Dissertations / Theses on the topic 'Neutrino'
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1
Cernohorsky, Jan. "Neutrino driven neutron star formation." Amsterdam : Amsterdam : Rodopi ; Universiteit van Amsterdam [Host], 1990. http://dare.uva.nl/document/91884.
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Delgadillo, Franco Luis Angel. "Sterile Neutrino Searches." Thesis, Virginia Tech, 2021. http://hdl.handle.net/10919/103875.
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In the first part of the thesis we explore the sensitivity to sterile neutrinos by
using a novel kaon tagging technology: ENUBET, the proposed experiment could
decisively test indications from the experiments Neutrino-4 and IceCube. In the second
part of the thesis we discuss the current status of sterile neutrino searches at nuclear
reactors, we present a study with the optimization of a green field, two baseline reactor
experiment with respect to the sensitivity for electron anti-neutrino disappearance in
search of a light sterile neutrino at both research and commercial reactors. We find
that a total of 5 tons of detectors deployed at a commercial reactor with a closest
approach of 25 m can probe the mixing angle sin 2 2θ down to ∼ 5 × 10 −3 around
∆m 2 ∼ 1 eV 2 . The same detector mass deployed at a research reactor can be sensitive
up to ∆m 2 ∼ 20 − 30 eV 2 assuming a closest approach of 3 m and excellent energy
resolution, such as that projected for TAO. We also find that lithium doping of the
reactor could be effective in increasing the sensitivity for higher ∆m 2 values.Master of Science
A sterile neutrino is a particle that is not included in the actual content of matter at the fundamental level. Our goal in this thesis was to search for an imprint of this particle at neutrino experiments. We performed numerical simulations using the experimental specification given in the literature to predict what this signal should look like. The importance of searching for this particle arises from indications at neutrino nuclear experiments, if this particle exists, that would imply new physics beyond our actual understanding of the matter content in the universe. The first search was performed at an experimental facility called ENUBET and the second search was performed at nuclear reactors. Testing this elusive particle means we need to determine two parameters from a model. The results of the aforementioned parameter space searches are presented in this thesis. The statistical significance in our findings is not entirely conclusive to either confirm or refute the sterile neutrino. The benefits of studying neutrinos at nuclear reactors is that they are produced in generating electrical power as well as monitoring nuclear weapons.
3
Miknaitis, Kathryn Kelly Schaffer. "A search for matter enhanced neutrino oscillations through measurements of day and night solar neutrino fluxes at the Sudbury Neutrino Observatory /." Thesis, Connect to this title online; UW restricted, 2005. http://hdl.handle.net/1773/9636.
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Tsang, Ka-vang. "A search for periodic neutrino signals and gamma-ray burst neutrinos with the Sudbury Neutrino Observatory." Click to view the E-thesis via HKUTO, 2005. http://sunzi.lib.hku.hk/hkuto/record/B3194324X.
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Tsang, Ka-vang, and 曾嘉宏. "A search for periodic neutrino signals and gamma-ray burst neutrinos with the Sudbury Neutrino Observatory." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2005. http://hub.hku.hk/bib/B3194324X.
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Iyer, Sharada Ramalingham. "A novel approach in the detection of muon neutrino to tau neutrino oscillation from extragalactic neutrinos." Diss., The University of Arizona, 2001. http://hdl.handle.net/10150/290068.
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A novel approach is proposed for studying the ν(μ) → ν(τ) oscillation and detection of extragalactic neutrinos. Active Galactic Nuclei (AGN), Gamma Ray Bursters (GRB) and Topological Defects are believed to be sources of ultrahigh energy ν(μ) and νₑ. These astrophysical sources provide a long baseline of 100Mpc, or more, for possible detection of ν(μ) → ν(τ) oscillation with mixing parameter Δm² down to 10⁻¹⁷ eV², many orders of magnitude below the current accelerator experiments. The propagation characteristics of upward going muon and tau neutrinos is studied to show that high energy tau neutrinos cascade down in energy as they propagate through the Earth, producing an enhancement of the incoming tau neutrino flux in the low energy region. By contrast, high energy muon neutrinos get attenuated as they traverse the Earth. It is observed that the relative steepness of the incoming neutrino flux spectrum and the nadir angle of the Earth are two important factors that influence the enhancement and cascade of nutau flux. This effect provides a novel way to search for tau neutrino appearance by measuring the angular dependence of tau neutrino induced upward muons; and upward hadronic and electromagnetic showers. A Monte Carlo evaluation of tau survival probability and its range shows that at energies below 10⁷ - 10⁸ GeV, depending on the material, only tau decays are important. However, at higher energies the tau energy losses are significant, hence reducing the survival probability of tau. Here, tau energy loss for energies up to 10⁹ GeV have been calculated taking into consideration the decay of tau. An understanding of tau energy loss at very high energies could help with the interpretation of long tracks produced by charged particles in large underground detectors.
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Manzanillas, Luis. "Development of the source calibration system of the STEREO experiment and search for sterile neutrinos at the ILL." Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAY079/document.
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L'expérience STEREO a été proposé afin de donner une réponse sans ambiguïté àl'idée d'un état de neutrino stérile léger ($Delta m^{2}sim 1eV^{2}$) comme l'origine del'anomalie réacteur des antineutrinos. Le but de l'expérience est de confirmer ou de rejetercette hypothèse en recherchant un patron d'oscillation à courte distance (9-11 m) dans lespectre en énergie des $overline{nu_{e}}$'s émis par le réacteur nucléaire de recherchede l'Institut Laue-Langevin à Grenoble (France). A cet effet, le détecteur estcomposé de 2 tonnes du liquide scintillant dopé au Gd et lu par un réseau detubes photomultiplicateurs, et est segmenté en 6 cellules dans la direction depropagation des antineutrinos. Les $overline{nu_{e}}$'s sont détectés par le processusIBD en observant un signal corrélé dans letemps d'un dépôt d'énergie rapide d'un positron et un signal retardé produitpar la capture d'un neutron. La mesure des petites oscillations deformantle spectre d'énergie des antineutrinos nécessite une bonne résolution en énergieet une excellente connaissance de la réponse du détecteur. Ce manuscrit présenteune étude de simulation détaillée basée sur le logiciel Geant4 STEREO, ce quia permis le développement du système de calibration par sources. Ce système aété conçu pour répondre à toutes les exigences physiques de STEREO: calibrerl'échelle de l'énergie et de l'efficacité de capture de neutrons au niveau de 2%,connaître la réponse en énergie dans le spectre d'énergie réacteur antineutrino(1-8 MeV), étudier et la caractériser la réponse et des non-uniformités dudétecteur. A cet effet, on propose un système de calibration consistant en trois sous-systèmes:un sous-système automatisé pour déplacer des sources radioactives autour dudétecteur pour calibrer l'échelle en énergie dans chaque cellule de manièreindépendante. Un second sous-système pour déplacer une source AmBe sous ledétecteur, dont l'objectif est d'inter-calibrerl'efficacité de capture de neutrons entre les cellules. Enfin, un troisième systèmemanuel qui consistent en trois tubes de calibration placés à l'intérieur du liquidescintillante pour évaluer l'efficacité absolue de la capture des neutrons danstrois cellules différentes. La dernièrepartie de ce manuscrit est consacré à l'étude et la caractérisation du bruite de fond gammaet les signaux neutrino attendusThe STEREO experiment has been proposed to give an unambiguous responseto the hypothesis of a light sterile neutrino state ($Delta m^{2}sim 1 eV^{2}$)as the origin of the reactor antineutrino anomaly. Its goal is to confirm or reject thishypothesis by searching at short distance (9-11 m) for a neutrino oscillation patternin the energy spectrum of the $overline{nu_{e}}$’s emitted by the research nuclear reactorof the Laue-Langevin Institute in Grenoble (France). To this end, the detector iscomposed of 2 tons of Gd-loaded liquid scintillator read out by an array of PMTs, andis segmented in 6 cells in the direction of the $overline{nu_{e}}$’s propagation. Antineutrinosare detected via the IBD process by observing a time correlatedsignal composed of a prompt energy deposit from a positron and a delayed signal produced bythe neutron capture. Measuring small oscillations superimposed on the reactor antineutrinoenergy spectrum requires a good energy resolution and an excellent knowledge ofthe detector response. This manuscript presents a dedicated Geant4 simulation studyof a calibration system based on radioactive sources.This system has been conceived to fulfill all the STEREO physics requirements:calibrating the energy scale and the neutron capture efficiency at the 2 % level,knowing the energy response in the reactor antineutrino energy spectrum (0-8 MeV),and characterizing the detector response in a broader sense (non-uniformities, non-linearity,particle identification, etc). To this end, we proposethree calibration subsystems: one automated subsystem to moveradioactive sources around the detector, whose main role is to calibrate the energy scale in each cellindependently; a second subsystem to inter-calibrate the neutron captureefficiency between cells by moving an AmBe source under the detector; and finally,a third subsystem consisting in three manualcalibration tubes inside the liquid scintillator, necessary to assess the absolute neutron captureefficiency inside three different cells. The final part of this manuscript is devoted tothe study of the selection criteria, and the proposal of methods to reject the expected gammabackground
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Lyon, Matthew Jeremy. "Neutron transport in the Sudbury neutrino detector." Thesis, University of Oxford, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.337422.
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Stachurska, Juliana. "Astrophysical Tau Neutrinos in IceCube." Doctoral thesis, Humboldt-Universität zu Berlin, 2020. http://dx.doi.org/10.18452/21611.
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Das IceCube Neutrino Observatorium am Südpol hat die Existenz eines diffusen astrophysikalischen Neutrinoflusses nachgewiesen. Die Flavor-Zusammensetzung astrophysikalischer Neutrinos trägt Informationen über Orte kosmischer Teilchenbeschleunigung und Auswirkungen potenzieller neuer Physik auf die Neutrinoausbreitung. Zur seiner Bestimmung ist die Beobachtung von Tau-Neutrinos nötig. Ab einer Energie von ~O(100 TeV) kann deren Wechselwirkung über geladene Ströme eine Doppelkaskaden-Topologie ergeben, bei der die zwei Energiedepositionen am Tau-Entstehungs- und Tau-Zerfallsvertex aufgelöst werden können. Diese wird zusammen mit den bereits bekannten Topologien Einzel-Kaskade und Spur zur Messung der Flavor-Zusammensetzung auf der Erde benutzt. In dieser Arbeit werden im Detektorvolumen von IceCube anfangende Ereignisse mit hohen Energien algorithmisch in drei Topologien klassifiziert. Im Datensatz mit einer Lebensdauer von 7.5 Jahren werden zum ersten Mal zwei Doppelkaskaden identifiziert; diese sind Kandidaten für Tau-Neutrinos. Die Eigenschaften der zwei Tau-Neutrino-Kandidaten werden in einer a-posteriori Analyse im Detail studiert. Die statistische Methode wird durch einen Log-Likelihood-Quotienten-Test mit multi-dimensionalen Wahrscheinlichkeitsdichten verbessert. Eine der Doppelkaskaden ist konsistent mit dem Szenario einer misklassifizierten Einzelkaskade, während für die zweite Doppelkaskade die Wahrscheinlichkeit eines nicht-Tau-Neutrino Szenarios auf nur 3% bestimmt wird. Die gemessene Flavor-Zusammensetzung ist konsistent mit der Annahme von astrophysikalischen Neutrinos sowie mit bisher veröffentlichen Resultaten. Die Messung ergibt einen astrophysikalischen Tau-Neutrino Fluss von dPhi / dE=3.0 (-1.8,+2.2) (E / 100TeV)^(-2.87) 10^(-18) GeV^(-1) cm^(-2) s^(-1) sr^(-1), was dem ersten positiven Ergebnis für die Tau-Normalisierung entspricht. Die Nichtexistenz eines astrophysikalischen Tau-Neutrino Flusses wird mit einer Signifikanz von 2.8 sigma abgelehnt.The IceCube neutrino observatory at the South Pole has confirmed the existence of a diffuse astrophysical neutrino flux. The flavor composition of astrophysical neutrinos carries information on the environments at the sites of cosmic particle acceleration as well as potential imprints of new physics acting during neutrino propagation. To measure the flavor composition the observation of the long-elusive tau neutrinos is required. Starting at an energy of ~O(100 TeV) a tau neutrino charged current interaction can produce a double cascade topology, where the two energy depositions from the tau creation and the tau decay vertices are resolvable. This topology together with the well-established track and single cascade topology is used to measure the flavor composition on Earth. In this work, high-energy events starting in IceCube's detector volume are classified algorithmically into the three topologies. In the dataset with a livetime of 7.5 years, two events are classified as double cascades for the first time, yielding multi-TeV tau-neutrino candidates. The properties of the two tau-neutrino candidates are investigated in an a-posteriori analysis. The statistical method is improved by performing a log-likelihood-ratio test using multi-dimensional probability densities. One of the double cascades is consistent with being a misclassified single cascade, while the second double cascade is found to have a misclassification probability of only 3%. The measured flavor composition nu_e:nu_mu:nu_tau = 0.20:0.39:0.42 is consistent with astrophysical neutrinos and with previously published results. The astrophysical tau-neutrino flux is measured to dPhi / dE=3.0 (-1.8,+2.2) (E / 100TeV)^(-2.87) 10^(-18) GeV^(-1) cm^(-2) s^(-1) sr^(-1) with spectral index gamma=2.87 (-0.20,+0.21), yielding the first non-zero results for the tau normalization. The absence of an astrophysical tau-neutrino flux is disfavored at 2.8 sigma.
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Basto, Gonzalez Victor Saul 1977. "Procura de indícios de neutrinos estéreis nos experimentos IceCube e KATRIN." [s.n.], 2014. http://repositorio.unicamp.br/jspui/handle/REPOSIP/276982.
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Orientador: Orlando Luis Goulart PeresTese (doutorado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin
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Resumo: Motivados pelos indícios experimentais da existência de um quarto neutrino, que surge nos dados de oscilações coletados nos experimentos de aparecimento e desaparecimento de neutrinos, e pela possibilidade teórica de explicar a pequena massa dos neutrinos através de dimensões extras grandes, fizemos análises em procura de vestígios destas duas motivações nos experimentos IceCube e KATRIN. A existência deste quarto neutrino implicaria 1) que existem mais neutrinos que os três tipos de neutrinos do Modelo Padrão da física de partículas, 2) que as interações deste novo neutrino não são descritas pelo Modelo Padrão, 3) que os parâmetros da mistura dos três tipos de neutrinos do Modelo Padrão seriam afetados pela mistura com este novo neutrino e 4) que a diferença dos quadrados das massas, ?m^{2}, associada a este neutrino seria grande, ?m^{2} ~1 eV^{2}. Usando os dados de neutrinos atmosféricos de IceCube, podemos indagar pela existência do quarto neutrino, pois para, ?m^{2} ~1 eV^{2} acontece uma conversão de sabor devida ao efeito de matéria sobre o neutrino no intervalo de energias analisado no IceCube. Assim, este efeito de matéria permite-nos pôr limites sobre os parâmetros que governam as oscilações de neutrinos estéreis. O experimento KATRIN procurará medir a massa do neutrino. Esta medida será feita analisando a cinemática dos elétrons emitidos no decaimento beta do Trítio que é uma medida independente do modelo físico, pois está fundamentada na conservação da energia. A presença de estados mais pesados, como os que existem quando neutrinos estéreis estão presentes, nos permitirá vincular estes neutrinos estéreis. Especificamente, analisamos em KATRIN indícios de um e dois neutrinos estéreis e também de dimensões extras grandes
Abstract: Motivated by the experimental evidence of the existence of a fourth neutrino, which arises from the data collected of neutrino oscillations in appearance and disappearance experiments, and by the theoretical possibility to explain the smallness of the mass of the neutrinos through large extra dimensions, we performed analyses in search of seeking indication of these two motivations in the IceCube and KATRIN experiments. The existence of this fourth neutrino would imply 1) that there are more types of neutrinos than the three types of neutrinos present in the Standard Model of particle physics, 2) that this new neutrino interactions are not described by the Standard Model, 3) that the parameters of the three neutrinos mixing would be affected by mixing with this new type of neutrino, and 4) that the squared-mass difference , ?m^{2} associated with this new neutrino would be large, , ?m^{2} ~1 eV^{2}. Using the atmospheric neutrino data from IceCube, we can investigate the existence of the fourth neutrino because a flavor conversion happens in the limit , ?m^{2} ~1 eV^{2} due to the effect of matter on the neutrino in the range of energies analyzed in the IceCube. Thus, this matter effect allows us to constrain the parameters that govern the sterile neutrino oscillations. The KATRIN experiment will seek to measure the neutrino mass. This measure will be performed by analyzing the kinematics of electrons emitted in the tritium beta decay, which is an independent measure of the physical model because it is based on energy conservation. The presence of heavier states such as those that exist when sterile neutrinos are present, will allow us to constrain these sterile neutrinos. Specifically, we analyze in KATRIN evidence of one and two sterile neutrinos and also of large extra dimensions
Doutorado
Física
Doutor em Ciências
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Gomes, Abner Leonel Gadelha. "Limites nos parâmetros do modelo de oscilação com decaimento de neutrinos usando os dados do experimento MINOS." Universidade Federal de Goiás, 2014. http://repositorio.bc.ufg.br/tede/handle/tede/7509.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
We use the and produced from MINOS beam line that recently reported a disappearence analysis using their full data and combining the beam line and atmospheric neutrinos and antineutrinos events. We used their beam data analysis to constrain the neutrino lifetime under the oscillation plus decay framework. Our analysis reports 3 < 1:4 103 GeV=s, which corresponds to a decay lifetime 3=m3 > 2:4 1012 s=eV , improving a previous MINOS measurement who is 3=m3 > 2:1 1012 s=eV .
Usamos dados de e produzidos da linha de feixe do experimento MINOS publicados recentemente em uma análise de desaparecimento de neutrinos muônicos utilizando dados completos de neutrinos e antineutrinos da linha de feixe e atmosféricos. Estabelecemos limites sobre a razão tempo de vida por massa do neutrino para o modelo de oscilação com decaimento. Obtivemos da análise um limite superior de 3 < 1;4 103 GeV=s, que corresponde a um tempo de vida de 3=m3 > 2;4 1012 s=eV no limite inferior, melhorando a medida anterior do MINOS que era de 3=m3 > 2;1 1012 s=eV .
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Astier, Pierre. "Recherche d'oscillations de neutrinos dans le canal neutrino-muon vers neutrino-electron aupres de l'accelerateur de brookhaven." Paris 7, 1987. http://www.theses.fr/1987PA077268.
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Astier, Pierre. "Recherche d'oscillations de neutrinos dans le canal neutrino-muon vers neutrino-électron auprès de l'accélérateur de Brookhaven." Grenoble 2 : ANRT, 1987. http://catalogue.bnf.fr/ark:/12148/cb37602428b.
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Laberge, Gaetan (Gaetan Joseph Henri) Carleton University Dissertation Physics. "212Pb assay for the determination of the neutral current background at the Sudbury Neutrino Observatory." Ottawa, 1995.
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Szafron, Robert. "General description of neutrino oscillations with non-standard interactions." Doctoral thesis, Katowice : Uniwersytet Śląski, 2012. http://hdl.handle.net/20.500.12128/5275.
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We present a formalism describing neutrino oscillations in any application beyond
the Standard Model theory. Instead of using the standard pure states approach,
we apply the density matrix formalism. In general, in New Physics models,
neutrino states are no longer as pure as they are in the Standard Model. We discuss
the details of the appearance of a mixed state, following which possible New Physics
effects are taken at the levels of both the production and detection processes. We
present a number of examples of calculations with our formalism, using muons as
a source of neutrinos and different detection process. We also show the connection
between normal formulae, derived by assuming pure states, and proper results
based on the density matrix approach. The difference occurs at the second order
in parameters describing the departure from the Standard Model. Finally, as an
application of our formalism, we also demonstrate that it is possible to distinguish
Dirac and Majorana neutrinos in oscillations when New Physics scalar interactions
are present.
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Gratieri, Diego Rossi 1982. "Fenomenologia de neutrinos atmosféricos com neutrinos de massa variável." [s.n.], 2012. http://repositorio.unicamp.br/jspui/handle/REPOSIP/278535.
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Orientador: Orlando Luis Goulart PeresTese (doutorado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin
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Resumo: Neste trabalho obtemos de forma independente a descrição da distribuição angular dos eventos de neutrinos atmosféricos vistos pelo detector Super-Kamiokande tanto para as regiões de sub-GeV como multi-GeV. Para tal, estudamos de forma detalhada a seção de choque neutrinonucleon para processos de espalhamento via corrente carregada para todo o intervalo de energia pelo qual o fluxo de neutrinos atmosféricos se estende. Integramos então o produto do fluxo de neutrinos atmosféricos pela seção de choque de detecção dos neutrinos e pela probabilidade de oscilação padrão de neutrinos atmosféricos e obtemos a distribuição angular de eventos em Super-Kamiokande. Através de análise de X2 obtivemos uma região permitida para os parâmetros de oscilação padrão de neutrinos atmosféricos, a diferença quadrática de massas, e o ângulo de mistura, sen2(2?23), compatível com a existente na literatura. Como um teste para oscilação não padrão introduzimos o modelo de neutrinos com massa variável(MaVaN¿s), no qual a massa dos neutrinos depende da densidade do meio. Tal efeito é obtido ao incluir um acoplamento do tipo Yukawa entre os neutrinos e um campo escalar neutro cuja concentração depende da densidade do meio. Estudamos como a inclusão deste efeito altera a probabilidade de oscilação Pµ?µ e, consequentemente, a descrição dos dados de Super-Kamiokande. Obtemos um limite para o parâmetro aMaV aN responsável pela intensidade deste novo efeito, sendo que soluções cuja intensidade do efeito de MaVaN é de 40% ou maior, em comparação com a intensidade da oscilação padrção são excluídas com 90% de nível de confiança
Abstract: In this work we obtain in a independent way the description of the angular distribution of atmospheric neutrino events as seen by the Super-Kamiokande collaboration for the events in the sub-GeV and multi-GeV range. As a first step in this description, we study the neutrino-nucleon charged current cross section for the hole energy range of the experiment, and obtain the number of neutrino events as a function of energy and zenith angle. Including neutrino oscillations in the picture allows us to describe the data from the Super-Kamiokande experiment. We obtain the allowed region for the oscillation parameters ?m223 and sin2(2?23) in reasonable agreement with the result found in the literature. As a test for a non-standard oscillation mechanism we introduce the concept of MaVaN (Mass Varying Neutrinos), derived from the coupling of the neutrinos with a neutral scalar who has its concentration depending of local matter density. The neutrino oscillation probability so changes from the standard oscillation with consequences for the allowed region of oscillation parameters. The parameter amavan describes the relative weight of usual oscillation terms and the MaVaN terms, being aMaV aN = 1 when the two terms are equal. We have found that aMaV aN should be smaller then 0,4 at 90 % C.L.
Doutorado
Física
Doutor em Ciências
17
Pascoal, Kellen Alves. "Neutrino-magnetohidrodinâmica, oscilações de neutrinos e instabilidades em plasmas." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2018. http://hdl.handle.net/10183/180517.
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Foi feita uma modificação da teoria magnetohidrodinâmica, incorporando a dinâmica dos neutrinos, chamada magnetohidrodinâmica de neutrinos. Elétrons e íons foram toma- dos como não-relativísticos, juntamente com os neutrinos eletrônicos (ultra) relativísticos acoplados via força eletro-fraca. Devido à ressonância com um feixe de neutrinos, foi prevista a desestabilização das ondas magnetosônicas rápidas. Admitindo modos oblí- quos, é possível detectar uma instabilidade que se torna mais forte quando o vetor de onda é paralelo ao campo magnético de equilíbrio, associando-se à onda magnetosônica lenta. Assumindo perturbações eletrostáticas em um plasma magnetizado composto por elétrons em um fundo iônico neutro, acoplado a neutrinos eletrônicos, foi considerado o papel desestabilizador dos feixes de neutrinos quanto aos modos de Trivelpiece-Gould. O campo magnético aumenta significativamente a taxa de crescimento linear, conforme cal- culado para os parâmetros de supernovas tipo II. Para o caso não magnetizado, a taxa de crescimento da instabilidade é encontrada para o vetor de onda paralelo ou perpendicular ao campo magnético substituindo-se a frequência de plasma pela frequência apropriada de Trivelpiece-Gould. Adicionalmente, considerou-se um modelo que combina as interações neutrino-plasma e as oscilações de sabores de neutrinos. Neste contexto, estudou-se o acoplamento entre ondas íon-acústicas e oscilações de sabores de neutrinos, obtendo-se uma nova instabilidade. Mostrou-se que a taxa de crescimento desta instabilidade não é modificada pela inclusão de efeitos colisionais.A modification of the magnetohydrodynamic theory was made incorporating the dyna- mics of neutrinos, called neutrino magnetohydrodynamics. Electrons and ions were taken as non-relativistic, along with (ultra) relativistic electron neutrinos coupled via electro- weak force. Due to the resonance with the neutrino beam the destabilization of the fast magnetosonic wave was predicted. Then, oblique modes were admitted, resulting in a detection of an instability, which becomes stronger when the wave vector is parallel to the equilibrium magnetic field, associating with the slow magnetosonic wave. For the simplest case, assuming electrostatic perturbations in a magnetized plasma composed of electrons on a neutral ionic background, coupled with electronic neutrinos, the destabilizing role of the neutrino beams in Trivelpiece-Gould modes was considered. The magnetic field signi- ficantly increases the linear growth rate, as calculated for type II supernova parameters. For the nonmagnetized case, the growth rate of instability is found for the wave vector parallel or perpendicular to the magnetic field, replacing the plasma frequency with the appropriate frequency of Trivelpiece-Gould. For oblique propagation the growth rate is also found. Subsequently, a model combining neutrino-plasma interactions and neutrino flavor oscillations was studied in the case of the coupling between the ion-acoustic wa- ves and the oscillations of neutrino flavors. When included collision effects, the rate of growth of instability has shown that the coupling between the ion-acoustic waves and the oscillations of neutrino flavors in a completely ionized plasma remain the same.
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Guillaud, Mathilde. "Neutrino oscillations at very high energy/matter density." Thesis, KTH, Fysik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-292510.
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Neutrino oscillations in matter can be studied in different regimes, depending on the energy of the incoming neutrinos and the matter density of the medium. In this thesis we investigate neutrino oscillations in dense matter at very high energy (TeV-PeV range), taking into account the absorption that the neutrinos may undergo in such dense media. This absorption phenomenon is relevant for neutrino telescope measurements of astrophysical neutrinos. We begin with a brief reminder on neutrino oscillations in vacuum and the construction of the PMNS matrix. Then, we proceed with calculations for dense matter. We then explore the accuracy of the resulting effective 2-neutrino mixing formulas. They present a good accuracy for Earth-like densities in our range of energies. We develop the calculations for oscillation probabilities in dense matter with absorption through charged-current inelastic scattering for both the two-neutrino and three-neutrino case. We find that in dense media, astrophysical neutrinos indeed undergoabsorption, which reduces signicantly the fluxes for each flavor, with a resonant absorption of electron-anti-neutrinos around E_{res}\simeq 6.3PeV. We discuss the impact of neutrino absorption in the Earth for neutrino telescopes measurements. We find that solar and lunar shadowing is not problematic for current telescopes but could be a good angular resolution indicator for new telescopes to come.Neutrinooscillationer i materia kan studeras i olika regimer beroende på inkommande neutrinernas energi och densiteten hos det bakomliggande mediet. I detta examensarbete undersöker vi neutrinooscillationer i gränsen av tät materia och mycket hög energi (TeV-PeV-intervall), och tar hänsyn till den absorption av neutriner som då kan inträffa i sådant materia. Detta absorptionsfenomen är relevant för neutrino-teleskopmätningar av astrofysiska neutriner. Vi börjar med att kort påminna oss om neutrinooscillationer i vakuum och konstruktionen av PMNS-matrisen. Vi försätter sedan med beräkningar av neutrinooscillationer i tät materia. Vi undersöker noggrannheten i resulterande effektiva 2-neutrino-blandningsformlerna. De uppvisar en god noggrannhet i jordlika materieprofiler i vårt intervall av energier. Vi utvecklar beräkningarna av oscillationssannolikheterna i tät materia inklusive absorption genom laddad ström oelastisk spridning i båda två- och tresmaksfallen. Vi finner att astrofysiska neutriner i tät materia absorberas, vilket minskar betydligt flödena för varje smak, med en resonansabsorption av elektron-antineutrino omkring E_res\simeq 6.3PeV. Vi diskuterar sedan effekterna av neutrinoabsorption på jorden för neutrino-teleskopmätningar. Vi finner att sol- och månskuggning är inte problematisk för nuvarande teleskop och kunde vara en bra vinkelupplösningsindikator för kommande teeskop.
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Pompa, Federica. "Neutrino physics with the XENONnT experiment." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amslaurea.unibo.it/19448/.
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One of the most active fields in physics is the search for Dark Matter, for which the XENON Project is one of the main protagonists. The new XENONnT experiment will be operative starting from 2020 in the underground Laboratori Nazionali del Gran Sasso, under 3600 meters water equivalent of mountain rock shield. It is a multi-ton detector for direct search of Dark Matter, consisting of a double phase liquid-gas xenon TPC which contains 5.9 t of liquid xenon target mass, inserted in a Cryostat surrounded by a tank containing 700 t of Gd-loaded water, instrumented with PMTs for muon and neutron tagging. Its aim, as that of its precursor XENON1T, is to detect WIMPs elastic scattering off xenon nucleus through the measure of the light and charge observable signals produced by recoils in LXe. A new neutron Veto system, surrounding the outer Cryostat and instrumented with 120 additional PMTs, will contribute to reduce the neutron background in the TPC. Thanks to the large xenon target used, this experiment is sensitive also to all flavors of Supernova neutrinos. These can be detected through two different interactions channels: through coherent elastic scatters on xenon nuclei in the TPC and through interactions of electron antineutrinos with protons of water via inverse beta decay process. In the first part of this work, after a theoretical introduction to neutrino physics, I present the results of a Monte Carlo simulation to predict the XENONnT detection efficiencies for neutrino events as IBD interactions in the neutron and muon Vetoes. In the last part of the thesis, I investigate the XENONnT possibility to detect neutrinoless double beta decay of Xe-136 isotope, a Standard Model forbidden decay which can prove the Majorana nature of neutrinos. Starting from evaluation of the ER background rate from Cryostat and PMTs in the energy region where we expect to observe neutrinoless double beta decay, the sensitivity of XENONnT for this nuclear decay was estimated.
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Boriero, Daniel Francisco 1981. "Cosmologia de neutrinos e o neutrino estéril como matéria escura." [s.n.], 2008. http://repositorio.unicamp.br/jspui/handle/REPOSIP/278601.
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Orientador: Pedro Cunha de HolandaDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin
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Resumo: Necessário na maioria das teorias para atribuir massa aos neutrinos e explicar o fenômeno de oscilação de sabores, o neutrino de mão direita, estéril em SU(2)L U(1)Y, é um candidato natural a matéria escura não bariônica. Cosmologicamente produzido via oscilação não ressonante de quiralidade do neutrino de mão esquerda e situado na categoria "Warm" de matéria escura, está atualmente desfavorecido como candidato a formar a totalidade da matéria escura. Apresentamos um cenário subdominante, no qual o neutrino estéril formaria apenas uma fração fs do total da matéria escura. Através da análise do sinal negativo do decaimento radiativo em raios-x difusos e ausência de supressão em estruturas de Lyman-a aplicadas na previsão de abundância gerada pelo modelo de massa n MSM, obtemos o limite de fs £ 0,65(2 s) em modelo cosmológico composto L (Ws +C)DM. Com esse resultado mostramos que o neutrino estéril ainda é um candidato viável para uma componente relativística da matéria escura, possível solução para o excesso de potência em pequena escala do modelo puramente "Cold".
Abstract: Needed in the most theories to confer mass to neutrinos and explain avour oscillations, the right-handed neutrino, sterile in SU(2)L U(1) Y , is a natural non-baryonic dark matter candidate. Cosmologicaly produced by non-resonant oscillattion with left-handed neutrinos and situated in the Warm regime, it's currently disfavored as composing the total dark matter. We present subdominant scenario where the sterile neutrino would compose only a fraction fs of the total dark matter, to constrain the model are utilized negative signals from diffuse X-Ray background and suppression from Lyman- a large scale structure applied to nMSM sterile neutrino theoretical production. We found the limit fs £ 0.65 (2 s) for a composed cosmological model L (Ws + C)DM. This result shows that the sterile neutrino is still a viable candidate for a relativistic component of dark matter and a possible solution to solve the excess power problem of the standard LCDM model in small scales.
Mestrado
Fisica das Particulas Elementares e Campos ; Cosmologia
Mestre em Física
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Godley, Andrew R. "A search for [nu mu to nu e] oscillations in the NOMAD experiment." Connect to full text, 2000. http://hdl.handle.net/2123/374.
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Thesis (Ph. D.)--University of Sydney, 2001.Squiggly right arrow used in title. Title from title screen (viewed Apr. 23, 2008). Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy to the School of Physics, Faculty of Science. Degree awarded 2001; thesis submitted 2000. Includes bibliography. Also available in print form.
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Pequignot, Maxime. "Les expériences Nucifer et Stéréo : étude des antineutrinos de réacteurs à courte distance." Thesis, Paris 11, 2015. http://www.theses.fr/2015PA112194/document.
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Interagissant très peu avec leur environnement, les neutrinos peuvent aujourd'hui être clairement détectés à l'aide d'une technologie largement éprouvée reposant sur l'utilisation de liquide scintillant et de photo-multiplicateurs. Les progrès réalisés ces dernières années permettent de réduire la taille et la complexité des détecteurs et laissent ainsi entrevoir les premières applications à ces particules. Première expérience placée à 7,2 m d'un coeur de réacteur nucléaire, le détecteur Nucifer démontre la possibilité de compter les antineutrinos venant du combustible à cette faible distance induisant un environnement très défavorable en terme de bruits de fond. Dans cette thèse, nous présentons l'analyse ayant permis de rejeter les différents bruits de fond venant du réacteur et de son circuit de désactivation mais aussi des muons atmosphériques. Une prédiction du taux d'antineutrinos avec différentes simulations Monte-Carlo a également été réalisée et se trouve en accord avec le taux mesuré dans la limite des incertitudes statistiques et systématiques. Sur près d'un an de prise de données, nous avons pu suivre l'évolution en puissance du réacteur Osiris. Une étude de sensibilité a montré que la présence de plutonium dans le coeur d'Osiris était détectable à 95 % CL dès que cet isotope contribue à hauteur de 10 % de la masse fissile (1,5 kg dans Osiris). En outre, le détecteur a montré une grande stabilité tout au long de la prise de données prouvant que le contrôle à distance des réacteurs nucléaires est possible. Cette expérience ouvre donc la voie à de nouveaux modes de contrôle des réacteurs nucléaires pour les autorités de sûreté. Dans le cadre des travaux sur les spectres d'antineutrinos émis par les réacteurs nucléaires, un déficit a récemment été mis en évidence dans le taux des antineutrinos mesurés pour les expériences à courte distance des réacteurs. Ce déficit, appelé anomalie réacteur, pourrait trouver son origine dans une nouvelle oscillation à travers un état stérile du neutrino à l'électronvolt. L'expérience Stéréo a pour but de trancher sur l'existence ou non de cette oscillation en se plaçant à 10 m du réacteur nucléaire de l'ILL. En observant une distorsion à la fois en énergie et en distance, le détecteur permettra en effet d'apporter une conclusion solide sur ce phénomène. Nous revenons ici sur le développement du projet et sur les différents choix technologiques réalisés pour améliorer la sensibilité de l'expérience. Une attention particulière est portée sur l'estimation des bruits de fond provenant du réacteur nucléaire ainsi que des expériences voisines utilisant des faisceaux de neutrons. Des mesures expérimentales alliées à des simulations ont permis de quantifier les flux de rayons gammas et de neutrons ainsi que leur direction afin de prévoir les blindages nécessaires. Enfin, nous présentons les performances du prototype correspondant à une cellule du détecteur finalIn spite of a faint interaction with their environment, neutrinos can be now clearly detected thanks to a proven technology based on liquid scintillators and photomultiplier tubes. The advances made these last years allow to reduce the size and the complexity of the detectors and therefore naturally lead to the first applications with these particles. As the first experiment to be placed at 7.2 m of a nuclear core, the Nucifer detector demonstrates the possibility of counting antineutrinos coming from the nuclear fuel at such a short baseline despite the very unfavourable environment in term of the background noises. In this thesis, we present an analysis which rejects the various background noises coming from the reactor and its deactivation circuit but also from the atmospheric muons. A prediction of the antineutrino rate with several Monte-Carlo simulations was also performed and is in good agreement with the measured rate, within statistical and systematic uncertainties. After nearly one year of data taking, we were able to follow the power evolution of the reactor Osiris. A sensibility study showed that the presence of plutonium in the Osiris core was detectable at 95 % CL as soon as this isotope contributes at the level of 10 % of the fissile mass (1,5 kg in Osiris). Besides, the detector was very stable throughout the data taking proving that the remote control of nuclear reactor with a neutrino detector is possible. Thus, this experiment opens the way to new control modes of nuclear reactors by the nuclear safety authorities. As part of the work on the antineutrino spectra emitted by nuclear reactors, a deficit was recently highlighted in the observed antineutrino rate for the experiments at short baseline. This deficit, called the reactor anomaly, could be explain by a new oscillation into a sterile state of the neutrino at the electronvolt scale. The Stereo experiment aims to test the existence of this oscillation by performing measurements 10 m away from the ILL nuclear reactor. By observing a distortion pattern of the energy and distance dependence of the neutrino spectrum, the detector will be able to provide a solid proof of this phenomenon. We present here the project development and the various technological choices that we have done to improve the experiment sensibility. The estimation of the background noise coming from the nuclear reactor as well as the nearby experiments using neutron beams has been performed with on-site measurements and simulations to design the shielding of the detector. Eventually we present the performances of the prototype which corresponds to one cell of the final detector
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Yildirim, Ihsan Ozan. "Measurement Of Neutron Background In Kuo-sheng Neutrino Laboratory." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614169/index.pdf.
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Particle physics experiments with low event rates highly depend on background suppression methods. Neutron component of the ambient background radiation is especially problematic since neutrons are difficult to shield directly. TEXONO collaboration has employed a hybrid neutron detector composed of two different scintillating materials to measure the neutron background directly in the Kuo-Sheng Neutrino Laboratory. Detector is operated after calibration and optimization studies and from collected data, neutron flux is obtained using computational methods.
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George, Jeffrey S. "Experimental study of the atmospheric [Nu][mu]/[Nu]e ratio in the multi-GeV energy range /." Thesis, Connect to this title online; UW restricted, 1998. http://hdl.handle.net/1773/9752.
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Paterson, David John Carleton University Dissertation Physics. "Studies of a novel method for solar neutrino neutral current detection in the Sudbury neutrino observatory." Ottawa, 1989.
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Terliuk, Andrii. "Measurement of atmospheric neutrino oscillations and search for sterile neutrino mixing with IceCube DeepCore." Doctoral thesis, Humboldt-Universität zu Berlin, 2018. http://dx.doi.org/10.18452/19304.
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Neutrinooszillation, ein Phänomen, das den Neutrino-Flavour nach ihrer Ausbreitung durch den Weltraum verändern kann, ist ein Beweis für nicht-verschwindende Neutrinomassen und ein Hinweis auf eine neue Physik außerhalb des Standardmodells. Diese Arbeit präsentiert die erste Messung zu atmosphärischen Neutrinooszillationen, die sechs Jahre zwischen Mai 2011 und Mai 2017 des IceCube DeepCore Experiment umfasst. Sie erweitert die bisher verfügbare Ereignisauswahl um eine neue Ereignissignatur und einen großeren Energiebereich. Diese Arbeit beschreibt die Methoden, die für die Simulationen der Wechselwirkungen der Neutrinos, die Ereignisauswahl, die Rekonstruktion und die statistische Behandlung von Messdaten und systematischen Messunsicherheiten benutzt werden. Die beste Abschätzung für die Neutrino-Mischungsparameter ist $\Delta m^2_{32} = 2.54^{+0.11}_{-0.12}\cdot 10^{-3}$~eV$^2$ und $\sin^2 \theta_{23} = 0.51\pm0.05$ (68\% C.L.) und gehört zurzeit zu den präzisesten Messungen atmosphärischer Neutrinos.
Darüber hinaus wird in dieser Arbeit das Standard-Drei-Flavour-Modell überprüft, indem ein steriles Neutrino mit einer Masse in der Größenordnung von 1 eV eingeführt wird. Die Suche nach Effekten steriler Neutrinos auf atmosphärischen Neutrinooszillationen wird auf drei Jahren Daten, genommen zwischen Mai 2011 und Mai 2014, durchgeführt. Die Ergebnisse stimmen mit dem Standard-Modell der Drei-Neutrino-Oszillation überein, was zu den Obergrenzen für sterilen Neutrino-Mischungsparameter $|U_{\mu4}|^2<0.11$ und $|U_{\tau4}|^2<0.15$ (90\% C.L.) für $\Delta m^2_{41}=1$~eV$^2$ führt. Dieser Ergebnis ist derzeit die stringenste Obergrenze für $|U_{\tau4}|^2$.Neutrino oscillations, a phenomenon that can change the flavour of neutrinos after their propagation through space, are a proof of non-zero neutrino masses and are an indication of new physics beyond the Standard Model. This work presents the first measurement of the atmospheric neutrino oscillations using six years of IceCube DeepCore data taken between May 2011 and May 2017. It extends the previously available event selection to include new event signatures and to use an extended energy range. This work discusses the techniques used for simulation of neutrino interactions, event selection, reconstruction, and the statistical treatment of data and systematic uncertainties. The best estimates for the neutrino mixing parameters are $\Delta m^2_{32} = 2.54^{+0.11}_{-0.12}\cdot 10^{-3}$~eV$^2$ and $\sin^2 \theta_{23} = 0.51\pm0.05$ (68\% C.L.), which are currently among the most precise measurements obtained with atmospheric neutrinos. In addition, this work tests the standard three-flavour paradigm by introducing one sterile neutrino with a mass on the order of 1~eV. The search for sterile neutrino effects in atmospheric neutrino oscillations is performed with three years of data taken between May 2011 and May 2014. The results are consistent with the standard three-neutrino oscillation picture, leading to limits on the allowed sterile neutrino mixing of $|U_{\mu4}|^2<0.11$ and $|U_{\tau4}|^2<0.15$ (90\% C.L.) for $\Delta m^2_{41}=1$~eV$^2$. Currently, the limit for $|U_{\tau4}|^2$ is the most stringent in the World.
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Blennow, Mattias. "Theoretical and Phenomenological Studies of Neutrino Physics." Doctoral thesis, Stockholm : Department of Theoretical Physics, Royal Institute of Technology, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4415.
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Heereman, von Zuydtwyck David. "HitSpooling: an improvement for the supernova neutrino detection system in icecube." Doctoral thesis, Universite Libre de Bruxelles, 2015. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209179.
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The IceCube Neutrino Observatory consists of a lattice of 5160 photomultiplier tubes (PMTs)which monitor one cubic kilometer of deep Antarctic ice at the geographic South Pole.
IceCube was primarily designed to detect neutrinos of energies greater than O(100 GeV).
Due to subfreezing ice temperatures, the photomultipliers' dark noise rates are particularly
low which enables IceCube to search for neutrinos from galactic supernovae by detecting
bursts of MeV neutrinos emitted during the core collapse and for several seconds following.
For that purpose, a dedicated online supernova DAQ system records the total number of hits
in the detector, without any further information from the PMTs, and generates supernova
candidate triggers in case of a significant detector rate enhancement. A new feature to the
standard DAQ, called HitSpooling, was implemented in IceCube during this thesis. The
HitSpooling system is implemented in the standard DAQ system and buffers the complete
raw data stream of the photomultipliers for several hours or days. By reading out time periods
of HitSpool data around supernova candidate triggers, generated by the online supernova
DAQ system, we overcome the limitations of the latter and have access to the entire information
of the detector in case of a supernova. Furthermore, HitSpool data is a powerful
source for studying and understanding the noise behavior of the detector as well as background
processes coming from atmospheric muons. The idea of HitSpooling was developed in the
scope of this thesis and is the basis of the work at hand. The developed interface between the
standard DAQ and the supernova DAQ system is presented. The correlated dark noise component
in optical modules of IceCube is quantified for the first time and possible explanations
are discussed. The possibility of identifying triggering and subthreshold atmospheric muons
in HitSpool data and subtracting them from a possible supernova signal is analyzed. Furthermore,
the conversion from HitSpool data to supernova DAQ type data was developed
which allows for a comparison of both data types with respect to lightcurves and significances
of selected supernova candidate triggers.
Doctorat en Sciences
info:eu-repo/semantics/nonPublished
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Roda, Marco. "Study of multiple vertices neutrino interactions in the OPERA experiment." Doctoral thesis, Università degli studi di Padova, 2016. http://hdl.handle.net/11577/3426767.
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OPERA is a long baseline neutrino experiment designed for tau neutrino searches in
an almost pure muon neutrino beam. The detection is performed on an event-by-event
basis which is possible thanks to the high spatial resolution of the detector.
In fact, the set-up is able to observe very short decaying particles produced
in neutrino interactions, such as tau or charmed particles. In particular, the
experiment searches for events with one secondary vertex within 1 mm from
the primary one.
An event was recorded with an unexpected topology: instead of one
secondary vertex it has two. Such an event was completely unexpected and
a totally new analysis was required in order to understand its nature. The
possibilities taken into account include most of the combinations of tau,
charmed particle and hadron re-interaction within the lead.
The new software, based on GEANT4, was set-up and successfully tested
using a dedicated OPERA test beam. Thus, an ad hoc Monte Carlo generation
was prepared in order to describe the properties of such a rare observation.
Finally, a sample having the interesting topology was obtained and a blind
procedure for the event identification could be developed.
The event turned out to be very likely an tau neutrino interaction with charm
production with a significance close to 3.5 sigma.OPERA è un esperimento per lo studio di neutrini da fascio progettato per ricerca di neutrini del tau in un fascio quasi puro di neutrini muonici. La ricerca è basata su un’analisi evento per evento che è resa possibile dall’elevata risoluzione spaziale del rivelatore. Infatti, l’apparato è in grado di osservare particelle emesse durante un’interazione di neutrino che decadono entro brevi distanze. In particolare, l’esperimento ricerca eventi che presentano vertici secondari entro circa un millimetro dal vertice primario di interazione. Un evento interessante è stato osservato con una topologia inaspettata: invece un solo vertice secondario ne sono stati osservati due. Questo tipo di eventi era completamente inaspettato e una nuova analisi era necessaria per capire la natura dell’evento. Le possibilità considerate includono quasi tutte le combinazioni di tau, particelle charmate e reinterazioni adroniche nel piombo. Un nuovo algoritmo di simulazione, basato su GEANT4, è stato sviluppato e testato con successo usando i dati di uno dei test beam di OPERA. Quindi, una nuova produzione Monte Carlo è stata preparata per poter descrivere le proprietà di questo raro fenomeno. Infine, è stata preparata un’analisi per l’identificazione dell’evento osservato. L’evento è risultato essere molto probabilmente un’interazione di neutrino del tau con produzione di charm, con una significanza di quasi 3.5 sigma.
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Thornewell, Peter Michael. "³He neutral current detectors for the Sudbury Neutrino Observatory." Thesis, University of Oxford, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.343004.
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Nakamura, Keigo. "Measurement of Neutrino Oscillation with a High Intensity Neutrino Beam." Kyoto University, 2019. http://hdl.handle.net/2433/236602.
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Prouse, Nicholas William. "The intermediate detector and neutrino phenomenology of the Hyper-Kamiokande experiment." Thesis, Queen Mary, University of London, 2018. http://qmro.qmul.ac.uk/xmlui/handle/123456789/46804.
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In this thesis, a number of aspects of neutrino oscillation physics are investigated, focusing on the design and phenomenology of next generation neutrino beam experiments. In working to optimise the sensitivity of the Hyper-Kamiokande experiment, new reconstruction software has been developed to meet the goal of fast, flexible reconstruction of particle positions, directions, energies and species. This is demonstrated for the TITUS intermediate detector, producing samples of neutrino interactions to constrain systematic uncertainties of oscillation analyses. Inclusion of these samples achieves a reduction of over 50% of systematic errors in measurements of 23 and and increases the parameter space for CP violation discovery after 10 years at 5 from 51% to 74%. A full analysis is presented of a potential neutron measurement at the E61 detector, including full simulations of all major backgrounds, a likelihood method of background removal, and a procedure for correcting for efficiency and backgrounds. Large, pure samples are produced, with the ability to accurately reproduce true distributions of neutron capture multiplicity, distance and angle relative to neutrino interactions, with true and reconstructed distributions agreeing within 2%. The sensitivities of Hyper-Kamiokande, including with a possible second tank in Korea, in combination with the DUNE experiment, have been thoroughly investigated. Several areas of strong synergy are identified, with the optimal combination of experiments possessing the ability to definitively resolve all remaining unknowns of 3-neutrino oscillations: determining both the octant of 23 and the mass-ordering in under 2 years and discovering CP violation at 5 for 50% of parameter space after 5 years. The highly predictive Littlest Seesaw flavour models of neutrino masses and mixing are tested against current oscillation data, finding no tension even at 1 . The ability of the next-generation experiments' oscillation measurements to probe these models is investigated, with all strands of the programme, including long baseline beam experiments and short and medium baseline reactor experiments, found to show high potential to exclude the models both individually and in combination.
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Bartet--Friburg, Pierre. "Mesure de la section efficace d'interaction des neutrinos muoniques par courant chargé sur du carbone, sans production de pions dans l'état final et en fonction de la multiplicité et de la cinématique des particules produites, en utilisant le détecteur proche de T2K." Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066351/document.
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Depuis la confirmation de l’existence du boson de Higgs et avec l’absence de signes de nouvelle physique au LHC, les oscillations des neutrinos sont parmi les seules à offrir des perspectivesd’observation et de mesure de phénomènes de nouvelle physique au delà du modèle standard.Le premier chapitre de cette thèse introduit le concept d’oscillation de saveur des neutrinospuis décrit l’état de l’art des connaissances ainsi que les perspectives expérimentales pour mesurer ou observer les pièces manquantes.Pour obtenir des résultats significatifs, ces futures expériences auront besoin de pouvoir profiter d’une meilleure compréhension des processus d’interaction des neutrinos. Le second chapitre décrit ces interactions d’un point de vu théorique.Le troisième chapitre présente l’expérience T2K ainsi que ses résultats sur les oscillationsdes neutrinos. Le quatrième décrit plus précisément le détecteur proche de T2K (ND280) etl’usage qu’on en fait dans les analyses d’oscillations.La couverture angulaire de la sélection des interactions dans le détecteur proche de T2K estlimitée par rapport à celle, complète, du détecteur lointain. Le chapitre 5 décrit deux sélections visant à améliorer cette couverture, ainsi que celle utilisée pour réaliser, dans le cadre de cette thèse, la mesure de la section efficace d’interaction des neutrinos muoniques par courant chargé sur le carbone sans production de pions dans l’état final.Le chapitre 6 décrit cette mesure, conçue pour ne pas dépendre de modèles théoriques d’interaction, et réalisée pour la première fois en fonction du nombre de protons éjectés et de leur cinématique. Les résultats sont montrés dans le chapitre 7Since the Higgs boson discovery and the absence of hints pointing to new physics at the LHC, neutrinos oscillations are one of the only perspectives to observe new physics phenomenon beyond the standard model. The first chapter of this thesis introduces the concept of neutrino flavour oscillation before describing the state of the art knowledges as well as the experimental perspectives of observing or measuring the missing parts.To obtain significant results, those future experiments will need a better understanding of neutrino interactions. The second chapter describes these interactions from a theoretical point of view. The third one describes the T2K experiment and its main results on neutrino oscillations. Chapter four focus on the T2K near detector (ND280) and on how it is used within neutrino oscillations analysis. The angular acceptance of the current ND280 selection is limited compared to the far detector one. Chapter 5 describes two selections developed in order to improve this angular acceptance. This chapter also describes the selection used to carry out this thesis main work : the cross-section measurement of muon neutrino charged current interactions on Carbon, with no pions in the final state and as a function of the outgoing particles multiplicity and kinematics. Chapter six describes this measurement, designed to be as model independent as possible, and made for the first time as a function of the protons multiplicity and of their kinematic. The results are shown in chapter seven
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Coleman, Stephen James. "A measurement of neutrino oscillations with muon neutrinos in the MINOS experiment." W&M ScholarWorks, 2011. https://scholarworks.wm.edu/etd/1539623581.
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Experimental evidence has established that neutrino flavor states evolve over time. A neutrino of a particular flavor that travels some distance can be detected in a different neutrino flavor state. The Main Injector Neutrino Oscillation Search (MINOS) is a long-baseline experiment that is designed to study this phenomenon, called neutrino oscillations. MI-NOS is based at Fermilab near Chicago, IL, and consists of two detectors: the Near Detector located at Fermilab, and the Far Detector, which is located in an old iron mine in Soudan, MN. Both detectors are exposed to a beam of muon neutrinos from the NuMI beamline, and MINOS measures the fraction of muon neutrinos that disappear after traveling the 734 km between the two detectors. One can measure the atmospheric neutrino mass splitting and mixing angle by observing the energy-dependence of this muon neutrino disappearance. MINOS has made several prior measurements of these parameters.;Here I describe recently-developed techniques used to enhance our sensitivity to the oscillation parameters, and I present the results obtained when they are applied to a dataset that is twice as large as has been previously analyzed. We measure the mass splitting Dm223=&parl0;2.32+0.12 -0.08&parr0; x 10-3 eV²/c4 and the mixing angle sin²(2theta32) > 0.90 at 90% C.L. These results comprise the world's best measurement of the atmospheric neutrino mass splitting. Alternative disappearance models are also tested. The neutrino decay hypothesis is disfavored at 7.2sigma and the neutrino quantum decoherence hypothesis is disfavored at 9.0sigma.
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Garza, Juan Pablo Yáñez. "Measurement of neutrino oscillations in atmospheric neutrinos with the IceCube DeepCore detector." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2014. http://dx.doi.org/10.18452/17016.
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Neutrinooszillationen sind ein sehr aktives Forschungsfeld. In den letzten Jahrzehnten haben viele Experimente das Phänomen untersucht und sind inzwischen zu Präazisionsmessungen vorangeschritten. Mit seiner Niederenergieerweiterung DeepCore kann das IceCube-Experiment zu diesem Forschungsfeld beitragen. IceCube ist ein 1 km^3 großes Tscherenkow-Neutrino-Teleskop, welches das tiefe, antarktische Eis des Südpols als optisches Medium nutzt. DeepCore ist eine Erweiterung mit dichterer Instrumentierung im unteren Teil des IceCube-Teleskops. Diese dichte Instrumentierung ermöglicht den Nachweis von Neutrinos mit Energien ab einer Energieschwelle von etwa 10 GeV. Jedes Jahr werden Tausende von atmosphärischen Neutrinos oberhalb dieser Schwelle in DeepCore detektiert. Eine Bestimmung der Energie der Neutrinos und des durch sie zurückgelegten Weges durch die Erde ermöglicht die Messung von Neutrinooszillationen. In dieser Arbeit werden zunächst die Möglichkeiten von DeepCore diskutiert, Oszillationen auf unterschiedliche Weise zu messen. Das Verschwinden von Myon-Neutrinos wird als erfolgsversprechender Prozess ausgewählt. Darauf folgt die Beschreibung einer Methode zur Identifizierung von Tscherenkow-Photonen, welche detektiert wurden, bevor sie gestreut wurden -sogenannte- direkte Photonen. Mit Hilfe dieser Photonen kann der Zenitwinkel der Myon-Neutrinos bestimmmt werden. Auch die Energie der Neutrinos wird rekonstruiert. In den Jahren 2011 und 2012 wurden innerhalb von 343 Tagen mit dieser Analyse 1487 Neutrinokandidaten mit Energien zwischen 7 GeV und 100 GeV in DeepCore gefunden. Vergleicht man diese Zahl mit der erwarteten Zahl vom atmosphärischen Neutrinofluss ohne Oszillationen, so ergibt sich ein Defizit von etwa 500 Ereignissen. Die Osziallationsparameter, die die Daten am besten beschreiben, sind im Einklang mit den Parametern, die von anderen Experimenten veröffentlicht wurden.The study of neutrino oscillations is an active field of research. During the last couple of decades many experiments have measured the effects of oscillations, pushing the field from the discovery stage towards an era of precision and deeper understanding of the phenomenon. The IceCube Neutrino Observatory, with its low energy subarray, DeepCore, has the possibility of contributing to this field. IceCube is a 1 km^3 ice Cherenkov neutrino telescope buried deep in the Antarctic glacier. DeepCore, a region of denser instrumentation in the lower center of IceCube, permits the detection of neutrinos with energies as low as 10 GeV. Every year, thousands of atmospheric neutrinos around these energies leave a strong signature in DeepCore. Due to their energy and the distance they travel before being detected, these neutrinos can be used to measure the phenomenon of oscillations. This work starts with a study of the potential of IceCube DeepCore to measure neutrino oscillations in different channels, from which the disappearance of muon neutrinos is chosen to move forward. It continues by describing a novel method for identifying Cherenkov photons that traveled without being scattered until detected direct photons. These photons are used to reconstruct the incoming zenith angle of muon neutrinos. The total energy of the interacting neutrino is also estimated. In data taken in 343 days during 2011-2012, 1487 neutrino candidates with an energy between 7 GeV and 100 GeV are found inside the DeepCore volume. Compared to the expectation from the atmospheric neutrino flux without oscillations, this corresponds to a deficit of about 500 muon neutrino events. The oscillation parameters that describe the data best are in agreement with the results reported by other experiments. The method and tools presented allow DeepCore to reach comparable precision with the current best results of on-going experiments once five years of data are collected.
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Ratz, Michael. "Running neutrino masses." [S.l.] : [s.n.], 2002. http://deposit.ddb.de/cgi-bin/dokserv?idn=965203654.
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Flohr, Jamin. "Massless neutrino mixing /." [St. Lucia, Qld.], 2006. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe19503.pdf.
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Biron, von Curland Alexander. "Search for atmospheric muon neutrinos and extraterrestric neutrino point sources in the 1997 AMANDA-B10 data." [S.l.] : [s.n.], 2002. http://deposit.ddb.de/cgi-bin/dokserv?idn=964841223.
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Bourret, Simon. "Neutrino oscillations and earth tomography with KM3NeT-ORCA." Thesis, Sorbonne Paris Cité, 2018. http://www.theses.fr/2018USPCC247.
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Les oscillations de saveur des neutrinos, découvertes au tournant du 21ème siècle, constituent à ce jour le signe le plus direct de physique au-delà du Modèle Standard. La collaboration KM3NeT a commencé la construction d'un détecteur à effet Tcherenkov de neutrinos au fond de la mer Méditerranée: ORCA (Oscillation Research with Cosmics in the Abyss). Le but principal d'ORCA sera la détermination de la hiérarchie de masse des neutrinos, un paramètre fondamental, encore inconnu, du modèle théorique des oscillations de neutrinos. Le principe de la mesure est la détection d'un large échantillon de neutrinos atmosphériques ayant traversé la Terre, et l'analyse de leurs oscillations de saveur. Ces oscillations sont modifiées et augmentées par les effets de matière, dus à la présence d'une densité d'électrons le long de la trajectoire des neutrinos. Au-delà de la hiérarchie de masse et de la mesure des paramètres d'oscillation atmosphériques, ORCA sera alors capable de mesurer la densité en électrons et donc, en principe, de fournir des informations nouvelles sur la composition chimique des couches profondes de la Terre. Cette thèse présente une nouvelle étude, menée au sein de la collaboration KM3NeT, de la sensibilité d'ORCA à la détermination de la hiérarchie de masse des neutrinos, aux paramètres d'oscillations atmosphériques, et à la densité en électrons dans le noyau externe et le manteau inférieur de la Terre. La thèse se concentre sur le développement d'une nouvelle méthode d'analyse dont le but est de rendre compte de la réponse du détecteur de la manière la plus précise possible. Pour cela, la méthode est basée sur l'utilisation de matrices de réponses corrélées et construites à partir de simulations Monte Carlo. Les méthodes statistiques et sources d'incertitude systématique sont aussi étudiées en détail. La méthode développée permet une première exploration de nouvelles stratégies d'analyse optimisées. Les études de sensibilité montrent qu'ORCA atteindra une sensibilité médiane à la hiérarchie de masse d'au moins 3 sigma après quelques années d'opération, le résultat dépendant en grande partie de la valeur réelle de la hiérarchie de masse et des autres paramètres d'oscillation encore inconnus. Une performance compétitive pour la mesure des paramètres d'oscillation atmosphériques est aussi attendue. Dans le cas où la hiérarchie de masse est normale et après 10 ans de prise de données, la densité en électrons pourra être mesurée avec une précision d'environ 5% dans le manteau inférieur, et 7% dans le noyau externeNeutrino flavour oscillations, discovered at the turn of the 21st century, currently provide the most direct window on physics beyond the Standard Model. The KM3NeT collaboration has started the construction of a megaton-scale Cherenkov neutrino detector deep underwater in the Mediterranean: ORCA (Oscillation Research with Cosmics in the Abyss). ORCA's main goal will be the determination of the neutrino mass hierarchy, a major unknown in the current understanding of neutrino oscillations, via the detection of large samples of atmospheric neutrinos crossing the Earth and the analysis of their flavour oscillations. These oscillations are enhanced by matter effects, sensitive to the electron density along the neutrino paths. Beyond the neutrino mass hierarchy and the measurement of atmospheric oscillation parameters, this will allow ORCA to measure the electron density of the deep Earth, and possibly provide constraints on the chemical composition of its innermost layers. This thesis presents a new study, undertaken within the KM3NeT collaboration, of the sensitivity of ORCA to the determination of the neutrino mass hierarchy, oscillation parameters, and the electron density in the outer core and lower mantle of the Earth. The focus is given to the development of a new analysis methodology intended to account for detector effects as precisely as possible by the use of a Monte Carlo based correlated model of detector response. Statistical methods and systematic uncertainties are also addressed in some detail. The methodology allows for a preliminary exploration of the potential of improved analysis strategies. Sensitivity studies show that ORCA is expected to achieve a median sensitivity to the NMH determination at the level of 3 sigma or better after a few years of operation, depending on the true hierarchy and true value of the oscillation parameters. Competitive performance for the measurement of atmospheric oscillation parameters is also expected. Assuming a normal mass hierarchy, the electron density can be measured with a precision of about 5% in the lower mantle, and 7% in the outer core
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Castillo, Fernández Raquel. "Measurement of the Muon Neutrino Charged Current interactions and the muon neutrino single pion cross section on CH using the T2K near detector." Doctoral thesis, Universitat Autònoma de Barcelona, 2015. http://hdl.handle.net/10803/305239.
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El experimento T2K es un experimento de neutrinos de largo recorrido
que utiliza un haz casi puro the neutrinos muónicos. El objetivo
principal del experimento es a medida de los parámetros de
oscilación del neutrino muónicos. Para conseguir éste
objetivo, T2K necesita una rigurosa predicción del índice de
interacciones en el detector lejano, Super-KamiokaNDE. El detector
cercano de T2K, ND280, calcula el índice de interacciones y estima
el número de eventos en el detector lejano.
Las interacciones de neutrino muónico de corriente cargada en el
detector cercano (ND280) son usadas para predecir el índice de
eventos en el detector lejano (Super-KamiokaNDE). Para una mejor
restricción de los parámetros de sección eficaz, los
cuales dominan el análisis junto con las incertezas de la
prediccion del flujo, categorizamos los eventos seleccionados en tres
grupos de acuerdo con el número de piones en el estado
final. Estas tres categorías permiten un mejor ajuste de la
señal del canal de oscilación (Corriente Cargada
Quasielástica) y el principal ruído en oscilaciones (Corriente
Cargada de 1 Pión Cargado).
Actuales y futuros experimentos de neutrinos están limitados por
las incertezas en las secciones eficaces de neutrinos. Los modelos
actuales de sección eficaz están en tension con los datos
experimentales en algunos rangos energéticos. Esto hace que sea
critico estudiar secciones eficaces de neutrino--nucleo en todos los
canales de interacción posibles. La producción the un solo
pión en interacciones de neutrino muónico de corriente cargada
es uno de los principales canales en tensión con los modelos. Como
segunda contribución, presentamos el cálculo de producción
the un solo pión en interacciones de neutrino muónico de
corriente cargada usando un enfoque indepenediente del modelo
explorando la capacidad total del detector ND280 para establecer las
distribuciones cinemáticas del evento. La mejore del conocimiento
de las interacciones, y en concreto del canal de producción de un
sólo pión, permitirá la reducción de las
incertidumbres sistemáticas en el análisis de oscilaciones.The T2K experiment is a long baseline neutrino experiment which utilizes an almost pure muon neutrino beam. The main goal of the experiment is the measurement of the oscillation parameters of the muon neutrinos. In order to achieve this goal, T2K requires an accurate prediction of the interaction rates in the far detector, Super-KamiokaNDE. The near detector of T2K, ND280, measures the interaction rates and estimates the number of events at the far detector. The muon neutrino charged current interactions in the near detector (ND280) are used to predict the rate at the far detector (Super-KamiokaNDE). To a better constrain of the cross section parameters, which are dominant in the analysis together with the flux uncertainty, we categorize the selected events in three different samples according to the number of pions in the final state. These categories allow for a better constrain of the oscillation signal channel (Charged Current Quasielastic) and the main oscillation background (Charged Current 1 Charged Pion). Current and future neutrino experiments are limited by neutrino cross section uncertainties. The actual cross section models are in tension with the experimental data in some energy ranges. It is still critical to study neutrino-nucleus cross sections on all possible interaction channels. The muon neutrino charged current single pion production is one of the main channels in tension with the model. As a second contribution, we present the measurement of the Charged Current single positive pion production cross section using a model independent approach exploring the full capability of the ND280 detector to determine the kinematical distributions of the event. The improved knowledge of the interactions, and in concrete for the single pion channel, will allow the reduction of the the systematical uncertainties in the oscillation analysis.
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Minaeva, Yulia. "Serch for Neutralino Dark Matter with the AMANDA-II Neutrino Telescope." Doctoral thesis, Stockholm University, Department of Physics, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-137.
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The annihilation of weakly interacting massive particles (WIMPs), accumulated in gravitational potentials (e.g., the core of the Earth, the Sun or the Galactic halo) would lead to neutrino production. This thesis investigates the possibility of searching for WIMPs in the form of the lightest supersymmetric particle (neutralino) trapped in the Sun using the AMANDA-II neutrino telescope. AMANDA-II is a large Cherenkov detector located deep in the ice at the geographical South Pole. The presented work is based on data taken during the year 2001. An analysis optimized to search for the neutralino-induced flux from the Sun has been developed. The observation of no excess with respect to the expected atmospheric neutrino background has been interpreted as an upper limit on the neutralino annihilation rate in the Sun and on the neutralino-induced muon flux in the vicinity of the detector.
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Elieff, Stefan H. P. "Determining properties of neutralino dark matter using high-energy neutrino events." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape15/PQDD_0014/MQ33841.pdf.
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Minaeva, Yulia S. "Search for neutralino dark matter with the AMANDA-II neutrino telescope /." Stockholm : Fysikum, Univ, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-137.
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Ehrlich, Ralf. "The search for neutralino dark matter with the AMANDA neutrino telescope." College Park, Md.: University of Maryland, 2008. http://hdl.handle.net/1903/9224.
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Thesis (Ph.D.) -- University of Maryland, College Park, 2008.Thesis research directed by: Dept. of Physics. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Shiraishi, Kiyoshi Keola. "Super-kamiokande atmospheric neutrino analysis of matter-dependent neutrino oscillation models /." Thesis, Connect to this title online; UW restricted, 2006. http://hdl.handle.net/1773/9771.
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Tapia, Herrera Luis Carlos 1982. "Fenomenologia dos decaimentos de neutrinos de supernova." [s.n.], 2011. http://repositorio.unicamp.br/jspui/handle/REPOSIP/278537.
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Orientador: Orlando Luis Goulart PeresDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin
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Resumo: Apresentamos neste trabalho um estudo da fenomenologias dos neutrinos, que inicia com um modelo além do Modelo Padrão, que gera massa e decaimento para os neutrinos. O modelo foi proposto por Gelmini e Roncadelli [3], no modelo é introducido um tripleto escalar que interage com o dubleto de Higgs a través de um potencial escalar. O tripleto interage também com os leptons da teoria a través de um potencial de Yukawa, é este potencial que conjuntamente com a quebra espontânea da simetria gera as massas e decaimentos para os neutrinos. O modelo foi descartado experimentalmente mas modelos mais gerais que estão baseados no modelo de Gelmini e Roncadelli, ainda podem ser testados experimentalmente. Como seguinte passo no nosso trabalho, estudamos os fluxos de neutrinos de Supernovas que aconteceram no passado do Universo e que chegam até à Terra. Estudamos os efeitos de oscilação na matéria, por causa de que o neutrino atravessa médios de densidades altas dentro da Supernova. Fizemos a comparação dos fluxos de neutrinos e antineutrinos eletrônicos, levando em conta dois casos com e sem oscilação. Encontramos que a oscilação faz com que o fluxo de neutrinos e antineutrinos seja menor, e mais quente para energias maiores a 10 MeV. Estudamos conjuntamente o decaimento e suas consequencias no fluxo de neutrinos de Supernova relíquia. Encontramos uma forte dependência com a hierarquia de massas dos neutrinos. Concluímos que se a hierarquia de massas é normal, o decaimento faz com que o fluxo de neutrinos e antineutrinos eletrônicos seja incrementado. Se a hierarquia é invertida encontramos que o fluxo dos dois tipos de neutrinos é suprimido. Fizemos também uma comparação dos fluxos obtidos neste trabalho, com valores de fluxos reportados na literatura. Finalmente estudamos o comportamento do número de eventos dos fluxos de neutrinos e antineutrinos eletrônicos, para distintos tempos de vida dos neutrinos
Abstract: Here we present a study of the phenomenology of neutrinos, which starts with a model beyond the Standard Model, which generates mass and decay to neutrinos. The model was proposed by Gelmini and Roncadelli cite Gelmini: 1981, the model needs a triplet that interacts with the scaling doublet Higgs through different potential climb. The triplet also interacts with leptons theory through different potential of Yukawa, is this potential which, together with spontaneous symmetry breaking generates the masses and decays to neutrinos. The model was experimentally ruled out but more general models that are based on the model of Gelmini and Roncadelli, can still be tested experimentally. As a next step in our work, we study the flow of neutrinos from supernovae that happened in the past of the universe and reach the Earth. We studied the effects of oscillations in matter, because of the neutrino cross mean high densities within the Supernova. We compared the flow of neutrinos and antineutrinos electronics, taking into consider two cases with and without oscillation. We have found that the oscillation causes the flux of neutrinos and antineutrinos is smaller and warmer to higher energies to 10 MeV We studied together and the decay and its consequences in the flow of neutrinos from supernova relic. We find a strong dependence on the hierarchy mass of neutrinos. We conclude that if the hierarchy is normal masses, the decay is that the flux of neutrinos and electronic antineutrinos is incremented. If the hierarchy is found that the reverse flow of the two types of neutrinos is deleted. We also a comparison of fluxes obtained in this work, with values of flows reported in the literature. Finally we study the behavior of the number of events flows of neutrinos and antineutrinos electronics, for different lifetimes of neutrinos
Mestrado
Física
Mestre em Física
47
Boriero, Daniel Francisco 1981. "Fenomenologia de neutrinos massivos em cosmologia." [s.n.], 2013. http://repositorio.unicamp.br/jspui/handle/REPOSIP/278586.
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Orientador: Pedro Cunha de HolandaTese (doutorado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin
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Resumo: Cosmologia de neutrinos é a atividade de pesquisa dedicada ao teste de propriedades de neutrinos através de observáveis cosmológicos. Particularmente, as propriedades estudadas e testadas ao longo desta tese de doutorado foram à massa dos neutrinos e o número de estados estéreis. Ambas as propriedades são motivadas pela observação em experimentos terrestres do fenômeno de oscilação entre estados de interação. Diferentemente da existência de estados massivos, os indícios da existência de estados estéreis são tenuemente sugeridos, contudo ambas as propriedades representariam um grande impacto no modelo cosmológico caso sejam observados sinais positivos de suas existências e por esse motivo justificam-se suas análises. A utilização da cosmologia como um laboratório de física de neutrinos é possível graças à imensa abundância de neutrinos remanescentes do universo primordial além da sensibilidade sem precedentes das observações realizadas. Telescópios e detectores em planejamento ou em implementação supostamente alcançarão a sensibilidade equivalente aos valores mínimos das massas determinados pelo fenômeno de oscilação. A perspectiva de tais sensibilidades experimentais deve ser acompanhada pelo aumento equivalente da precisão obtida nas previsões teóricas dos efeitos pelos quais pretende-se detectar a presença de neutrinos massivos ou de estados estéreis. Nesta tese de doutorado, além de ser detalhadamente desenvolvida a teoria e a metodologia convencionais na análise de dados cosmológicos para obtenção de medidas ou limites para estes dois parâmetros, também foram desenvolvidos métodos para aumentar a precisão da previsibilidade teórica. Foram abordados dois desafios teóricos prementes, a imprecisão das previsões no regime não-linear de perturbação para neutrinos massivos e a degenerescência em relação aos parâmetros de modelos cosmológicos estendidos. As melhorias obtidas não compõem soluções definitivas, mas sim metodologias a serem desenvolvidas sistematicamente ao longo da obtenção de novos dados reais e simulados.
Abstract: Neutrino cosmology is the research activity dedicated to test neutrino properties by cosmological observables. Specially, the properties studied and tested along this graduate research were the neutrino mass and the sterile states. Both properties are motivated from observations in terrestrial experiments of the phenomenon of oscillation between interaction states. Differently from the existence of massive states, the signals of sterile states are weakly suggested, however both properties would mean a sizeable impact in the cosmological model in case any positive signal is detected and, therefore, their analysis are justified. The utilization of cosmology as a laboratory of neutrino physics is possible thanks to the high abundance of remaining neutrinos from the primordial universe, besides the unprecedented sensitivity of experimental observations. Telescopes and detectors planned or under construction will supposedly reach the sensitivity equivalent to the minimal neutrinos masses given by the oscillation phenomenum. The perspective of such experimental sensitivities must be followed by the equivalent improvement in the theoretical predictability for the effects with which it is intended to detect a positive signal of massive neutrinos or sterile states. In this Ph.D. Thesis, besides being developed in detail the theory and methodology used in the analysis of cosmological data to measure or constrain these two parameters, we also developed methods and tools to improve the theoretical predictability. Two pressing theoretical challenges were addressed, the imprecision of the predictions in the non-linear regime of perturbations for massive neutrinos and the degeneracy related to parameters of extended cosmological models. The improvements obtained do not make up a definitive solution, but rather methodologies to be systematically developed along with the achivement or the eventuality of new real and simulated data.
Doutorado
Física
Doutor em Ciências
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Chang, Pi-Jung. "Double Chooz neutrino detector: neutron detection systematic errors and detector seasonal stability." Diss., Kansas State University, 2013. http://hdl.handle.net/2097/16861.
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Doctor of PhilosophyDepartment of Physics
Glenn Horton-Smith
In March 2012, the Double Chooz reactor neutrino experiment published its most precise result so far: sin[superscript]2 2theta13 = 0.109 +/- 0.030(stat.) +/- 0.025(syst.). The statistical significance is 99.8% away from the no-oscillation hypothesis. The systematic uncertainties from background and detection efficiency are smaller than the first publication of the Double Chooz experiment. The neutron detection efficiency, one of the biggest contributions in detection systematic uncertainties, is a primary topic of this dissertation. The neutron detection efficiency is the product of three factors: the Gd-capture fraction, the efficiency of time difference between prompt and delayed signals, and the efficiency of energy containment. [superscript]252 Cf is used to determine the three factors in this study. The neutron detection efficiency from the [superscript]252 Cf result is confirmed by the electron antineutrino data and Monte Carlo simulations. The systematic uncertainty from the neutron detection efficiency is 0.91% used in the sin[superscript]2 2theta13 analysis. The seasonal variation in detector performance and the seasonal variations of the muon intensity are described in detail as well. The detector stability is confirmed by observation of two phenomena: 1) the [electron antineutrino] rate, which is seen to be uncorrelated with the liquid scintillator temperature, and 2) the daily muon rate, which has the expected correspondence with the effective atmospheric temperature. The correlation between the muon rate and effective atmospheric temperature is further analyzed in this thesis to determine the ratio of kaon to pion in the local atmosphere. An upper limit on instability of the neutron detection efficiency is established in the final chapter. The systematic error, 0.13%, from the relative instability is the deviation of the calibration runs. This thesis concludes with the potential systematic errors of neutron detection efficiency and estimation of how these potential systematic errors affect the result of sin[superscript]2 2theta13.
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Sibille, Valérian. "Mesure de l'angle de mélange θ₁₃ avec les deux détecteurs de Double Chooz." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLS582/document.
Full textAbstract:
L'expérience Double Chooz a pour but de mesurer l'angle de mélange leptonique θ₁₃ avec précision. Pour ce faire, l'expérience met à profit deux détecteurs identiques -- remplis de liquide scintillant dopé au gadolinium -- afin d'étudier les $antinue$ produits par les deux réacteurs nucléaires de 4.25GWth de la centrale de Chooz. Le détecteur lointain -- situé à une distance moyenne de $SI{1050}{m}$ des coeurs -- prend des données depuis Avril 2011. Le détecteur proche -- à une distance moyenne de 400m des coeurs -- observe les réacteurs depuis Décembre 2014. Le paramètre de mélange θ₁₃ conduit à la disparition d'$antinue$, lorsque ceux-ci voyagent des coeurs jusqu'aux sites de détection; la dépendance en énergie de ce déficit permet d'extraire la valeur de sin² 2θ₁₃, par ajustement. Les systématiques de détection, ainsi que l'incertitude sur la prédiction du flux $antinue$, sont formidablement réduites par le biais de corrélations entre les détecteurs et la configuration iso-flux du site. Par conséquent, la précision relative à la mesure de θ₁₃ est dominée par les incertitudes sur les bruits de fond et sur la normalisation relative des taux d'$antinue$. Le bruit de fond principal provient de la désintégration des émetteurs βn -- produits par spallation des muons -- dans le détecteur lui-même. Les spectres de ces isotopes cosmogéniques ont été simulés et complétés par un traitement d'erreur rigoureux. Ces prédictions sont en bon accord avec les données, elles-mêmes extraites à l'aide d'un veto actif, dont la performance a été étudiée pour les deux sites. Le taux d'évènements cosmogéniques restant parmi les candidats $antinue$ a également été estimé. En outre, la normalisation relative du taux d'$antinue$, liée aux nombres de protons dans les cibles de chaque détecteur, a été évaluée. Tous ces travaux se sont inscrits au sein des premières analyses Double Chooz à l'aide de deux détecteurs, produisant sin² (2θ₁₃) = 0.111±0.018The Double Chooz experiment aims at accurately measuring the value of the leptonic mixing angle θ₁₃. To this intent, the experiment makes the most of two identical detectors -- filled with gadolinium-loaded liquid scintillator -- observing $antinue$'s released by the two 4.25GWth nuclear reactors of the French Chooz power plant. The so-called "far detector" -- located at an average distance of 1050m from the two nuclear cores -- has been taking data since April 2011. The "near detector" -- at an average distance of 400}m from the cores -- has monitored the reactor since December 2014. The θ₁₃ mixing parameter leads to an energy dependent disappearance of $antinue$'s as they propagate from the nuclear cores to the detection sites, which allows for a fit of the sin² 2θ₁₃ value. By reason of correlations between the detectors and an iso-flux site layout, the detection systematics and the $antinue$ flux uncertainty on the θ₁₃ measurement are dramatically suppressed. In consequence, the precision of the θ₁₃ measurement is dominated by the uncertainty on the backgrounds and the relative normalisation of the $antinue$-rates. The main background originates from the decay of βn-emitters -- generated by $mu$-spallation -- within the detector itself. The energy spectra of these cosmogenic isotopes have been simulated and complemented by a diligent error treatment. These predictions have been successfully compared to the corresponding data spectra, extracted by means of an active veto, whose performance has been studied at both sites. The rate of cosmogenic background remaining within the $antinue$ candidates has also been assessed. Addtionally, the normalisation of the $antinue$ rates, bound to the number of target protons within each detector, has been evaluated. All these works were part of the first Double Chooz multi-detector results, yielding sin² (2θ₁₃) = 0.111±0.018
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Bhattacharya, Atri, Rikard Enberg, Yu Seon Jeong, C. S. Kim, Mary Hall Reno, Ina Sarcevic, and Anna Stasto. "Prompt atmospheric neutrino fluxes: perturbative QCD models and nuclear effects." SPRINGER, 2016. http://hdl.handle.net/10150/622473.
Full textAbstract:
We evaluate the prompt atmospheric neutrino flux at high energies using three different frameworks for calculating the heavy quark production cross section in QCD: NLO perturbative QCD, k(T) factorization including low-x resummation, and the dipole model including parton saturation. We use QCD parameters, the value for the charm quark mass and the range for the factorization and renormalization scales that provide the best description of the total charm cross section measured at fixed target experiments, at RHIC and at LHC. Using these parameters we calculate differential cross sections for charm and bottom production and compare with the latest data on forward charm meson production from LHCb at 7TeV and at 13TeV, finding good agreement with the data. In addition, we investigate the role of nuclear shadowing by including nuclear parton distribution functions (PDF) for the target air nucleus using two different nuclear PDF schemes. Depending on the scheme used, we find the reduction of the flux due to nuclear effects varies from 10% to 50% at the highest energies. Finally, we compare our results with the IceCube limit on the prompt neutrino flux, which is already providing valuable information about some of the QCD models.