Submitted by Luciana Ferreira (lucgeral@gmail.com) on 2014-08-12T15:33:42Z No. of bitstreams: 2 Kelen Cristiane Noleto da Costa.pdf: 3124445 bytes, checksum: 8f805839a0c1fe1136fb4081d7be5d18 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Made available in DSpace on 2014-08-12T15:33:42Z (GMT). No. of bitstreams: 2 Kelen Cristiane Noleto da Costa.pdf: 3124445 bytes, checksum: 8f805839a0c1fe1136fb4081d7be5d18 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2011-09-30 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Several analysis can be performed using atmospheric muons produced in chain reactions caused by a cosmic ray particle. We can study the muon flux for different parameterizations of the atmosphere, the moon and sun shadowing effect, the muon charge ratio, etc. In this work, we are interested in the atmospheric muon charge ratio (rμ = Nμ+/Nμ−). This ratio has been observed by several experiments, for different energy ranges. The MINOS experiment has determined the muon charge ratio (rμ) in the GeV energy scale using the Near Detector and in the TeV energy scale using the Far Detector. This experiment has observed an increase of the muon charge ratio from 1.27 to 1.37 when the energy of the primary particle changed from ∼ 100 GeV to ∼ 1 TeV. This fact can be explained by the properties of the pions ( ) and the kaons (K). For higher energies, around 10 TeV, the decay of charming hadrons becomes important as a source of atmospheric leptons. Investigating the parameterization given by the Gaisser equation in order to study the intensity of positive and negative muons separately, it is possible to obtain the equation of the pion-kaon ( K) model. Using this model it was made an adjust with the of MINOS Near and Far Detector data, finding the f and fK parameters. These parameters are the fractions that contribute to the production of positive muons coming from de e K, respectively. The experimental values obtained were: f = 0.55 and fK = 0.70. In this work we simulated extensive air showers using the CORSIKA code. Different models that describe the hadronic interactions for high energy particles were used. Our goal was to verify if the models could reproduce the increase of muon charge ratio. This increase is associated with physics involving pion and kaon decays. We found the following parameters: f = 0.547 ± 0.003 and fK = 0.64 ± 0.02 for the QGSJET 01C model, f = 0.604 ± 0.003 and fK = 0.73 ± 0.02 for the SIBYLL model, f = 0.572 ± 0.003 and fK = 0.70 ± 0.02 for the VENUS model, f = 0.545 ± 0.004 and fK = 0.62 ± 0.03 for the QGSJETII model and f = 0.570 ± 0.003 and fK = 0.65 ± 0.02 for the DPMJET model. The increase of the muon charge ratio found in the MINOS data was 7.8%. In our simulation we found an increase of 3.2%, 8.3%, 5.7%, %4.0 and 2.5% for each one of the models, respectively. With these results, it was possible to observe that simulation models also show a significant increase of ratio, when we moved from scale GeV scale for TeV. And of course, this increase is characterized by properties of pions and kaons noting that physics is considered by the codes of models. / Várias análises podem ser feitas a partir de múons atmosféricos produzidos na reação em cadeia provocada por uma partícula de raio cósmico, como o estudo do fluxo de múons para diferentes parametrizações da atmosfera, da sombra da lua e do sol, da razão da carga entre múons atmosféricos. Neste trabalho estamos interessados na razão da carga entre múons atmosféricos (rμ = Nμ+/Nμ−). Essa razão foi determinada por diversos experimentos, para diferentes intervalos de energias. Especificamente, o experimento MINOS determinou a razão (rμ) na escala GeV com o Near Detector e na escala TeV com o Far Detector. Esse experimento observou um aumento da razão de 1,27 para 1,37 com o aumento da energia de ∼100 GeV para ∼ 1 TeV. O aumento dessa razão pode ser entendido a partir das propriedades dos píons ( ) e káons (K). Para energias maiores, cerca de 10 TeV, o decaimento de hádrons charmosos torna-se importante como fonte de léptons atmosféricos. Investigando a parametrização dada pela equação de Gaisser para estudar separadamente a intensidade dos múons positivos e negativos, é possível chegar na equação do modelo píon-káon ( K). Utilizando este modelo, foi feito um ajuste com os dados do MINOS Near e Far Detector, encontrando os parâmetros f e fK. Esses parâmetros são as frações que contribuem para a produção de múons positivos vindos de e K, respectivamente. Os valores experimentais encontrados foram: f = 0,55 e fK = 0,70. Neste trabalho simulamos chuveiros atmosféricos com o código CORSIKA. Diferentes modelos de interações hadrônicas de altas energias foram utilizados. O objetivo foi verificar se os modelos conseguiriam reproduzir o aumento da razão da carga de múons entre GeV e TeV. Esse aumento está associado à física envolvida no decaimento dos píons e káons. Encontramos os seguintes parâmetros: f = 0,550 ± 0,006 e fK = 0,61±0,03 para o modelo QGSJET 01C, f = 0,611±0,004 e fK = 0,67±0,02 para o modelo SIBYLL, f = 0,571 ± 0,005 e fK = 0,70 ± 0,03 para o modelo VENUS, f = 0,547±0,006 e fK = 0,61±0,04 para o modelo QGSJETII e para o modelo DPMJET, f = 0,574±0,004 e fK = 0,63±0,02. O aumento da razão para os dados do experimento MINOS foi de 7,8%; para a nossa simulação o aumento foi de 3,2%; 8,3%; 5,7%; 2,4% e 2,9%; respectivamente. Com esses resultados, foi possível observar que os modelos de simulação também evidenciam um aumento significativo da razão, quando passamos da escala GeV para escala TeV. Esse aumento é caracterizado pelas propriedades dos píons e káons, constatando que essa física é considerada pelos códigos dos modelos.

La matière nucléaire classique se caractérise par des densités d'énergie de l'ordre de " = 0,17 GeV/fm3. Pour des conditions critiques en densité d'énergie 5 -10 " ou en température de 150 - 200 MeV, la chromodynamique quantique (QCD) sur réseau prédit une transition de phase entre la matière nucléaire classique et un nouvel état de la matière : le Plasma de Quarks et de Gluons (PQG) dans lequel les quarks et les gluons seraient déconfinés. Les collisions d'ions lourds ultra-relativistes permettent de créer des conditions thermodynamiques, i.e. un milieu dense et chaud, très favorable à la formation du PQG. Le LHC offre la possibilité de faire des collisions proton-proton et des collisions d'ions lourds à des énergies de plusieurs TeV par nucléon. Les énergies disponibles permettront de tester expérimentalement différents formalismes théoriques de la QCD développés afin de décrire les collisions d'ions lourds dans la limite des hautes énergies. La compréhension des conditions initiales de la collision est obligatoire afin de comprendre l'évolution du système vers un état de PQG. L'un des formalismes les plus discutés depuis ces dernières années qui décrit ces conditions initiales est le Color Glass Condensate (CGC). Il prédit la saturation de la densité partonique au sein des noyaux dans le domaine des petites valeurs de Bjorken-x correspondant à de grandes pseudorapidités. ALICE est l'une des expériences du LHC consacrée à l'étude des collisions d'ions lourds ultra-relativistes et en particulier à l'analyse des propriétés du PQG. Une des signatures possibles de la création du PQG est la suppression des taux de production des quarkonia (J/ , ) par écrantage de couleur dans un milieu déconfiné. Le spectromètre à muons de l'expérience ALICE permettra de mesurer les taux de production des quarkonia via leur canal de désintégration muonique dans un domaine de pseudorapidité -4 < < -2,5. Les effets de saturation, plus importants à grande pseudorapidité, font du spectromètre à muons d'ALICE un détecteur tout particulièrement approprié pour cette étude. La première partie de ce travail porte sur l'installation et la préparation du spectromètre à muons d'ALICE en vue des premières prises des données. Les tests de l'électronique frontale et des chambres du système de trajectographie du spectromètre à muons conduisent à la conclusion que la station 1 du spectromètre à muons est prête à enregistrer les premières données physiques. La seconde partie présente l'étude du CGC par deux voies expérimentales : la production des saveurs lourdes (charme et beauté) et la multiplicité des particules chargées. Nous montrons que l'état final de la collision est affecté par l'existence du CGC dans l'état initial. Ce travail mène à la conclusion que le LHC permettra une étude de cette nouvelle physique jamais explorée auparavant.

Reproduction de : Thèse de doctorat : Physique des particules : Lyon 1 : 2004. / Titre provenant de l'écran titre. 103 réf. bibliogr.

The Daya Bay reactor neutrino experiment aims to determine sin2 2θ13 with a sensitivity of 0.01 or better at 90% confidence level. One of the major backgrounds to neutrino measurements is the muon-induced neutrons. An ex- periment had been set up inside the Aberdeen Tunnel laboratory, Hong Kong, to study spallation neutrons induced by cosmic-ray muons in an underground environment similar to the Daya Bay experiment. The Aberdeen Tunnel laboratory is 22 m above sea level at 22:23?N and 114:6?E. The amount of overburden is approximately 235 m of rocks, which is equivalent to 611 m.w.e. Rock compositions in the Aberdeen Tunnel area is similar to that in Daya Bay. MUSIC simulation results showed that in the laboratory the mean energy of muons 〈Eμ〉= 122 GeV and the integrated muon intensity I = 9:64 X10??6 cm??2 s??1. A Bonner Spheres Neutron Spectrometer (BSS) was developed to measure the ambient neutron energy spectrum. The BSS consists of a thermal neutron detector and a set of eight polyethylene spherical shells. The overall detection efficiency of the BSS was (96:7 +3:3 ??13:1)% with a detector background rate of (1:96_0:03)_10??3 s??1. The total neutron fluence rate measured at the Surface Assembly Building (SAB) of the Daya Bay experiment was (5:20 +0:81 ??0:44) _ 10??3 cm??2 s??1, which agreed with the neutron fluence rate measured in the air/ground interface in Taiwan. The unfolded SAB neutron energy spectrum showed a clear thermal-neutron peak around 20 meV and a cascade peak around 100 MeV. Detectable number of neutrons could be seen at 1 GeV. The neutron fluence rate measured at the Aberdeen Tunnel (ABT) laboratory was significantly higher then some other underground laboratories. The unfolded ABT neutron energy spectrum showed a pronounced evaporation peak around 1 MeV, and a sup- pression in the cascade peak. Detections of muon-induced neutrons inside the Aberdeen Tunnel laboratory is achieved by a Muon Tracker and a Neutron Detector. The Muon Tracker consists of three main layers of crossed plastic scintillator hodoscopes capable of determining the incoming direction of muons. The average efficiency for most of the hodoscopes was above 95%. The Neutron Detector consists of about 760 L of gadolinium-doped liquid scintillator and sixteen photomultiplier tubes. The liquid scintillator target is shield by about 1900 L of mineral oil from external radiations. The overall average detection efficiency of muon-induced neutrons was about 16%. The measurement of muon-induced neutrons in the Aberdeen Tunnel lab- oratory started from June 2011, with a total live time of about 30 days. The average rate of the accepted muon events was 0.013 Hz. The muon-induced neutron yield was determined to be Nn = (8:5 _ 0:4(syst.) _ 1:8(stat.)) _ 10??5 neutron/(μg cm??2). This value agreed with the parametrization of FLUKA-1999 simulation results if the muon energy dependence of muon-induced neutron yields was considered. / published_or_final_version / Physics / Doctoral / Doctor of Philosophy

The muon-induced radioactive isotopes, especially neutrons, are dangerous background component for rare-event detection in underground experiments, like neutrino-less double-beta decay and dark matter search. Understanding these cosmogenic backgrounds is crucial for these experiments. An underground experiment aiming at measuring the cosmic-ray muons' flux and their neutron production yield in liquid scintillator through spallation process is being carried out in the Aberdeen Tunnel laboratory located in Hong Kong with a total vertical overburden of 235 m of rocks (611 m.w.e.). The Aberdeen Tunnel detection system is constituted of a Muon Tracker (MT) for muon tagging and a Neutron Detector (ND) for neutron detection. The MT consists of 60 plastic scintillator hodoscopes to determine the incoming muon direction and the ND is a two-zone detector containing 760 L of gadolinium-doped liquid scintillator as target volume and 1900 L of mineral oil as shields. The experiment has been taking data stably since 2012. To obtain reliable results, the detector performance and the stability of the experiment have been studied in this work. Muon-induced fast neutrons can be captured in Gd-LS with characteristic energies released and the capture time follows a characteristic exponential distribution. By using the capture time and energy information, we can select the neutron candidates and thus calculate the neutron production yield. The energy of a neutron capture event is reconstructed from the calibrated photo-multiplier tube signals, while the directions of cosmic-ray muons can be reconstructed from the MT. The mean energy of the incoming muons that pass the selection criteria was estimated by a simulation code MUSIC that transported atmospheric muon spectrum through the mountains to the laboratory, and is found to be 92 GeV. The neutron production yield is calculated to be Yn = (3:28 ±0:12(sta:) ±0:24(sys:)) X 〖10〗^(-4) (n/μ〖gcm〗^(-2)) for both the showering muon and single muon events. This result is about two times higher than the expectation value from previous simulations and experiments. The neutron production yield of the single muons is calculated to be Yn = (1:04 ± 0:08(sta:) ± 0:07(sys:)) X 〖10〗^(-4) (n/μ〖gcm〗^(-2)). This reveals a enhancement of the neutron production from the muons accompanied by showers. / published_or_final_version / Physics / Master / Master of Philosophy

published_or_final_version / Physics / Doctoral / Doctor of Philosophy

Graduate

Thesis (Ph. D.)--University of Washington, 1997. / Vita. Includes bibliographical references (p. [107]-111).

Orientador: Ernesto Kemp / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin / Made available in DSpace on 2018-08-26T09:14:52Z (GMT). No. of bitstreams: 1 Santos_LucasMendes_M.pdf: 4540067 bytes, checksum: e343af03dff0bc991b7d23f46a50a44b (MD5) Previous issue date: 2014 / Resumo: O neutrino, atualmente, é uma das partículas de maior interesse para estudo. Seu comportamento oscilatório requer que os neutrinos tenham massa, em escalas desafiadoras para uma simples acomodação com o mecanismo de Higgs possibilitado pelas simetrias eletrofracas. Do ponto de vista de detecção, sua baixa secção de choque introduz grande dificuldade no projeto de detectores eficientes. O Projeto Neutrinos-ANGRA visa, através da detecção de neutrinos, monitorar o reator ANGRA-II situado no Complexo Nuclear de Angra dos Reis - Rio de Janeiro. Para tanto, propõe utilizar um detector de radiação Cherenkov em água, instalado na superfície. Contudo, a esse nível, as taxas de ruído provenientes principalmente de raios cósmicos, são ordens de grandeza maior que a frequência efetiva da passagem do neutrino pelo material ativo. Em uma proposta para reduzir essas taxas, o alvo central será circundado com uma blindagem com elementos ativos e passivos. Nesta dissertação foi dado um enfoque especial à blindagem ativa quanto a incidência de múons, principal componente da radiação cósmica, sobre o detector. Neste estudo foram simulados 3×10^(6)múons não correlacionados temporalmente, porém obedecendo parâmetros bem estabelecidos das distribuição angular e de energia, e foi observado o comportamento da eficiência da blindagem à diferentes critérios de corte. Por fim, foram analisadas as taxas de ruídos aleatórios (não-correlacionados), fixando com uma das partículas participantes o múon. Foi possível determinar um critério de trigger para ao sistema de veto ativo (sinal > 50 fotoelétrons). Nestas condições, o sistema mostrou-se 99,73% eficiente, reduzindo a taxa de sinal:ruído, considerando a presença de pelo menos um múon, de 0,6:1 para 22:1 / Abstract: The neutrino is currently one of the particles of greatest interest to study. its oscillatory behavior requires that neutrinos have mass, in challenging scales for a simple accommodation with the Higgs mechanism enabled by the electroweak symmetry. From the viewpoint of detection, the low cross-section introduces a great distress in designing efficient detectors. The Neutrino-ANGRA Project aims, through the detection of neutrinos, monitor ANGRA-II reactor located in Angra dos Reis Nuclear Complex - Rio de Janeiro. We propose to use a detector of Cherenkov radiation in water, installed on the surface. However, at this level, rates of noise mainly from cosmic rays, are orders of magnitude greater than the effective frequency of the passage of the neutrino active material. In a bid to reduce these rates, the central target will be surrounded with a shield with active and passive elements. In this work a special focus to the active shielding as the incidence of muons, the main component of cosmic radiation on the detector, was given. This study simulated muon 3×10^(6) time-uncorrelated but obeying the well-established angular distribution and energy parameters, and the behavior of the shielding efficiency of different criteria cutting was observed. Finally, the rates of (uncorrelated) random noise, with a setting of the muon particle participants were analyzed. It was possible to derive a criterion to trigger the active veto (signal > 50 photoelectrons) system. Accordingly, the system proved to be 99.73% efficient, reducing the rate signal:noise, whereas the presence of at least one muon from 0.6: 1 to 22:1 / Mestrado / Física / Mestre em Física

The anomalous Low Energy Excess (LEE) of electron neutrinos and antineutrinos in MiniBooNE has inspired both theories and entire experiments to probe the heart of its mystery. One such experiment is MicroBooNE. This dissertation presents an important facet of its LEE investigation: how a powerful systematic can be levied on this signal through parallel study of a highly correlated channel in muon neutrinos. This constraint serves to strengthen MicroBooNE's ability to confirm or validate the cause of the LEE and will lay the groundwork for future oscillation experiments in Liquid Argon Time Projection Chamber (LArTPC) detector experiments like SBN and DUNE. In addition, this muon channel can be used to test oscillations directly, demonstrated through the world's first muon neutrino disappearance search with LArTPC data.