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Radon-induced surface contaminations in neutrinoless double beta decay and dark matter experimentsPattavina, Luca 17 January 2011 (has links)
Pas de résumé en français / In experiments looking for rare events, like neutrinoless double beta decay (DBD0v) and dark matter search (DM), one of the main issues is to increase the experimental sensitivity through the material selection and production. In the specific the background contribution coming from the materials used for the detector realization has to be minimized. Moreover the net reduction of the background produced by the bulk part of the apparatus has raised concerns about the background contribution coming from the surfaces. Many procedures and techniques were developed during the last years in order to remove and to minimize the presence of possible contaminants on detector surfaces. To succeed in this strategy a big effort was put in defining all possible mechanisms that lead to surface contaminations, as well as specific cleaning procedures, which are able to reduce and control the surface radioactivity. The presence in air and gases of possible radioactive elements that can stick on the detector surfaces can lead to a recontamination process that will vanish all the applied cleaning procedures. Here is presented and analyzed the contribution to the background of rare events experiments like CUORE (DBD0v) and EDELWEISS (DM) produced by an exposure of their detector components to a big activity of 222Rn, radioactive daughter isotope from the 238U chain
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Estudo fenomenológico dos neutrinos em experimentos que utilizam fontes terrestres / Phenomenological study of neutrino experiments that use land-based sourcesTeves, Walter José da Costa 17 December 2003 (has links)
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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Development of luminescent bolometers and light detectors for neutrinoless double beta decay search / Développement de bolomètres luminescents et détecteurs de lumière pour la recherche de la double désintégration bêta sans émission de neutrinosTenconi, Margherita 28 September 2015 (has links)
L'étude de la double désintégration bêta sans neutrinos joue un rôle important dans plusieurs questions en physique des particules et cosmologie. Ce processus nucléaire hypothétique viole la conservation du nombre leptonique par deux unités et jusqu'à présent il est le seule moyen pratique pour dévoiler la nature du neutrino : sa détection implique forcement que neutrino et antineutrino sont la même particule. En outre, le taux de décroissance est sensible à la masse efficace de Majorana du neutrino, du coup à l'échelle absolue des valeurs propres de la masse et leur hiérarchie. La marque expérimentale de la DDB0ν est un pic monochromatique dans le spectre énergétique de la somme des deux électrons émis. Le but des expériences de prochaine génération est une sensibilité sur la masse efficace du neutrino de l'ordre de dizaines de meV, c'est-à-dire demi-vies de l'ordre de 10²⁷-10²⁸ années : en pratique, il s'agit de construire des sources de quelques centaines de kg d'isotope candidat, au moins, et les sonder par des détecteurs très efficients, tout en gardant le bruit de fond dans la région énergétique d'intérêt au niveau d'un coup/tonne/an. Les bolomètres luminescents sont une technique prometteuse vu leur excellentes résolutions énergétiques, haute efficacité de détection, ample choix pour les matériaux et extensibilité modulaire à grande échelle; de plus, grâce à la détection simultanée de chaleur et lumière produites par l'interaction des particules, il est possible de discriminer les contaminations α, dangereuse source de bruit aux énergies d'intérêt pour plusieurs noyaux candidats à la DDB0ν. Cette thèse a été effectuée dans le contexte de l'expérience LUMINEU : une expérience pilote qui a pour but la construction d'une expérience de prochaine génération basée sur les bolomètres scintillants en molybdate de zinc, pour l'étude de l'isotope candidat ¹⁰⁰Mo. En vue de la construction d'une expérience à grande échelle, il est nécessaire d'effectuer des caractérisations systématiques pour s'assurer des performances et de la reproductibilité des détecteurs et leurs composantes. La disponibilité d'installations expérimentales en surface, facilement accessibles, est souhaitable pour des tests routiniers : j'ai mené la plupart des expériences au CSNSM, où j'ai aussi travaillé à l'installation d'un nouvel cryostat à dilution basé sur la technologie du Pulse-Tube. Une partie de ma thèse a concerné l'étude de détecteurs bolométriques de lumière aux absorbeurs en germanium et thermomètres NTD (thermistors Neutron Transmutation Doped) : une structure standard pour LUMINEU a été établie et on a mesuré les performances des bolomètres telles que sensibilité, résolution énergétique, bruit de base et reproductibilité. Les résultats sont satisfaisants en vue d'un emploi dans une expérience avec bolomètres scintillants, bien que la configuration soit très sensible à la microphonie. En outre, j'ai testé avec succès des détecteurs bolométriques de lumière exploitants l'effet Neganov-Luke, qui augmente le rapport signal-bruit au niveau compatible avec la détection de la lumière Cherenkov pour la discrimination des événements. Une autre partie a vu la caractérisation des bolomètres scintillants en molybdate de zinc avec masse allant jusqu'à environ 300 g : couplés aux capteurs de lumière susmentionnés et lus par thermistors NTD, ils ont été refroidis en surface au CSNSM et en endroit souterrain à Modane, dans l'installation de l'expérience EDELWEISS pour la Matière Noire. Grâce à la détection simultanée de lumière et chaleur, les interactions des particules β/γ sont séparées des contaminations α. Les résultats démontrent que la caractérisation de bolomètres massifs, presque la taille cible des détecteurs finaux, est possible même en surface, en dépit du rayonnement cosmique. En outre, ces tests ont permis d'optimiser la compatibilité de l'installation de Modane avec les exigences des bolomètres scintillants pour la recherche de la DDB0ν. / Neutrinoless Double Beta Decay (0νDBD) is regarded as an important key in the decryption of some hot astroparticle and cosmological enigmas: it violates lepton number by two units and it is currently the only known practical way to shed light on the neutrino nature, being possible only in case of a Majorana neutrino, identical to its antiparticle. Moreover, the 0νDBD rate is sensitive to the effective neutrino mass, so it would be useful to define the absolute neutrino mass scale and hierarchy. The experimental footprint of 0νDBD is a monochromatic peak in the sum energy spectrum of the two emitted electrons. Next-generation experiments aim at reaching a sensitivity on the effective neutrino mass of the order of ten meV, corresponding to half lives in the range 10²⁷-10²⁸ years: this means to be able to gather, at least, a few hundred kilograms of 0νDBD candidate isotope source and to efficiently scrutinize it with very sensitive detectors. Meanwhile, background levels in the energy region of interest of the 0νDBD signal should be lowered to less than one count/ton/y. Cryogenic luminescent bolometers are a promising technique for 0νDBD search, as they feature excellent energy resolutions, high detection efficiency, flexibility in the material choice and easy scalability to large modular experiments; furthermore, the simultaneous read-out of heat and light signals produced by particle interactions provides an active discrimination method against the dangerous α contaminations, populating the 0νDBD energy region of several interesting candidate isotopes. The work presented in this dissertation was carried out in the context of the LUMINEU project: a pilot experiment focused on zinc molybdate scintillating bolometers, to define the strategies for the construction of a next-generation experiment based on the 0νDBD candidate ¹⁰⁰Mo. In view of the construction of a large 0νDBD experiment, involving hundreds of modules, systematic cryogenic measurements have to be performed to ensure good performance and reproducibility of the detectors and their components. Aboveground facilities are preferred for routinary tests because of their easier accessibility: most of the tests were carried out at CSNSM, where I also worked on the setup of a new cryogenic apparatus, based on the Pulse-Tube technology. One part of my thesis work saw the study of bolometric light detectors based on germanium absorbers and Neutron Transmutation Doped (NTD) thermometers: a proper design was developed in view of LUMINEU and the devices were characterized in terms of sensitivity, energy resolution, baseline noise and reproducibility. The results are compatible with a 0νDBD search final experiment, though this detector configuration is very sensitive to vibrational noise. In addition, the feasibility of bolometric light detectors based on NTD thermometers and Neganov-Luke amplification was investigated, demonstrating that this technique can actually boost the signal-to-noise gain to a level compatible with event discrimination based on Cherenkov light detection. Another part of my work dealt with the test of scintillating zinc molybdate bolometers of mass up to ~300 g, coupled to the aforementioned light detectors and operated both in the aboveground facilities at CSNSM and underground at Modane, in the cryostat of the EDELWEISS Dark Matter search experiment. Good event discrimination capability was achieved: thanks to double read-out of heat and light, it is possible to identify α particles, the threatening background for 0νDBD interests, against β/γ interactions. The results proved the possibility to pre-characterize aboveground detectors of mass close to the one of a final experiment module, despite the high cosmic rays rates. Besides, the measurements opened the way to the mutual compatibility of the underground setup, conceived for another kind of experiment, and LUMINEU 0νDBD search detectors.
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Desenvolvimento de metodos de medida de atividade empregando sistemas de coincidencia para radionuclideos que desintegram pela dupla emissao beta sup(-) - beta sup(+) / captura eletronica - aplicacao na padronizacao do sup(192)Ir, sup(152)Eu e sup (186) ReHILARIO, KATIA A.F. 09 October 2014 (has links)
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Desenvolvimento de metodos de medida de atividade empregando sistemas de coincidencia para radionuclideos que desintegram pela dupla emissao beta sup(-) - beta sup(+) / captura eletronica - aplicacao na padronizacao do sup(192)Ir, sup(152)Eu e sup (186) ReHILARIO, KATIA A.F. 09 October 2014 (has links)
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Estudo fenomenológico dos neutrinos em experimentos que utilizam fontes terrestres / Phenomenological study of neutrino experiments that use land-based sourcesWalter José da Costa Teves 17 December 2003 (has links)
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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Expérience SuperNEMO pour la recherche de la double désintégration bêta sans émission de neutrino : conception et réalisation du système de déclenchement du module démonstrateur / SuperNEMO experiment for the search of neutrinoless double beta decay : design and implementation of the trigger system for the demonstrator moduleOliviero, Guillaume 16 October 2018 (has links)
L’expérience SuperNEMO est conçue pour la recherche de la double désintégration bêta (ββ) sans émission de neutrinos impliquant un neutrino de Majorana (ν ≡ ν̄) massif. Le module démonstrateur de l’expérience est actuellement en cours d’installation au Laboratoire Souterrain de Modane (LSM). La technique de détection utilisée, dite tracko-calo, permet la mesure en énergie des particules traversant le détecteur ainsi qu’une reconstruction complète de leur cinématique.Cette thèse présente la conception, la simulation et l’implémentation d’un système de déclenchement de l’électronique pour le module démonstrateur de SuperNEMO. Le but de ce système est de maximiser l’efficacité de détection pour des évènements ββ ainsi que pour des évènements dits de bruits de fond issus de la radioactivité naturelle tout en réduisant le taux d’acquisition pour des évènements d’autodéclenchement des détecteurs. Un ensemble d’algorithmes de reconnaissances de traces et d’association calorimètre–trajectographe a été développé et implémenté dans les cartes électroniques après validation par des simulations Monte-Carlo. Les objectifs de performance ont été atteints en prenant en compte les différentes contraintes (physique des détecteurs, électronique, temps réel) maximisant les efficacités de détection pour des évènements d’intérêt physique. / The SuperNEMO experiment is designed for the neutrinoless double beta decay (ββ) research involving a massive Majorana neutrino (ν ≡ ν̄). The demonstrator module of the experiment is currently being installed at the Laboratoire Souterrain de Modane (LSM). The so-called tracko-calo detection technique allows the energy measurement of the particles passing through the detector and a complete reconstruction of their kinematics.This thesis presents the design, simulation and implementation of the electronics trigger system for the SuperNEMO demonstrator module. The purpose of this system is to maximize the detection efficiency for ββ events as well as for background events due to natural radioactivity while reducing the acquisition rate caused by spurious events. Pattern recognition and calorimeter-tracker association algorithms have been developed and implemented in electronic boards after validation by Monte-Carlo simulations. The performance targets have been reached, taking into account different constraints (physics of the detectors, electronics, real time) with maximized detection efficiency for events of interest.
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Predictions of Effective Models in Neutrino PhysicsBergström, Johannes January 2011 (has links)
Experiments on neutrino oscillations have confirmed that neutrinos have small, but non-zero masses, and that the interacting neutrino states do not have definite masses, but are mixtures of such states.The seesaw models make up a group of popular models describing the small neutrino masses and the corresponding mixing.In these models, new, heavy fields are introduced and the neutrino masses are suppressed by the ratio between the electroweak scale and the large masses of the new fields. Usually, the new fields introduced have masses far above the electroweak scale, outside the reach of any foreseeable experiments, making these versions of seesaw models essentially untestable. However, there are also so-called low-scale seesaw models, where the new particles have masses above the electroweak scale, but within the reach of future experiments, such as the LHC.In quantum field theories, quantum corrections generally introduce an energy-scale dependence on all their parameters, described by the renormalization group equations. In this thesis, the energy-scale dependence of the neutrino parameters in two low-scale seesaw models, the low-scale type I and inverse seesaw models, are considered. Also, the question of whether the neutrinos are Majorana particles, \ie , their own antiparticles, has not been decided experimentally. Future experiments on neutrinoless double beta decay could confirm the Majorana nature of neutrinos. However, there could also be additional contributions to the decay, which are not directly related to neutrino masses. We have investigated the possible future bounds on the strength of such additional contributions to neutrinoless double beta decay, depending on the outcome of ongoing and planned experiments related to neutrino masses. / QC 20110812
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Models in Neutrino Physics : Numerical and Statistical StudiesBergström, Johannes January 2013 (has links)
The standard model of particle physics can excellently describe the vast majorityof data of particle physics experiments. However, in its simplest form, it cannot account for the fact that the neutrinos are massive particles and lepton flavorsmixed, as required by the observation of neutrino oscillations. Hence, the standardmodel must be extended in order to account for these observations, opening up thepossibility to explore new and interesting physical phenomena. There are numerous models proposed to accommodate massive neutrinos. Thesimplest of these are able to describe the observations using only a small numberof effective parameters. Furthermore, neutrinos are the only known existing particleswhich have the potential of being their own antiparticles, a possibility that isactively being investigated through experiments on neutrinoless double beta decay.In this thesis, we analyse these simple models using Bayesian inference and constraintsfrom neutrino-related experiments, and we also investigate the potential offuture experiments on neutrinoless double beta decay to probe other kinds of newphysics. In addition, more elaborate theoretical models of neutrino masses have beenproposed, with the seesaw models being a particularly popular group of models inwhich new heavy particles generate neutrino masses. We study low-scale seesawmodels, in particular the resulting energy-scale dependence of the neutrino parameters,which incorporate new particles with masses within the reach of current andfuture experiments, such as the LHC. / Standardmodellen för partikelfysik beskriver den stora majoriteten data från partikelfysikexperimentutmärkt. Den kan emellertid inte i sin enklaste form beskrivadet faktum att neutriner är massiva partiklar och leptonsmakerna är blandande,vilket krävs enligt observationerna av neutrinooscillationer. Därför måste standardmodellenutökas för att ta hänsyn till detta, vilket öppnar upp möjligheten att utforska nya och intressanta fysikaliska fenomen. Det finns många föreslagna modeller för massiva neutriner. De enklaste av dessakan beskriva observationerna med endast ett fåtal effektiva parametrar. Dessutom är neutriner de enda kända befintliga partiklar som har potentialen att vara sinaegna antipartiklar, en möjlighet som aktivt undersöks genom experiment på neutrinolöst dubbelt betasönderfall. I denna avhandling analyserar vi dessa enkla modellermed Bayesisk inferens och begränsningar från neutrinorelaterade experiment och undersöker även potentialen för framtida experiment på neutrinolöst dubbelt betasönderfall att bergänsa andra typer av ny fysik. Även mer avancerade teoretiska modeller för neutrinomassor har föreslagits, med seesawmodeller som en särskilt populär grupp av modeller där nya tunga partiklargenererar neutrinomassor. Vi studerar seesawmodeller vid låga energier, i synnerhetneutrinoparametrarnas resulterande energiberoende, vilka inkluderar nya partiklarmed massor inom räckh°all för nuvarande och framtida experiment såsom LHC. / <p>QC 20130830</p>
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