63 research outputs found

    Measurement of the antineutrino flux and cross section at the near detector of the T2K experiment

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    T2K (Tokai to Kamioka) is a long-baseline neutrino oscillation experiment installed in Japan. It is designed to measure neutrino flavor oscillation using an off-axis neutrino beam produced at the J-PARC accelerator facility in Tokai. In 2014 T2K has switched its beam magnet polarities to run with an antineutrino beam to enhance its sensitivity to the charge-parity violation in the leptonic sector. The beam is dominated by muon antineutrinos and contains a sizable contamination of muon neutrinos. The analysis of both neutrino and antineutrino charged-current interactions in the off-axis near detector (ND280), provides a significant reduction of the flux and cross-section modeling uncertainties on the oscillation analysis. ND280 data also gives the opportunity to measure antineutrinos cross-sections at the energy around 600 MeV. This thesis is focused on three different arguments. First the selection of charged current interactions in the off-axis near detector of muon neutrinos in the antineutrino beam is shown. In a first iteration the selected sample has been divided into two sub-sample based on the track multiplicity, then with more statistic a separation into three sub-samples based on the pion content in each event was possible. The second argument is the simultaneous measurement of the double-differential muon neutrino and antineutrino charged-current cross-section without pions in the final state at ND280. The cross-sections will be simultaneously extracted as a function of muon kinematics, allowing the evaluation of the sum, difference and asymmetry between the two cross-sections. Sum and difference can shed light on the processes involved in neutrino interactions. The asymmetry is a direct estimation on any possible bias on the charge-parity violation measurement due to cross section mismodeling. The last topic concerns the proposal of the multi-PMT technology as detector for Hyper-Kamiokande, the upgrade of Super-Kamiokande, and the intermediate water Cherenkov proposed to study the neutrino flux at about 1-2 km from the beam production point. A multi-PMT is a plastic sphere filled with 26 photomultiplier tube that could improve the reconstruction efficiency and the granularity of such Cherenkov detectors

    An analysis of feature relevance in the classification of astronomical transients with machine learning methods

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    The exploitation of present and future synoptic (multi-band and multi-epoch) surveys requires an extensive use of automatic methods for data processing and data interpretation. In this work, using data extracted from the Catalina Real Time Transient Survey (CRTS), we investigate the classification performance of some well tested methods: Random Forest, MLPQNA (Multi Layer Perceptron with Quasi Newton Algorithm) and K-Nearest Neighbors, paying special attention to the feature selection phase. In order to do so, several classification experiments were performed. Namely: identification of cataclysmic variables, separation between galactic and extra-galactic objects and identification of supernovae.Comment: Accepted by MNRAS, 11 figures, 18 page

    Switch from enzyme replacement therapy to oral chaperone migalastat for treating fabry disease: real-life data

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    The treatment options for Fabry disease (FD) are enzyme replacement therapy (ERT) with agalsidase alfa or beta, and the oral pharmacological chaperone migalastat. Since few data are available on the effects of switching from ERT to migalastat, we performed a single-center observational study on seven male Fabry patients (18-66 years) to assess the effects of the switch on renal, cardiac, and neurologic function, health status, pain, lyso-Gb3, α-Gal A activity and adverse effects. Data were retrospectively collected at time of diagnosis of FD (baseline, T0), and after 12 months of ERT (T1), and prospectively after 1 year of therapy with migalastat (T2). No patient died or reported renal, cardiac, or cerebrovascular events during the study period. The predefined measures for cardiac, renal and neurologic function, and FD-related symptoms and questionnaires were stable between baseline and the switch, and remained unchanged with migalastat. However, a significant improvement was observed in left ventricular mass index from baseline to T2 (p = 0.016), with a significative difference between the treatments (p = 0.028), and in median proteinuria from T2 vs T1 (p = 0.048). Moreover, scores of the BPI improved from baseline to T1, and remained stable with migalastat. Plasma lyso-Gb3 levels significantly decreased from baseline to T1 (P = 0.007) and T2 (P = 0.003), while did not significantly differ between the two treatments. α-Gal A activity increased from T0 to T2 (p < 0.0001). The frequency of adverse effects under migalastat and ERT was comparable (28% for both drugs). In conclusion, switching from ERT to migalastat is valid, safe and well tolerated

    Research and Development for Near Detector Systems Towards Long Term Evolution of Ultra-precise Long-baseline Neutrino Experiments

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    With the discovery of non-zero value of θ13\theta_{13} mixing angle, the next generation of long-baseline neutrino (LBN) experiments offers the possibility of obtaining statistically significant samples of muon and electron neutrinos and anti-neutrinos with large oscillation effects. In this document we intend to highlight the importance of Near Detector facilities in LBN experiments to both constrain the systematic uncertainties affecting oscillation analyses but also to perform, thanks to their close location, measurements of broad benefit for LBN physics goals. A strong European contribution to these efforts is possible

    Mesure du flux et de la section efficace des antineutrinos dans le détecteur proche de l'expérience T2K

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    T2K (Tokai to Kamioka) is a long-baseline neutrino oscillation experiment installed in Japan and designed to measure neutrino flavor oscillation using an off-axis neutrino beam produced at the J-PARC accelerator facility in Tokai. Since its discovery of electron neutrino appearance in 2013, T2K has switched its beam magnet polarities to run in antineutrino beam mode in order to enhance its sensitivity to the charge-parity violation in the leptonic sector. The beam is dominated by muon antineutrinos, but it also contains a sizable contamination from muon neutrinos. The analysis of both neutrino and antineutrino charged-current interactions in the off-axis near detector ND280, provides a significant reduction of the flux prediction and cross-section modeling systematic uncertainties in the oscillation analysis. ND280 data also gives us the opportunity to measure antineutrinos cross-sections at the energy around 600 MeV. Information on (anti)neutrino scattering is vital for the interpretation of neutrino oscillation. Many theoretical models have been developed to describe the nuclear effects in (anti)neutrino scattering, but a consistent picture has yet to emerge. In particular, various measurements of charged-current cross-section without production of pions in the final state have suggested the presence of another channel where neutrinos interact with pairs of correlated nucleons and more than one nucleon is knocked-out from the nucleus (multi-nucleon component). Various models have proposed different estimations of such process and a precise and unambiguous measurement is not yet available. This thesis work is focused on three different arguments. First the selections of CC interactions of muon neutrinos in antineutrino beam in the off-axis near detector. In a first iteration this sample has been divided into two sub-sample based on the track multiplicity, then with more statistic a separation into three sub-samples based on the pion content in each event was possible. Then on the simultaneous measurement of the double-differential muon neutrino and antineutrino charged-current cross-section without pions in the final state using the off-axis near detector. The neutrino and antineutrino cross-sections will be simultaneously extracted as a function of muon momentum and angle with a likelihood fit, including proper estimation of the correlations, allowing the evaluation of the sum, difference and asymmetry between the two cross-sections. The sum isolates the axial-vector interference term of the cross-section, and the difference enhances the sensitivity to the multinucleon component. The asymmetry is a direct estimation on any possible bias due to mismodeling of (anti)neutrino interactions on the measurement of the CP violation phase in neutrino oscillation. The last topic concerns the proposal of the multi-PMT technology as detector for Hyper-Kamiokande, the upgrade of Super-Kamiokande, and the intermediate water v Cherenkov proposed to study the neutrino flux at ~2 km from the beam production point. A multi-PMT is a plastic sphere filled with 26 photomultiplier tube that could improve the efficiency of the Cherenkov detectors foreseen in the future.T2K (Tokai to Kamioka) est une expérience d’oscillation de neutrinos muoniques sur une longue ligne de base, située au Japon. Elle est conçue pour mesurer le changement de saveur des neutrinos d’un faisceau produit à l’aide d’un accélérateur au laboratoire JPARC de Tokai. Les détecteurs proche et lointain sont placés légèrement hors axe par rapport au faisceau. Depuis la découverte en 2013 de l’apparition de neutrinos électroniques, T2K a inversé la polarité des cornes magnétiques intervenant dans la production du faisceau, afin de produire un faisceau d’antineutrinos et d’augmenter la sensibilité de l’expérience à la violation de la charge-parité dans le secteur leptonique. Le faisceau produit est alors dominé par les antineutrinos muoniques avec une composante mesurable de neutrinos muoniques. L’analyse simultanée, dans les données prises avec le faisceau de neutrinos et le faisceau d’antineutrinos, des interactions par courant chargé dans le détecteur proche ND280, permet de réduire l’impact sur les analyses d’oscillation des incertitudes liées au flux de (anti)neutrinos et à leur section efficace d’interaction. Les données de ND280 permettent également de mesurer les sections efficaces d’interaction des antineutrinos d’énergie proche de 600 MeV. La bonne connaissance du processus d’interaction des (anti)neutrinos avec les noyaux atomiques est cruciale pour interpréter les résultats de l’expérience en termes d’oscillations. De nombreux modèles théoriques ont été développés pour décrire les effets nucléaires lors des interactions des (anti)neutrinos, mais une vison globale cohérente n’a pas encore émergé. En particulier, des mesures variées de section efficace d’interaction par courant chargé sans production de pion dans l’état final suggèrent la possibilité pour les neutrinos d’interagir avec des paires de nucléons corrélés, entrainant l’éjection de plus d’un nucleon hors du noyau (composante dite “multi-nucléon”). Divers modèles ont proposé des estimations différentes de ce processus et une mesure précise et sans ambiguité n’est pas encore disponible. Ce travail de thèse se concentre sur trois études. La première détaille la sélection des interactions de neutrinos muoniques par courant chargé dans le détecteur proche hors axe. Dans un premier temps l’échantillon de données était divisé en deux selon le nombre de traces chargées de l’événement, puis l’accumulation de davantage de données a permis la séparation de l’échantillon en trois lots selon le contenu en pions de l’événement. La seconde étude consiste en la mesure simultanée de la section efficace d’interaction des neutrinos et des antineutrinos muoniques par courant chargé, conduisant à un état final sans pion mesuré dans le détecteur ND280. Ces sections efficaces sont extraites en fonction de l’impulsion et de l’angle du muon issu de l’interaction, permettant ainsi d’évaluer la somme, la différence et l’asymétrie entre les sections efficaces des neutrinos et des antineutrinos. La somme permet d’isoler la composante d’interférence vecteur-axial de la section efficace, et la différence est sensible à la composante multi-nucléons. L’asymétrie permet d’estimer directement le biais éventuel sur la mesure de la phase de violation de CP dû à la modélisation des sections efficaces, dans l’analyse d’oscillation de neutrinos. La dernière partie de la thèse étudie la proposition d’utiliser la technologie dite de multi-PMT pour le detector Hyper-Kamiokande, version à plus grande échelle de Super-Kamiokande, ainsi que la possibilité d’étudier le flux de neutrinos avec un détecteur basé sur le rayonnement Cherenkov dans l’eau, et placé à environ 2 km de l’origine du faisceau de neutrinos. Un multi-PMT est une sphère de plastique contenant 26 tubes photomultiplicateurs, qui pourrait améliorer l’efficacité des futurs détecteurs basés sur le rayonnement Cherenkov dans l’eau
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