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1
POZZI, STEFANO. "Search for double-beta decay of 130Te to the excited states of 130Xe in CUORE-0." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2017. http://hdl.handle.net/10281/158137.
Full textAbstract:
CUORE-0 è stato un esperimento bolometrico, mantenuto in funzione dal 2013 al 2015, il cui scopo scientifico principale è stata la ricerca del decadimento doppio beta senza emissione di neutrini (0vbb) nel 130Te. Il rivelatore era costituito da 52 cristalli di TeO2, usati sia come rivelatore che come sorgente dell'isotopo di interesse. I cristalli erano organizzati in una singola torre e contenuti in un criostato capace di raggiungere la temperatura di 10 mK. Grazie al basso fondo radioattivo raggiunto dall'esperimento, la ricerca di altri processi rari, oltre al decadimento doppio beta senza emissione di neutrini, è stata possibile. In questa tesi descrivo i metodi che ho usato per la ricerca del decadimento doppio beta del 130Te sugli stati eccitati del 130Xe. Questo decadimento è caratterizzato dall'emissione di due elettroni, seguiti da una cascata di fotoni, dandogli una segnatura chiaramente identificabile. Ho studiato due processi distinti, il decadimento con l'emissione di due neutrino, permesso dal Modello Standard, e il decadimento senza emissione di neutrini. Per poter identificare chiaramente la segnatura di questi decadimenti è stato necessario ottimizzare una procedura di analisi dedicata, che ha richiesto l'uso sia di dati reali che simulati. I due decadimenti non sono stati osservati in CUORE-0, ma è stato possibile dare un limite inferiore al relativo tempo di dimezzamento: per il decadimento senza emissione di neutrini T1/2 > 5.44x10^23 anni, mentre per il decadimento con l'emissione di due neutrini T1/2 > 1.85x10^23 anni. In particolare, il risultato per il canale con l'emissione di due neutrini rappresenta un netto miglioramento rispetto al limite preesistente, determinato dall'esperimento Cuoricino e pari a 1.30x10^23 anni. La combinazione dei risultati di CUORE-0 e Cuoricino permette di raggiungere limiti ancora migliori: T1/2 > 1.48x10^24 anni per il decadimento senza neutrini e T1/2 > 2.19x10^23 anni per il decadimento con due neutrini. Questi risultati rappresentano i limiti più stringenti disponibili al momento per entrambi i processi.CUORE-0 was a bolometric experiment, operated between 2013 and 2015, whose main scientific goal was the search for neutrinoless double-beta decay (0vbb) in 130Te. The detector consisted of 52 TeO2 crystals, used both as a detector and a source for the isotope under investigation. The crystals were arranged in a single tower and contained in a cryostat capable of reaching the temperature of 10 mK. Thanks to the low background of the experiment, searches for rare events other than 0vbb are possible. In this thesis I describe the methods used to search for double-beta decay of 130Te on the excited states of 130Xe. This decay is characterized by the emission of two electrons followed by a photon cascade, giving it a very characteristic signature. I studied two distinct processes, the SM-allowed two neutrino double-beta decay and neutrinoless double-beta decay on the excited states. In order to properly detect the signatures of these decays a dedicated optimization of the analysis procedure, involving both real and simulated data, was required. The two decays are not observed in CUORE-0, but a lower limit on the half-life of both processes can be set: for the neutrinoless decay, T1/2 > 5.44x10^23 yr, and for the two neutrino decay T1/2 > 1.85x10^23. The result from the two neutrino channel from CUORE-0 was a clear improvement over the previously existing half-life limit, set by the Cuoricino experiment at 1.30x#10^23 years. The combination of the results from CUORE-0 and Cuoricino yields even better limits: T1/2 > 1.48x10^24 years for the neutrinoless channel and T1/2 > 2.19x10^23 for the two neutrino channel. These results represent the most stringent limits currently available for both processes.
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Wong, Chan Fai. "Phenomenology of sterile neutrinos at different mass scales : neutrinoless double beta decay and neutrino oscillations." Thesis, Durham University, 2012. http://etheses.dur.ac.uk/4931/.
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The existence of neutrino oscillation is the first evidence of physics beyond the Standard Model. It proves that neutrinos are massive and motivates the study of the neutrino nature, mixings and mass generation models. To have a better understanding of neutrino masses and mixings, the existence and character of sterile neutrinos would be an important factor. In this thesis, we will describe the phenomena of neutrinoless double beta decay and sterile neutrino oscillations. The studies of these two topics will contribute to understanding the properties of sterile neutrinos in the heavy and light mass regime. We first study the neutrinoless double beta decay process to tackle the issue about the nature of neutrino. Establishing the nature of neutrinos, whether they are Dirac or Majorana particles is one of the fundamental questions we need to answer in particle physics, and is related to the conservation of lepton number. Neutrinoless double beta decay is the tool of choice for testing the Majorana nature of neutrinos. However, up to now, this process has not been observed, but a wide experimental effort is taking place worldwide and soon new results will become available. Different mechanisms can induce neutrinoless double beta decay and might interfere with each other, potentially leading to suppressed contributions to the decay rate. This possibility would become of great interest if upcoming neutrino mass measurements from KATRIN and cosmological observations found that neutrino mass is larger than 0.2 eV but no positive signal was observed in neutrinoless double beta decay experiments. We focus on the possible interference between light Majorana neutrino exchange with other mechanisms, such as heavy sterile neutrinos and R-parity violating supersymmetric models. We show that in some cases the use of different nuclei would allow to disentangle the different contributions and allow to test the hypothesis of destructive interference. Finally, we present a model in which such interference can emerge and we discuss the range of parameters which would lead to a significant suppression of the decay rate. Heavy sterile neutrino is involved in the studies of neutrinoless double beta decay and mass generation involve. On the other hand, the effect of light sterile neutrino may be present in the oscillation experiments. To measure the light sterile neutrino mixing, high statistics measurements are necessary. A neutrino factory has been suggested as a powerful tool for studying new physics, for example, sterile neutrinos, exploiting its near detectors. Here, we use the new version of GLoBES to study the potential of a low energy neutrino factory (LENF) in constraining the sterile mixing angles and the mass-square difference. Unlike in conventional long baseline neutrino experiments, the electron neutrino disappearance and appearance channels are also included, since they have been proved helpful in constraining some of the mixing angles. We will explore the dependence of the performance of the LENF depending on different experimental setups, such as the detector type (TASD and LiAr), the energy range, the systematic errors. etc. Moreover, the re-analysis of reactor neutrino experiments suggests the presence of neutrino oscillations due to large sterile neutrino mixing with electron neutrino. We show that, with a near detector, LENF can constrain the sterile parameter values in a very small range and helps us to check the recent Reactor Anomaly.
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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
4
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.
5
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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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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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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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
9
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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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
11
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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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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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.
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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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Zolotarova, Anastasiia. "Study and selection of scintillating crystals for the bolometric search for neutrinoless double beta decay." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS293/document.
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L'observation de la désintégration double bêta sans émission de neutrino (0ν2β) fournirait des informations essentielles sur la nature du neutrino et son échelle de masse absolue. Ce processus consiste en la transformation simultanée de deux protons en deux neutrons avec l'émission de deux électrons et aucun neutrino. Cette transition n'est possible que si les neutrinos sont égaux aux antineutrinos (nature Majorana du neutrino). Les recherches pour une désintégration à ce point rare représentent un défi technique complexe, car les expériences de prochaine génération visent des sensibilités de l'ordre de 10^27-10^28 ans afin d'avoir un potentiel de découverte élevé. Cette thèse est focalisée sur les projets LUMINEU et CUPID-Mo, développant la technique des bolomètres scintillants pour la recherche de désintégration 0ν2β avec le radio-isotope 100Mo.Les bolomètres sont des détecteurs cryogéniques mesurant l'énergie des particules déposées via un changement de température dans l'absorbeur. Si des cristaux scintillants sont utilisés comme absorbeurs, les signaux lumineux peuvent être enregistrés avec un bolomètre auxiliaire, sensible à l'énergie totale déposée par les photons de scintillation. Une telle configuration permet de séparer les particules α des γ/β, en rejetant le fond le plus difficile. La technologie des bolomètres scintillants est décrite en détail comme une option pour une future expérience cryogénique à l'échelle d'une tonne, appelée CUPID, qui peut couvrir complètement la région de masses de neutrinos dans la hiérarchie inverséeNeutrinoless double beta (0ν2β) decay is a process of great interest for neutrino physics: its observation would provide essential information on neutrino nature and its absolute mass scale. This process consists of the simultaneous transformation of two protons into two neutrons with the emission of two electrons and no neutrino, implying the violation of the total lepton number. Such transition is possible only if neutrinos are equal to antineutrinos (Majorana particles). The searches for such a rare decay are becoming a complicated technical challenge, as next generation of 0ν2β experiments aim at sensitivities of the order of half-life at 10^27-10^28 yr. This thesis is focused on LUMINEU and CUPID-Mo projects, developing the scintillating bolometers technique for 0ν2β decay search with 100Mo with Li2MoO4 crystals. Bolometers are cryogenic detectors measuring the deposited particle energy as a change of temperature in the absorber. The use of scintillating crystals allows to perform discrimination of α particles from γ/β ones due to different light output of these two particle types, rejecting the most challenging background. The scintillating bolometers technology is described in details as an option for a future ton-scale cryogenic experiment, named CUPID, which can completely cover the inverted hierarchy region of neutrino masses
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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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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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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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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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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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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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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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Miguez, Bruno Silva Rodriguez 1986. "Extraindo limites para o fluxo difuso de neutrinos não eletrônicos de supernovas dos dados do SNO." [s.n.], 2010. http://repositorio.unicamp.br/jspui/handle/REPOSIP/277727.
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Orientadores: Ernesto Kemp , Orlando Luis Goulart PeresDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin
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Resumo: É predita a existência de um fluxo de neutrino difusos, gerado pela integração no tempo de todas as supernovas que ocorreram ao longo da evolução do universo e ponderado pelas taxas de formação estelar e de ocorrência de supernovas. As características espectrais destes neutrinos se diferenciam de neutrinos de supernovas recentes principalmente por dois motivos: a redução de seus fluxos e o desvio para energias menores causado pela expansão do universo. Logo, mesmo que o efeito gerado por uma supernova seja um pulso temporal de eventos, seu efeito acumulado gera um fluxo estacionário de neutrinos difusos em todo o universo. Estes neutrinos nunca foram observados antes. Apenas limites superiores para seu fluxo foi reportados pelas colaborações associadas a telescópios de neutrinos. Recentemente a Colaboração SNO fez uma análise dependente do modelo de supernova que estabeleceu experimentalmente 9.3x 101 vecm-2s-1 como o limite superior para o fluxo total de neutrinos eletrônicos difusos. Esta análise reduziu em cerca de 2 ordens de grandeza o limite experimental anterior estabelecido pela Colaboração LSD. Atualmente, os limites mais restritivos para o fluxo difuso de neutrinos não eletrônicos é de » 10 3 vcm-2s-1 e foram estabelecidos por estudos fenomenológicos, uma análise de dados feitas por cientistas externos a colaboração, de dados do Superkamiokande. No entanto, os melhores limites experimentais ainda são os da Colaboração LSD » 107 vcm-2s-l. Neste trabalho, extendemos a análise do SNO incluindo espalhamento elástico em elétrons via interações de corrente neutra para extrair informações do fluxo difuso de neutrinos não eletrônicos (vm , vt). Também foram feitas comparações como os outros limites atualmente aceitos
Abstract: There is a prediction of a diffuse neutrino flux yield from the lime integration of all supernova a1ready exploded in the past governed by stellar fomation and supemovae occurrence rates. The spectral characteristics of these neutrinos differ from those from recent supernovae mainly in two features: the reduction in their fluxes and their energy "red-shift" due the expansion of lhe universe. Thus, despite the fact that one single supernova is a transient state, their cumulative effect produces a steady flux of diffuse neutrinos everywhere in universe. These neutnnos have never been observed before. Only upper limits on their fluxes have been reported by lhe collaborations operating neutrino telescopes. Recently lhe SNO experiment have made an analysis where the total flux of diftuse electron neutrinos has an upper limit of 9.3 x 101 vecm-2s-1, depending on a specific supernova model. This analysis reduced by a factor 100 the anterior best limit, estabilished by LSD Collaborotion. At the present, the best limit for lhe diffuse flux of non-electron neutrinos is » 10³vcm-² s-¹, resulted from an fenomenological analysis of lhe Super-Kamiokande data. However, the best experimental limits are » 107 vcm-²s-¹, estabilished by LSD Collaboration. In this work we have extended lhe SNO analysis including lhe elastic scattering on electrons via neutral current interactions to extract intormation on diftuse flux of lhe non-electron neutrino flavours (i.e. muon and tauon neutrinos). We make a comparison among our results and others currently accepted.
Mestrado
Física das Particulas Elementares e Campos
Mestre em Física
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Carneiro, Mateus Fernandes 1988. "Fenomenologia de modelos MaVanN's em neutrinos de reator." [s.n.], 2012. http://repositorio.unicamp.br/jspui/handle/REPOSIP/276991.
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Orientador: Pedro Cunha de HolandaDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin
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Resumo: Mecanismos de Neutrinos de Massa Variável (Mass Varying Neutrinos - MaVaN¿s) são propostos para ligar a escala de massa dos neutrinos com a energia escura no intuito de resolver o problema da coincidência cósmica. Em alguns cenários essa massa pode apresentar uma dependência com a densidade bariônica sentida pelos neutrinos, criando uma massa efetiva que pode depender da densidade bariônica do meio, assim como da densidade de neutrinos. Nesse trabalho nós estudamos as consequências fenomenológicas dessa dependência da massa do neutrino com o meio e nos concentramos onde ela é induzida por interações de Yukawa com um escalar leve que se acopla com neutrinos e outros componentes da matéria ordinária. Sob a hipótese de dominância de uma escala de massa fazemos uma análise de dados do experimento KamLAND que depende de 4 parâmetros: os padrões de oscilação padrão, ?m^{2}_{0,21} e tg^{2}?12, dois novos coeficientes que parametrizam o efeito MaVaN. Além disso introduzimos uma descrição específica da crosta terrestre, onde introduzimos perfis específicos de densidade para cada uma das fontes do experimento. Concluímos que a descrição específica da densidade não afeta a análise no regime do Modelo Padrão. No caso do modelo MaVaN encontramos um efeito de primeira ordem que se manifesta para baixas densidades e melhora consideravelmente a descrição dos dados. A análise permite que encontremos limites para os termos de dependência do meio
Abstract: Mass Varying neutrino mechanisms were proposed to link the neutrino mass scale with the dark energy, addressing the coincidence problem. In some scenarios this mass can present a dependence on the baryonic density felt by neutrinos, creating an effective neutrino mass that depends both on the neutrino and baryonic densities. In this work we study the phenomenological consequences of the environment dependence of neutrino mass and we concentrate on mass varying neutrino (MaVaN¿s) scenarios in which the enviroment dependence is induced by Yukawa interactions of a light neutral scalar particle which couples to neutrino and matter. Under the assumption of one mass scale dominance, we perform a analysis of KamLAND neutrino data wich depends on 4 parameters: the two standard oscillation parameters, ?m^{2}_{0,21} and tg^2?12, and two new coefficients which parameterize the enviroment dependence of neutrino mass. We introduce a Earth¿s crust model to compute precisely the density in each point along the neutrino trajectory. We show that this new description of density does not affect the analysis with the Standard Model case. With the MaVaN model implemented we observe a first order effect in lower densitys, wich lead to a improvement on the description of the data. The analysis allow us to place constraints on the size of the enviroment dependence terms
Mestrado
Física
Mestre em Física
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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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Heron, Heidi. "Techniques to measure the NC background in the SNO experiment." Thesis, University of Oxford, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.244578.
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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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DeKok, Alan (Alan T. ). Carleton University Dissertation Physics. "A Process degasser for the SNO Ultra-pure light water facility." Ottawa, 1996.
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Gonzalez, Yuber Ferney Perez. "Massive Neutrinos: Phenomenological and Cosmological Consequences." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/43/43134/tde-14122017-162727/.
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The XX century witnessed the quantum and relativistic revolutions in physics. The development of these two theories, namely, Quantum Mechanics and Relativity, was the inception of many crucial discoveries and technological advances. Among them, one stands out due to its uniqueness, the neutrino discovery. However, several neutrino properties are still obscure. Neutrinos are the only fundamental particles whose nature is currently unknown. Such fermions can either be different from their antiparticles, i.e., Dirac fermions, or be their own antiparticles, that is, Majorana fermions. On the other hand, the smallness of neutrino masses is a problem seemingly related to the neutrino nature; thus, as essential task consists in addressing the phenomenologically viable models in both cases. Furthermore, it is important to search for other physical process in which the neutrino nature may manifest through different experimental signatures. A rather difficult but promising method corresponds to the detection of the cosmic neutrino background, viz. neutrinos which are relics from the Big Bang. Previous works have shown that detection rates for Dirac and Majorana neutrinos can give different results. Nevertheless, this distinction was obtained considering the Standard Model framework only. Therefore, it is important to understand the consequences of having Non-Standard Interactions contributing to the detection of neutrinos from the cosmic background. Another remarkable relic predicted by Cosmology is the unidentified Dark Matter, composing ~25% of the Universe. All searches regarding the Weakly Interacting Massive Particle, one of the principal candidates for Dark Matter, have given negative results; this has compelled experiments to increase their sensitivity. Notwithstanding, neutrinos may stand in the way of such experimental searches given that they may constitute an irreducible background. In this thesis, we will address these three different phenomena, neutrino mass models, detection of the cosmic neutrino background and the neutrino background in Dark Matter searches, by considering the different characteristics in each case. In the study of neutrino mass models, we will consider models for both Majorana and Dirac neutrinos; specifically, we will probe the neutrinophilic two-Higgs-doublet model. Regarding the detection of relic neutrinos, we will analyse the consequences of the existence of the beyond Standard Model physics in the capture rate by tritium. Finally, we will scrutinize the impact of neutrinos in Direct Detection WIMP searches, by considering Standard Model plus additional interactions in the form of simplified models.Ao longo do século XX testemunhamos as revoluções quântica e relativista que aconteceram na Física. O desenvolvimento da Mecânica quântica e da teoria da relatividade foi o prelúdio de inúmeras descobertas e avanços tecnológicos fundamentais; em particular, a descoberta dos neutrinos. No entanto, a sua total compreensão ainda é um mistério para a física de partículas. Entendidos como partículas fermiônicas fundamentais, os neutrinos possuem sua natureza desconhecida. Podendo ser diferentes de suas antipartículas, denominadas férmions de Dirac, ou também podendo ser as suas próprias antipartícula, sendo conhecidas como férmions de Majorana. Por outro lado, o valor de sua massa continua sendo um problema em aberto, supostamente relacionado à sua natureza. Portanto, é importante estudarmos modelos fenomenológicos viáveis para as duas naturezas possíves dos neutrinos. Além disso, é necessário procurar outros processos físicos cujos resultados experimentais sejam distintos de acordo com a natureza do neutrino. Um método bastante difícil, mas promissor, corresponde à detecção do fundo de neutrinos cósmicos, isto é, os neutrinos relíquia do Big Bang. Análises prévias mostraram que as taxas de detecção para neutrinos de Dirac e de Majorana resultam em valores distintos. Porém, este resultado foi obtido supondo como base o Modelo Padrão; assim, é crucial entender as possíveis consequências da existência de interações desconhecidas na detecção dos neutrinos da radiação cósmica de fundo. Outra relíquia notável prevista pela Cosmologia é a desconhecida Matéria Escura, que compõe ~25% do Universo. Todas as buscas por WIMPs (do inglês Weakly Interactive Massive Particles), um dos principais candidatos a Matéria Escura, tem dado resultados negativos. Isto tem forçado a criação de experimentos cada vez mais sensíveis. Contudo, os neutrinos poderão ser um obstáculo nessas buscas experimentais, pois estes convertir-se-ão em um fundo irredutível. Na presente tese, abordaremos estes três fenômenos diferentes, modelos de massa para os neutrinos, a detecção do fundo de neutrinos cósmicos e o fundo de neutrinos em experimentos de detecção direta de Matéria Escura, considerando as distintas características em cada caso. No estudo dos modelos de massa para os neutrinos consideraremos modelos para neutrinos de Majorana e Dirac; exploraremos modelos neutrinofílicos com dois dubletos de Higgs. Enquanto à detecção dos neutrinos relíquia, analisaremos as consequências da presença de física além do Modelo Padrão na taxa de captura pelo trítio. Finalmente, examinaremos o impacto dos neutrinos em experimentos de detecção direta de WIMPs, supondo as interações do Modelo Padrão junto com interações adicionais na forma de modelos simplificados.
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Picoreti, Renan. "Neutrinos astrofísicos = mecanismo de produção e razão entre sabores." [s.n.], 2011. http://repositorio.unicamp.br/jspui/handle/REPOSIP/278534.
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Orientador: Orlando Luis Goulart PeresDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin
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Resumo: Neutrinos Astrofísicos são produzidos quando prótons ou núcleos, acelerados numa fonte astrofísica, interagem com a matéria nas imediações gerando méons que decaem fracamente produzindo neutrinos. Remanescentes de Supernovas, Núcleos Ativos de Galáxias (AGN) e Explosões de Raios Gama (GRB) são alguns dos candidatos a fontes, e a detecção desses neutrinos pode fornecer informações tanto sobre esses objetos astrofísicos quanto sobre a física de neutrinos. Neste trabalho, supomos, de forma simplificada, que nas fontes são produzidos mésons ¶ ± num espectro de lei de potência da energia, 8 E¶ -a . Calculando-se os espectros de produção dos neutrinos gerados na cadeia de decaimento, obtém-se, no limite em que as partículas são ultrarrelativísticas, uma razão entre sabores de neutrinos muônicos e eletrônicos que é função do expoente do espectro inicial, a, dos píons. Calculamos uma correção a essa razão devido a termos proporcionais à massa do elétron, geralmente desprezada na literatura, e verificamos a validade da razão na aproximação ultrarrelativística. Entre produção e detecção, a razão entre sabores deve se modificar devido ao fenômeno da oscilação de neutrinos. Assim, discutimos a possibilidade de, através da detecção destes neutrinos e da medição da razão entre os sabores, inferir-se propriedades da produção dos neutrinos na fonte ou mesmo verificar-se a existência de novos fenômenos da física de neutrinos, em especial, o decaimento de neutrinos
Abstract: Astrophysical Neutrinos are produced when protons or nuclei, accelerated in a astrophysical source, interact with the surrounding matter generating weakly decaying mesons that decay producing neutrinos. Supernova Remnants, Active Galactic Nuclei (AGN) and Gamma-ray Bursts (GRB) are some of the candidates to such sources, and the detection of those neutrinos may provide information about these astrophysical objects and about neutrino physics. In this work, we suppose, in a simplified manner, that the sources produce ¶ ± mesons with a power law spectrum, 8¶ -a .Upon calculation of the neutrino production spectra on the pion decay chain, it is obtained, on the ultra-relativistic limit, the flavor ratio between muon and electron neutrinos as a function of the slope of the initial pion spectrum. We calculated a correction to this flavor ratio due to non-vanishing electron mass, usually disregarded, and we verified if the ultra-relativistic limit is reasonable. Between neutrino production and detection, the flavor ratio is modified due to the neutrino flavor oscillation. Thus, we discuss the possibility of inferring the source properties or new neutrino physics phenomena, such as neutrino decay, through the detection of astrophysical neutrinos and the measurement of its flavor ratio
Mestrado
Física das Particulas Elementares e Campos
Mestre em Física
35
Fischer, Vincent. "Beta-decay emitted electronic antineutrinos as a tool for unsolved problems in neutrino oscillation physics." Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066237/document.
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Le cadre global des oscillations de neutrinos est maintenant bien compris et nous quittons une ère d'exploration pour une ère de précision. L'expérience Double Chooz a pour but de mesurer l'angle de mélange theta13 par l'étude des oscillations des antineutrinos électroniques produits par les réacteurs de la centrale nucléaire de Chooz. Dans cette thèse, une sélection préliminaire des neutrinos détectés dans le détecteur proche est présentée. Les résultats les plus récents de Double Chooz, desquels sont extraits la mesure de theta13 la plus précise que l'expérience peut fournir à ce jour, seront également discutés. La géométrie de l'expérience, relativement simple, représente un avantage considérable afin d'effecteur des études de directionalité des neutrinos dont les résultats, obtenus en analysant les jeux de données les plus récents avec captures sur Gd et H, sont présentés. Ce concept de directionalité peut être appliqué à l'astronomie/astrophysique en offrant la possibilité de localiser des supernovas après détection de leurs neutrinos. Les résultats de simulations de directionalité effectuées avec différentes combinaisons de détecteurs seront présentées. Enfin, plusieurs anomalies pourraient s'expliquer par l'existence de nouveaux états, stériles, de neutrinos. Le but de l¿expérience CeSOX est de confirmer ou réfuter cette hypothèse en déployant une source radioactive à coté d'un grand détecteur comme KamLAND ou Borexino. Dans cette thèse seront présentés les résultats des simulations de signaux et de bruits de fond effectuées afin de valider le principe de l'expérience et de s'assurer de sa sensibilité à l'observation d'une oscillation vers un neutrino stérileThe framework of neutrino oscillations is quite well-understood and now requires precision rather than exploration. The Double Chooz experiment aims at measuring the theta13 mixing angle through the oscillations of electronic antineutrinos produced by the reactors of the Chooz nuclear power plant. The comparison of the interaction rates and spectral shapes in the two Double Chooz's detectors allows the observation of a disappearance and a spectral distortion, both driven by theta13. In this thesis, a preliminary neutrino selection with the near detector, whose data taking started in December 2014, has been performed. The most recent results of Double Chooz, providing the most precise measurement of the experiment, are presented as well.The simple layout of Double Chooz is a strong advantage to conduct directionality studies. Results of these studies using the most recent neutrino candidates with neutron captures on Gd and H are showed. Neutrino directionality can be applied to astronomy, with the localization of core-collapse supernovae. To this purpose, results of directionality measurements performed with combinations of large neutrino detectors over the globe are presented.Finally, recent anomalies observed in short baseline experiments provided hints of the hypothetical existence of additional sterile neutrino states. The goal of the CeLAND/CeSOX experiment is to test this hypothesis by deploying a radioactive source next to a large liquid scintillator detector such as KamLAND or Borexino. In this thesis, are presented results of signal and background simulations performed to validate the design and assess the sensitivity of such an experiment
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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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Back, Ashley Robert. "Probing new physics mechanisms in neutrinoless double-beta decay with SNO+." Thesis, Queen Mary, University of London, 2018. http://qmro.qmul.ac.uk/xmlui/handle/123456789/33945.
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In this thesis, I present the theory of neutrinoless double-beta decay (0 2 ), particularly the theory of exotic modes of 0 2 involving the emission of one or two Majorons. Alongside this, I summarise the most recent results in the experimental search for 0 2 , including limits on the rate of these exotic processes. I describe the SNO+ experiment and it's physics goals, which include the search for 0 2 . As part of the SNO+ collaboration, I have made a signi cant contribution towards the development of the data quality software that is essential for ensuring SNO+ can achieve its physics goals-including in 0 2 searches. I describe how I developed a software package that performs the high-level data quality checks. Continuing with the software theme, I then describe a python-based limit-setting and tting software package called echidna. I have been a lead developer of echidna as part of my PhD, so I describe the software in detail and how it can be used to set limits on 0 2 signals. By reproducing the sensitivity results of the KamLAND-Zen experiment, in four key Majoronemitting 0 2 modes, I verify the use of echidna as a limit-setting tool for this type of search. Finally, I present the results of a comprehensive sensitivity study, where I determine the potential sensitivity of SNO+ to the same set of Majoron-emitting modes that KamLAND-Zen and other 0 2 experiments have already investigated.
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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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Euler, Sebastian [Verfasser]. "Observation of oscillations of atmospheric neutrinos with the IceCube Neutrino Observatory / Sebastian Euler." Aachen : Hochschulbibliothek der Rheinisch-Westfälischen Technischen Hochschule Aachen, 2014. http://d-nb.info/1058238922/34.
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Loach, James Chilton. "Measurement of the Flux of 8B Solar Neutrinos at the Sudbury Neutrino Observatory." Thesis, University of Oxford, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.490107.
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The Sudbury Neutrino Observatory (SNO) was a heavy water Cerenkov detector that had the unique ability to measure both the total il active flux of solar neutrino, using a neutral current (NC) interaction, and the flux of electron neutrinos, using a charged current (CC) interaction. The experiment has demonstrated that neutrinos 3 change flavour and that the total neutrino flux is consistent with the prediction of solar models.
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Felix, Regina Celia Medeiros. "Estudo de determinação dos parâmetros que descrevem a dinâmica de uma supernova galática por um detector de neutrinos futuro." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/43/43134/tde-17082009-084349/.
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O objetivo desta dissertação foi estudar os sinais que neutrinos provenientes de supernovas galáticas poderão produzir em detectores futuros, através de simulações de eventos observados na Terra por um detector Cherenkov pela reação de decaimento beta inverso. Por ser um local único em que neutrinos se encontram em condições de equilíbrio térmico, a física de neutrinos de supernova pode ser fonte de novo conhecimento na física de partículas elementares. Iniciamos o trabalho apresentando os aspectos mais importantes da física de neutrinos tal como é conhecida hoje, seguido de um estudo do papel do neutrino na explosão de uma supernova do tipo II e a influência das oscilações em futuras observações. As simulações foram feitas primeiramente considerando uma supernova de potencial estático, com a determinação de limites nos principais parâmetros que descrevem sua dinâmica. Utilizamos os casos de hierarquia normal e inversa e ângulos de mistura nos limites totalmente adiabático e não-adiabático. Posteriormente consideramos uma supernova de potencial dinâmico, a partir da qual estudamos o comportamento das probabilidades de transição e o perfil do espectro detectado nos mesmos casos anteriores. Com este potencial também foi possível observar o comportamento temporal do espectro e como este pode ser modificado com a hierarquia e ângulo de mistura. Mostramos que em uma futura detecção, o número de eventos e conseqüentemente sua variação com parâmetros de supernova não terão interferência considerável do efeito de onda de choque. Contudo, este pode causar distorções no espectro energético e temporal que poderão ter papel importante na determinação da hierarquia de massa e maior delimitação do ângulo de mistura.The goal of this dissertation is to study the signals that supernova neutrinos could produce in future detectors, through simulations of events observed on Earth by a Cherenkov detector and inverse beta decay reaction. Since a supernova has been the only situation in which neutrinos are able to reach thermal equilibrium, the physics of supernova neutrinos can be source of a new knowledge in physics of elementary particles. We begin this work presenting the most important aspects of neutrino physics as known today, and then studying the role of neutrino in a type II supernova explosion and the oscillation influence in future observations. The simulations were initially performed considering a static potential, defining limits for the main parameters that describe its dynamics. We considered the cases of normal and inverse mass hierarchy and mixing angles within fully adiabatic and non-adiabatic limits. Later we used a supernova dynamic potential to study behavior of transitions probabilities and the profile of the spectrum detected in these previous cases. From this potential we also observed the temporal behavior of the spectrum and how it can be modified with the hierarchy and the mixing angle. We show that, in a future detection, the number of events and hence their variations with supernova parameters, will not suffer interference of the shock wave effect. However, this effect can cause distortions in the energy and time spectrum that could have an important role in determining the mass hierarchy and better constraints for the mixing angle.
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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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Haberland, Marcus. "A search for a prompt atmospheric muon neutrino flux in the northern hemisphere using data releases from IceCube." Thesis, Uppsala universitet, Högenergifysik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-415984.
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The IceCube Neutrino Observatory is a cubic kilometre scale detector for high-energy neutrinos above hundreds of GeV produced in Earth’s atmosphere as well as outside our solar system whenever particles are accelerated to ultra-relativistic energies. The prompt atmospheric contribution is a result of the creation of heavy mesons with charm components in the atmosphere. Past studies from IceCube using a maximum likelihood estimation over the whole neutrino energy spectrum always reported a best-fit zero prompt contribution so far [1–5], contrary to theory [6, 7]. In this analysis we tried to measure this prompt atmospheric flux in muon neutrino event data from different IceCube releases. In contrast to past studies we performed a binned least-squares fit of the conventional atmospheric flux from data at low energies and subtracted this fit and an astrophysical flux reported by IceCube to measure a prompt contribution. Due to a lack of statistics and accessible information from data releases, our results are also compatible with a zero prompt contribution.
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Salagnac, Thomas. "Recherche d'un neutrino stérile avec l'expérience STEREO : développement de l'électronique et identification des neutrinos." Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAY068/document.
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Depuis 2011, la réévaluation de plus d’une vingtaine de mesures de flux de neutrinos de réacteur mesurés à courtes distances suggère la présence d’un déficit de 7 % par rapport aux prédictions. Cette anomalie est statistiquement significative à environ 3 sigmas, tout comme une autre anomalie similaire correspondant à l’observation d’un déficit de neutrinos émis par des sources intenses de désintégrations beta. Ces anomalies peuvent être expliquées soit par un biais dans la prédiction des flux de neutrinos, soit par l’existence d’un nouvel état de neutrino, un neutrino stérile léger, vers lequel les trois neutrinos du modèle standard pourraient osciller. Ce nouveau neutrino, n’interagissant pas par interaction faible, serait uniquement « visible » grâce à ces oscillations. L’objectif de l’expérience STEREO est de répondre à la question de l’existence d'un neutrino stérile avec une masse de l’ordre de 1 eV, en utilisant le flux de neutrinos émis par le réacteur de recherche de l’« Institut Laue-Langevin » (ILL) à Grenoble, en France. Pour cela, le détecteur STEREO est segmenté en 6 cellules afin de mesurer l’hypothétique distorsion du spectre en énergie des neutrinos en fonction de la distance au réacteur (entre 9 et 11m de distance). Après quelques années de construction du détecteur et de préparation, l’expérience STEREO a pu commencer la prise de données en novembre 2016 avec une premier période d’acquisition qui s’est terminée en mars 2017. Cette thèse s’inscrit dans ces deux périodes distinctes de l’expérience STEREO. Une première partie a été consacrée à la caractérisation et la validation de l’électronique tout au long du processus de développement jusqu’à sa conception finale. Dans ce cadre, une méthode de mesure de la linéarité de la réponse en charge des photomultiplicateurs et de leurs embases a été développée avec une précision meilleure que 1 %, pour répondre au exigence de sensibilité à l’hypothèse d’un neutrino stérile. Cette exigence a d'ailleurs été validée par une analyse statistique de l’expérience. Une deuxième partie de la thèse a concerné l’analyse des premières données et plus particulièrement, l’identification des différents types de bruit de fond et la recherche des candidats neutrinosSince 2011, the re-evaluation of about twenty neutrino flux measurements at short distance from reactors suggests a deficit of about 7 % with respect to predictions. This anomaly has a 3 sigmas significance, as another similar anomaly which corresponds to the deficit of neutrinos emitted from intense source of beta-decay. These anomalies could be explain either by a bias in the flux prediction or by the existence of a new neutrino state, a light sterile neutrino, possibly mixing with the three neutrino states of the standard model. This new neutrino, with no ordinary weak interaction, could only be “visible” via the neutrino oscillation. The STEREO experiment goal is to answer the question of the sterile neutrino existence with mass around 1 eV, using neutrino flux emitted from the research reactor of the « Institut Laue-Langevin » (ILL) at Grenoble, France. To achieve this, the STEREO detector is segmented in 6 cells to measure a hypothetical distortion of the neutrino energy spectrum at different distances from the reactor (between 9 et 11m). Afters few years of detector construction and preparation, the STEREO experiment has started taking data in November 2016 with a first period over in Mars 2017. This thesis took place during two distinct phases of the STEREO experiment. A first part was dedicated to the characterisation and the validation of the electronics, during all its development process until its final conception. In this context, a method to measure the charge response linearity of photomultipliers and their bases, with a precision better than 1 %, has been developed, in order to fulfill the desired sensitivity to the light sterile neutrino hypothesis. This requirement on the precision has been validated by a statistical analysis of the experiment. The second part of the thesis was devoted to the analysis of the first data and more particularly to the identification of the different kinds of background and to the search of neutrino candidates
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Stasik, Alexander Johannes. "Search for High Energetic Neutrinos from Core Collapse Supernovae using the IceCube Neutrino Telescope." Doctoral thesis, Humboldt-Universität zu Berlin, 2018. http://dx.doi.org/10.18452/18729.
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Die Entdeckung eines hochenergetischen Flusses astrophysikalischer Neutrinos stellt einen wesentlichen physikalischen Durchbruch der letzten Jahre dar. Trotz allem ist der Ursprung dieser Neutrinos immer noch unbekannt. Die Suche nach den Quellen der hochenergetischen kosmischen Strahlung ist direkt verbunden mit der Suche nach Neutrinos, da diese in den gleichen hadronischen Prozessen erzeugt werden und eine Neutrinoquelle deshalb einen direkten Hinweis auf eine Quelle der kosmischen Strahlung darstellen würde. Viele potentielle Quellen der Neutrinos werden diskutiert, darunter Kern-Kollaps Supernovae.
In dieser Arbeit werden sieben Jahre Daten des IceCube Neutrinoteleskopes mit der Richtung mehreren Hundert Kernkollaps-Supernovae auf Korrelation getestet. Die Analyse gewinnt dabei durch die gute Richtungsrekonstruktion der 700000 Muonspurdaten und der großen Datenbank optische beobachteter Supernovae. Die Sensitivität der zeitabhängigen Likelihood-Analyse wird durch die Kombination mehrere Quellen in einer einzigen Analyse gesteigert.
Es wurde kein statistisch signifikantes Cluster von Neutrinos an den Positionen der Supernovae gefunden. Daraus wurden obere Grenzen für verschiedene Modelle berechnet und der Beitrag von Kernkollaps-Supernovae zum diffusen Neutrinofluss eingeschränkt. Daraus können bestimmte Typen von Supernovae als dominate Quelle der diffusen hochenergetischen astrophysikalischen Neutrinos ausgeschlossen werden.The recent discovery of a high energy flux of astrophysical neutrinos was one of the breakthroughs of the last years. However, the origin of these neutrinos remains still unknown. Also, the search for the sources of high-energy cosmic rays is closely connected to neutrinos since neutrinos are produced in hadronic interactions, and thus the detection of a neutrino source would be a \textit{smoking gun} signature for cosmic rays. Many potential neutrino source classes have been discussed, among these are core-collapse supernovae. In this thesis, seven years of data from the IceCube neutrino observatory are tested for correlation with the direction of hundreds of core-collapse supernovae. The analysis benefits from the good angular reconstruction of the order of one degree and below of the about 700000 muon track events and an extensive database of optical observations of supernovae. Using a time-dependent likelihood method, the sensitivity of the analysis is increased by stacking the sources in a combined analysis. No significant clustering of neutrino events around the position of core-collapse supernovae is found. Upper limits of different neutrino light curve models are computed, and the contribution of core-collapse supernovae to the measured diffuse high energetic neutrino background is constrained. These limits allow excluding certain types of core-collapse supernovae as the dominant source of the observed high energetic astrophysical neutrino flux.
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Grégoire, Timothée. "Search for high energy neutrinos from the Galactic plane with the ANTARES neutrino telescope." Thesis, Sorbonne Paris Cité, 2018. http://www.theses.fr/2018USPCC129/document.
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Deux analyses sont présentées dans cette thèse. Une première analyse exploite les données du télescope à neutrino ANTARES pour sonder la présence d'un flux de neutrino diffus galactique. Cette analyse se base sur un modèle récent de propagation des rayons cosmiques dans la galaxie, le modèle KRAγ. Ce modèle prédit un flux de neutrinos particulièrement élevé et proche de la sensibilité des télescopes à neutrinos actuels. Il existe deux versions de ce modèle correspondant à différentes coupures sur l'énergie des rayons cosmiques, à 5 et 50 PeV/nucléon. Une méthode de maximisation d'une fonction de vraisemblance est utilisée pour prendre en compte les caractéristiques du modèle, autant spatiales qu'en énergie. Cette analyse a également été combinée avec les données de l'expérience IceCube dans le but d'exploiter au mieux les données actuelles. Des limites ont été mises sur ce modèle rejetant la version avec une coupure à 50 PeV et limitant la version avec une coupure à 5 PeV à moins de 1,2 fois le flux prédit par le modèle. Une deuxième analyse de suivi du signal d'ondes gravitationnelles GW170817 par le télescope à neutrino ANTARES est également présentée. Le signal d'onde gravitationnelles GW170817 résulte de la coalescence d'une binaire d'étoiles à neutrons. Cette deuxième analyse a pour objectif de sonder la présence d'un flux de neutrinos provenant de cet événement en cherchant des neutrinos corrélés spatialement et temporellement. J'ai pris part à cette analyse en y ajoutant les événement de type cascade. Aucun événement n'a été détecté en corrélation, des limites ont été mises sur le flux de neutrino attenduTwo analyses are detailed in this thesis. A first analysis exploit the data of the ANTARES neutrino telescope to probe the presence of a Galactic diffuse neutrino flux. This analysis is based on a recent model of cosmic ray propagation in the Galaxy, the KRAγ model. This model predict a neutrino flux particularly high and close to the sensitivity of the current neutrino telescopes. Two versions of this model exist corresponding to different cuts in the cosmic ray energy, one at 5 PeV/nucleon and an other one at 50 PeV/nucleon. A method of maximization of a likelihood function is used in order to account for the model characteristics in energy and space. The analysis has also been combined with the data of the IceCube experiment in order to exploit all the available data. Limits have been put on this model rejecting the version of the model with the 50 PeV cut and limiting the version with the 5 PeV cut to less than 1.2 times the predicted flux.A second analysis of gravitational wave signal follow-up by the ANTARES neutrino telescope is also presented in this work. The GW170817 gravitational wave signal results from the coalescence of a binary neutron star system. This second analysis aims at probing the presence of a neutrino flux coming from this event looking for neutrino events correlated in space and time. I took part to this analysis by adding the shower-like event sample. No event has been detected in correlation, limits have been put on the expected neutrino flux
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Basto, Gonzalez Victor Saul 1977. "Neutrinos de supernovas." [s.n.], 2008. http://repositorio.unicamp.br/jspui/handle/REPOSIP/278491.
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Orientador: Orlando Luis Goulart Peres.Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin.
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Resumo: Com este trabalho buscamos entender o fenômeno de oscilações de neutrinos na matéria. Para isto, estudamos a propagação de neutrinos em Supernovas. O estudo é feito nestes objetos astrofísicos, pois são produzidos neutrinos de todos os sabores quando a estrela progenitor da Supernova é muito massiva. Além de isto, estes corpos celestes atingem densidades muito maiores que a densidade solar. Uma razão adicional muito importante é que os neutrinos são mensageiros ideais e poderão ser observados antes mesmo da observação óptica da explosão de Supernova, assim eles podem fornecer informação sobre os processo que levam à formação de Supernova. Para fazer esse estudo consideramos os valores atuais dos parâmetros de oscilações de neutrinos e um perfil de densidade para a matéria da estrela moribunda. Encontramos que os neutrinos experimentam o efeito Mikheyev-Smirnov-Wolfenstein (MSW) em dois regimes de densidades diferentes. A existência destas regiões dependerá da hierarquia nas massas dos neutrinos e se é partícula/antipartícula. Encontramos que para no caso de antineutrinos eletrônicos o fluxo na Terra dependerá do tipo de hierarquia e do valor do ângulo de mistura q13, esse ângulo de mistura modificará o tipo de transição pela zona de ressonância de densidades altas na Supernova. Encontramos que o número de eventos, para esses antineutrinos, è diferente se a hierarquia na massa é normal ou invertida. A diferença é mais notória se a luminosidade em neutrinos não está equipartida. Também encontramos que o número de eventos no detector Super-Kamiokande dependerá do tipo de propagação na região mais interna de Supernova para hierarquia invertida e caso q 13 10-3 , podemos ter informação sobre esses ângulo de mistura caso conseguiremos diferenciar o espectro sem oscilação e com oscilação induzido por efeito puramente adiabático. Neste estudo não tivemos em conta o efeito da matéria na Terra.
Abstract: In this work we study the behaviour of the neutrino oscillations in the matter. To do so, we studied the propagation of neutrinos in Supernovae. The study is done on this astrophysical objects because there are produced all avor of neutrinos when the Supernova progenitor star is very massive. Moreover, this celestial bodies reach much higher densities than the solar density. An additional and very important reason to study neutrinos in Supernova is because neutrinos are ideal messengers, thus they could be detected even before of the optical observation of the Supernova explosion. We considered the updated oscillation parameter values for neutrinos and a density profile of the matter in the dying star. Also, we consider that in the neutrino propagation in a medium it is modified by the medium density, being known as Mikheyev-Smirnov-Wolfenstein (MSW) effect. The existence of regions in which the MSW effect is very relevant will depend on the mass hierarchy of the neutrinos/antineutrinos and if they are neutrinos or antineutrinos. We found in the case of anti electron neutrinos that the ux in the Earth will depend on the type of hierarchy and on the value of the mixing angle q 13, that angle will modify the kind of transition in the resonance zone in the regime of high densities in the Supernova. We calculated the number of events for those antineutrinos and we have found that the value depend if the mass hierarchy is normal or inverted. The difference is even more evident if the total luminosity of the neutrinos is not equally distributed between the all neutrino avors. Finally, we also found that the number of events in the Super-Kamiokande detector will depend on the propagation in the Supernova inner region for the inverted hierarchy and when the mixture angle q 13 10-3. In this study we will not consider the Earth¿s matter effect.
Mestrado
Física das Particulas Elementares e Campos
Mestre em Física
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Teves, Walter José da Costa. "Estudo fenomenológico dos neutrinos em experimentos que utilizam fontes terrestres." Universidade de São Paulo, 2003. http://www.teses.usp.br/teses/disponiveis/43/43134/tde-17072012-125738/.
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Nesta tese, realizamos dois tipos de estudos fenomenológicos através de uma análise detalhada de alguns experimentos terrestres atuais e futuros. No primeiro, estudamos dois mecanismos exóticos de conversão de sabor: descoerência quântica e interações não padrão do neutrino com a matéria. Para descoerência, vinculamos o parâmetro de descoerência bem como testamos como distinguir a solução de descoerência pura do mecanismo padrão de oscilação no contexto de duas gerações. No caso das interações não padrão, assumimos que esta é subdominante frente ao mecanismo de oscilação padrão, e encontramos os possíveis limites que poderão ser obtidos para essas interações utilizando uma fábrica de neutrinos futura. No segundo tipo de estudo, determinamos os parâmetros de oscilação solares pela análise combinada dos dados dos neutrinos solares e de KamLAND, e estimamos a precisão nos parâmetros de mistura atmosféricos que poderá ser atingida pelos experimentos de LongBaseLine futuros MINOS, ICARUS e OPERA. Por fim, investigamos a possibilidade dos experimentos futuros do duplo decaimento sem neutrinos de determinar os parâmetros de não oscilação.In this thesis, we have done two kind of phenomenological studies through a detailed analysis of present and future terrestrial experiments. In the first study, we analyze two exotic mechanisms of flavour conversion: quantum decoherence and non-standard neutrino-matter interactions. In the case of decoherence, we impose constraints on the decoherence parameter and test how to distinguish between the pure decoherence solution and the standard neutrino ascillation mechanism in the contexto f two neutrino generations. For non-standard interactions, assuming it as a sub-leading process compared to the standard oscillation, we find the possible limits that can be achieved on the strength of these interactions using a future neutrino factory. In the second part of the study, we determine the solar oscillation parameters using a combined analysis of solar neutrino and KamLAND data, and estimate the precision on the atmospheric mixing parameters by that can be accomplished by the LongBaseline experiments MINOS, ICARUS and OPERA. Finally, we investigate the capability of future neutrinoless Double beta decay experiments to determine the non-oscillation parameters.
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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.
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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.
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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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