The T2K experiment is a long-baseline neutrino oscillation experiment, in which a muon neutrino beam is directed over a 295 km baseline from the J-PARC facility to the Super-Kamiokande detector. This allows neutrino oscillation to be studied in two channels: disappearance of &nu;_&mu; and appearance of &nu;_e. The T2K beam can be run either in neutrino or antineutrino configuration, for a neutrino beam which is predominantly composed of &nu;_&mu; or anti -&nu;_&mu; respectively. This thesis presents the first oscillation analysis to combine neutrino-mode and antineutrino-mode data sets, giving the first ever sensitivity to the CP-violating phase &delta;_CP from T2K data alone, as well as the most precise T2K measurement of the other neutrino oscillation parameters. The analysis uses a Markov Chain Monte Carlo method to construct a sample from the Bayesian posterior distribution, from which the oscillation parameters of interest and their uncertainties are estimated. Data samples from the T2K near detector, ND280, are fit simultaneously with data from the far detector in order to reduce the uncertainty in the far-detector prediction. When fitting the T2K data alone, the best-fit oscillation parameter values are sin² &theta;₂₃= 0.519^+0.031<sub style='position: relative; left: -2.8em;'>-0.059</sub>, sin² &theta;₁₃= 0.0257^+0.0106<sub style='position: relative; left: -3.2em;'>-0.0440</sub>, &Delta;m²<sub style='position: relative; left: -0.4em;'>32</sub>= 2.54^+0.12<sub style='position: relative; left: -2em;'>-0.10</sub> x 10^-3eV²,and &delta;_CP=-1.91 rad. The 90&percnt; credible interval for &delta;_CP excludes values around &pi;/2: &delta;_CP &notin; [0.38, 2.60] rad. When fitting the T2K data with a constraint on sin² &theta;₁₃ from measurements by reactor experiments, the best-fit oscillation parameter values are sin² &theta;₂₃= 0.519^+0.061<sub style='position: relative; left: -2.8em;'>-0.029</sub>, sin² &theta;₁₃= ^+0.0014<sub style='position: relative; left: -3.2em;'>-0.0014</sub>, Dm²<sub style='position: relative; left: -0.4em;'>32</sub>= 2.54^+0.12<sub style='position: relative; left: -2em;'>-0.12</sub> x 10^-3eV², and &delta;_CP=-1.72 rad. The 90&percnt; credible interval for &delta;_CP contains values &delta;_CP &isin; [-3.10,-0.17] rad, excluding the CP-conserving values 0 and ± &pi; at 90&percnt; probability.

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 attendus. / The 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.

Submitted by JÚLIO HEBER SILVA (julioheber@yahoo.com.br) on 2017-06-23T17:07:23Z No. of bitstreams: 2 Dissertação - Abner Leonel Gadelha Gomes - 2013.pdf: 12566466 bytes, checksum: de6788671342c72dc83a388cf0a1f093 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Cláudia Bueno (claudiamoura18@gmail.com) on 2017-07-07T20:24:16Z (GMT) No. of bitstreams: 2 Dissertação - Abner Leonel Gadelha Gomes - 2013.pdf: 12566466 bytes, checksum: de6788671342c72dc83a388cf0a1f093 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2017-07-07T20:24:16Z (GMT). No. of bitstreams: 2 Dissertação - Abner Leonel Gadelha Gomes - 2013.pdf: 12566466 bytes, checksum: de6788671342c72dc83a388cf0a1f093 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2014-03-13 / 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 10􀀀3 GeV=s, which corresponds to a decay lifetime 3=m3 > 2:4 10􀀀12 s=eV , improving a previous MINOS measurement who is 3=m3 > 2:1 10􀀀12 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 10􀀀3 GeV=s, que corresponde a um tempo de vida de 3=m3 > 2;4 10􀀀12 s=eV no limite inferior, melhorando a medida anterior do MINOS que era de 3=m3 > 2;1 10􀀀12 s=eV .

Orientador: Orlando Luis Goulart Peres. / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin. / Made available in DSpace on 2018-08-12T10:38:02Z (GMT). No. of bitstreams: 1 BastoGonzalez_VictorSaul_M.pdf: 1541009 bytes, checksum: b798dea659147d5050c68800d40ceb0a (MD5) Previous issue date: 2008 / 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

Orientador: Orlando Luis Goulart Peres / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin / Made available in DSpace on 2018-08-24T13:21:19Z (GMT). No. of bitstreams: 1 BastoGonzalez_VictorSaul_D.pdf: 37659795 bytes, checksum: f4492cea9594ac4fbffc288a0c46526a (MD5) Previous issue date: 2014 / 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

京都大学 / 新制・課程博士 / 博士(理学) / 甲第22993号 / 理博第4670号 / 新制||理||1670(附属図書館) / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)准教授 吉岡 興一, 教授 田中 貴浩, 准教授 髙山 史宏 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第19219号 / 理博第4111号 / 新制||理||1592(附属図書館) / 32218 / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)教授 中家 剛, 教授 谷森 達, 准教授 市川 温子 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM

This thesis studies neutrino oscillations at the proposed ESSnuSB experiment and the effects of invisible decay, where the neutrino mass states are assumed to be able to decay, on the planned measurements and the physics potential for this experiment to detect neutrino decays. This is accomplished by simulating a combined scenario of neutrino oscillations and invisible neutrino decay. It is found that the ESSnuSB experiment would be able to put a bound on the decay parameter $\tau_3 / m_3 = 2.64 (1.68) \times 10^{-11}$~s/eV for the baseline option $360 (540)$~km at $3\sigma$. Further, the effect of invisible neutrino decay on measurements of CP-violation and the precision measurements of $\delta_{\mathrm{CP}}$ for both baseline options are investigated. The results show that the effect is not significant in any case for CP-violation measurements. A significant difference in the precision measurements of $\delta_{\mathrm{CP}}$ is found only when decay is assumed to exist but is not accounted for in the theoretical model. / Det här arbetet undersöker neutrinooscillationer vid det föreslagna experimentet ESSnuSB och ett nytt scenario med osynligt sönderfall av neutriner, där neutriner antas sönderfalla till partiklar som inte växelverkar. Arbetet undersöker hur väl ESSnuSB experimentet kan skilja en modell med neutrinosönderfall från Standardmodellen för neutriner utan sönderfall och hur experimentets andra tester påverkas av neutrinosönderfall. Studien har genomförts genom att simulera en kombinerad modell av neutrinooscillationer och neutrinosönderfall för ESSnuSB-experimentet. Analysen visar att ESSnuSB-experimentet skulle kunna sätta en $3\sigma$-gräns på sönderfallsparametern $\tau_3 / m_3 = 2.64 (1.68) \times 10^{-11}$~s/eV för baslinjelängden $360 (540)$~km. Vidare så studeras hur neutrinosönderfall påverkar mätningar av CP-symmetribrott och precisionsmätning av parametern $\delta_{\mathrm{CP}}$ för båda baslinjelängderna. Resultaten visar att påverkan av neutrinosönderfall på mätningar av CP-symmetribrott är liten. En signifikant skillnad i precisionsmätning av $\delta_{\mathrm{CP}}$ kan ses enbart då neutrinosönderfall antas sant men inte inkluderas i den teoretiska modellen.

京都大学 / 新制・課程博士 / 博士(理学) / 甲第24962号 / 理博第4987号 / 新制||理||1712(附属図書館) / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)教授 中家 剛, 教授 永江 知文, 教授 田島 治 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM

Over the past 20 years, the detection of neutrino oscillation has reported a lot of important results. The oscillation phenomenon itself has been well proved by various experiments. Some oscillation parameters has been measured and now in the area of precise determination. On the other hand, some new questions like the possibility of the existence of light sterile neutrinos and unexpected 5 MeV bump were raised during the measurement. The Neutrino Lattice Experiment (NuLat) is a detector based on the Raghavan Optical Lattice (ROL). It should be able to offer a compact design of an effective detector with good mobility. It can be extremely useful in the short baseline reactor neutrino oscillation detection community to resolve several confusing issues. In this thesis, we present the calibration results we got from the first active NuLat detector and show what kind of improvements we need for the next version of the NuLat detector based on these results. / Ph. D.