence is likely important. In particular, the goal of the thesis is to study the emission produced by these phenomena, in the range of X-rays to gamma-rays, whether to disentangle their individual contributions or to detect emission resulting from their interaction. The thesis intends to provide data to continue the study of the starburst-AGN connection, and new models to explain the production of gamma rays in other galaxies.
Part I focuses on the X-ray analysis of a local sample of LIRGs. The Great Observatories All-Sky LIRG survey (GOALS) is a project to study the brightest infrared galaxies at z < 0.1, in all possible wavelengths. In this part we analyze data for 63 LIRGs in the lower luminosity range of GOALS. We provide X-ray images, fluxes, luminosities and radial profiles for 84 individual galaxies, spanning a wide range of activity types and merger stages. We also provide information on AGN presence using X-ray and IR diagnostics, and compare the results to those derived for the brightest GOALS galaxies. The data provided in this part will help shine light into the importance of AGN presence in LIRGs, in the context of galaxy evolution.
Parts II and III focus on the interaction of AGN jets with stellar populations. When the jet of an AGN impacts a stellar wind, or a blob of material, a shock is formed in which particles can be accelerated up to relativistic energies. We estimate, for different scenarios, the dynamical evolution of the obstacles in the jet and gamma-ray emission generated by the accelerated particles. Part II focuses on the presence of whole populations of stars with high mass-loss rates interacting with the jet, whether because they are inside it, or because they expel layers of accumulated shocked material at the moment they penetrate it. Part III deals with single obstacles, in particular the remnant of a supernova explosion that takes place within the jet. In both parts II and III we include dynamical simulations that illustrate the process and how it affects the jet.
Part IV focuses on the interaction of AGN jets with the environment at large scales, in this case considering them as possible sources of reionization at z=6. We estimate the number of jetted sources at the epoch of reionization using rest-UV detections of AGN. We then correct the observed density of sources for effects of obscuration using X-ray data. Jets at high redshift interact strongly with the CMB, upscattering its photons up to ionizing wavelengths through IC, and possibly ionizing the ambient medium significantly.Esta tesis tiene como objetivo el estudio de fenómenos altamente energéticos en las regiones centrales de las galaxias activas. La formación intensa de estrellas se produce tras una fusión de galaxias, y este mismo fenómeno puede resultar en la acreción de material sobre el agujero negro supermasivo central (AGN). Incluso cuando el episodio de formación de estrellas ha terminado, este ha dado lugar a un bulbo galáctico; por lo que las densidades estelares en las zonas centrales de las galaxias son típicamente elevadas. Por lo tanto, es de esperar que las interacciones entre estrellas y AGN sean un fenómeno frecuente, que puede dar lugar a una gran cantidad de fenómenos interesantes. En particular, la tesis tiene como objetivo estudiar la emisión producida por estos fenómenos, en el rango de rayos X a rayos gamma, ya sea para distinguir las contribuciones individuales de cada uno o para estudiar la emisión generada en su interacción. La tesis pretende proveer datos para continuar el estudio de la relación entre formación estelar y actividad AGN, y nuevos modelos para explicar la producción de rayos gamma en otras galaxias. La primera parte de la tesis es un estudio en rayos X de galaxias lumínicas en el infrarojo. Se analiza una muestra local, proporcionando imágenes, flujos, luminosidades y perfiles radiales en rayos X de 84 galaxias individuales. También se proporciona información sobre la presencia de AGN en ellas, usando datos en rayos X e infrarojo. La parte central de la tesis se centra en el estudio de la interacción entre jets de AGN y estrellas, ya sea porque estas se encuentran dentro de él, porque le inyectan material al penetrarlo, o porque explotan como supernovas en su interior. Se estudia la evolución dinámica de estos fenómenos, y los rayos gamma producidos. La última parte estima la contribución de los jets de AGN a la reionización del universo, puesto que su interacción con los fotones del fondo cósmico de microondas puede resultar en radiación ionizante a través del mecanismo de Compton inverso.
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Fabbri, Filippo <1979>. "4H silicon carbide particle detectors: study of the defects induced by high energy neutron irradiation." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2008. http://amsdottorato.unibo.it/845/1/Tesi_Fabbri_Filippo.pdf.
Full textAbstract:
During the last decade advances in the field of sensor design and improved base materials have
pushed the radiation hardness of the current silicon detector technology to impressive performance.
It should allow operation of the tracking systems of the Large Hadron Collider (LHC) experiments
at nominal luminosity (1034
cm-2s-1) for about 10 years. The current silicon detectors are unable to
cope with such an environment. Silicon carbide (SiC), which has recently been recognized as
potentially radiation hard, is now studied. In this work it was analyzed the effect of high energy
neutron irradiation on 4H-SiC particle detectors. Schottky and junction particle detectors were
irradiated with 1 MeV neutrons up to fluence of 1016
cm-2. It is well known that the degradation of
the detectors with irradiation, independently of the structure used for their realization, is caused by
lattice defects, like creation of point-like defect, dopant deactivation and dead layer formation and
that a crucial aspect for the understanding of the defect kinetics at a microscopic level is the correct
identification of the crystal defects in terms of their electrical activity. In order to clarify the defect
kinetic it were carried out a thermal transient spectroscopy (DLTS and PICTS) analysis of different
samples irradiated at increasing fluences. The defect evolution was correlated with the transport
properties of the irradiated detector, always comparing with the un-irradiated one. The charge
collection efficiency degradation of Schottky detectors induced by neutron irradiation was related to
the increasing concentration of defects as function of the neutron fluence.
45
Fabbri, Filippo <1979>. "4H silicon carbide particle detectors: study of the defects induced by high energy neutron irradiation." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2008. http://amsdottorato.unibo.it/845/.
Full textAbstract:
During the last decade advances in the field of sensor design and improved base materials have
pushed the radiation hardness of the current silicon detector technology to impressive performance.
It should allow operation of the tracking systems of the Large Hadron Collider (LHC) experiments
at nominal luminosity (1034
cm-2s-1) for about 10 years. The current silicon detectors are unable to
cope with such an environment. Silicon carbide (SiC), which has recently been recognized as
potentially radiation hard, is now studied. In this work it was analyzed the effect of high energy
neutron irradiation on 4H-SiC particle detectors. Schottky and junction particle detectors were
irradiated with 1 MeV neutrons up to fluence of 1016
cm-2. It is well known that the degradation of
the detectors with irradiation, independently of the structure used for their realization, is caused by
lattice defects, like creation of point-like defect, dopant deactivation and dead layer formation and
that a crucial aspect for the understanding of the defect kinetics at a microscopic level is the correct
identification of the crystal defects in terms of their electrical activity. In order to clarify the defect
kinetic it were carried out a thermal transient spectroscopy (DLTS and PICTS) analysis of different
samples irradiated at increasing fluences. The defect evolution was correlated with the transport
properties of the irradiated detector, always comparing with the un-irradiated one. The charge
collection efficiency degradation of Schottky detectors induced by neutron irradiation was related to
the increasing concentration of defects as function of the neutron fluence.
46
Sandalski, Stou. "Neptune| An astrophysical smooth particle hydrodynamics code for massively parallel computer architectures." California State University, Long Beach, 2013.
Find full text
47
Arms, Kregg E. "Study of tau lepton decays to three charged hadrons and one neutral pion." Connect to this title online, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1112803154.
Full textAbstract:
Thesis (Ph. D.)--Ohio State University, 2005.Title from first page of PDF file. Document formatted into pages; contains xv, 81 p.; also includes graphics (some col.) Includes bibliographical references (p. 79-81). Available online via OhioLINK's ETD Center
48
DeWolf, R. S. "Charged and neutral particle production in proton-antiproton interactions at 200 and 900 GeV centre of mass energies." Thesis, University of Cambridge, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.481568.
Full text
49
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.
Full textAbstract:
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.
50
Anandakrishnan, Archana. "Yukawa Unified GUTs in the era of the Large Hadron Collider." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1420475282.
Full text