OPERA stands for Oscillation Project with Emulsion t-Racking Apparatus. The main goal of the OPERA experiment is to search for tau neutrino appearance in almost pure muon neutrino beam. The detector is located at Gran Sasso, 730 km away from the neutrino source, at CERN. In this thesis, the reconstruction efficiency and purity of neutrino interactions in the OPERA target have been studied by using Monte Carlo simulation. The efficiency of primary vertex reconstruction for muon neutrino Charge Current (CC) events is estimated as 83.2 percent. The main source of inefficiency is due to Quasi-elastic like topologies in which only one track is reconstructed. The purity of primary vertex tracks is found to be 99 percent. On the other hand, the reconstruction efficiency for muon neutrino CC charm events is estimated to be 90.2 percent, while the purity of the primary tracks is 67 percent. The low purity is due the fact that the secondary vertex tracks are wrongly assigned in the primary vertex. This spoils the purity.

The OPERA experiment was designed to search for nu-mu to nu-tau oscillations through the observation of nu-tau charged-current interactions in the OPERA target. This search requires a massive detector and very high spatial accuracy. Both requirements are ful

The Neutrinos at the Main Injector (NuMI) facility at Fermi National Accelerator Laboratory (FNAL) produces an intense muon neutrino beam used by the Main Injector Neutrino Oscillation Search (MINOS), a neutrino oscillation experiment, and the Main INjector ExpeRiment [nu]-A, (MINER[nu]A), a neutrino interaction experiment. Absolute neutrino cross sections are determined via [mathematical equation], where the numerator is the measured number of neutrino interactions in the MINOS Detector and the denominator is the flux of incident neutrinos. Many past neutrino experiments have measured relative cross sections due to a lack of precise measurements of the incident neutrino flux, normalizing to better established reaction processes, such as quasielastic neutrino-nucleon scattering. But recent measurements of neutrino interactions on nuclear targets have brought to light questions about our understanding of nuclear effects in neutrino interactions. In this thesis the [nu subscript mu] inclusive charged current cross section on iron is measured using the MINOS Detector. The MINOS detector consists of alternating planes of steel and scintillator. The MINOS detector is optimized to measure muons produced in charged current [nu subscript mu] interactions. Along with muons, these interactions produce hadronic showers. The neutrino energy is measured from the total energy the particles deposit in the detector. The incident neutrino flux is measured using the muons produced alongside the neutrinos in meson decay. Three ionization chamber monitors located in the downstream portion of the NuMI beamline are used to measure the muon flux and thereby infer the neutrino flux by relation to the underlying pion and kaon meson flux. This thesis describes the muon flux instrumentation in the NuMI beam, its operation over the two year duration of this measurement, and the techniques used to derive the neutrino flux. / text

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 neutrinos. / Since 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.

Made available in DSpace on 2015-03-03T15:15:30Z (GMT). No. of bitstreams: 1 FlavioMVS_DISSERT.pdf: 786675 bytes, checksum: 15c59d932af3a41769e781bb08d4e3e9 (MD5) Previous issue date: 2014-04-24 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / The study of solar neutrinos is very important to a better comprehension of the set of nuclear reactions that occurs inside the Sun and in solar type stars. The ux of neutrinos provides a better comprehension of the stellar structure as a whole. In this dissertation we study the ux of neutrinos in a solar model, addressing the neutrino oscillation, analyzing with the intention of determining and verify the distribution from a statistical point of view, since this ux depends on the particles intrinsic velocity distributions in stellar plasma. The main tool for this analysis was the Toulouse-Geneva Stellar Evolution Code, or TGEC, which allow us to obtain the neutrino ux values per reaction and per layer inside the Sun, allowing us to compare the observational results for the neutrino ux detected on experiments based on Cl37 (Homestake), Ga71 (SAGE, Gallex/GNO) and water (SNO). Our results show the nal distribution for neutrino ux as a function of the depth using the coordinates of mass and radius. The dissertation also shows that the equations for this ux are present in TGEC. / O estudo do neutrino solar ? muito importante para uma melhor compreens?o sobre o conjunto de rea??es nucleares que ocorrem no interior do Sol e nas estrelas do tipo solar. O fluxo de neutrino tamb?m proporciona uma melhor compreens?o da estrutura estelar como um todo. Nesta disserta??o, estudamos o fluxo de neutrinos em um modelo Solar, abordando a oscila??o de neutrinos, analisando com intuito de determinar e verificar a distribui??o do fluxo do ponto de vista estat?stico, uma vez que este fluxo depende das distribui??es intr?nsecas de velocidades das part?culas no plasma estelar. A principal ferramenta desta analise foi o c?digo de evolu??o estelar Toulouse-Geneva (Stellar Evolution Code, ou TGEC), o qual permite-nos obter os valores do fluxo de neutrino por rea??o e por camada no interior do Sol, e assim podemos comparar com os resultados observacionais para o fluxo de neutrino detectado a partir de experimentos com base no Cl37 (Homestake), Ga71 (SAGE, Gallex/GNO) e agua (SNO). Nosso resultado mostra a distribui??o final para o fluxo de neutrinos em fun??o da profundidade em coordenadas de massa e raio. A referida disserta??o apresenta ainda as equa??es relacionadas com este fluxo que est?o presentes no TGEC

Le démonstrateur de SuperNEMO est un détecteur de nouvelle génération pour la recherche de la décroissance double bêta sans émission de neutrinos. Comme son prédécesseur NEMO3, la technique expérimentale utilisée associe un trajectographe et un calorimètre afin de pouvoir identifier les électrons des décroissances double bêta tout en permettant la différenciation des différentes composantes du bruit de fond. Le démonstrateur est en cours d’installation au Laboratoire Souterrain de Modane et commencera à prendre des données à la fin de l’année 2017 afin d’atteindre une sensibilité supérieure à 1026 ans sur la demi-vie de la décroissance ββ0ν du 82Se dans la version finale du détecteur (100 kg d’isotopes pour une exposition totale de 5 ans).Ce travail de thèse a consisté à étudier la réponse en énergie et en temps des modules optiques du calorimètre (association d'un scintillateur plastique et d'un photomultiplicateur). Une simulation optique basée sur le logiciel GEANT4 a été développée afin de reproduire l'ensemble des phénomènes optiques ayant lieu au sein du scintillateur et du photomultiplicateur : scintillation, atténuation de Birks, émission Cerenkov, propagation et collection des photons. Ces travaux ont abouti à la mise au point de termes correctifs de hautes précisions sur l’énergie afin que le Monte Carlo de SuperNEMO soit au plus proche des données. Ces corrections ont alors été appliquées dans le cas du démonstrateur afin d’étudier l'impact sur la sensibilité au processus ββ0ν du 82Se. Ces simulations optiques ont également été étendues jusqu’à la modélisation de la forme temporelle des signaux du calorimètre. / The SuperNEMO demonstrator is a next generation experimental device, looking for neutrinoless double beta decay. Like its predecessor NEMO3, the experimental technique employed is based on a combination of a tracker and a calorimeter to identify the electrons from the double beta decay process while allowing the differentiation and identification of the different background components. The SuperNEMO’s demonstrator is currently being installed at the Modane Underground Laboratory and will begin to register data by the end of 2017. The aim is to reach a sensivity greater than 1026 years on the half-life of the 82Se ββ0ν process in the final version of the detector (100 kg of isotopes for a 5 years’ total exposure).This thesis contribution to the SuperNEMO, consisted in studying the energy and time response of the calorimeter optical modules (association of a plastic scintillator and a photomultiplier). To do so, an optical simulation based on the GEANT4 software was developed, which enabled to reproduce and simulate all the optical phenomena inside a scintillator and a photomultiplier: scintillation, Birks attenuation, Cerenkov emission, propagation and photon collection. The outcome and result of this thesis has been to develop high-precision corrective factors on the energy linked, so that the Monte-Carlo’s SuperNEMO is closest to the real data experimental records. These corrections were applied to the demonstrator simulation in order to study the impact on the ββ0ν sensitivity. These optical simulations have also been extended to the modeling of the temporal shape of the calorimeter signals.

Orientador: Pedro Cunha de Holanda / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin / Made available in DSpace on 2018-08-12T10:44:00Z (GMT). No. of bitstreams: 1 Boriero_DanielFrancisco_M.pdf: 4969339 bytes, checksum: 948e129914cf07a208b25eb26a168a96 (MD5) Previous issue date: 2008 / 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

Orientador: Orlando Luis Goulart Peres / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin / Made available in DSpace on 2018-08-20T17:03:07Z (GMT). No. of bitstreams: 1 Gratieri_DiegoRossi_D.pdf: 1179296 bytes, checksum: 9a313c3efcf6512bd55d97d0b99d491b (MD5) Previous issue date: 2012 / 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

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 7. / Since 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.

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 inversée. / Neutrinoless 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.